utilities.ts

import {
    __String,
    AccessExpression,
    AccessorDeclaration,
    addEmitFlags,
    addRange,
    affectsDeclarationPathOptionDeclarations,
    affectsEmitOptionDeclarations,
    AllAccessorDeclarations,
    AmbientModuleDeclaration,
    AmpersandAmpersandEqualsToken,
    AnyImportOrBareOrAccessedRequire,
    AnyImportOrReExport,
    type AnyImportOrRequireStatement,
    AnyImportSyntax,
    AnyValidImportOrReExport,
    append,
    arrayFrom,
    ArrayLiteralExpression,
    ArrayTypeNode,
    ArrowFunction,
    AsExpression,
    AssertionExpression,
    assertType,
    AssignmentDeclarationKind,
    AssignmentExpression,
    AssignmentOperatorToken,
    BarBarEqualsToken,
    BinaryExpression,
    binarySearch,
    BindableObjectDefinePropertyCall,
    BindableStaticAccessExpression,
    BindableStaticElementAccessExpression,
    BindableStaticNameExpression,
    BindingElement,
    BindingElementOfBareOrAccessedRequire,
    Block,
    CallExpression,
    CallLikeExpression,
    CallSignatureDeclaration,
    canHaveDecorators,
    canHaveLocals,
    canHaveModifiers,
    CanHaveModuleSpecifier,
    CanonicalDiagnostic,
    CaseBlock,
    CaseClause,
    CaseOrDefaultClause,
    CatchClause,
    changeAnyExtension,
    CharacterCodes,
    CheckFlags,
    ClassDeclaration,
    ClassElement,
    ClassExpression,
    classHasDeclaredOrExplicitlyAssignedName,
    ClassLikeDeclaration,
    ClassStaticBlockDeclaration,
    combinePaths,
    CommaListExpression,
    CommandLineOption,
    CommentDirective,
    CommentDirectivesMap,
    CommentDirectiveType,
    CommentRange,
    comparePaths,
    compareStringsCaseSensitive,
    compareValues,
    Comparison,
    CompilerOptions,
    CompilerOptionsValue,
    ComputedPropertyName,
    computeLineAndCharacterOfPosition,
    computeLineOfPosition,
    computeLineStarts,
    concatenate,
    ConditionalExpression,
    ConstructorDeclaration,
    ConstructSignatureDeclaration,
    ContainerFlags,
    contains,
    containsPath,
    createGetCanonicalFileName,
    createMultiMap,
    createScanner,
    createTextSpan,
    createTextSpanFromBounds,
    Debug,
    Declaration,
    DeclarationName,
    DeclarationWithTypeParameterChildren,
    DeclarationWithTypeParameters,
    Decorator,
    DefaultClause,
    DestructuringAssignment,
    Diagnostic,
    DiagnosticArguments,
    DiagnosticCollection,
    DiagnosticMessage,
    DiagnosticMessageChain,
    DiagnosticRelatedInformation,
    Diagnostics,
    DiagnosticWithDetachedLocation,
    DiagnosticWithLocation,
    directorySeparator,
    DoStatement,
    DynamicNamedBinaryExpression,
    DynamicNamedDeclaration,
    ElementAccessExpression,
    EmitFlags,
    EmitHost,
    EmitResolver,
    EmitTextWriter,
    emptyArray,
    endsWith,
    ensurePathIsNonModuleName,
    ensureTrailingDirectorySeparator,
    EntityName,
    EntityNameExpression,
    EntityNameOrEntityNameExpression,
    EnumDeclaration,
    EqualityComparer,
    equalOwnProperties,
    EqualsToken,
    equateValues,
    escapeLeadingUnderscores,
    EvaluationResolver,
    EvaluatorResult,
    every,
    ExportAssignment,
    ExportDeclaration,
    ExportSpecifier,
    Expression,
    ExpressionStatement,
    ExpressionWithTypeArguments,
    Extension,
    ExternalModuleReference,
    factory,
    FileExtensionInfo,
    fileExtensionIs,
    fileExtensionIsOneOf,
    FileReference,
    FileWatcher,
    filter,
    find,
    findAncestor,
    findBestPatternMatch,
    findIndex,
    findLast,
    firstDefined,
    firstOrUndefined,
    flatMap,
    flatMapToMutable,
    flatten,
    forEach,
    forEachChild,
    forEachChildRecursively,
    ForInOrOfStatement,
    ForInStatement,
    ForOfStatement,
    ForStatement,
    FunctionBody,
    FunctionDeclaration,
    FunctionExpression,
    FunctionLikeDeclaration,
    GetAccessorDeclaration,
    getAllJSDocTags,
    getBaseFileName,
    GetCanonicalFileName,
    getCombinedModifierFlags,
    getCombinedNodeFlags,
    getCommonSourceDirectory,
    getContainerFlags,
    getDirectoryPath,
    getImpliedNodeFormatForEmitWorker,
    getJSDocAugmentsTag,
    getJSDocDeprecatedTagNoCache,
    getJSDocImplementsTags,
    getJSDocOverrideTagNoCache,
    getJSDocParameterTags,
    getJSDocParameterTagsNoCache,
    getJSDocPrivateTagNoCache,
    getJSDocProtectedTagNoCache,
    getJSDocPublicTagNoCache,
    getJSDocReadonlyTagNoCache,
    getJSDocReturnType,
    getJSDocSatisfiesTag,
    getJSDocTags,
    getJSDocType,
    getJSDocTypeParameterTags,
    getJSDocTypeParameterTagsNoCache,
    getJSDocTypeTag,
    getLeadingCommentRanges,
    getLineAndCharacterOfPosition,
    getLinesBetweenPositions,
    getLineStarts,
    getModeForUsageLocation,
    getNameOfDeclaration,
    getNodeChildren,
    getNormalizedAbsolutePath,
    getNormalizedPathComponents,
    getOwnKeys,
    getParseTreeNode,
    getPathComponents,
    getPathFromPathComponents,
    getRelativePathFromDirectory,
    getRelativePathToDirectoryOrUrl,
    getResolutionModeOverride,
    getRootLength,
    getSnippetElement,
    getStringComparer,
    getSymbolId,
    getTrailingCommentRanges,
    HasExpressionInitializer,
    hasExtension,
    HasFlowNode,
    HasInferredType,
    HasInitializer,
    hasInitializer,
    HasJSDoc,
    hasJSDocNodes,
    HasModifiers,
    hasProperty,
    HasType,
    HasTypeArguments,
    HeritageClause,
    Identifier,
    identifierToKeywordKind,
    IdentifierTypePredicate,
    identity,
    idText,
    IfStatement,
    ignoredPaths,
    ImportAttribute,
    ImportCall,
    ImportClause,
    ImportDeclaration,
    ImportEqualsDeclaration,
    ImportMetaProperty,
    ImportSpecifier,
    ImportTypeNode,
    IndexInfo,
    indexOfAnyCharCode,
    IndexSignatureDeclaration,
    InferTypeNode,
    InitializedVariableDeclaration,
    insertSorted,
    InstanceofExpression,
    InterfaceDeclaration,
    InternalEmitFlags,
    InternalSymbolName,
    IntroducesNewScopeNode,
    isAccessor,
    isAnyDirectorySeparator,
    isArray,
    isArrayLiteralExpression,
    isArrowFunction,
    isAssertionExpression,
    isAutoAccessorPropertyDeclaration,
    isBigIntLiteral,
    isBinaryExpression,
    isBindingElement,
    isBindingPattern,
    isBlock,
    isCallExpression,
    isCaseClause,
    isClassDeclaration,
    isClassElement,
    isClassExpression,
    isClassLike,
    isClassStaticBlockDeclaration,
    isCommaListExpression,
    isComputedPropertyName,
    isConstructorDeclaration,
    isConstTypeReference,
    isDeclaration,
    isDeclarationFileName,
    isDecorator,
    isDefaultClause,
    isElementAccessExpression,
    isEnumDeclaration,
    isEnumMember,
    isExportAssignment,
    isExportDeclaration,
    isExpressionStatement,
    isExpressionWithTypeArguments,
    isExternalModule,
    isExternalModuleReference,
    isFileProbablyExternalModule,
    isForStatement,
    isFunctionDeclaration,
    isFunctionExpression,
    isFunctionLike,
    isFunctionLikeDeclaration,
    isFunctionLikeOrClassStaticBlockDeclaration,
    isGetAccessorDeclaration,
    isHeritageClause,
    isIdentifier,
    isIdentifierStart,
    isIdentifierText,
    isImportDeclaration,
    isImportTypeNode,
    isInterfaceDeclaration,
    isJSDoc,
    isJSDocAugmentsTag,
    isJSDocFunctionType,
    isJSDocImplementsTag,
    isJSDocImportTag,
    isJSDocLinkLike,
    isJSDocMemberName,
    isJSDocNameReference,
    isJSDocNode,
    isJSDocOverloadTag,
    isJSDocParameterTag,
    isJSDocPropertyLikeTag,
    isJSDocReturnTag,
    isJSDocSatisfiesTag,
    isJSDocSignature,
    isJSDocTag,
    isJSDocTemplateTag,
    isJSDocTypeExpression,
    isJSDocTypeLiteral,
    isJSDocTypeTag,
    isJsxChild,
    isJsxFragment,
    isJsxNamespacedName,
    isJsxOpeningLikeElement,
    isJsxText,
    isLeftHandSideExpression,
    isLineBreak,
    isLiteralTypeNode,
    isMappedTypeNode,
    isMemberName,
    isMetaProperty,
    isMethodDeclaration,
    isMethodOrAccessor,
    isModifierLike,
    isModuleBlock,
    isModuleDeclaration,
    isModuleOrEnumDeclaration,
    isNamedDeclaration,
    isNamespaceExport,
    isNamespaceExportDeclaration,
    isNamespaceImport,
    isNonNullExpression,
    isNoSubstitutionTemplateLiteral,
    isNullishCoalesce,
    isNumericLiteral,
    isObjectBindingPattern,
    isObjectLiteralExpression,
    isOmittedExpression,
    isOptionalChain,
    isParameter,
    isParameterPropertyDeclaration,
    isParenthesizedExpression,
    isParenthesizedTypeNode,
    isPrefixUnaryExpression,
    isPrivateIdentifier,
    isPropertyAccessExpression,
    isPropertyAssignment,
    isPropertyDeclaration,
    isPropertyName,
    isPropertySignature,
    isQualifiedName,
    isRootedDiskPath,
    isSetAccessorDeclaration,
    isShiftOperatorOrHigher,
    isShorthandPropertyAssignment,
    isSourceFile,
    isString,
    isStringLiteral,
    isStringLiteralLike,
    isTypeAliasDeclaration,
    isTypeElement,
    isTypeLiteralNode,
    isTypeNode,
    isTypeParameterDeclaration,
    isTypeQueryNode,
    isTypeReferenceNode,
    isVariableDeclaration,
    isVariableStatement,
    isVoidExpression,
    isWhiteSpaceLike,
    isWhiteSpaceSingleLine,
    JSDoc,
    JSDocArray,
    JSDocCallbackTag,
    JSDocEnumTag,
    JSDocImportTag,
    JSDocMemberName,
    JSDocOverloadTag,
    JSDocParameterTag,
    JSDocSatisfiesExpression,
    JSDocSatisfiesTag,
    JSDocSignature,
    JSDocTag,
    JSDocTemplateTag,
    JSDocTypedefTag,
    JsonSourceFile,
    JsxAttributeName,
    JsxChild,
    JsxElement,
    JsxEmit,
    JsxFragment,
    JsxNamespacedName,
    JsxOpeningElement,
    JsxOpeningLikeElement,
    JsxSelfClosingElement,
    JsxTagNameExpression,
    KeywordSyntaxKind,
    LabeledStatement,
    LanguageVariant,
    last,
    lastOrUndefined,
    LateVisibilityPaintedStatement,
    length,
    libMap,
    LiteralImportTypeNode,
    LiteralLikeElementAccessExpression,
    LiteralLikeNode,
    LogicalOperator,
    LogicalOrCoalescingAssignmentOperator,
    mangleScopedPackageName,
    map,
    mapDefined,
    MapLike,
    MemberName,
    memoize,
    MetaProperty,
    MethodDeclaration,
    MethodSignature,
    ModeAwareCache,
    ModifierFlags,
    ModifierLike,
    ModuleBlock,
    ModuleDeclaration,
    ModuleDetectionKind,
    ModuleExportName,
    ModuleKind,
    ModuleResolutionKind,
    moduleResolutionOptionDeclarations,
    MultiMap,
    NamedDeclaration,
    NamedExports,
    NamedImports,
    NamedImportsOrExports,
    NamespaceExport,
    NamespaceImport,
    NewExpression,
    NewLineKind,
    Node,
    NodeArray,
    NodeFlags,
    nodeModulesPathPart,
    NonNullExpression,
    noop,
    normalizePath,
    NoSubstitutionTemplateLiteral,
    NumberLiteralType,
    NumericLiteral,
    ObjectFlags,
    ObjectFlagsType,
    ObjectLiteralElement,
    ObjectLiteralExpression,
    ObjectLiteralExpressionBase,
    ObjectTypeDeclaration,
    optionsAffectingProgramStructure,
    or,
    OuterExpressionKinds,
    PackageId,
    ParameterDeclaration,
    ParenthesizedExpression,
    ParenthesizedTypeNode,
    parseConfigFileTextToJson,
    PartiallyEmittedExpression,
    Path,
    pathIsRelative,
    Pattern,
    PostfixUnaryExpression,
    PrefixUnaryExpression,
    PrimitiveLiteral,
    PrinterOptions,
    PrintHandlers,
    PrivateIdentifier,
    ProjectReference,
    PrologueDirective,
    PropertyAccessEntityNameExpression,
    PropertyAccessExpression,
    PropertyAssignment,
    PropertyDeclaration,
    PropertyName,
    PropertyNameLiteral,
    PropertySignature,
    PseudoBigInt,
    PunctuationOrKeywordSyntaxKind,
    PunctuationSyntaxKind,
    QualifiedName,
    QuestionQuestionEqualsToken,
    ReadonlyCollection,
    ReadonlyTextRange,
    removeTrailingDirectorySeparator,
    RequireOrImportCall,
    RequireVariableStatement,
    ResolutionMode,
    ResolvedModuleFull,
    ResolvedModuleWithFailedLookupLocations,
    ResolvedProjectReference,
    ResolvedTypeReferenceDirective,
    ResolvedTypeReferenceDirectiveWithFailedLookupLocations,
    resolvePath,
    returnFalse,
    ReturnStatement,
    returnUndefined,
    SatisfiesExpression,
    ScriptKind,
    ScriptTarget,
    semanticDiagnosticsOptionDeclarations,
    SetAccessorDeclaration,
    setOriginalNode,
    setTextRange,
    ShorthandPropertyAssignment,
    shouldAllowImportingTsExtension,
    Signature,
    SignatureDeclaration,
    SignatureFlags,
    singleElementArray,
    singleOrUndefined,
    skipOuterExpressions,
    skipTrivia,
    SnippetKind,
    some,
    SortedArray,
    SourceFile,
    SourceFileLike,
    SourceFileMayBeEmittedHost,
    SourceMapSource,
    startsWith,
    startsWithUseStrict,
    Statement,
    StringLiteral,
    StringLiteralLike,
    StringLiteralType,
    stringToToken,
    SuperCall,
    SuperProperty,
    SwitchStatement,
    Symbol,
    SymbolFlags,
    SymbolTable,
    SyntaxKind,
    TaggedTemplateExpression,
    targetOptionDeclaration,
    TemplateExpression,
    TemplateLiteral,
    TemplateLiteralLikeNode,
    TemplateLiteralToken,
    TemplateLiteralTypeSpan,
    TemplateSpan,
    TextRange,
    TextSpan,
    ThisTypePredicate,
    toFileNameLowerCase,
    Token,
    TokenFlags,
    tokenToString,
    toPath,
    toSorted,
    tracing,
    TransformFlags,
    TransientSymbol,
    TriviaSyntaxKind,
    tryCast,
    tryRemovePrefix,
    TryStatement,
    TsConfigSourceFile,
    TupleTypeNode,
    Type,
    TypeAliasDeclaration,
    TypeAssertion,
    TypeChecker,
    TypeCheckerHost,
    TypeElement,
    TypeFlags,
    TypeLiteralNode,
    TypeNode,
    TypeNodeSyntaxKind,
    TypeParameter,
    TypeParameterDeclaration,
    TypePredicate,
    TypePredicateKind,
    TypeReferenceNode,
    unescapeLeadingUnderscores,
    UnionOrIntersectionTypeNode,
    UniqueESSymbolType,
    UserPreferences,
    ValidImportTypeNode,
    VariableDeclaration,
    VariableDeclarationInitializedTo,
    VariableDeclarationList,
    VariableLikeDeclaration,
    VariableStatement,
    visitEachChild,
    WhileStatement,
    WithStatement,
    WrappedExpression,
    WriteFileCallback,
    WriteFileCallbackData,
    YieldExpression,
} from "./_namespaces/ts.js";

/** @internal */
export const resolvingEmptyArray: never[] = [];

/** @internal */
export const externalHelpersModuleNameText = "tslib";

/** @internal */
export const defaultMaximumTruncationLength = 160;
/** @internal */
export const noTruncationMaximumTruncationLength = 1_000_000;
/** @internal */
export const defaultHoverMaximumTruncationLength = 500;

/** @internal */
export function getDeclarationOfKind<T extends Declaration>(symbol: Symbol, kind: T["kind"]): T | undefined {
    const declarations = symbol.declarations;
    if (declarations) {
        for (const declaration of declarations) {
            if (declaration.kind === kind) {
                return declaration as T;
            }
        }
    }

    return undefined;
}

/** @internal */
export function getDeclarationsOfKind<T extends Declaration>(symbol: Symbol, kind: T["kind"]): T[] {
    return filter(symbol.declarations || emptyArray, d => d.kind === kind) as T[];
}

/** @internal */
export function createSymbolTable(symbols?: readonly Symbol[]): SymbolTable {
    const result = new Map<__String, Symbol>();
    if (symbols) {
        for (const symbol of symbols) {
            result.set(symbol.escapedName, symbol);
        }
    }
    return result;
}

/** @internal */
export function isTransientSymbol(symbol: Symbol): symbol is TransientSymbol {
    return (symbol.flags & SymbolFlags.Transient) !== 0;
}

/**
 * True if the symbol is for an external module, as opposed to a namespace.
 *
 * @internal
 */
export function isExternalModuleSymbol(moduleSymbol: Symbol): boolean {
    return !!(moduleSymbol.flags & SymbolFlags.Module) && (moduleSymbol.escapedName as string).charCodeAt(0) === CharacterCodes.doubleQuote;
}

const stringWriter = createSingleLineStringWriter();

function createSingleLineStringWriter(): EmitTextWriter {
    // Why var? It avoids TDZ checks in the runtime which can be costly.
    // See: https://github.com/microsoft/TypeScript/issues/52924
    /* eslint-disable no-var */
    var str = "";
    /* eslint-enable no-var */
    const writeText: (text: string) => void = text => str += text;
    return {
        getText: () => str,
        write: writeText,
        rawWrite: writeText,
        writeKeyword: writeText,
        writeOperator: writeText,
        writePunctuation: writeText,
        writeSpace: writeText,
        writeStringLiteral: writeText,
        writeLiteral: writeText,
        writeParameter: writeText,
        writeProperty: writeText,
        writeSymbol: (s, _) => writeText(s),
        writeTrailingSemicolon: writeText,
        writeComment: writeText,
        getTextPos: () => str.length,
        getLine: () => 0,
        getColumn: () => 0,
        getIndent: () => 0,
        isAtStartOfLine: () => false,
        hasTrailingComment: () => false,
        hasTrailingWhitespace: () => !!str.length && isWhiteSpaceLike(str.charCodeAt(str.length - 1)),

        // Completely ignore indentation for string writers.  And map newlines to
        // a single space.
        writeLine: () => str += " ",
        increaseIndent: noop,
        decreaseIndent: noop,
        clear: () => str = "",
    };
}

/** @internal */
export function changesAffectModuleResolution(oldOptions: CompilerOptions, newOptions: CompilerOptions): boolean {
    return oldOptions.configFilePath !== newOptions.configFilePath ||
        optionsHaveModuleResolutionChanges(oldOptions, newOptions);
}

function optionsHaveModuleResolutionChanges(oldOptions: CompilerOptions, newOptions: CompilerOptions) {
    return optionsHaveChanges(oldOptions, newOptions, moduleResolutionOptionDeclarations);
}

/** @internal */
export function changesAffectingProgramStructure(oldOptions: CompilerOptions, newOptions: CompilerOptions): boolean {
    return optionsHaveChanges(oldOptions, newOptions, optionsAffectingProgramStructure);
}

/** @internal */
export function optionsHaveChanges(oldOptions: CompilerOptions, newOptions: CompilerOptions, optionDeclarations: readonly CommandLineOption[]): boolean {
    return oldOptions !== newOptions && optionDeclarations.some(o => !isJsonEqual(getCompilerOptionValue(oldOptions, o), getCompilerOptionValue(newOptions, o)));
}

/** @internal */
export function forEachAncestor<T>(node: Node, callback: (n: Node) => T | undefined | "quit"): T | undefined {
    while (true) {
        const res = callback(node);
        if (res === "quit") return undefined;
        if (res !== undefined) return res;
        if (isSourceFile(node)) return undefined;
        node = node.parent;
    }
}

/**
 * Calls `callback` for each entry in the map, returning the first truthy result.
 * Use `map.forEach` instead for normal iteration.
 *
 * @internal
 */
export function forEachEntry<K, V, U>(map: ReadonlyMap<K, V>, callback: (value: V, key: K) => U | undefined): U | undefined {
    const iterator = map.entries();
    for (const [key, value] of iterator) {
        const result = callback(value, key);
        if (result) {
            return result;
        }
    }
    return undefined;
}

/**
 * `forEachEntry` for just keys.
 *
 * @internal
 */
export function forEachKey<K, T>(map: ReadonlyCollection<K>, callback: (key: K) => T | undefined): T | undefined {
    const iterator = map.keys();
    for (const key of iterator) {
        const result = callback(key);
        if (result) {
            return result;
        }
    }
    return undefined;
}

/**
 * Copy entries from `source` to `target`.
 *
 * @internal
 */
export function copyEntries<K, V>(source: ReadonlyMap<K, V>, target: Map<K, V>): void {
    source.forEach((value, key) => {
        target.set(key, value);
    });
}

/** @internal */
export function usingSingleLineStringWriter(action: (writer: EmitTextWriter) => void): string {
    const oldString = stringWriter.getText();
    try {
        action(stringWriter);
        return stringWriter.getText();
    }
    finally {
        stringWriter.clear();
        stringWriter.writeKeyword(oldString);
    }
}

/** @internal */
export function getFullWidth(node: Node): number {
    return node.end - node.pos;
}

/** @internal */
export function projectReferenceIsEqualTo(oldRef: ProjectReference, newRef: ProjectReference): boolean {
    return oldRef.path === newRef.path &&
        !oldRef.prepend === !newRef.prepend &&
        !oldRef.circular === !newRef.circular;
}

/** @internal */
export function moduleResolutionIsEqualTo(oldResolution: ResolvedModuleWithFailedLookupLocations, newResolution: ResolvedModuleWithFailedLookupLocations): boolean {
    return oldResolution === newResolution ||
        oldResolution.resolvedModule === newResolution.resolvedModule ||
        !!oldResolution.resolvedModule &&
            !!newResolution.resolvedModule &&
            oldResolution.resolvedModule.isExternalLibraryImport === newResolution.resolvedModule.isExternalLibraryImport &&
            oldResolution.resolvedModule.extension === newResolution.resolvedModule.extension &&
            oldResolution.resolvedModule.resolvedFileName === newResolution.resolvedModule.resolvedFileName &&
            oldResolution.resolvedModule.originalPath === newResolution.resolvedModule.originalPath &&
            packageIdIsEqual(oldResolution.resolvedModule.packageId, newResolution.resolvedModule.packageId) &&
            oldResolution.alternateResult === newResolution.alternateResult;
}

/** @internal */
export function getResolvedModuleFromResolution(resolution: ResolvedModuleWithFailedLookupLocations): ResolvedModuleFull | undefined {
    return resolution.resolvedModule;
}

/** @internal */
export function getResolvedTypeReferenceDirectiveFromResolution(resolution: ResolvedTypeReferenceDirectiveWithFailedLookupLocations): ResolvedTypeReferenceDirective | undefined {
    return resolution.resolvedTypeReferenceDirective;
}

/** @internal */
export function createModuleNotFoundChain(sourceFile: SourceFile, host: TypeCheckerHost, moduleReference: string, mode: ResolutionMode, packageName: string): DiagnosticMessageChain {
    const alternateResult = host.getResolvedModule(sourceFile, moduleReference, mode)?.alternateResult;
    const alternateResultMessage = alternateResult && (getEmitModuleResolutionKind(host.getCompilerOptions()) === ModuleResolutionKind.Node10
        ? [Diagnostics.There_are_types_at_0_but_this_result_could_not_be_resolved_under_your_current_moduleResolution_setting_Consider_updating_to_node16_nodenext_or_bundler, [alternateResult]] as const
        : [
            Diagnostics.There_are_types_at_0_but_this_result_could_not_be_resolved_when_respecting_package_json_exports_The_1_library_may_need_to_update_its_package_json_or_typings,
            [alternateResult, alternateResult.includes(nodeModulesPathPart + "@types/") ? `@types/${mangleScopedPackageName(packageName)}` : packageName],
        ] as const);
    const result = alternateResultMessage
        ? chainDiagnosticMessages(
            /*details*/ undefined,
            alternateResultMessage[0],
            ...alternateResultMessage[1],
        )
        : host.typesPackageExists(packageName)
        ? chainDiagnosticMessages(
            /*details*/ undefined,
            Diagnostics.If_the_0_package_actually_exposes_this_module_consider_sending_a_pull_request_to_amend_https_Colon_Slash_Slashgithub_com_SlashDefinitelyTyped_SlashDefinitelyTyped_Slashtree_Slashmaster_Slashtypes_Slash_1,
            packageName,
            mangleScopedPackageName(packageName),
        )
        : host.packageBundlesTypes(packageName)
        ? chainDiagnosticMessages(
            /*details*/ undefined,
            Diagnostics.If_the_0_package_actually_exposes_this_module_try_adding_a_new_declaration_d_ts_file_containing_declare_module_1,
            packageName,
            moduleReference,
        )
        : chainDiagnosticMessages(
            /*details*/ undefined,
            Diagnostics.Try_npm_i_save_dev_types_Slash_1_if_it_exists_or_add_a_new_declaration_d_ts_file_containing_declare_module_0,
            moduleReference,
            mangleScopedPackageName(packageName),
        );
    if (result) result.repopulateInfo = () => ({ moduleReference, mode, packageName: packageName === moduleReference ? undefined : packageName });
    return result;
}

/** @internal */
export function createModeMismatchDetails(currentSourceFile: SourceFile): DiagnosticMessageChain {
    const ext = tryGetExtensionFromPath(currentSourceFile.fileName);
    const scope = currentSourceFile.packageJsonScope;
    const targetExt = ext === Extension.Ts ? Extension.Mts : ext === Extension.Js ? Extension.Mjs : undefined;
    const result = scope && !scope.contents.packageJsonContent.type ?
        targetExt ?
            chainDiagnosticMessages(
                /*details*/ undefined,
                Diagnostics.To_convert_this_file_to_an_ECMAScript_module_change_its_file_extension_to_0_or_add_the_field_type_Colon_module_to_1,
                targetExt,
                combinePaths(scope.packageDirectory, "package.json"),
            ) :
            chainDiagnosticMessages(
                /*details*/ undefined,
                Diagnostics.To_convert_this_file_to_an_ECMAScript_module_add_the_field_type_Colon_module_to_0,
                combinePaths(scope.packageDirectory, "package.json"),
            ) :
        targetExt ?
        chainDiagnosticMessages(
            /*details*/ undefined,
            Diagnostics.To_convert_this_file_to_an_ECMAScript_module_change_its_file_extension_to_0_or_create_a_local_package_json_file_with_type_Colon_module,
            targetExt,
        ) :
        chainDiagnosticMessages(
            /*details*/ undefined,
            Diagnostics.To_convert_this_file_to_an_ECMAScript_module_create_a_local_package_json_file_with_type_Colon_module,
        );
    result.repopulateInfo = () => true;
    return result;
}

function packageIdIsEqual(a: PackageId | undefined, b: PackageId | undefined): boolean {
    return a === b || !!a && !!b && a.name === b.name && a.subModuleName === b.subModuleName && a.version === b.version && a.peerDependencies === b.peerDependencies;
}

/** @internal */
export function packageIdToPackageName({ name, subModuleName }: PackageId): string {
    return subModuleName ? `${name}/${subModuleName}` : name;
}

/** @internal */
export function packageIdToString(packageId: PackageId): string {
    return `${packageIdToPackageName(packageId)}@${packageId.version}${packageId.peerDependencies ?? ""}`;
}

/** @internal */
export function typeDirectiveIsEqualTo(oldResolution: ResolvedTypeReferenceDirectiveWithFailedLookupLocations, newResolution: ResolvedTypeReferenceDirectiveWithFailedLookupLocations): boolean {
    return oldResolution === newResolution ||
        oldResolution.resolvedTypeReferenceDirective === newResolution.resolvedTypeReferenceDirective ||
        !!oldResolution.resolvedTypeReferenceDirective &&
            !!newResolution.resolvedTypeReferenceDirective &&
            oldResolution.resolvedTypeReferenceDirective.resolvedFileName === newResolution.resolvedTypeReferenceDirective.resolvedFileName &&
            !!oldResolution.resolvedTypeReferenceDirective.primary === !!newResolution.resolvedTypeReferenceDirective.primary &&
            oldResolution.resolvedTypeReferenceDirective.originalPath === newResolution.resolvedTypeReferenceDirective.originalPath;
}

/** @internal */
export function hasChangesInResolutions<K, V>(
    names: readonly K[],
    newResolutions: readonly V[],
    getOldResolution: (name: K) => V | undefined,
    comparer: (oldResolution: V, newResolution: V) => boolean,
): boolean {
    Debug.assert(names.length === newResolutions.length);

    for (let i = 0; i < names.length; i++) {
        const newResolution = newResolutions[i];
        const entry = names[i];
        const oldResolution = getOldResolution(entry);
        const changed = oldResolution
            ? !newResolution || !comparer(oldResolution, newResolution)
            : newResolution;
        if (changed) {
            return true;
        }
    }
    return false;
}

// Returns true if this node contains a parse error anywhere underneath it.
/** @internal */
export function containsParseError(node: Node): boolean {
    aggregateChildData(node);
    return (node.flags & NodeFlags.ThisNodeOrAnySubNodesHasError) !== 0;
}

function aggregateChildData(node: Node): void {
    if (!(node.flags & NodeFlags.HasAggregatedChildData)) {
        // A node is considered to contain a parse error if:
        //  a) the parser explicitly marked that it had an error
        //  b) any of it's children reported that it had an error.
        const thisNodeOrAnySubNodesHasError = ((node.flags & NodeFlags.ThisNodeHasError) !== 0) ||
            forEachChild(node, containsParseError);

        // If so, mark ourselves accordingly.
        if (thisNodeOrAnySubNodesHasError) {
            (node as Mutable<Node>).flags |= NodeFlags.ThisNodeOrAnySubNodesHasError;
        }

        // Also mark that we've propagated the child information to this node.  This way we can
        // always consult the bit directly on this node without needing to check its children
        // again.
        (node as Mutable<Node>).flags |= NodeFlags.HasAggregatedChildData;
    }
}

/** @internal */
export function getSourceFileOfNode(node: Node): SourceFile;
/** @internal */
export function getSourceFileOfNode(node: Node | undefined): SourceFile | undefined;
/** @internal */
export function getSourceFileOfNode(node: Node | undefined): SourceFile | undefined {
    while (node && node.kind !== SyntaxKind.SourceFile) {
        node = node.parent;
    }
    return node as SourceFile;
}

/** @internal */
export function getSourceFileOfModule(module: Symbol): SourceFile | undefined {
    return getSourceFileOfNode(module.valueDeclaration || getNonAugmentationDeclaration(module));
}

/** @internal */
export function isPlainJsFile(file: SourceFile | undefined, checkJs: boolean | undefined): boolean {
    return !!file && (file.scriptKind === ScriptKind.JS || file.scriptKind === ScriptKind.JSX) && !file.checkJsDirective && checkJs === undefined;
}

/** @internal */
export function isStatementWithLocals(node: Node): boolean {
    switch (node.kind) {
        case SyntaxKind.Block:
        case SyntaxKind.CaseBlock:
        case SyntaxKind.ForStatement:
        case SyntaxKind.ForInStatement:
        case SyntaxKind.ForOfStatement:
            return true;
    }
    return false;
}

/** @internal */
export function getStartPositionOfLine(line: number, sourceFile: SourceFileLike): number {
    Debug.assert(line >= 0);
    return getLineStarts(sourceFile)[line];
}

// This is a useful function for debugging purposes.
/** @internal @knipignore */
export function nodePosToString(node: Node): string {
    const file = getSourceFileOfNode(node);
    const loc = getLineAndCharacterOfPosition(file, node.pos);
    return `${file.fileName}(${loc.line + 1},${loc.character + 1})`;
}

/** @internal */
export function getEndLinePosition(line: number, sourceFile: SourceFileLike): number {
    Debug.assert(line >= 0);
    const lineStarts = getLineStarts(sourceFile);

    const lineIndex = line;
    const sourceText = sourceFile.text;
    if (lineIndex + 1 === lineStarts.length) {
        // last line - return EOF
        return sourceText.length - 1;
    }
    else {
        // current line start
        const start = lineStarts[lineIndex];
        // take the start position of the next line - 1 = it should be some line break
        let pos = lineStarts[lineIndex + 1] - 1;
        Debug.assert(isLineBreak(sourceText.charCodeAt(pos)));
        // walk backwards skipping line breaks, stop the the beginning of current line.
        // i.e:
        // <some text>
        // $ <- end of line for this position should match the start position
        while (start <= pos && isLineBreak(sourceText.charCodeAt(pos))) {
            pos--;
        }
        return pos;
    }
}

/**
 * Returns a value indicating whether a name is unique globally or within the current file.
 * Note: This does not consider whether a name appears as a free identifier or not, so at the expression `x.y` this includes both `x` and `y`.
 *
 * @internal
 */
export function isFileLevelUniqueName(sourceFile: SourceFile, name: string, hasGlobalName?: PrintHandlers["hasGlobalName"]): boolean {
    return !(hasGlobalName && hasGlobalName(name)) && !sourceFile.identifiers.has(name);
}

// Returns true if this node is missing from the actual source code. A 'missing' node is different
// from 'undefined/defined'. When a node is undefined (which can happen for optional nodes
// in the tree), it is definitely missing. However, a node may be defined, but still be
// missing.  This happens whenever the parser knows it needs to parse something, but can't
// get anything in the source code that it expects at that location. For example:
//
//          let a: ;
//
// Here, the Type in the Type-Annotation is not-optional (as there is a colon in the source
// code). So the parser will attempt to parse out a type, and will create an actual node.
// However, this node will be 'missing' in the sense that no actual source-code/tokens are
// contained within it.
/** @internal */
export function nodeIsMissing(node: Node | undefined): boolean {
    if (node === undefined) {
        return true;
    }

    return node.pos === node.end && node.pos >= 0 && node.kind !== SyntaxKind.EndOfFileToken;
}

/** @internal */
export function nodeIsPresent(node: Node | undefined): boolean {
    return !nodeIsMissing(node);
}

/**
 * Tests whether `child` is a grammar error on `parent`.
 * @internal
 */
export function isGrammarError(parent: Node, child: Node | NodeArray<Node>): boolean {
    if (isTypeParameterDeclaration(parent)) return child === parent.expression;
    if (isClassStaticBlockDeclaration(parent)) return child === parent.modifiers;
    if (isPropertySignature(parent)) return child === parent.initializer;
    if (isPropertyDeclaration(parent)) return child === parent.questionToken && isAutoAccessorPropertyDeclaration(parent);
    if (isPropertyAssignment(parent)) return child === parent.modifiers || child === parent.questionToken || child === parent.exclamationToken || isGrammarErrorElement(parent.modifiers, child, isModifierLike);
    if (isShorthandPropertyAssignment(parent)) return child === parent.equalsToken || child === parent.modifiers || child === parent.questionToken || child === parent.exclamationToken || isGrammarErrorElement(parent.modifiers, child, isModifierLike);
    if (isMethodDeclaration(parent)) return child === parent.exclamationToken;
    if (isConstructorDeclaration(parent)) return child === parent.typeParameters || child === parent.type || isGrammarErrorElement(parent.typeParameters, child, isTypeParameterDeclaration);
    if (isGetAccessorDeclaration(parent)) return child === parent.typeParameters || isGrammarErrorElement(parent.typeParameters, child, isTypeParameterDeclaration);
    if (isSetAccessorDeclaration(parent)) return child === parent.typeParameters || child === parent.type || isGrammarErrorElement(parent.typeParameters, child, isTypeParameterDeclaration);
    if (isNamespaceExportDeclaration(parent)) return child === parent.modifiers || isGrammarErrorElement(parent.modifiers, child, isModifierLike);
    return false;
}

function isGrammarErrorElement<T extends Node>(nodeArray: NodeArray<T> | undefined, child: Node | NodeArray<Node>, isElement: (node: Node) => node is T) {
    if (!nodeArray || isArray(child) || !isElement(child)) return false;
    return contains(nodeArray, child);
}

function insertStatementsAfterPrologue<T extends Statement>(to: T[], from: readonly T[] | undefined, isPrologueDirective: (node: Node) => boolean): T[] {
    if (from === undefined || from.length === 0) return to;
    let statementIndex = 0;
    // skip all prologue directives to insert at the correct position
    for (; statementIndex < to.length; ++statementIndex) {
        if (!isPrologueDirective(to[statementIndex])) {
            break;
        }
    }
    to.splice(statementIndex, 0, ...from);
    return to;
}

function insertStatementAfterPrologue<T extends Statement>(to: T[], statement: T | undefined, isPrologueDirective: (node: Node) => boolean): T[] {
    if (statement === undefined) return to;
    let statementIndex = 0;
    // skip all prologue directives to insert at the correct position
    for (; statementIndex < to.length; ++statementIndex) {
        if (!isPrologueDirective(to[statementIndex])) {
            break;
        }
    }
    to.splice(statementIndex, 0, statement);
    return to;
}

function isAnyPrologueDirective(node: Node) {
    return isPrologueDirective(node) || !!(getEmitFlags(node) & EmitFlags.CustomPrologue);
}

/**
 * Prepends statements to an array while taking care of prologue directives.
 *
 * @internal
 */
export function insertStatementsAfterStandardPrologue<T extends Statement>(to: T[], from: readonly T[] | undefined): T[] {
    return insertStatementsAfterPrologue(to, from, isPrologueDirective);
}

/** @internal */
export function insertStatementsAfterCustomPrologue<T extends Statement>(to: T[], from: readonly T[] | undefined): T[] {
    return insertStatementsAfterPrologue(to, from, isAnyPrologueDirective);
}

/**
 * Prepends statements to an array while taking care of prologue directives.
 *
 * @internal
 * @knipignore
 */
export function insertStatementAfterStandardPrologue<T extends Statement>(to: T[], statement: T | undefined): T[] {
    return insertStatementAfterPrologue(to, statement, isPrologueDirective);
}

/** @internal */
export function insertStatementAfterCustomPrologue<T extends Statement>(to: T[], statement: T | undefined): T[] {
    return insertStatementAfterPrologue(to, statement, isAnyPrologueDirective);
}

/**
 * Determine if the given comment is a triple-slash
 *
 * @return true if the comment is a triple-slash comment else false
 *
 * @internal
 */
export function isRecognizedTripleSlashComment(text: string, commentPos: number, commentEnd: number): boolean {
    // Verify this is /// comment, but do the regexp match only when we first can find /// in the comment text
    // so that we don't end up computing comment string and doing match for all // comments
    if (
        text.charCodeAt(commentPos + 1) === CharacterCodes.slash &&
        commentPos + 2 < commentEnd &&
        text.charCodeAt(commentPos + 2) === CharacterCodes.slash
    ) {
        const textSubStr = text.substring(commentPos, commentEnd);
        return fullTripleSlashReferencePathRegEx.test(textSubStr) ||
                fullTripleSlashAMDReferencePathRegEx.test(textSubStr) ||
                fullTripleSlashAMDModuleRegEx.test(textSubStr) ||
                fullTripleSlashReferenceTypeReferenceDirectiveRegEx.test(textSubStr) ||
                fullTripleSlashLibReferenceRegEx.test(textSubStr) ||
                defaultLibReferenceRegEx.test(textSubStr) ?
            true : false;
    }
    return false;
}

/** @internal */
export function isPinnedComment(text: string, start: number): boolean {
    return text.charCodeAt(start + 1) === CharacterCodes.asterisk &&
        text.charCodeAt(start + 2) === CharacterCodes.exclamation;
}

/** @internal */
export function createCommentDirectivesMap(sourceFile: SourceFile, commentDirectives: CommentDirective[]): CommentDirectivesMap {
    const directivesByLine = new Map(
        commentDirectives.map(commentDirective => [
            `${getLineAndCharacterOfPosition(sourceFile, commentDirective.range.end).line}`,
            commentDirective,
        ]),
    );

    const usedLines = new Map<string, boolean>();

    return { getUnusedExpectations, markUsed };

    function getUnusedExpectations() {
        return arrayFrom(directivesByLine.entries())
            .filter(([line, directive]) => directive.type === CommentDirectiveType.ExpectError && !usedLines.get(line))
            .map(([_, directive]) => directive);
    }

    function markUsed(line: number) {
        if (!directivesByLine.has(`${line}`)) {
            return false;
        }

        usedLines.set(`${line}`, true);
        return true;
    }
}

/** @internal */
export function getTokenPosOfNode(node: Node, sourceFile?: SourceFileLike, includeJsDoc?: boolean): number {
    // With nodes that have no width (i.e. 'Missing' nodes), we actually *don't*
    // want to skip trivia because this will launch us forward to the next token.
    if (nodeIsMissing(node)) {
        return node.pos;
    }

    if (isJSDocNode(node) || node.kind === SyntaxKind.JsxText) {
        // JsxText cannot actually contain comments, even though the scanner will think it sees comments
        return skipTrivia((sourceFile ?? getSourceFileOfNode(node)).text, node.pos, /*stopAfterLineBreak*/ false, /*stopAtComments*/ true);
    }

    if (includeJsDoc && hasJSDocNodes(node)) {
        return getTokenPosOfNode(node.jsDoc![0], sourceFile);
    }

    // For a syntax list, it is possible that one of its children has JSDocComment nodes, while
    // the syntax list itself considers them as normal trivia. Therefore if we simply skip
    // trivia for the list, we may have skipped the JSDocComment as well. So we should process its
    // first child to determine the actual position of its first token.
    if (node.kind === SyntaxKind.SyntaxList) {
        sourceFile ??= getSourceFileOfNode(node);
        const first = firstOrUndefined(getNodeChildren(node, sourceFile));
        if (first) {
            return getTokenPosOfNode(first, sourceFile, includeJsDoc);
        }
    }

    return skipTrivia(
        (sourceFile ?? getSourceFileOfNode(node)).text,
        node.pos,
        /*stopAfterLineBreak*/ false,
        /*stopAtComments*/ false,
        isInJSDoc(node),
    );
}

/** @internal */
export function getNonDecoratorTokenPosOfNode(node: Node, sourceFile?: SourceFileLike): number {
    const lastDecorator = !nodeIsMissing(node) && canHaveModifiers(node) ? findLast(node.modifiers, isDecorator) : undefined;
    if (!lastDecorator) {
        return getTokenPosOfNode(node, sourceFile);
    }

    return skipTrivia((sourceFile || getSourceFileOfNode(node)).text, lastDecorator.end);
}

/** @internal */
export function getSourceTextOfNodeFromSourceFile(sourceFile: SourceFile, node: Node, includeTrivia = false): string {
    return getTextOfNodeFromSourceText(sourceFile.text, node, includeTrivia);
}

function isJSDocTypeExpressionOrChild(node: Node): boolean {
    return !!findAncestor(node, isJSDocTypeExpression);
}

/** @internal */
export function isExportNamespaceAsDefaultDeclaration(node: Node): boolean {
    return !!(isExportDeclaration(node) && node.exportClause && isNamespaceExport(node.exportClause) && moduleExportNameIsDefault(node.exportClause.name));
}

/** @internal */
export function moduleExportNameTextUnescaped(node: ModuleExportName): string {
    return node.kind === SyntaxKind.StringLiteral ? node.text : unescapeLeadingUnderscores(node.escapedText);
}

/** @internal */
export function moduleExportNameTextEscaped(node: ModuleExportName): __String {
    return node.kind === SyntaxKind.StringLiteral ? escapeLeadingUnderscores(node.text) : node.escapedText;
}

/**
 * Equality checks against a keyword without underscores don't need to bother
 * to turn "__" into "___" or vice versa, since they will never be equal in
 * either case. So we can ignore those cases to improve performance.
 *
 * @internal
 */
export function moduleExportNameIsDefault(node: ModuleExportName): boolean {
    return (node.kind === SyntaxKind.StringLiteral ? node.text : node.escapedText) === InternalSymbolName.Default;
}

/** @internal */
export function getTextOfNodeFromSourceText(sourceText: string, node: Node, includeTrivia = false): string {
    if (nodeIsMissing(node)) {
        return "";
    }

    let text = sourceText.substring(includeTrivia ? node.pos : skipTrivia(sourceText, node.pos), node.end);

    if (isJSDocTypeExpressionOrChild(node)) {
        // strip space + asterisk at line start
        text = text.split(/\r\n|\n|\r/).map(line => line.replace(/^\s*\*/, "").trimStart()).join("\n");
    }

    return text;
}

/** @internal */
export function getTextOfNode(node: Node, includeTrivia = false): string {
    return getSourceTextOfNodeFromSourceFile(getSourceFileOfNode(node), node, includeTrivia);
}

function getPos(range: Node) {
    return range.pos;
}

/**
 * Note: it is expected that the `nodeArray` and the `node` are within the same file.
 * For example, searching for a `SourceFile` in a `SourceFile[]` wouldn't work.
 *
 * @internal
 */
export function indexOfNode(nodeArray: readonly Node[], node: Node): number {
    return binarySearch(nodeArray, node, getPos, compareValues);
}

/**
 * Gets flags that control emit behavior of a node.
 *
 * @internal
 */
export function getEmitFlags(node: Node): EmitFlags {
    const emitNode = node.emitNode;
    return emitNode && emitNode.flags || 0;
}

/**
 * Gets flags that control emit behavior of a node.
 *
 * @internal
 */
export function getInternalEmitFlags(node: Node): InternalEmitFlags {
    const emitNode = node.emitNode;
    return emitNode && emitNode.internalFlags || 0;
}

// Map from a type name, to a map of targets to array of features introduced to the type at that target.
/** @internal */
export type ScriptTargetFeatures = ReadonlyMap<string, ReadonlyMap<string, string[]>>;

// NOTE: We must reevaluate the target for upcoming features when each successive TC39 edition is ratified in
//       June of each year. This includes changes to `LanguageFeatureMinimumTarget`, `ScriptTarget`,
//       `ScriptTargetFeatures`, `CommandLineOptionOfCustomType`, transformers/esnext.ts, compiler/commandLineParser.ts,
//       compiler/utilitiesPublic.ts, and the contents of each lib/esnext.*.d.ts file.
/** @internal */
export const getScriptTargetFeatures: () => ScriptTargetFeatures = /* @__PURE__ */ memoize((): ScriptTargetFeatures =>
    new Map(Object.entries({
        Array: new Map(Object.entries({
            es2015: [
                "find",
                "findIndex",
                "fill",
                "copyWithin",
                "entries",
                "keys",
                "values",
            ],
            es2016: [
                "includes",
            ],
            es2019: [
                "flat",
                "flatMap",
            ],
            es2022: [
                "at",
            ],
            es2023: [
                "findLastIndex",
                "findLast",
                "toReversed",
                "toSorted",
                "toSpliced",
                "with",
            ],
        })),
        Iterator: new Map(Object.entries({
            es2015: emptyArray,
        })),
        AsyncIterator: new Map(Object.entries({
            es2015: emptyArray,
        })),
        ArrayBuffer: new Map(Object.entries({
            es2024: [
                "maxByteLength",
                "resizable",
                "resize",
                "detached",
                "transfer",
                "transferToFixedLength",
            ],
        })),
        Atomics: new Map(Object.entries({
            es2017: [
                "add",
                "and",
                "compareExchange",
                "exchange",
                "isLockFree",
                "load",
                "or",
                "store",
                "sub",
                "wait",
                "notify",
                "xor",
            ],
            es2024: [
                "waitAsync",
            ],
            esnext: [
                "pause",
            ],
        })),
        SharedArrayBuffer: new Map(Object.entries({
            es2017: [
                "byteLength",
                "slice",
            ],
            es2024: [
                "growable",
                "maxByteLength",
                "grow",
            ],
        })),
        AsyncIterable: new Map(Object.entries({
            es2018: emptyArray,
        })),
        AsyncIterableIterator: new Map(Object.entries({
            es2018: emptyArray,
        })),
        AsyncGenerator: new Map(Object.entries({
            es2018: emptyArray,
        })),
        AsyncGeneratorFunction: new Map(Object.entries({
            es2018: emptyArray,
        })),
        RegExp: new Map(Object.entries({
            es2015: [
                "flags",
                "sticky",
                "unicode",
            ],
            es2018: [
                "dotAll",
            ],
            es2024: [
                "unicodeSets",
            ],
        })),
        RegExpConstructor: new Map(Object.entries({
            es2025: [
                "escape",
            ],
        })),
        Reflect: new Map(Object.entries({
            es2015: [
                "apply",
                "construct",
                "defineProperty",
                "deleteProperty",
                "get",
                "getOwnPropertyDescriptor",
                "getPrototypeOf",
                "has",
                "isExtensible",
                "ownKeys",
                "preventExtensions",
                "set",
                "setPrototypeOf",
            ],
        })),
        ArrayConstructor: new Map(Object.entries({
            es2015: [
                "from",
                "of",
            ],
            esnext: [
                "fromAsync",
            ],
        })),
        ObjectConstructor: new Map(Object.entries({
            es2015: [
                "assign",
                "getOwnPropertySymbols",
                "keys",
                "is",
                "setPrototypeOf",
            ],
            es2017: [
                "values",
                "entries",
                "getOwnPropertyDescriptors",
            ],
            es2019: [
                "fromEntries",
            ],
            es2022: [
                "hasOwn",
            ],
            es2024: [
                "groupBy",
            ],
        })),
        NumberConstructor: new Map(Object.entries({
            es2015: [
                "isFinite",
                "isInteger",
                "isNaN",
                "isSafeInteger",
                "parseFloat",
                "parseInt",
            ],
        })),
        Math: new Map(Object.entries({
            es2015: [
                "clz32",
                "imul",
                "sign",
                "log10",
                "log2",
                "log1p",
                "expm1",
                "cosh",
                "sinh",
                "tanh",
                "acosh",
                "asinh",
                "atanh",
                "hypot",
                "trunc",
                "fround",
                "cbrt",
            ],
            es2025: [
                "f16round",
            ],
        })),
        Map: new Map(Object.entries({
            es2015: [
                "entries",
                "keys",
                "values",
            ],
            esnext: [
                "getOrInsert",
                "getOrInsertComputed",
            ],
        })),
        MapConstructor: new Map(Object.entries({
            es2024: [
                "groupBy",
            ],
        })),
        Set: new Map(Object.entries({
            es2015: [
                "entries",
                "keys",
                "values",
            ],
            es2025: [
                "union",
                "intersection",
                "difference",
                "symmetricDifference",
                "isSubsetOf",
                "isSupersetOf",
                "isDisjointFrom",
            ],
        })),
        PromiseConstructor: new Map(Object.entries({
            es2015: [
                "all",
                "race",
                "reject",
                "resolve",
            ],
            es2020: [
                "allSettled",
            ],
            es2021: [
                "any",
            ],
            es2024: [
                "withResolvers",
            ],
            es2025: [
                "try",
            ],
        })),
        Symbol: new Map(Object.entries({
            es2015: [
                "for",
                "keyFor",
            ],
            es2019: [
                "description",
            ],
        })),
        WeakMap: new Map(Object.entries({
            es2015: [
                "entries",
                "keys",
                "values",
            ],
            esnext: [
                "getOrInsert",
                "getOrInsertComputed",
            ],
        })),
        WeakSet: new Map(Object.entries({
            es2015: [
                "entries",
                "keys",
                "values",
            ],
        })),
        String: new Map(Object.entries({
            es2015: [
                "codePointAt",
                "includes",
                "endsWith",
                "normalize",
                "repeat",
                "startsWith",
                "anchor",
                "big",
                "blink",
                "bold",
                "fixed",
                "fontcolor",
                "fontsize",
                "italics",
                "link",
                "small",
                "strike",
                "sub",
                "sup",
            ],
            es2017: [
                "padStart",
                "padEnd",
            ],
            es2019: [
                "trimStart",
                "trimEnd",
                "trimLeft",
                "trimRight",
            ],
            es2020: [
                "matchAll",
            ],
            es2021: [
                "replaceAll",
            ],
            es2022: [
                "at",
            ],
            es2024: [
                "isWellFormed",
                "toWellFormed",
            ],
        })),
        StringConstructor: new Map(Object.entries({
            es2015: [
                "fromCodePoint",
                "raw",
            ],
        })),
        DateTimeFormat: new Map(Object.entries({
            es2017: [
                "formatToParts",
            ],
        })),
        Promise: new Map(Object.entries({
            es2015: emptyArray,
            es2018: [
                "finally",
            ],
        })),
        RegExpMatchArray: new Map(Object.entries({
            es2018: [
                "groups",
            ],
        })),
        RegExpExecArray: new Map(Object.entries({
            es2018: [
                "groups",
            ],
        })),
        Intl: new Map(Object.entries({
            es2018: [
                "PluralRules",
            ],
            es2020: [
                "RelativeTimeFormat",
                "Locale",
                "DisplayNames",
            ],
            es2021: [
                "ListFormat",
                "DateTimeFormat",
            ],
            es2022: [
                "Segmenter",
            ],
            es2025: [
                "DurationFormat",
            ],
        })),
        NumberFormat: new Map(Object.entries({
            es2018: [
                "formatToParts",
            ],
        })),
        SymbolConstructor: new Map(Object.entries({
            es2020: [
                "matchAll",
            ],
            esnext: [
                "metadata",
                "dispose",
                "asyncDispose",
            ],
        })),
        DataView: new Map(Object.entries({
            es2020: [
                "setBigInt64",
                "setBigUint64",
                "getBigInt64",
                "getBigUint64",
            ],
            es2025: [
                "setFloat16",
                "getFloat16",
            ],
        })),
        BigInt: new Map(Object.entries({
            es2020: emptyArray,
        })),
        RelativeTimeFormat: new Map(Object.entries({
            es2020: [
                "format",
                "formatToParts",
                "resolvedOptions",
            ],
        })),
        Int8Array: new Map(Object.entries({
            es2022: [
                "at",
            ],
            es2023: [
                "findLastIndex",
                "findLast",
                "toReversed",
                "toSorted",
                "toSpliced",
                "with",
            ],
        })),
        Uint8Array: new Map(Object.entries({
            es2022: [
                "at",
            ],
            es2023: [
                "findLastIndex",
                "findLast",
                "toReversed",
                "toSorted",
                "toSpliced",
                "with",
            ],
            esnext: [
                "toBase64",
                "setFromBase64",
                "toHex",
                "setFromHex",
            ],
        })),
        Uint8ClampedArray: new Map(Object.entries({
            es2022: [
                "at",
            ],
            es2023: [
                "findLastIndex",
                "findLast",
                "toReversed",
                "toSorted",
                "toSpliced",
                "with",
            ],
        })),
        Int16Array: new Map(Object.entries({
            es2022: [
                "at",
            ],
            es2023: [
                "findLastIndex",
                "findLast",
                "toReversed",
                "toSorted",
                "toSpliced",
                "with",
            ],
        })),
        Uint16Array: new Map(Object.entries({
            es2022: [
                "at",
            ],
            es2023: [
                "findLastIndex",
                "findLast",
                "toReversed",
                "toSorted",
                "toSpliced",
                "with",
            ],
        })),
        Int32Array: new Map(Object.entries({
            es2022: [
                "at",
            ],
            es2023: [
                "findLastIndex",
                "findLast",
                "toReversed",
                "toSorted",
                "toSpliced",
                "with",
            ],
        })),
        Uint32Array: new Map(Object.entries({
            es2022: [
                "at",
            ],
            es2023: [
                "findLastIndex",
                "findLast",
                "toReversed",
                "toSorted",
                "toSpliced",
                "with",
            ],
        })),
        Float16Array: new Map(Object.entries({
            es2025: emptyArray,
        })),
        Float32Array: new Map(Object.entries({
            es2022: [
                "at",
            ],
            es2023: [
                "findLastIndex",
                "findLast",
                "toReversed",
                "toSorted",
                "toSpliced",
                "with",
            ],
        })),
        Float64Array: new Map(Object.entries({
            es2022: [
                "at",
            ],
            es2023: [
                "findLastIndex",
                "findLast",
                "toReversed",
                "toSorted",
                "toSpliced",
                "with",
            ],
        })),
        BigInt64Array: new Map(Object.entries({
            es2020: emptyArray,
            es2022: [
                "at",
            ],
            es2023: [
                "findLastIndex",
                "findLast",
                "toReversed",
                "toSorted",
                "toSpliced",
                "with",
            ],
        })),
        BigUint64Array: new Map(Object.entries({
            es2020: emptyArray,
            es2022: [
                "at",
            ],
            es2023: [
                "findLastIndex",
                "findLast",
                "toReversed",
                "toSorted",
                "toSpliced",
                "with",
            ],
        })),
        Error: new Map(Object.entries({
            es2022: [
                "cause",
            ],
        })),
        ErrorConstructor: new Map(Object.entries({
            esnext: [
                "isError",
            ],
        })),
        Uint8ArrayConstructor: new Map(Object.entries({
            esnext: [
                "fromBase64",
                "fromHex",
            ],
        })),
        Date: new Map(Object.entries({
            esnext: [
                "toTemporalInstant",
            ],
        })),
        DisposableStack: new Map(Object.entries({
            esnext: emptyArray,
        })),
        AsyncDisposableStack: new Map(Object.entries({
            esnext: emptyArray,
        })),
    }))
);

/** @internal */
export const enum GetLiteralTextFlags {
    None = 0,
    NeverAsciiEscape = 1 << 0,
    JsxAttributeEscape = 1 << 1,
    TerminateUnterminatedLiterals = 1 << 2,
    AllowNumericSeparator = 1 << 3,
}

/** @internal */
export function getLiteralText(node: LiteralLikeNode, sourceFile: SourceFile | undefined, flags: GetLiteralTextFlags): string {
    // If we don't need to downlevel and we can reach the original source text using
    // the node's parent reference, then simply get the text as it was originally written.
    if (sourceFile && canUseOriginalText(node, flags)) {
        return getSourceTextOfNodeFromSourceFile(sourceFile, node);
    }

    // If we can't reach the original source text, use the canonical form if it's a number,
    // or a (possibly escaped) quoted form of the original text if it's string-like.
    switch (node.kind) {
        case SyntaxKind.StringLiteral: {
            const escapeText = flags & GetLiteralTextFlags.JsxAttributeEscape ? escapeJsxAttributeString :
                flags & GetLiteralTextFlags.NeverAsciiEscape || (getEmitFlags(node) & EmitFlags.NoAsciiEscaping) ? escapeString :
                escapeNonAsciiString;
            if ((node as StringLiteral).singleQuote) {
                return "'" + escapeText(node.text, CharacterCodes.singleQuote) + "'";
            }
            else {
                return '"' + escapeText(node.text, CharacterCodes.doubleQuote) + '"';
            }
        }
        case SyntaxKind.NoSubstitutionTemplateLiteral:
        case SyntaxKind.TemplateHead:
        case SyntaxKind.TemplateMiddle:
        case SyntaxKind.TemplateTail: {
            // If a NoSubstitutionTemplateLiteral appears to have a substitution in it, the original text
            // had to include a backslash: `not \${a} substitution`.
            const escapeText = flags & GetLiteralTextFlags.NeverAsciiEscape || (getEmitFlags(node) & EmitFlags.NoAsciiEscaping) ? escapeString :
                escapeNonAsciiString;

            const rawText = (node as TemplateLiteralLikeNode).rawText ?? escapeTemplateSubstitution(escapeText(node.text, CharacterCodes.backtick));
            switch (node.kind) {
                case SyntaxKind.NoSubstitutionTemplateLiteral:
                    return "`" + rawText + "`";
                case SyntaxKind.TemplateHead:
                    return "`" + rawText + "${";
                case SyntaxKind.TemplateMiddle:
                    return "}" + rawText + "${";
                case SyntaxKind.TemplateTail:
                    return "}" + rawText + "`";
            }
            break;
        }
        case SyntaxKind.NumericLiteral:
        case SyntaxKind.BigIntLiteral:
            return node.text;
        case SyntaxKind.RegularExpressionLiteral:
            if (flags & GetLiteralTextFlags.TerminateUnterminatedLiterals && node.isUnterminated) {
                return node.text + (node.text.charCodeAt(node.text.length - 1) === CharacterCodes.backslash ? " /" : "/");
            }
            return node.text;
    }

    return Debug.fail(`Literal kind '${node.kind}' not accounted for.`);
}

function canUseOriginalText(node: LiteralLikeNode, flags: GetLiteralTextFlags): boolean {
    if (nodeIsSynthesized(node) || !node.parent || (flags & GetLiteralTextFlags.TerminateUnterminatedLiterals && node.isUnterminated)) {
        return false;
    }

    if (isNumericLiteral(node)) {
        if (node.numericLiteralFlags & TokenFlags.IsInvalid) {
            return false;
        }
        if (node.numericLiteralFlags & TokenFlags.ContainsSeparator) {
            return !!(flags & GetLiteralTextFlags.AllowNumericSeparator);
        }
    }

    return !isBigIntLiteral(node);
}

/** @internal */
export function getTextOfConstantValue(value: string | number): string {
    return isString(value) ? `"${escapeString(value)}"` : "" + value;
}

// Make an identifier from an external module name by extracting the string after the last "/" and replacing
// all non-alphanumeric characters with underscores
/** @internal */
export function makeIdentifierFromModuleName(moduleName: string): string {
    return getBaseFileName(moduleName).replace(/^(\d)/, "_$1").replace(/\W/g, "_");
}

/** @internal */
export function isBlockOrCatchScoped(declaration: Declaration): boolean {
    return (getCombinedNodeFlags(declaration) & NodeFlags.BlockScoped) !== 0 ||
        isCatchClauseVariableDeclarationOrBindingElement(declaration);
}

/** @internal */
export function isCatchClauseVariableDeclarationOrBindingElement(declaration: Declaration): boolean {
    const node = getRootDeclaration(declaration);
    return node.kind === SyntaxKind.VariableDeclaration && node.parent.kind === SyntaxKind.CatchClause;
}

/** @internal */
export function isAmbientModule(node: Node): node is AmbientModuleDeclaration {
    return isModuleDeclaration(node) && (node.name.kind === SyntaxKind.StringLiteral || isGlobalScopeAugmentation(node));
}

/** @internal */
export function isModuleWithStringLiteralName(node: Node): node is ModuleDeclaration {
    return isModuleDeclaration(node) && node.name.kind === SyntaxKind.StringLiteral;
}

/** @internal */
export function isNonGlobalAmbientModule(node: Node): node is ModuleDeclaration & { name: StringLiteral; } {
    return isModuleDeclaration(node) && isStringLiteral(node.name);
}

/**
 * An effective module (namespace) declaration is either
 * 1. An actual declaration: namespace X { ... }
 * 2. A Javascript declaration, which is:
 *    An identifier in a nested property access expression: Y in `X.Y.Z = { ... }`
 */
function isEffectiveModuleDeclaration(node: Node) {
    return isModuleDeclaration(node) || isIdentifier(node);
}

/**
 * Given a symbol for a module, checks that it is a shorthand ambient module.
 *
 * @internal
 */
export function isShorthandAmbientModuleSymbol(moduleSymbol: Symbol): boolean {
    return isShorthandAmbientModule(moduleSymbol.valueDeclaration);
}

function isShorthandAmbientModule(node: Node | undefined): boolean {
    // The only kind of module that can be missing a body is a shorthand ambient module.
    return !!node && node.kind === SyntaxKind.ModuleDeclaration && (!(node as ModuleDeclaration).body);
}

/** @internal */
export function isBlockScopedContainerTopLevel(node: Node): boolean {
    return node.kind === SyntaxKind.SourceFile ||
        node.kind === SyntaxKind.ModuleDeclaration ||
        isFunctionLikeOrClassStaticBlockDeclaration(node);
}

/** @internal */
export function isGlobalScopeAugmentation(module: ModuleDeclaration): boolean {
    return !!(module.flags & NodeFlags.GlobalAugmentation);
}

/** @internal */
export function isExternalModuleAugmentation(node: Node): node is AmbientModuleDeclaration {
    return isAmbientModule(node) && isModuleAugmentationExternal(node);
}

/** @internal */
export function isModuleAugmentationExternal(node: AmbientModuleDeclaration): boolean {
    // external module augmentation is a ambient module declaration that is either:
    // - defined in the top level scope and source file is an external module
    // - defined inside ambient module declaration located in the top level scope and source file not an external module
    switch (node.parent.kind) {
        case SyntaxKind.SourceFile:
            return isExternalModule(node.parent);
        case SyntaxKind.ModuleBlock:
            return isAmbientModule(node.parent.parent) && isSourceFile(node.parent.parent.parent) && !isExternalModule(node.parent.parent.parent);
    }
    return false;
}

/** @internal */
export function getNonAugmentationDeclaration(symbol: Symbol): Declaration | undefined {
    return symbol.declarations?.find(d => !isExternalModuleAugmentation(d) && !(isModuleDeclaration(d) && isGlobalScopeAugmentation(d)));
}

function isCommonJSContainingModuleKind(kind: ModuleKind) {
    return kind === ModuleKind.CommonJS || ModuleKind.Node16 <= kind && kind <= ModuleKind.NodeNext;
}

/** @internal */
export function isEffectiveExternalModule(node: SourceFile, compilerOptions: CompilerOptions): boolean {
    return isExternalModule(node) || (isCommonJSContainingModuleKind(getEmitModuleKind(compilerOptions)) && !!node.commonJsModuleIndicator);
}

/**
 * Returns whether the source file will be treated as if it were in strict mode at runtime.
 *
 * @internal
 */
export function isEffectiveStrictModeSourceFile(node: SourceFile, compilerOptions: CompilerOptions): boolean {
    // We can only verify strict mode for JS/TS files
    switch (node.scriptKind) {
        case ScriptKind.JS:
        case ScriptKind.TS:
        case ScriptKind.JSX:
        case ScriptKind.TSX:
            break;
        default:
            return false;
    }
    // Strict mode does not matter for declaration files.
    if (node.isDeclarationFile) {
        return false;
    }
    // If `alwaysStrict` is set, then treat the file as strict.
    if (getAlwaysStrict(compilerOptions)) {
        return true;
    }
    // Starting with a "use strict" directive indicates the file is strict.
    if (startsWithUseStrict(node.statements)) {
        return true;
    }
    if (isExternalModule(node) || getIsolatedModules(compilerOptions)) {
        // Modules are always strict.
        return true;
    }
    return false;
}

/** @internal */
export function isAmbientPropertyDeclaration(node: PropertyDeclaration): boolean {
    return !!(node.flags & NodeFlags.Ambient) || hasSyntacticModifier(node, ModifierFlags.Ambient);
}

/** @internal */
export function isBlockScope(node: Node, parentNode: Node | undefined): boolean {
    switch (node.kind) {
        case SyntaxKind.SourceFile:
        case SyntaxKind.CaseBlock:
        case SyntaxKind.CatchClause:
        case SyntaxKind.ModuleDeclaration:
        case SyntaxKind.ForStatement:
        case SyntaxKind.ForInStatement:
        case SyntaxKind.ForOfStatement:
        case SyntaxKind.Constructor:
        case SyntaxKind.MethodDeclaration:
        case SyntaxKind.GetAccessor:
        case SyntaxKind.SetAccessor:
        case SyntaxKind.FunctionDeclaration:
        case SyntaxKind.FunctionExpression:
        case SyntaxKind.ArrowFunction:
        case SyntaxKind.PropertyDeclaration:
        case SyntaxKind.ClassStaticBlockDeclaration:
            return true;

        case SyntaxKind.Block:
            // function block is not considered block-scope container
            // see comment in binder.ts: bind(...), case for SyntaxKind.Block
            return !isFunctionLikeOrClassStaticBlockDeclaration(parentNode);
    }

    return false;
}

/** @internal */
export function isDeclarationWithTypeParameters(node: Node): node is DeclarationWithTypeParameters {
    Debug.type<DeclarationWithTypeParameters>(node);
    switch (node.kind) {
        case SyntaxKind.JSDocCallbackTag:
        case SyntaxKind.JSDocTypedefTag:
        case SyntaxKind.JSDocSignature:
            return true;
        default:
            assertType<DeclarationWithTypeParameterChildren>(node);
            return isDeclarationWithTypeParameterChildren(node);
    }
}

/** @internal */
export function isDeclarationWithTypeParameterChildren(node: Node): node is DeclarationWithTypeParameterChildren {
    Debug.type<DeclarationWithTypeParameterChildren>(node);
    switch (node.kind) {
        case SyntaxKind.CallSignature:
        case SyntaxKind.ConstructSignature:
        case SyntaxKind.MethodSignature:
        case SyntaxKind.IndexSignature:
        case SyntaxKind.FunctionType:
        case SyntaxKind.ConstructorType:
        case SyntaxKind.JSDocFunctionType:
        case SyntaxKind.ClassDeclaration:
        case SyntaxKind.ClassExpression:
        case SyntaxKind.InterfaceDeclaration:
        case SyntaxKind.TypeAliasDeclaration:
        case SyntaxKind.JSDocTemplateTag:
        case SyntaxKind.FunctionDeclaration:
        case SyntaxKind.MethodDeclaration:
        case SyntaxKind.Constructor:
        case SyntaxKind.GetAccessor:
        case SyntaxKind.SetAccessor:
        case SyntaxKind.FunctionExpression:
        case SyntaxKind.ArrowFunction:
            return true;
        default:
            assertType<never>(node);
            return false;
    }
}

/** @internal */
export function isAnyImportSyntax(node: Node): node is AnyImportSyntax {
    switch (node.kind) {
        case SyntaxKind.ImportDeclaration:
        case SyntaxKind.ImportEqualsDeclaration:
            return true;
        default:
            return false;
    }
}

/** @internal */
export function isAnyImportOrBareOrAccessedRequire(node: Node): node is AnyImportOrBareOrAccessedRequire {
    return isAnyImportSyntax(node) || isVariableDeclarationInitializedToBareOrAccessedRequire(node);
}

/** @internal */
export function isAnyImportOrRequireStatement(node: Node): node is AnyImportOrRequireStatement {
    return isAnyImportSyntax(node) || isRequireVariableStatement(node);
}

/** @internal */
export function isLateVisibilityPaintedStatement(node: Node): node is LateVisibilityPaintedStatement {
    switch (node.kind) {
        case SyntaxKind.ImportDeclaration:
        case SyntaxKind.ImportEqualsDeclaration:
        case SyntaxKind.VariableStatement:
        case SyntaxKind.ClassDeclaration:
        case SyntaxKind.FunctionDeclaration:
        case SyntaxKind.ModuleDeclaration:
        case SyntaxKind.TypeAliasDeclaration:
        case SyntaxKind.InterfaceDeclaration:
        case SyntaxKind.EnumDeclaration:
            return true;
        default:
            return false;
    }
}

/** @internal */
export function hasPossibleExternalModuleReference(node: Node): node is AnyImportOrReExport | ModuleDeclaration | ImportTypeNode | ImportCall {
    return isAnyImportOrReExport(node) || isModuleDeclaration(node) || isImportTypeNode(node) || isImportCall(node);
}

/** @internal */
export function isAnyImportOrReExport(node: Node): node is AnyImportOrReExport {
    return isAnyImportSyntax(node) || isExportDeclaration(node);
}

/** @internal */
export function getEnclosingContainer(node: Node): Node | undefined {
    return findAncestor(node.parent, n => !!(getContainerFlags(n) & ContainerFlags.IsContainer));
}

// Gets the nearest enclosing block scope container that has the provided node
// as a descendant, that is not the provided node.
/** @internal */
export function getEnclosingBlockScopeContainer(node: Node): Node {
    return findAncestor(node.parent, current => isBlockScope(current, current.parent))!;
}

/** @internal */
export function forEachEnclosingBlockScopeContainer(node: Node, cb: (container: Node) => void): void {
    let container = getEnclosingBlockScopeContainer(node);
    while (container) {
        cb(container);
        container = getEnclosingBlockScopeContainer(container);
    }
}

// Return display name of an identifier
// Computed property names will just be emitted as "[<expr>]", where <expr> is the source
// text of the expression in the computed property.
/** @internal */
export function declarationNameToString(name: DeclarationName | QualifiedName | undefined): string {
    return !name || getFullWidth(name) === 0 ? "(Missing)" : getTextOfNode(name);
}

/** @internal */
export function getNameFromIndexInfo(info: IndexInfo): string | undefined {
    return info.declaration ? declarationNameToString(info.declaration.parameters[0].name) : undefined;
}

/** @internal */
export function isComputedNonLiteralName(name: PropertyName): boolean {
    return name.kind === SyntaxKind.ComputedPropertyName && !isStringOrNumericLiteralLike(name.expression);
}

/** @internal */
export function tryGetTextOfPropertyName(name: PropertyName | NoSubstitutionTemplateLiteral | JsxAttributeName): __String | undefined {
    switch (name.kind) {
        case SyntaxKind.Identifier:
        case SyntaxKind.PrivateIdentifier:
            return name.emitNode?.autoGenerate ? undefined : name.escapedText;
        case SyntaxKind.StringLiteral:
        case SyntaxKind.NumericLiteral:
        case SyntaxKind.BigIntLiteral:
        case SyntaxKind.NoSubstitutionTemplateLiteral:
            return escapeLeadingUnderscores(name.text);
        case SyntaxKind.ComputedPropertyName:
            if (isStringOrNumericLiteralLike(name.expression)) return escapeLeadingUnderscores(name.expression.text);
            return undefined;
        case SyntaxKind.JsxNamespacedName:
            return getEscapedTextOfJsxNamespacedName(name);
        default:
            return Debug.assertNever(name);
    }
}

/** @internal */
export function getTextOfPropertyName(name: PropertyName | NoSubstitutionTemplateLiteral | JsxAttributeName): __String {
    return Debug.checkDefined(tryGetTextOfPropertyName(name));
}

/** @internal */
export function entityNameToString(name: EntityNameOrEntityNameExpression | JSDocMemberName | JsxTagNameExpression | PrivateIdentifier): string {
    switch (name.kind) {
        case SyntaxKind.ThisKeyword:
            return "this";
        case SyntaxKind.PrivateIdentifier:
        case SyntaxKind.Identifier:
            return getFullWidth(name) === 0 ? idText(name) : getTextOfNode(name);
        case SyntaxKind.QualifiedName:
            return entityNameToString(name.left) + "." + entityNameToString(name.right);
        case SyntaxKind.PropertyAccessExpression:
            if (isIdentifier(name.name) || isPrivateIdentifier(name.name)) {
                return entityNameToString(name.expression) + "." + entityNameToString(name.name);
            }
            else {
                return Debug.assertNever(name.name);
            }
        case SyntaxKind.JSDocMemberName:
            return entityNameToString(name.left) + "#" + entityNameToString(name.right);
        case SyntaxKind.JsxNamespacedName:
            return entityNameToString(name.namespace) + ":" + entityNameToString(name.name);
        default:
            return Debug.assertNever(name);
    }
}

/** @internal */
export function createDiagnosticForNode(node: Node, message: DiagnosticMessage, ...args: DiagnosticArguments): DiagnosticWithLocation {
    const sourceFile = getSourceFileOfNode(node);
    return createDiagnosticForNodeInSourceFile(sourceFile, node, message, ...args);
}

/** @internal */
export function createDiagnosticForNodeArray(sourceFile: SourceFile, nodes: NodeArray<Node>, message: DiagnosticMessage, ...args: DiagnosticArguments): DiagnosticWithLocation {
    const start = skipTrivia(sourceFile.text, nodes.pos);
    return createFileDiagnostic(sourceFile, start, nodes.end - start, message, ...args);
}

/** @internal */
export function createDiagnosticForNodeInSourceFile(sourceFile: SourceFile, node: Node, message: DiagnosticMessage, ...args: DiagnosticArguments): DiagnosticWithLocation {
    const span = getErrorSpanForNode(sourceFile, node);
    return createFileDiagnostic(sourceFile, span.start, span.length, message, ...args);
}

/** @internal */
export function createDiagnosticForNodeFromMessageChain(sourceFile: SourceFile, node: Node, messageChain: DiagnosticMessageChain, relatedInformation?: DiagnosticRelatedInformation[]): DiagnosticWithLocation {
    const span = getErrorSpanForNode(sourceFile, node);
    return createFileDiagnosticFromMessageChain(sourceFile, span.start, span.length, messageChain, relatedInformation);
}

/** @internal */
export function createDiagnosticForNodeArrayFromMessageChain(sourceFile: SourceFile, nodes: NodeArray<Node>, messageChain: DiagnosticMessageChain, relatedInformation?: DiagnosticRelatedInformation[]): DiagnosticWithLocation {
    const start = skipTrivia(sourceFile.text, nodes.pos);
    return createFileDiagnosticFromMessageChain(sourceFile, start, nodes.end - start, messageChain, relatedInformation);
}

function assertDiagnosticLocation(sourceText: string, start: number, length: number) {
    Debug.assertGreaterThanOrEqual(start, 0);
    Debug.assertGreaterThanOrEqual(length, 0);
    Debug.assertLessThanOrEqual(start, sourceText.length);
    Debug.assertLessThanOrEqual(start + length, sourceText.length);
}

/** @internal */
export function createFileDiagnosticFromMessageChain(file: SourceFile, start: number, length: number, messageChain: DiagnosticMessageChain, relatedInformation?: DiagnosticRelatedInformation[]): DiagnosticWithLocation {
    assertDiagnosticLocation(file.text, start, length);
    return {
        file,
        start,
        length,
        code: messageChain.code,
        category: messageChain.category,
        messageText: messageChain.next ? messageChain : messageChain.messageText,
        relatedInformation,
        canonicalHead: messageChain.canonicalHead,
    };
}

/** @internal */
export function createDiagnosticForFileFromMessageChain(sourceFile: SourceFile, messageChain: DiagnosticMessageChain, relatedInformation?: DiagnosticRelatedInformation[]): DiagnosticWithLocation {
    return {
        file: sourceFile,
        start: 0,
        length: 0,
        code: messageChain.code,
        category: messageChain.category,
        messageText: messageChain.next ? messageChain : messageChain.messageText,
        relatedInformation,
    };
}

/** @internal */
export function createDiagnosticMessageChainFromDiagnostic(diagnostic: DiagnosticRelatedInformation): DiagnosticMessageChain {
    return typeof diagnostic.messageText === "string" ? {
        code: diagnostic.code,
        category: diagnostic.category,
        messageText: diagnostic.messageText,
        next: (diagnostic as DiagnosticMessageChain).next,
    } : diagnostic.messageText;
}

/** @internal */
export function createDiagnosticForRange(sourceFile: SourceFile, range: TextRange, message: DiagnosticMessage): DiagnosticWithLocation {
    return {
        file: sourceFile,
        start: range.pos,
        length: range.end - range.pos,
        code: message.code,
        category: message.category,
        messageText: message.message,
    };
}

/** @internal */
export function getCanonicalDiagnostic(message: DiagnosticMessage, ...args: string[]): CanonicalDiagnostic {
    return {
        code: message.code,
        messageText: formatMessage(message, ...args),
    };
}

/** @internal */
export function getSpanOfTokenAtPosition(sourceFile: SourceFile, pos: number): TextSpan {
    const scanner = createScanner(sourceFile.languageVersion, /*skipTrivia*/ true, sourceFile.languageVariant, sourceFile.text, /*onError*/ undefined, pos);
    scanner.scan();
    const start = scanner.getTokenStart();
    return createTextSpanFromBounds(start, scanner.getTokenEnd());
}

/** @internal */
export function scanTokenAtPosition(sourceFile: SourceFile, pos: number): SyntaxKind {
    const scanner = createScanner(sourceFile.languageVersion, /*skipTrivia*/ true, sourceFile.languageVariant, sourceFile.text, /*onError*/ undefined, pos);
    scanner.scan();
    return scanner.getToken();
}

function getErrorSpanForArrowFunction(sourceFile: SourceFile, node: ArrowFunction): TextSpan {
    const pos = skipTrivia(sourceFile.text, node.pos);
    if (node.body && node.body.kind === SyntaxKind.Block) {
        const { line: startLine } = getLineAndCharacterOfPosition(sourceFile, node.body.pos);
        const { line: endLine } = getLineAndCharacterOfPosition(sourceFile, node.body.end);
        if (startLine < endLine) {
            // The arrow function spans multiple lines,
            // make the error span be the first line, inclusive.
            return createTextSpan(pos, getEndLinePosition(startLine, sourceFile) - pos + 1);
        }
    }
    return createTextSpanFromBounds(pos, node.end);
}

/** @internal */
export function getErrorSpanForNode(sourceFile: SourceFile, node: Node): TextSpan {
    let errorNode: Node | undefined = node;
    switch (node.kind) {
        case SyntaxKind.SourceFile: {
            const pos = skipTrivia(sourceFile.text, 0, /*stopAfterLineBreak*/ false);
            if (pos === sourceFile.text.length) {
                // file is empty - return span for the beginning of the file
                return createTextSpan(0, 0);
            }
            return getSpanOfTokenAtPosition(sourceFile, pos);
        }
        // This list is a work in progress. Add missing node kinds to improve their error
        // spans.
        case SyntaxKind.VariableDeclaration:
        case SyntaxKind.BindingElement:
        case SyntaxKind.ClassDeclaration:
        case SyntaxKind.ClassExpression:
        case SyntaxKind.InterfaceDeclaration:
        case SyntaxKind.ModuleDeclaration:
        case SyntaxKind.EnumDeclaration:
        case SyntaxKind.EnumMember:
        case SyntaxKind.FunctionDeclaration:
        case SyntaxKind.FunctionExpression:
        case SyntaxKind.MethodDeclaration:
        case SyntaxKind.GetAccessor:
        case SyntaxKind.SetAccessor:
        case SyntaxKind.TypeAliasDeclaration:
        case SyntaxKind.PropertyDeclaration:
        case SyntaxKind.PropertySignature:
        case SyntaxKind.NamespaceImport:
            errorNode = (node as NamedDeclaration).name;
            break;
        case SyntaxKind.ArrowFunction:
            return getErrorSpanForArrowFunction(sourceFile, node as ArrowFunction);
        case SyntaxKind.CaseClause:
        case SyntaxKind.DefaultClause: {
            const start = skipTrivia(sourceFile.text, (node as CaseOrDefaultClause).pos);
            const end = (node as CaseOrDefaultClause).statements.length > 0 ? (node as CaseOrDefaultClause).statements[0].pos : (node as CaseOrDefaultClause).end;
            return createTextSpanFromBounds(start, end);
        }
        case SyntaxKind.ReturnStatement:
        case SyntaxKind.YieldExpression: {
            const pos = skipTrivia(sourceFile.text, (node as ReturnStatement | YieldExpression).pos);
            return getSpanOfTokenAtPosition(sourceFile, pos);
        }
        case SyntaxKind.SatisfiesExpression: {
            const pos = skipTrivia(sourceFile.text, (node as SatisfiesExpression).expression.end);
            return getSpanOfTokenAtPosition(sourceFile, pos);
        }
        case SyntaxKind.JSDocSatisfiesTag: {
            const pos = skipTrivia(sourceFile.text, (node as JSDocSatisfiesTag).tagName.pos);
            return getSpanOfTokenAtPosition(sourceFile, pos);
        }
        case SyntaxKind.Constructor: {
            const constructorDeclaration = node as ConstructorDeclaration;
            const start = skipTrivia(sourceFile.text, constructorDeclaration.pos);
            const scanner = createScanner(sourceFile.languageVersion, /*skipTrivia*/ true, sourceFile.languageVariant, sourceFile.text, /*onError*/ undefined, start);
            let token = scanner.scan();
            while (token !== SyntaxKind.ConstructorKeyword && token !== SyntaxKind.EndOfFileToken) {
                token = scanner.scan();
            }
            const end = scanner.getTokenEnd();
            return createTextSpanFromBounds(start, end);
        }
    }

    if (errorNode === undefined) {
        // If we don't have a better node, then just set the error on the first token of
        // construct.
        return getSpanOfTokenAtPosition(sourceFile, node.pos);
    }

    Debug.assert(!isJSDoc(errorNode));

    const isMissing = nodeIsMissing(errorNode);
    const pos = isMissing || isJsxText(node)
        ? errorNode.pos
        : skipTrivia(sourceFile.text, errorNode.pos);

    // These asserts should all be satisfied for a properly constructed `errorNode`.
    if (isMissing) {
        Debug.assert(pos === errorNode.pos, "This failure could trigger https://github.com/Microsoft/TypeScript/issues/20809");
        Debug.assert(pos === errorNode.end, "This failure could trigger https://github.com/Microsoft/TypeScript/issues/20809");
    }
    else {
        Debug.assert(pos >= errorNode.pos, "This failure could trigger https://github.com/Microsoft/TypeScript/issues/20809");
        Debug.assert(pos <= errorNode.end, "This failure could trigger https://github.com/Microsoft/TypeScript/issues/20809");
    }

    return createTextSpanFromBounds(pos, errorNode.end);
}

/** @internal */
export function isGlobalSourceFile(node: Node): boolean {
    return node.kind === SyntaxKind.SourceFile && !isExternalOrCommonJsModule(node as SourceFile);
}

/** @internal */
export function isExternalOrCommonJsModule(file: SourceFile): boolean {
    return (file.externalModuleIndicator || file.commonJsModuleIndicator) !== undefined;
}

/** @internal */
export function isJsonSourceFile(file: SourceFile): file is JsonSourceFile {
    return file.scriptKind === ScriptKind.JSON;
}

/** @internal */
export function isEnumConst(node: EnumDeclaration): boolean {
    return !!(getCombinedModifierFlags(node) & ModifierFlags.Const);
}

/** @internal */
export function isDeclarationReadonly(declaration: Declaration): boolean {
    return !!(getCombinedModifierFlags(declaration) & ModifierFlags.Readonly && !isParameterPropertyDeclaration(declaration, declaration.parent));
}

/**
 * Gets whether a bound `VariableDeclaration` or `VariableDeclarationList` is part of an `await using` declaration.
 * @internal
 */
export function isVarAwaitUsing(node: VariableDeclaration | VariableDeclarationList): boolean {
    return (getCombinedNodeFlags(node) & NodeFlags.BlockScoped) === NodeFlags.AwaitUsing;
}

/**
 * Gets whether a bound `VariableDeclaration` or `VariableDeclarationList` is part of a `using` declaration.
 * @internal
 */
export function isVarUsing(node: VariableDeclaration | VariableDeclarationList): boolean {
    return (getCombinedNodeFlags(node) & NodeFlags.BlockScoped) === NodeFlags.Using;
}

/**
 * Gets whether a bound `VariableDeclaration` or `VariableDeclarationList` is part of a `const` declaration.
 * @internal
 */
export function isVarConst(node: VariableDeclaration | VariableDeclarationList): boolean {
    return (getCombinedNodeFlags(node) & NodeFlags.BlockScoped) === NodeFlags.Const;
}

/**
 * Gets whether a bound `VariableDeclaration` or `VariableDeclarationList` is part of a `const`, `using` or `await using` declaration.
 * @internal
 */
export function isVarConstLike(node: VariableDeclaration | VariableDeclarationList): boolean {
    const blockScopeKind = getCombinedNodeFlags(node) & NodeFlags.BlockScoped;
    return blockScopeKind === NodeFlags.Const ||
        blockScopeKind === NodeFlags.Using ||
        blockScopeKind === NodeFlags.AwaitUsing;
}

/**
 * Gets whether a bound `VariableDeclaration` or `VariableDeclarationList` is part of a `let` declaration.
 * @internal
 */
export function isLet(node: Node): boolean {
    return (getCombinedNodeFlags(node) & NodeFlags.BlockScoped) === NodeFlags.Let;
}

/** @internal */
export function isSuperCall(n: Node): n is SuperCall {
    return n.kind === SyntaxKind.CallExpression && (n as CallExpression).expression.kind === SyntaxKind.SuperKeyword;
}

/** @internal */
export function isImportCall(n: Node): n is ImportCall {
    if (n.kind !== SyntaxKind.CallExpression) return false;
    const e = (n as CallExpression).expression;
    return e.kind === SyntaxKind.ImportKeyword || (
        isMetaProperty(e)
        && e.keywordToken === SyntaxKind.ImportKeyword
        && e.name.escapedText === "defer"
    );
}

/** @internal */
export function isImportMeta(n: Node): n is ImportMetaProperty {
    return isMetaProperty(n)
        && n.keywordToken === SyntaxKind.ImportKeyword
        && n.name.escapedText === "meta";
}

/** @internal */
export function isLiteralImportTypeNode(n: Node): n is LiteralImportTypeNode {
    return isImportTypeNode(n) && isLiteralTypeNode(n.argument) && isStringLiteral(n.argument.literal);
}

/** @internal */
export function isPrologueDirective(node: Node): node is PrologueDirective {
    return node.kind === SyntaxKind.ExpressionStatement
        && (node as ExpressionStatement).expression.kind === SyntaxKind.StringLiteral;
}

/** @internal */
export function isCustomPrologue(node: Statement): boolean {
    return !!(getEmitFlags(node) & EmitFlags.CustomPrologue);
}

/** @internal */
export function isHoistedFunction(node: Statement): boolean {
    return isCustomPrologue(node)
        && isFunctionDeclaration(node);
}

function isHoistedVariable(node: VariableDeclaration) {
    return isIdentifier(node.name)
        && !node.initializer;
}

/** @internal */
export function isHoistedVariableStatement(node: Statement): boolean {
    return isCustomPrologue(node)
        && isVariableStatement(node)
        && every(node.declarationList.declarations, isHoistedVariable);
}

/** @internal */
export function getLeadingCommentRangesOfNode(node: Node, sourceFileOfNode: SourceFile): CommentRange[] | undefined {
    return node.kind !== SyntaxKind.JsxText ? getLeadingCommentRanges(sourceFileOfNode.text, node.pos) : undefined;
}

/** @internal */
export function getJSDocCommentRanges(node: Node, text: string): CommentRange[] | undefined {
    const commentRanges = (node.kind === SyntaxKind.Parameter ||
            node.kind === SyntaxKind.TypeParameter ||
            node.kind === SyntaxKind.FunctionExpression ||
            node.kind === SyntaxKind.ArrowFunction ||
            node.kind === SyntaxKind.ParenthesizedExpression ||
            node.kind === SyntaxKind.VariableDeclaration ||
            node.kind === SyntaxKind.ExportSpecifier) ?
        concatenate(getTrailingCommentRanges(text, node.pos), getLeadingCommentRanges(text, node.pos)) :
        getLeadingCommentRanges(text, node.pos);
    // True if the comment starts with '/**' but not if it is '/**/'
    return filter(commentRanges, comment =>
        comment.end <= node.end && // Due to parse errors sometime empty parameter may get comments assigned to it that end up not in parameter range
        text.charCodeAt(comment.pos + 1) === CharacterCodes.asterisk &&
        text.charCodeAt(comment.pos + 2) === CharacterCodes.asterisk &&
        text.charCodeAt(comment.pos + 3) !== CharacterCodes.slash);
}

const fullTripleSlashReferencePathRegEx = /^\/\/\/\s*<reference\s+path\s*=\s*(?:'[^']*'|"[^"]*").*?\/>/;
const fullTripleSlashReferenceTypeReferenceDirectiveRegEx = /^\/\/\/\s*<reference\s+types\s*=\s*(?:'[^']*'|"[^"]*").*?\/>/;
const fullTripleSlashLibReferenceRegEx = /^\/\/\/\s*<reference\s+lib\s*=\s*(?:'[^']*'|"[^"]*").*?\/>/;
const fullTripleSlashAMDReferencePathRegEx = /^\/\/\/\s*<amd-dependency\s+path\s*=\s*(?:'[^']*'|"[^"]*").*?\/>/;
const fullTripleSlashAMDModuleRegEx = /^\/\/\/\s*<amd-module\s+(?:\S.*?)??\/>/;
const defaultLibReferenceRegEx = /^\/\/\/\s*<reference\s+no-default-lib\s*=\s*(?:'[^']*'|"[^"]*")\s*\/>/;

export function isPartOfTypeNode(node: Node): boolean {
    if (SyntaxKind.FirstTypeNode <= node.kind && node.kind <= SyntaxKind.LastTypeNode) {
        return true;
    }

    switch (node.kind) {
        case SyntaxKind.AnyKeyword:
        case SyntaxKind.UnknownKeyword:
        case SyntaxKind.NumberKeyword:
        case SyntaxKind.BigIntKeyword:
        case SyntaxKind.StringKeyword:
        case SyntaxKind.BooleanKeyword:
        case SyntaxKind.SymbolKeyword:
        case SyntaxKind.ObjectKeyword:
        case SyntaxKind.UndefinedKeyword:
        case SyntaxKind.NullKeyword:
        case SyntaxKind.NeverKeyword:
            return true;
        case SyntaxKind.VoidKeyword:
            return node.parent.kind !== SyntaxKind.VoidExpression;
        case SyntaxKind.ExpressionWithTypeArguments:
            return isPartOfTypeExpressionWithTypeArguments(node);
        case SyntaxKind.TypeParameter:
            return node.parent.kind === SyntaxKind.MappedType || node.parent.kind === SyntaxKind.InferType;

        // Identifiers and qualified names may be type nodes, depending on their context. Climb
        // above them to find the lowest container
        case SyntaxKind.Identifier:
            // If the identifier is the RHS of a qualified name, then it's a type iff its parent is.
            if (node.parent.kind === SyntaxKind.QualifiedName && (node.parent as QualifiedName).right === node) {
                node = node.parent;
            }
            else if (node.parent.kind === SyntaxKind.PropertyAccessExpression && (node.parent as PropertyAccessExpression).name === node) {
                node = node.parent;
            }
            // At this point, node is either a qualified name or an identifier
            Debug.assert(node.kind === SyntaxKind.Identifier || node.kind === SyntaxKind.QualifiedName || node.kind === SyntaxKind.PropertyAccessExpression, "'node' was expected to be a qualified name, identifier or property access in 'isPartOfTypeNode'.");
            // falls through

        case SyntaxKind.QualifiedName:
        case SyntaxKind.PropertyAccessExpression:
        case SyntaxKind.ThisKeyword: {
            const { parent } = node;
            if (parent.kind === SyntaxKind.TypeQuery) {
                return false;
            }
            if (parent.kind === SyntaxKind.ImportType) {
                return !(parent as ImportTypeNode).isTypeOf;
            }
            // Do not recursively call isPartOfTypeNode on the parent. In the example:
            //
            //     let a: A.B.C;
            //
            // Calling isPartOfTypeNode would consider the qualified name A.B a type node.
            // Only C and A.B.C are type nodes.
            if (SyntaxKind.FirstTypeNode <= parent.kind && parent.kind <= SyntaxKind.LastTypeNode) {
                return true;
            }
            switch (parent.kind) {
                case SyntaxKind.ExpressionWithTypeArguments:
                    return isPartOfTypeExpressionWithTypeArguments(parent);
                case SyntaxKind.TypeParameter:
                    return node === (parent as TypeParameterDeclaration).constraint;
                case SyntaxKind.JSDocTemplateTag:
                    return node === (parent as JSDocTemplateTag).constraint;
                case SyntaxKind.PropertyDeclaration:
                case SyntaxKind.PropertySignature:
                case SyntaxKind.Parameter:
                case SyntaxKind.VariableDeclaration:
                    return node === (parent as HasType).type;
                case SyntaxKind.FunctionDeclaration:
                case SyntaxKind.FunctionExpression:
                case SyntaxKind.ArrowFunction:
                case SyntaxKind.Constructor:
                case SyntaxKind.MethodDeclaration:
                case SyntaxKind.MethodSignature:
                case SyntaxKind.GetAccessor:
                case SyntaxKind.SetAccessor:
                    return node === (parent as FunctionLikeDeclaration).type;
                case SyntaxKind.CallSignature:
                case SyntaxKind.ConstructSignature:
                case SyntaxKind.IndexSignature:
                    return node === (parent as SignatureDeclaration).type;
                case SyntaxKind.TypeAssertionExpression:
                    return node === (parent as TypeAssertion).type;
                case SyntaxKind.CallExpression:
                case SyntaxKind.NewExpression:
                case SyntaxKind.TaggedTemplateExpression:
                    return contains((parent as CallExpression | TaggedTemplateExpression).typeArguments, node);
            }
        }
    }

    return false;
}

function isPartOfTypeExpressionWithTypeArguments(node: Node) {
    return isJSDocImplementsTag(node.parent)
        || isJSDocAugmentsTag(node.parent)
        || isHeritageClause(node.parent) && !isExpressionWithTypeArgumentsInClassExtendsClause(node);
}

// Warning: This has the same semantics as the forEach family of functions,
//          in that traversal terminates in the event that 'visitor' supplies a truthy value.
/** @internal */
export function forEachReturnStatement<T>(body: Block | Statement, visitor: (stmt: ReturnStatement) => T): T | undefined {
    return traverse(body);

    function traverse(node: Node): T | undefined {
        switch (node.kind) {
            case SyntaxKind.ReturnStatement:
                return visitor(node as ReturnStatement);
            case SyntaxKind.CaseBlock:
            case SyntaxKind.Block:
            case SyntaxKind.IfStatement:
            case SyntaxKind.DoStatement:
            case SyntaxKind.WhileStatement:
            case SyntaxKind.ForStatement:
            case SyntaxKind.ForInStatement:
            case SyntaxKind.ForOfStatement:
            case SyntaxKind.WithStatement:
            case SyntaxKind.SwitchStatement:
            case SyntaxKind.CaseClause:
            case SyntaxKind.DefaultClause:
            case SyntaxKind.LabeledStatement:
            case SyntaxKind.TryStatement:
            case SyntaxKind.CatchClause:
                return forEachChild(node, traverse);
        }
    }
}

// Warning: This has the same semantics as the forEach family of functions,
//          in that traversal terminates in the event that 'visitor' supplies a truthy value.
/** @internal */
export function forEachYieldExpression<T>(body: Block, visitor: (expr: YieldExpression) => T): T | undefined {
    return traverse(body);

    function traverse(node: Node): T | undefined {
        switch (node.kind) {
            case SyntaxKind.YieldExpression:
                const value = visitor(node as YieldExpression);
                if (value) {
                    return value;
                }
                const operand = (node as YieldExpression).expression;
                if (!operand) {
                    return;
                }
                return traverse(operand);
            case SyntaxKind.EnumDeclaration:
            case SyntaxKind.InterfaceDeclaration:
            case SyntaxKind.ModuleDeclaration:
            case SyntaxKind.TypeAliasDeclaration:
                // These are not allowed inside a generator now, but eventually they may be allowed
                // as local types. Regardless, skip them to avoid the work.
                return;
            default:
                if (isFunctionLike(node)) {
                    if (node.name && node.name.kind === SyntaxKind.ComputedPropertyName) {
                        // Note that we will not include methods/accessors of a class because they would require
                        // first descending into the class. This is by design.
                        return traverse(node.name.expression);
                    }
                }
                else if (!isPartOfTypeNode(node)) {
                    // This is the general case, which should include mostly expressions and statements.
                    // Also includes NodeArrays.
                    return forEachChild(node, traverse);
                }
        }
    }
}

/**
 * Gets the most likely element type for a TypeNode. This is not an exhaustive test
 * as it assumes a rest argument can only be an array type (either T[], or Array<T>).
 *
 * @param node The type node.
 *
 * @internal
 */
export function getRestParameterElementType(node: TypeNode | undefined): TypeNode | undefined {
    if (node && node.kind === SyntaxKind.ArrayType) {
        return (node as ArrayTypeNode).elementType;
    }
    else if (node && node.kind === SyntaxKind.TypeReference) {
        return singleOrUndefined((node as TypeReferenceNode).typeArguments);
    }
    else {
        return undefined;
    }
}

/** @internal */
export function getMembersOfDeclaration(node: Declaration): NodeArray<ClassElement | TypeElement | ObjectLiteralElement> | undefined {
    switch (node.kind) {
        case SyntaxKind.InterfaceDeclaration:
        case SyntaxKind.ClassDeclaration:
        case SyntaxKind.ClassExpression:
        case SyntaxKind.TypeLiteral:
            return (node as ObjectTypeDeclaration).members;
        case SyntaxKind.ObjectLiteralExpression:
            return (node as ObjectLiteralExpression).properties;
    }
}

/** @internal */
export function isVariableLike(node: Node): node is VariableLikeDeclaration {
    if (node) {
        switch (node.kind) {
            case SyntaxKind.BindingElement:
            case SyntaxKind.EnumMember:
            case SyntaxKind.Parameter:
            case SyntaxKind.PropertyAssignment:
            case SyntaxKind.PropertyDeclaration:
            case SyntaxKind.PropertySignature:
            case SyntaxKind.ShorthandPropertyAssignment:
            case SyntaxKind.VariableDeclaration:
                return true;
        }
    }
    return false;
}

/** @internal */
export function isVariableDeclarationInVariableStatement(node: VariableDeclaration): boolean {
    return node.parent.kind === SyntaxKind.VariableDeclarationList
        && node.parent.parent.kind === SyntaxKind.VariableStatement;
}

/** @internal */
export function isCommonJsExportedExpression(node: Node): boolean {
    if (!isInJSFile(node)) return false;
    return (isObjectLiteralExpression(node.parent) && isBinaryExpression(node.parent.parent) && getAssignmentDeclarationKind(node.parent.parent) === AssignmentDeclarationKind.ModuleExports) ||
        isCommonJsExportPropertyAssignment(node.parent);
}

/** @internal */
export function isCommonJsExportPropertyAssignment(node: Node): boolean {
    if (!isInJSFile(node)) return false;
    return (isBinaryExpression(node) && getAssignmentDeclarationKind(node) === AssignmentDeclarationKind.ExportsProperty);
}

/** @internal */
export function isValidESSymbolDeclaration(node: Node): boolean {
    return (isVariableDeclaration(node) ? isVarConst(node) && isIdentifier(node.name) && isVariableDeclarationInVariableStatement(node) :
        isPropertyDeclaration(node) ? hasEffectiveReadonlyModifier(node) && hasStaticModifier(node) :
        isPropertySignature(node) && hasEffectiveReadonlyModifier(node)) || isCommonJsExportPropertyAssignment(node);
}

/** @internal */
export function introducesArgumentsExoticObject(node: Node): boolean {
    switch (node.kind) {
        case SyntaxKind.MethodDeclaration:
        case SyntaxKind.MethodSignature:
        case SyntaxKind.Constructor:
        case SyntaxKind.GetAccessor:
        case SyntaxKind.SetAccessor:
        case SyntaxKind.FunctionDeclaration:
        case SyntaxKind.FunctionExpression:
            return true;
    }
    return false;
}

/** @internal */
export function unwrapInnermostStatementOfLabel(node: LabeledStatement, beforeUnwrapLabelCallback?: (node: LabeledStatement) => void): Statement {
    while (true) {
        if (beforeUnwrapLabelCallback) {
            beforeUnwrapLabelCallback(node);
        }
        if (node.statement.kind !== SyntaxKind.LabeledStatement) {
            return node.statement;
        }
        node = node.statement as LabeledStatement;
    }
}

/** @internal */
export function isFunctionBlock(node: Node): boolean {
    return node && node.kind === SyntaxKind.Block && isFunctionLike(node.parent);
}

/** @internal */
export function isObjectLiteralMethod(node: Node): node is MethodDeclaration {
    return node && node.kind === SyntaxKind.MethodDeclaration && node.parent.kind === SyntaxKind.ObjectLiteralExpression;
}

/** @internal */
export function isObjectLiteralOrClassExpressionMethodOrAccessor(node: Node): node is MethodDeclaration | AccessorDeclaration {
    return (node.kind === SyntaxKind.MethodDeclaration || node.kind === SyntaxKind.GetAccessor || node.kind === SyntaxKind.SetAccessor) &&
        (node.parent.kind === SyntaxKind.ObjectLiteralExpression ||
            node.parent.kind === SyntaxKind.ClassExpression);
}

/** @internal */
export function isIdentifierTypePredicate(predicate: TypePredicate): predicate is IdentifierTypePredicate {
    return predicate && predicate.kind === TypePredicateKind.Identifier;
}

/** @internal */
export function isThisTypePredicate(predicate: TypePredicate): predicate is ThisTypePredicate {
    return predicate && predicate.kind === TypePredicateKind.This;
}

/** @internal */
export function forEachPropertyAssignment<T>(objectLiteral: ObjectLiteralExpression | undefined, key: string, callback: (property: PropertyAssignment) => T | undefined, key2?: string): T | undefined {
    return forEach(objectLiteral?.properties, property => {
        if (!isPropertyAssignment(property)) return undefined;
        const propName = tryGetTextOfPropertyName(property.name);
        return key === propName || (key2 && key2 === propName) ?
            callback(property) :
            undefined;
    });
}

/** @internal */
export function getTsConfigObjectLiteralExpression(tsConfigSourceFile: TsConfigSourceFile | undefined): ObjectLiteralExpression | undefined {
    if (tsConfigSourceFile && tsConfigSourceFile.statements.length) {
        const expression = tsConfigSourceFile.statements[0].expression;
        return tryCast(expression, isObjectLiteralExpression);
    }
}

/** @internal */
export function getTsConfigPropArrayElementValue(tsConfigSourceFile: TsConfigSourceFile | undefined, propKey: string, elementValue: string): StringLiteral | undefined {
    return forEachTsConfigPropArray(tsConfigSourceFile, propKey, property =>
        isArrayLiteralExpression(property.initializer) ?
            find(property.initializer.elements, (element): element is StringLiteral => isStringLiteral(element) && element.text === elementValue) :
            undefined);
}

/** @internal */
export function forEachTsConfigPropArray<T>(tsConfigSourceFile: TsConfigSourceFile | undefined, propKey: string, callback: (property: PropertyAssignment) => T | undefined): T | undefined {
    return forEachPropertyAssignment(getTsConfigObjectLiteralExpression(tsConfigSourceFile), propKey, callback);
}

/** @internal */
export function getContainingFunction(node: Node): SignatureDeclaration | undefined {
    return findAncestor(node.parent, isFunctionLike);
}

/** @internal */
export function getContainingFunctionDeclaration(node: Node): FunctionLikeDeclaration | undefined {
    return findAncestor(node.parent, isFunctionLikeDeclaration);
}

/** @internal */
export function getContainingClass(node: Node): ClassLikeDeclaration | undefined {
    return findAncestor(node.parent, isClassLike);
}

/** @internal */
export function getContainingClassStaticBlock(node: Node): Node | undefined {
    return findAncestor(node.parent, n => {
        if (isClassLike(n) || isFunctionLike(n)) {
            return "quit";
        }
        return isClassStaticBlockDeclaration(n);
    });
}

/** @internal */
export function getContainingFunctionOrClassStaticBlock(node: Node): SignatureDeclaration | ClassStaticBlockDeclaration | undefined {
    return findAncestor(node.parent, isFunctionLikeOrClassStaticBlockDeclaration);
}

/** @internal */
export function getContainingClassExcludingClassDecorators(node: Node): ClassLikeDeclaration | undefined {
    const decorator = findAncestor(node.parent, n => isClassLike(n) ? "quit" : isDecorator(n));
    return decorator && isClassLike(decorator.parent) ? getContainingClass(decorator.parent) : getContainingClass(decorator ?? node);
}

/** @internal */
export type ThisContainer =
    | FunctionDeclaration
    | FunctionExpression
    | ModuleDeclaration
    | ClassStaticBlockDeclaration
    | PropertyDeclaration
    | PropertySignature
    | MethodDeclaration
    | MethodSignature
    | ConstructorDeclaration
    | GetAccessorDeclaration
    | SetAccessorDeclaration
    | CallSignatureDeclaration
    | ConstructSignatureDeclaration
    | IndexSignatureDeclaration
    | EnumDeclaration
    | SourceFile;

/** @internal */
export function getThisContainer(node: Node, includeArrowFunctions: false, includeClassComputedPropertyName: false): ThisContainer;
/** @internal */
export function getThisContainer(node: Node, includeArrowFunctions: false, includeClassComputedPropertyName: boolean): ThisContainer | ComputedPropertyName;
/** @internal */
export function getThisContainer(node: Node, includeArrowFunctions: boolean, includeClassComputedPropertyName: false): ThisContainer | ArrowFunction;
/** @internal */
export function getThisContainer(node: Node, includeArrowFunctions: boolean, includeClassComputedPropertyName: boolean): ThisContainer | ArrowFunction | ComputedPropertyName;
export function getThisContainer(node: Node, includeArrowFunctions: boolean, includeClassComputedPropertyName: boolean) {
    Debug.assert(node.kind !== SyntaxKind.SourceFile);
    while (true) {
        node = node.parent;
        if (!node) {
            return Debug.fail(); // If we never pass in a SourceFile, this should be unreachable, since we'll stop when we reach that.
        }
        switch (node.kind) {
            case SyntaxKind.ComputedPropertyName:
                // If the grandparent node is an object literal (as opposed to a class),
                // then the computed property is not a 'this' container.
                // A computed property name in a class needs to be a this container
                // so that we can error on it.
                if (includeClassComputedPropertyName && isClassLike(node.parent.parent)) {
                    return node as ComputedPropertyName;
                }
                // If this is a computed property, then the parent should not
                // make it a this container. The parent might be a property
                // in an object literal, like a method or accessor. But in order for
                // such a parent to be a this container, the reference must be in
                // the *body* of the container.
                node = node.parent.parent;
                break;
            case SyntaxKind.Decorator:
                // Decorators are always applied outside of the body of a class or method.
                if (node.parent.kind === SyntaxKind.Parameter && isClassElement(node.parent.parent)) {
                    // If the decorator's parent is a Parameter, we resolve the this container from
                    // the grandparent class declaration.
                    node = node.parent.parent;
                }
                else if (isClassElement(node.parent)) {
                    // If the decorator's parent is a class element, we resolve the 'this' container
                    // from the parent class declaration.
                    node = node.parent;
                }
                break;
            case SyntaxKind.ArrowFunction:
                if (!includeArrowFunctions) {
                    continue;
                }
                // falls through

            case SyntaxKind.FunctionDeclaration:
            case SyntaxKind.FunctionExpression:
            case SyntaxKind.ModuleDeclaration:
            case SyntaxKind.ClassStaticBlockDeclaration:
            case SyntaxKind.PropertyDeclaration:
            case SyntaxKind.PropertySignature:
            case SyntaxKind.MethodDeclaration:
            case SyntaxKind.MethodSignature:
            case SyntaxKind.Constructor:
            case SyntaxKind.GetAccessor:
            case SyntaxKind.SetAccessor:
            case SyntaxKind.CallSignature:
            case SyntaxKind.ConstructSignature:
            case SyntaxKind.IndexSignature:
            case SyntaxKind.EnumDeclaration:
            case SyntaxKind.SourceFile:
                return node as ThisContainer | ArrowFunction;
        }
    }
}

/**
 * @returns Whether the node creates a new 'this' scope for its children.
 *
 * @internal
 */
export function isThisContainerOrFunctionBlock(node: Node): boolean {
    switch (node.kind) {
        // Arrow functions use the same scope, but may do so in a "delayed" manner
        // For example, `const getThis = () => this` may be before a super() call in a derived constructor
        case SyntaxKind.ArrowFunction:
        case SyntaxKind.FunctionDeclaration:
        case SyntaxKind.FunctionExpression:
        case SyntaxKind.PropertyDeclaration:
            return true;
        case SyntaxKind.Block:
            switch (node.parent.kind) {
                case SyntaxKind.Constructor:
                case SyntaxKind.MethodDeclaration:
                case SyntaxKind.GetAccessor:
                case SyntaxKind.SetAccessor:
                    // Object properties can have computed names; only method-like bodies start a new scope
                    return true;
                default:
                    return false;
            }
        default:
            return false;
    }
}

/** @internal */
export function isInTopLevelContext(node: Node): boolean {
    // The name of a class or function declaration is a BindingIdentifier in its surrounding scope.
    if (isIdentifier(node) && (isClassDeclaration(node.parent) || isFunctionDeclaration(node.parent)) && node.parent.name === node) {
        node = node.parent;
    }
    const container = getThisContainer(node, /*includeArrowFunctions*/ true, /*includeClassComputedPropertyName*/ false);
    return isSourceFile(container);
}

/** @internal */
export function getNewTargetContainer(node: Node): FunctionDeclaration | ConstructorDeclaration | FunctionExpression | undefined {
    const container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false);
    if (container) {
        switch (container.kind) {
            case SyntaxKind.Constructor:
            case SyntaxKind.FunctionDeclaration:
            case SyntaxKind.FunctionExpression:
                return container;
        }
    }

    return undefined;
}

/** @internal */
export type SuperContainer =
    | PropertyDeclaration
    | PropertySignature
    | MethodDeclaration
    | MethodSignature
    | ConstructorDeclaration
    | GetAccessorDeclaration
    | SetAccessorDeclaration
    | ClassStaticBlockDeclaration;

/** @internal */
export type SuperContainerOrFunctions =
    | SuperContainer
    | FunctionDeclaration
    | FunctionExpression
    | ArrowFunction;

/**
 * Given an super call/property node, returns the closest node where
 * - a super call/property access is legal in the node and not legal in the parent node the node.
 *   i.e. super call is legal in constructor but not legal in the class body.
 * - the container is an arrow function (so caller might need to call getSuperContainer again in case it needs to climb higher)
 * - a super call/property is definitely illegal in the container (but might be legal in some subnode)
 *   i.e. super property access is illegal in function declaration but can be legal in the statement list
 *
 * @internal
 */
export function getSuperContainer(node: Node, stopOnFunctions: false): SuperContainer | undefined;
/** @internal */
export function getSuperContainer(node: Node, stopOnFunctions: boolean): SuperContainerOrFunctions | undefined;
export function getSuperContainer(node: Node, stopOnFunctions: boolean) {
    while (true) {
        node = node.parent;
        if (!node) {
            return undefined;
        }
        switch (node.kind) {
            case SyntaxKind.ComputedPropertyName:
                node = node.parent;
                break;
            case SyntaxKind.FunctionDeclaration:
            case SyntaxKind.FunctionExpression:
            case SyntaxKind.ArrowFunction:
                if (!stopOnFunctions) {
                    continue;
                }
                // falls through

            case SyntaxKind.PropertyDeclaration:
            case SyntaxKind.PropertySignature:
            case SyntaxKind.MethodDeclaration:
            case SyntaxKind.MethodSignature:
            case SyntaxKind.Constructor:
            case SyntaxKind.GetAccessor:
            case SyntaxKind.SetAccessor:
            case SyntaxKind.ClassStaticBlockDeclaration:
                return node as SuperContainerOrFunctions;
            case SyntaxKind.Decorator:
                // Decorators are always applied outside of the body of a class or method.
                if (node.parent.kind === SyntaxKind.Parameter && isClassElement(node.parent.parent)) {
                    // If the decorator's parent is a Parameter, we resolve the this container from
                    // the grandparent class declaration.
                    node = node.parent.parent;
                }
                else if (isClassElement(node.parent)) {
                    // If the decorator's parent is a class element, we resolve the 'this' container
                    // from the parent class declaration.
                    node = node.parent;
                }
                break;
        }
    }
}

/** @internal */
export function getImmediatelyInvokedFunctionExpression(func: Node): CallExpression | undefined {
    if (func.kind === SyntaxKind.FunctionExpression || func.kind === SyntaxKind.ArrowFunction) {
        let prev = func;
        let parent = func.parent;
        while (parent.kind === SyntaxKind.ParenthesizedExpression) {
            prev = parent;
            parent = parent.parent;
        }
        if (parent.kind === SyntaxKind.CallExpression && (parent as CallExpression).expression === prev) {
            return parent as CallExpression;
        }
    }
}

/**
 * Determines whether a node is a property or element access expression for `super`.
 *
 * @internal
 */
export function isSuperProperty(node: Node): node is SuperProperty {
    const kind = node.kind;
    return (kind === SyntaxKind.PropertyAccessExpression || kind === SyntaxKind.ElementAccessExpression)
        && (node as PropertyAccessExpression | ElementAccessExpression).expression.kind === SyntaxKind.SuperKeyword;
}

/**
 * Determines whether a node is a property or element access expression for `this`.
 *
 * @internal
 */
export function isThisProperty(node: Node): boolean {
    const kind = node.kind;
    return (kind === SyntaxKind.PropertyAccessExpression || kind === SyntaxKind.ElementAccessExpression)
        && (node as PropertyAccessExpression | ElementAccessExpression).expression.kind === SyntaxKind.ThisKeyword;
}

/** @internal */
export function isThisInitializedDeclaration(node: Node | undefined): boolean {
    return !!node && isVariableDeclaration(node) && node.initializer?.kind === SyntaxKind.ThisKeyword;
}

/** @internal */
export function isThisInitializedObjectBindingExpression(node: Node | undefined): boolean {
    return !!node
        && (isShorthandPropertyAssignment(node) || isPropertyAssignment(node))
        && isBinaryExpression(node.parent.parent)
        && node.parent.parent.operatorToken.kind === SyntaxKind.EqualsToken
        && node.parent.parent.right.kind === SyntaxKind.ThisKeyword;
}

/** @internal */
export function getEntityNameFromTypeNode(node: TypeNode): EntityNameOrEntityNameExpression | undefined {
    switch (node.kind) {
        case SyntaxKind.TypeReference:
            return (node as TypeReferenceNode).typeName;

        case SyntaxKind.ExpressionWithTypeArguments:
            return isEntityNameExpression((node as ExpressionWithTypeArguments).expression)
                ? (node as ExpressionWithTypeArguments).expression as EntityNameExpression
                : undefined;

        // TODO(rbuckton): These aren't valid TypeNodes, but we treat them as such because of `isPartOfTypeNode`, which returns `true` for things that aren't `TypeNode`s.
        case SyntaxKind.Identifier as TypeNodeSyntaxKind:
        case SyntaxKind.QualifiedName as TypeNodeSyntaxKind:
            return (node as Node as EntityName);
    }

    return undefined;
}

/** @internal */
export function getInvokedExpression(node: CallLikeExpression): Expression | JsxTagNameExpression {
    switch (node.kind) {
        case SyntaxKind.TaggedTemplateExpression:
            return node.tag;
        case SyntaxKind.JsxOpeningElement:
        case SyntaxKind.JsxSelfClosingElement:
            return node.tagName;
        case SyntaxKind.BinaryExpression:
            return node.right;
        case SyntaxKind.JsxOpeningFragment:
            return node;
        default:
            return node.expression;
    }
}

/** @internal */
export function nodeCanBeDecorated(useLegacyDecorators: boolean, node: ClassDeclaration): true;
/** @internal */
export function nodeCanBeDecorated(useLegacyDecorators: boolean, node: ClassExpression): boolean;
/** @internal */
export function nodeCanBeDecorated(useLegacyDecorators: boolean, node: ClassElement, parent: Node): boolean;
/** @internal */
export function nodeCanBeDecorated(useLegacyDecorators: boolean, node: Node, parent: Node, grandparent: Node): boolean;
/** @internal */
export function nodeCanBeDecorated(useLegacyDecorators: boolean, node: Node, parent?: Node, grandparent?: Node): boolean {
    // private names cannot be used with decorators yet
    if (useLegacyDecorators && isNamedDeclaration(node) && isPrivateIdentifier(node.name)) {
        return false;
    }

    switch (node.kind) {
        case SyntaxKind.ClassDeclaration:
            // class declarations are valid targets
            return true;

        case SyntaxKind.ClassExpression:
            // class expressions are valid targets for native decorators
            return !useLegacyDecorators;

        case SyntaxKind.PropertyDeclaration:
            // property declarations are valid if their parent is a class declaration.
            return parent !== undefined
                && (useLegacyDecorators ? isClassDeclaration(parent) : isClassLike(parent) && !hasAbstractModifier(node) && !hasAmbientModifier(node));

        case SyntaxKind.GetAccessor:
        case SyntaxKind.SetAccessor:
        case SyntaxKind.MethodDeclaration:
            // if this method has a body and its parent is a class declaration, this is a valid target.
            return (node as FunctionLikeDeclaration).body !== undefined
                && parent !== undefined
                && (useLegacyDecorators ? isClassDeclaration(parent) : isClassLike(parent));

        case SyntaxKind.Parameter:
            // TODO(rbuckton): Parameter decorator support for ES decorators must wait until it is standardized
            if (!useLegacyDecorators) return false;
            // if the parameter's parent has a body and its grandparent is a class declaration, this is a valid target.
            return parent !== undefined
                && (parent as FunctionLikeDeclaration).body !== undefined
                && (parent.kind === SyntaxKind.Constructor
                    || parent.kind === SyntaxKind.MethodDeclaration
                    || parent.kind === SyntaxKind.SetAccessor)
                && getThisParameter(parent as FunctionLikeDeclaration) !== node
                && grandparent !== undefined
                && grandparent.kind === SyntaxKind.ClassDeclaration;
    }

    return false;
}

/** @internal */
export function nodeIsDecorated(useLegacyDecorators: boolean, node: ClassDeclaration | ClassExpression): boolean;
/** @internal */
export function nodeIsDecorated(useLegacyDecorators: boolean, node: ClassElement, parent: Node): boolean;
/** @internal */
export function nodeIsDecorated(useLegacyDecorators: boolean, node: Node, parent: Node, grandparent: Node): boolean;
/** @internal */
export function nodeIsDecorated(useLegacyDecorators: boolean, node: Node, parent?: Node, grandparent?: Node): boolean {
    return hasDecorators(node)
        && nodeCanBeDecorated(useLegacyDecorators, node, parent!, grandparent!);
}

/** @internal */
export function nodeOrChildIsDecorated(useLegacyDecorators: boolean, node: ClassDeclaration | ClassExpression): boolean;
/** @internal */
export function nodeOrChildIsDecorated(useLegacyDecorators: boolean, node: ClassElement, parent: Node): boolean;
/** @internal */
export function nodeOrChildIsDecorated(useLegacyDecorators: boolean, node: Node, parent: Node, grandparent: Node): boolean;
/** @internal */
export function nodeOrChildIsDecorated(useLegacyDecorators: boolean, node: Node, parent?: Node, grandparent?: Node): boolean {
    return nodeIsDecorated(useLegacyDecorators, node, parent!, grandparent!)
        || childIsDecorated(useLegacyDecorators, node, parent!);
}

/** @internal */
export function childIsDecorated(useLegacyDecorators: boolean, node: ClassDeclaration | ClassExpression): boolean;
/** @internal */
export function childIsDecorated(useLegacyDecorators: boolean, node: Node, parent: Node): boolean;
/** @internal */
export function childIsDecorated(useLegacyDecorators: boolean, node: Node, parent?: Node): boolean {
    switch (node.kind) {
        case SyntaxKind.ClassDeclaration:
            return some((node as ClassDeclaration).members, m => nodeOrChildIsDecorated(useLegacyDecorators, m, node, parent!));
        case SyntaxKind.ClassExpression:
            return !useLegacyDecorators && some((node as ClassExpression).members, m => nodeOrChildIsDecorated(useLegacyDecorators, m, node, parent!));
        case SyntaxKind.MethodDeclaration:
        case SyntaxKind.SetAccessor:
        case SyntaxKind.Constructor:
            return some((node as FunctionLikeDeclaration).parameters, p => nodeIsDecorated(useLegacyDecorators, p, node, parent!));
        default:
            return false;
    }
}

/** @internal */
export function classOrConstructorParameterIsDecorated(useLegacyDecorators: boolean, node: ClassDeclaration | ClassExpression): boolean {
    if (nodeIsDecorated(useLegacyDecorators, node)) return true;
    const constructor = getFirstConstructorWithBody(node);
    return !!constructor && childIsDecorated(useLegacyDecorators, constructor, node);
}

/** @internal */
export function classElementOrClassElementParameterIsDecorated(useLegacyDecorators: boolean, node: ClassElement, parent: ClassDeclaration | ClassExpression): boolean {
    let parameters: NodeArray<ParameterDeclaration> | undefined;
    if (isAccessor(node)) {
        const { firstAccessor, secondAccessor, setAccessor } = getAllAccessorDeclarations(parent.members, node);
        const firstAccessorWithDecorators = hasDecorators(firstAccessor) ? firstAccessor :
            secondAccessor && hasDecorators(secondAccessor) ? secondAccessor :
            undefined;
        if (!firstAccessorWithDecorators || node !== firstAccessorWithDecorators) {
            return false;
        }
        parameters = setAccessor?.parameters;
    }
    else if (isMethodDeclaration(node)) {
        parameters = node.parameters;
    }
    if (nodeIsDecorated(useLegacyDecorators, node, parent)) {
        return true;
    }
    if (parameters) {
        for (const parameter of parameters) {
            if (parameterIsThisKeyword(parameter)) continue;
            if (nodeIsDecorated(useLegacyDecorators, parameter, node, parent)) return true;
        }
    }
    return false;
}

/** @internal */
export function isEmptyStringLiteral(node: StringLiteral): boolean {
    if (node.textSourceNode) {
        switch (node.textSourceNode.kind) {
            case SyntaxKind.StringLiteral:
                return isEmptyStringLiteral(node.textSourceNode);
            case SyntaxKind.NoSubstitutionTemplateLiteral:
                return node.text === "";
        }
        return false;
    }
    return node.text === "";
}

/** @internal */
export function isJSXTagName(node: Node): boolean {
    const { parent } = node;
    if (
        parent.kind === SyntaxKind.JsxOpeningElement ||
        parent.kind === SyntaxKind.JsxSelfClosingElement ||
        parent.kind === SyntaxKind.JsxClosingElement
    ) {
        return (parent as JsxOpeningLikeElement).tagName === node;
    }
    return false;
}

/** @internal */
export function isExpressionNode(node: Node): boolean {
    switch (node.kind) {
        case SyntaxKind.SuperKeyword:
        case SyntaxKind.NullKeyword:
        case SyntaxKind.TrueKeyword:
        case SyntaxKind.FalseKeyword:
        case SyntaxKind.RegularExpressionLiteral:
        case SyntaxKind.ArrayLiteralExpression:
        case SyntaxKind.ObjectLiteralExpression:
        case SyntaxKind.PropertyAccessExpression:
        case SyntaxKind.ElementAccessExpression:
        case SyntaxKind.CallExpression:
        case SyntaxKind.NewExpression:
        case SyntaxKind.TaggedTemplateExpression:
        case SyntaxKind.AsExpression:
        case SyntaxKind.TypeAssertionExpression:
        case SyntaxKind.SatisfiesExpression:
        case SyntaxKind.NonNullExpression:
        case SyntaxKind.ParenthesizedExpression:
        case SyntaxKind.FunctionExpression:
        case SyntaxKind.ClassExpression:
        case SyntaxKind.ArrowFunction:
        case SyntaxKind.VoidExpression:
        case SyntaxKind.DeleteExpression:
        case SyntaxKind.TypeOfExpression:
        case SyntaxKind.PrefixUnaryExpression:
        case SyntaxKind.PostfixUnaryExpression:
        case SyntaxKind.BinaryExpression:
        case SyntaxKind.ConditionalExpression:
        case SyntaxKind.SpreadElement:
        case SyntaxKind.TemplateExpression:
        case SyntaxKind.OmittedExpression:
        case SyntaxKind.JsxElement:
        case SyntaxKind.JsxSelfClosingElement:
        case SyntaxKind.JsxFragment:
        case SyntaxKind.YieldExpression:
        case SyntaxKind.AwaitExpression:
            return true;
        case SyntaxKind.MetaProperty:
            // `import.defer` in `import.defer(...)` is not an expression
            return !isImportCall(node.parent) || node.parent.expression !== node;
        case SyntaxKind.ExpressionWithTypeArguments:
            return !isHeritageClause(node.parent) && !isJSDocAugmentsTag(node.parent);
        case SyntaxKind.QualifiedName:
            while (node.parent.kind === SyntaxKind.QualifiedName) {
                node = node.parent;
            }
            return node.parent.kind === SyntaxKind.TypeQuery || isJSDocLinkLike(node.parent) || isJSDocNameReference(node.parent) || isJSDocMemberName(node.parent) || isJSXTagName(node);
        case SyntaxKind.JSDocMemberName:
            while (isJSDocMemberName(node.parent)) {
                node = node.parent;
            }
            return node.parent.kind === SyntaxKind.TypeQuery || isJSDocLinkLike(node.parent) || isJSDocNameReference(node.parent) || isJSDocMemberName(node.parent) || isJSXTagName(node);
        case SyntaxKind.PrivateIdentifier:
            return isBinaryExpression(node.parent) && node.parent.left === node && node.parent.operatorToken.kind === SyntaxKind.InKeyword;
        case SyntaxKind.Identifier:
            if (node.parent.kind === SyntaxKind.TypeQuery || isJSDocLinkLike(node.parent) || isJSDocNameReference(node.parent) || isJSDocMemberName(node.parent) || isJSXTagName(node)) {
                return true;
            }
            // falls through

        case SyntaxKind.NumericLiteral:
        case SyntaxKind.BigIntLiteral:
        case SyntaxKind.StringLiteral:
        case SyntaxKind.NoSubstitutionTemplateLiteral:
        case SyntaxKind.ThisKeyword:
            return isInExpressionContext(node);
        default:
            return false;
    }
}

/** @internal */
export function isInExpressionContext(node: Node): boolean {
    const { parent } = node;
    switch (parent.kind) {
        case SyntaxKind.VariableDeclaration:
        case SyntaxKind.Parameter:
        case SyntaxKind.PropertyDeclaration:
        case SyntaxKind.PropertySignature:
        case SyntaxKind.EnumMember:
        case SyntaxKind.PropertyAssignment:
        case SyntaxKind.BindingElement:
            return (parent as HasInitializer).initializer === node;
        case SyntaxKind.ExpressionStatement:
        case SyntaxKind.IfStatement:
        case SyntaxKind.DoStatement:
        case SyntaxKind.WhileStatement:
        case SyntaxKind.ReturnStatement:
        case SyntaxKind.WithStatement:
        case SyntaxKind.SwitchStatement:
        case SyntaxKind.CaseClause:
        case SyntaxKind.ThrowStatement:
            return (parent as ExpressionStatement).expression === node;
        case SyntaxKind.ForStatement:
            const forStatement = parent as ForStatement;
            return (forStatement.initializer === node && forStatement.initializer.kind !== SyntaxKind.VariableDeclarationList) ||
                forStatement.condition === node ||
                forStatement.incrementor === node;
        case SyntaxKind.ForInStatement:
        case SyntaxKind.ForOfStatement:
            const forInOrOfStatement = parent as ForInOrOfStatement;
            return (forInOrOfStatement.initializer === node && forInOrOfStatement.initializer.kind !== SyntaxKind.VariableDeclarationList) ||
                forInOrOfStatement.expression === node;
        case SyntaxKind.TypeAssertionExpression:
        case SyntaxKind.AsExpression:
            return node === (parent as AssertionExpression).expression;
        case SyntaxKind.TemplateSpan:
            return node === (parent as TemplateSpan).expression;
        case SyntaxKind.ComputedPropertyName:
            return node === (parent as ComputedPropertyName).expression;
        case SyntaxKind.Decorator:
        case SyntaxKind.JsxExpression:
        case SyntaxKind.JsxSpreadAttribute:
        case SyntaxKind.SpreadAssignment:
            return true;
        case SyntaxKind.ExpressionWithTypeArguments:
            return (parent as ExpressionWithTypeArguments).expression === node && !isPartOfTypeNode(parent);
        case SyntaxKind.ShorthandPropertyAssignment:
            // TODO(jakebailey): it's possible that node could be the name, too
            return (parent as ShorthandPropertyAssignment).objectAssignmentInitializer === node;
        case SyntaxKind.SatisfiesExpression:
            return node === (parent as SatisfiesExpression).expression;
        default:
            return isExpressionNode(parent);
    }
}

/** @internal */
export function isPartOfTypeQuery(node: Node): boolean {
    while (node.kind === SyntaxKind.QualifiedName || node.kind === SyntaxKind.Identifier) {
        node = node.parent;
    }
    return node.kind === SyntaxKind.TypeQuery;
}

/** @internal */
export function isNamespaceReexportDeclaration(node: Node): boolean {
    return isNamespaceExport(node) && !!node.parent.moduleSpecifier;
}

/** @internal */
export function isExternalModuleImportEqualsDeclaration(node: Node): node is ImportEqualsDeclaration & { moduleReference: ExternalModuleReference; } {
    return node.kind === SyntaxKind.ImportEqualsDeclaration && (node as ImportEqualsDeclaration).moduleReference.kind === SyntaxKind.ExternalModuleReference;
}

/** @internal */
export function getExternalModuleImportEqualsDeclarationExpression(node: Node): Expression {
    Debug.assert(isExternalModuleImportEqualsDeclaration(node));
    return ((node as ImportEqualsDeclaration).moduleReference as ExternalModuleReference).expression;
}

/** @internal */
export function getExternalModuleRequireArgument(node: Node): false | StringLiteral {
    return isVariableDeclarationInitializedToBareOrAccessedRequire(node) && (getLeftmostAccessExpression(node.initializer) as CallExpression).arguments[0] as StringLiteral;
}

/** @internal */
export function isInternalModuleImportEqualsDeclaration(node: Node): node is ImportEqualsDeclaration {
    return node.kind === SyntaxKind.ImportEqualsDeclaration && (node as ImportEqualsDeclaration).moduleReference.kind !== SyntaxKind.ExternalModuleReference;
}

/** @internal */
export function isFullSourceFile(sourceFile: object): sourceFile is SourceFile {
    return (sourceFile as Partial<SourceFile>)?.kind === SyntaxKind.SourceFile;
}

/** @internal */
export function isSourceFileJS(file: SourceFile): boolean {
    return isInJSFile(file);
}

/** @internal */
export function isInJSFile(node: Node | undefined): boolean {
    return !!node && !!(node.flags & NodeFlags.JavaScriptFile);
}

/** @internal */
export function isInJsonFile(node: Node | undefined): boolean {
    return !!node && !!(node.flags & NodeFlags.JsonFile);
}

/** @internal */
export function isSourceFileNotJson(file: SourceFile): boolean {
    return !isJsonSourceFile(file);
}

/** @internal */
export function isInJSDoc(node: Node | undefined): boolean {
    return !!node && !!(node.flags & NodeFlags.JSDoc);
}

/** @internal */
export function isJSDocIndexSignature(node: TypeReferenceNode | ExpressionWithTypeArguments): boolean | undefined {
    return isTypeReferenceNode(node) &&
        isIdentifier(node.typeName) &&
        node.typeName.escapedText === "Object" &&
        node.typeArguments && node.typeArguments.length === 2 &&
        (node.typeArguments[0].kind === SyntaxKind.StringKeyword || node.typeArguments[0].kind === SyntaxKind.NumberKeyword);
}

/**
 * Returns true if the node is a CallExpression to the identifier 'require' with
 * exactly one argument (of the form 'require("name")').
 * This function does not test if the node is in a JavaScript file or not.
 *
 * @internal
 */
export function isRequireCall(callExpression: Node, requireStringLiteralLikeArgument: true): callExpression is RequireOrImportCall & { expression: Identifier; arguments: [StringLiteralLike]; };
/** @internal */
export function isRequireCall(callExpression: Node, requireStringLiteralLikeArgument: boolean): callExpression is CallExpression;
/** @internal */
export function isRequireCall(callExpression: Node, requireStringLiteralLikeArgument: boolean): callExpression is CallExpression {
    if (callExpression.kind !== SyntaxKind.CallExpression) {
        return false;
    }
    const { expression, arguments: args } = callExpression as CallExpression;

    if (expression.kind !== SyntaxKind.Identifier || (expression as Identifier).escapedText !== "require") {
        return false;
    }

    if (args.length !== 1) {
        return false;
    }
    const arg = args[0];
    return !requireStringLiteralLikeArgument || isStringLiteralLike(arg);
}

/**
 * Returns true if the node is a VariableDeclaration initialized to a require call (see `isRequireCall`).
 * This function does not test if the node is in a JavaScript file or not.
 *
 * @internal
 */
export function isVariableDeclarationInitializedToRequire(node: Node): node is VariableDeclarationInitializedTo<RequireOrImportCall> {
    return isVariableDeclarationInitializedWithRequireHelper(node, /*allowAccessedRequire*/ false);
}

/**
 * Like {@link isVariableDeclarationInitializedToRequire} but allows things like `require("...").foo.bar` or `require("...")["baz"]`.
 *
 * @internal
 */
export function isVariableDeclarationInitializedToBareOrAccessedRequire(node: Node): node is VariableDeclarationInitializedTo<RequireOrImportCall | AccessExpression> {
    return isVariableDeclarationInitializedWithRequireHelper(node, /*allowAccessedRequire*/ true);
}

/** @internal */
export function isBindingElementOfBareOrAccessedRequire(node: Node): node is BindingElementOfBareOrAccessedRequire {
    return isBindingElement(node) && isVariableDeclarationInitializedToBareOrAccessedRequire(node.parent.parent);
}

/** @internal */
export function getModuleSpecifierOfBareOrAccessedRequire(node: VariableDeclarationInitializedTo<RequireOrImportCall | AccessExpression>): StringLiteralLike | undefined {
    if (isVariableDeclarationInitializedToRequire(node)) {
        return node.initializer.arguments[0];
    }
    if (isVariableDeclarationInitializedToBareOrAccessedRequire(node)) {
        const leftmost = getLeftmostAccessExpression(node.initializer);
        if (isRequireCall(leftmost, /*requireStringLiteralLikeArgument*/ true)) {
            return leftmost.arguments[0];
        }
    }
    return undefined;
}

function isVariableDeclarationInitializedWithRequireHelper(node: Node, allowAccessedRequire: boolean) {
    return isVariableDeclaration(node) &&
        !!node.initializer &&
        isRequireCall(allowAccessedRequire ? getLeftmostAccessExpression(node.initializer) : node.initializer, /*requireStringLiteralLikeArgument*/ true);
}

/** @internal */
export function isRequireVariableStatement(node: Node): node is RequireVariableStatement {
    return isVariableStatement(node)
        && node.declarationList.declarations.length > 0
        && every(node.declarationList.declarations, decl => isVariableDeclarationInitializedToRequire(decl));
}

/** @internal */
export function isSingleOrDoubleQuote(charCode: number): boolean {
    return charCode === CharacterCodes.singleQuote || charCode === CharacterCodes.doubleQuote;
}

/** @internal */
export function isStringDoubleQuoted(str: StringLiteralLike, sourceFile: SourceFile): boolean {
    return getSourceTextOfNodeFromSourceFile(sourceFile, str).charCodeAt(0) === CharacterCodes.doubleQuote;
}

/** @internal */
export function isAssignmentDeclaration(decl: Declaration): boolean {
    return isBinaryExpression(decl) || isAccessExpression(decl) || isIdentifier(decl) || isCallExpression(decl);
}

/**
 * Get the initializer, taking into account defaulted Javascript initializers
 *
 * @internal
 */
export function getEffectiveInitializer(node: HasExpressionInitializer): Expression | undefined {
    if (
        isInJSFile(node) && node.initializer &&
        isBinaryExpression(node.initializer) &&
        (node.initializer.operatorToken.kind === SyntaxKind.BarBarToken || node.initializer.operatorToken.kind === SyntaxKind.QuestionQuestionToken) &&
        node.name && isEntityNameExpression(node.name) && isSameEntityName(node.name, node.initializer.left)
    ) {
        return node.initializer.right;
    }
    return node.initializer;
}

/**
 * Get the declaration initializer when it is container-like (See getExpandoInitializer).
 *
 * @internal
 */
export function getDeclaredExpandoInitializer(node: HasExpressionInitializer): Expression | undefined {
    const init = getEffectiveInitializer(node);
    return init && getExpandoInitializer(init, isPrototypeAccess(node.name));
}

function hasExpandoValueProperty(node: ObjectLiteralExpression, isPrototypeAssignment: boolean) {
    return forEach(node.properties, p =>
        isPropertyAssignment(p) &&
        isIdentifier(p.name) &&
        p.name.escapedText === "value" &&
        p.initializer &&
        getExpandoInitializer(p.initializer, isPrototypeAssignment));
}

/**
 * Get the assignment 'initializer' -- the righthand side-- when the initializer is container-like (See getExpandoInitializer).
 * We treat the right hand side of assignments with container-like initializers as declarations.
 *
 * @internal
 */
export function getAssignedExpandoInitializer(node: Node | undefined): Expression | undefined {
    if (node && node.parent && isBinaryExpression(node.parent) && node.parent.operatorToken.kind === SyntaxKind.EqualsToken) {
        const isPrototypeAssignment = isPrototypeAccess(node.parent.left);
        return getExpandoInitializer(node.parent.right, isPrototypeAssignment) ||
            getDefaultedExpandoInitializer(node.parent.left, node.parent.right, isPrototypeAssignment);
    }
    if (node && isCallExpression(node) && isBindableObjectDefinePropertyCall(node)) {
        const result = hasExpandoValueProperty(node.arguments[2], node.arguments[1].text === "prototype");
        if (result) {
            return result;
        }
    }
}

/**
 * Recognized expando initializers are:
 * 1. (function() {})() -- IIFEs
 * 2. function() { } -- Function expressions
 * 3. class { } -- Class expressions
 * 4. {} -- Empty object literals
 * 5. { ... } -- Non-empty object literals, when used to initialize a prototype, like `C.prototype = { m() { } }`
 *
 * This function returns the provided initializer, or undefined if it is not valid.
 *
 * @internal
 */
export function getExpandoInitializer(initializer: Node, isPrototypeAssignment: boolean): Expression | undefined {
    if (isCallExpression(initializer)) {
        const e = skipParentheses(initializer.expression);
        return e.kind === SyntaxKind.FunctionExpression || e.kind === SyntaxKind.ArrowFunction ? initializer : undefined;
    }
    if (
        initializer.kind === SyntaxKind.FunctionExpression ||
        initializer.kind === SyntaxKind.ClassExpression ||
        initializer.kind === SyntaxKind.ArrowFunction
    ) {
        return initializer as Expression;
    }
    if (isObjectLiteralExpression(initializer) && (initializer.properties.length === 0 || isPrototypeAssignment)) {
        return initializer;
    }
}

/**
 * A defaulted expando initializer matches the pattern
 * `Lhs = Lhs || ExpandoInitializer`
 * or `var Lhs = Lhs || ExpandoInitializer`
 *
 * The second Lhs is required to be the same as the first except that it may be prefixed with
 * 'window.', 'global.' or 'self.' The second Lhs is otherwise ignored by the binder and checker.
 */
function getDefaultedExpandoInitializer(name: Expression, initializer: Expression, isPrototypeAssignment: boolean) {
    const e = isBinaryExpression(initializer)
        && (initializer.operatorToken.kind === SyntaxKind.BarBarToken || initializer.operatorToken.kind === SyntaxKind.QuestionQuestionToken)
        && getExpandoInitializer(initializer.right, isPrototypeAssignment);
    if (e && isSameEntityName(name, initializer.left)) {
        return e;
    }
}

/** @internal */
export function isDefaultedExpandoInitializer(node: BinaryExpression): boolean | undefined {
    const name = isVariableDeclaration(node.parent) ? node.parent.name :
        isBinaryExpression(node.parent) && node.parent.operatorToken.kind === SyntaxKind.EqualsToken ? node.parent.left :
        undefined;
    return name && getExpandoInitializer(node.right, isPrototypeAccess(name)) && isEntityNameExpression(name) && isSameEntityName(name, node.left);
}

/**
 * Given an expando initializer, return its declaration name, or the left-hand side of the assignment if it's part of an assignment declaration.
 *
 * @internal
 */
export function getNameOfExpando(node: Declaration): DeclarationName | undefined {
    if (isBinaryExpression(node.parent)) {
        const parent = ((node.parent.operatorToken.kind === SyntaxKind.BarBarToken || node.parent.operatorToken.kind === SyntaxKind.QuestionQuestionToken) && isBinaryExpression(node.parent.parent)) ? node.parent.parent : node.parent;
        if (parent.operatorToken.kind === SyntaxKind.EqualsToken && isIdentifier(parent.left)) {
            return parent.left;
        }
    }
    else if (isVariableDeclaration(node.parent)) {
        return node.parent.name;
    }
}

/**
 * Is the 'declared' name the same as the one in the initializer?
 * @return true for identical entity names, as well as ones where the initializer is prefixed with
 * 'window', 'self' or 'global'. For example:
 *
 * var my = my || {}
 * var min = window.min || {}
 * my.app = self.my.app || class { }
 *
 * @internal
 */
export function isSameEntityName(name: Expression, initializer: Expression): boolean {
    if (isPropertyNameLiteral(name) && isPropertyNameLiteral(initializer)) {
        return getTextOfIdentifierOrLiteral(name) === getTextOfIdentifierOrLiteral(initializer);
    }
    if (
        isMemberName(name) && isLiteralLikeAccess(initializer) &&
        (initializer.expression.kind === SyntaxKind.ThisKeyword ||
            isIdentifier(initializer.expression) &&
                (initializer.expression.escapedText === "window" ||
                    initializer.expression.escapedText === "self" ||
                    initializer.expression.escapedText === "global"))
    ) {
        return isSameEntityName(name, getNameOrArgument(initializer));
    }
    if (isLiteralLikeAccess(name) && isLiteralLikeAccess(initializer)) {
        return getElementOrPropertyAccessName(name) === getElementOrPropertyAccessName(initializer)
            && isSameEntityName(name.expression, initializer.expression);
    }
    return false;
}

/** @internal */
export function getRightMostAssignedExpression(node: Expression): Expression {
    while (isAssignmentExpression(node, /*excludeCompoundAssignment*/ true)) {
        node = node.right;
    }
    return node;
}

/** @internal */
export function isExportsIdentifier(node: Node): boolean {
    return isIdentifier(node) && node.escapedText === "exports";
}

/** @internal */
export function isModuleIdentifier(node: Node): boolean {
    return isIdentifier(node) && node.escapedText === "module";
}

/** @internal */
export function isModuleExportsAccessExpression(node: Node): node is LiteralLikeElementAccessExpression & { expression: Identifier; } {
    return (isPropertyAccessExpression(node) || isLiteralLikeElementAccess(node))
        && isModuleIdentifier(node.expression)
        && getElementOrPropertyAccessName(node) === "exports";
}

/// Given a BinaryExpression, returns SpecialPropertyAssignmentKind for the various kinds of property
/// assignments we treat as special in the binder
/** @internal */
export function getAssignmentDeclarationKind(expr: BinaryExpression | CallExpression): AssignmentDeclarationKind {
    const special = getAssignmentDeclarationKindWorker(expr);
    return special === AssignmentDeclarationKind.Property || isInJSFile(expr) ? special : AssignmentDeclarationKind.None;
}

/** @internal */
export function isBindableObjectDefinePropertyCall(expr: CallExpression): expr is BindableObjectDefinePropertyCall {
    return length(expr.arguments) === 3 &&
        isPropertyAccessExpression(expr.expression) &&
        isIdentifier(expr.expression.expression) &&
        idText(expr.expression.expression) === "Object" &&
        idText(expr.expression.name) === "defineProperty" &&
        isStringOrNumericLiteralLike(expr.arguments[1]) &&
        isBindableStaticNameExpression(expr.arguments[0], /*excludeThisKeyword*/ true);
}

/**
 * x.y OR x[0]
 */
function isLiteralLikeAccess(node: Node): node is LiteralLikeElementAccessExpression | PropertyAccessExpression {
    return isPropertyAccessExpression(node) || isLiteralLikeElementAccess(node);
}

/**
 * x[0] OR x['a'] OR x[Symbol.y]
 */
function isLiteralLikeElementAccess(node: Node): node is LiteralLikeElementAccessExpression {
    return isElementAccessExpression(node) && isStringOrNumericLiteralLike(node.argumentExpression);
}

/**
 * Any series of property and element accesses.
 *
 * @internal
 */
export function isBindableStaticAccessExpression(node: Node, excludeThisKeyword?: boolean): node is BindableStaticAccessExpression {
    return isPropertyAccessExpression(node) && (!excludeThisKeyword && node.expression.kind === SyntaxKind.ThisKeyword || isIdentifier(node.name) && isBindableStaticNameExpression(node.expression, /*excludeThisKeyword*/ true))
        || isBindableStaticElementAccessExpression(node, excludeThisKeyword);
}

/**
 * Any series of property and element accesses, ending in a literal element access
 *
 * @internal
 */
export function isBindableStaticElementAccessExpression(node: Node, excludeThisKeyword?: boolean): node is BindableStaticElementAccessExpression {
    return isLiteralLikeElementAccess(node)
        && ((!excludeThisKeyword && node.expression.kind === SyntaxKind.ThisKeyword) ||
            isEntityNameExpression(node.expression) ||
            isBindableStaticAccessExpression(node.expression, /*excludeThisKeyword*/ true));
}

/** @internal */
export function isBindableStaticNameExpression(node: Node, excludeThisKeyword?: boolean): node is BindableStaticNameExpression {
    return isEntityNameExpression(node) || isBindableStaticAccessExpression(node, excludeThisKeyword);
}

/** @internal */
export function getNameOrArgument(expr: PropertyAccessExpression | LiteralLikeElementAccessExpression): MemberName | (Expression & (NumericLiteral | StringLiteralLike)) {
    if (isPropertyAccessExpression(expr)) {
        return expr.name;
    }
    return expr.argumentExpression;
}

function getAssignmentDeclarationKindWorker(expr: BinaryExpression | CallExpression): AssignmentDeclarationKind {
    if (isCallExpression(expr)) {
        if (!isBindableObjectDefinePropertyCall(expr)) {
            return AssignmentDeclarationKind.None;
        }
        const entityName = expr.arguments[0];
        if (isExportsIdentifier(entityName) || isModuleExportsAccessExpression(entityName)) {
            return AssignmentDeclarationKind.ObjectDefinePropertyExports;
        }
        if (isBindableStaticAccessExpression(entityName) && getElementOrPropertyAccessName(entityName) === "prototype") {
            return AssignmentDeclarationKind.ObjectDefinePrototypeProperty;
        }
        return AssignmentDeclarationKind.ObjectDefinePropertyValue;
    }
    if (expr.operatorToken.kind !== SyntaxKind.EqualsToken || !isAccessExpression(expr.left) || isVoidZero(getRightMostAssignedExpression(expr))) {
        return AssignmentDeclarationKind.None;
    }
    if (isBindableStaticNameExpression(expr.left.expression, /*excludeThisKeyword*/ true) && getElementOrPropertyAccessName(expr.left) === "prototype" && isObjectLiteralExpression(getInitializerOfBinaryExpression(expr))) {
        // F.prototype = { ... }
        return AssignmentDeclarationKind.Prototype;
    }
    return getAssignmentDeclarationPropertyAccessKind(expr.left);
}

function isVoidZero(node: Node) {
    return isVoidExpression(node) && isNumericLiteral(node.expression) && node.expression.text === "0";
}

/**
 * Does not handle signed numeric names like `a[+0]` - handling those would require handling prefix unary expressions
 * throughout late binding handling as well, which is awkward (but ultimately probably doable if there is demand)
 *
 * @internal
 */
export function getElementOrPropertyAccessArgumentExpressionOrName(node: AccessExpression): Identifier | PrivateIdentifier | StringLiteralLike | NumericLiteral | ElementAccessExpression | undefined {
    if (isPropertyAccessExpression(node)) {
        return node.name;
    }
    const arg = skipParentheses(node.argumentExpression);
    if (isNumericLiteral(arg) || isStringLiteralLike(arg)) {
        return arg;
    }
    return node;
}

/** @internal */
export function getElementOrPropertyAccessName(node: LiteralLikeElementAccessExpression | PropertyAccessExpression): __String;
/** @internal */
export function getElementOrPropertyAccessName(node: AccessExpression): __String | undefined;
/** @internal */
export function getElementOrPropertyAccessName(node: AccessExpression): __String | undefined {
    const name = getElementOrPropertyAccessArgumentExpressionOrName(node);
    if (name) {
        if (isIdentifier(name)) {
            return name.escapedText;
        }
        if (isStringLiteralLike(name) || isNumericLiteral(name)) {
            return escapeLeadingUnderscores(name.text);
        }
    }
    return undefined;
}

/** @internal */
export function getAssignmentDeclarationPropertyAccessKind(lhs: AccessExpression): AssignmentDeclarationKind {
    if (lhs.expression.kind === SyntaxKind.ThisKeyword) {
        return AssignmentDeclarationKind.ThisProperty;
    }
    else if (isModuleExportsAccessExpression(lhs)) {
        // module.exports = expr
        return AssignmentDeclarationKind.ModuleExports;
    }
    else if (isBindableStaticNameExpression(lhs.expression, /*excludeThisKeyword*/ true)) {
        if (isPrototypeAccess(lhs.expression)) {
            // F.G....prototype.x = expr
            return AssignmentDeclarationKind.PrototypeProperty;
        }

        let nextToLast = lhs;
        while (!isIdentifier(nextToLast.expression)) {
            nextToLast = nextToLast.expression as Exclude<BindableStaticNameExpression, Identifier>;
        }
        const id = nextToLast.expression;
        if (
            (id.escapedText === "exports" ||
                id.escapedText === "module" && getElementOrPropertyAccessName(nextToLast) === "exports") &&
            // ExportsProperty does not support binding with computed names
            isBindableStaticAccessExpression(lhs)
        ) {
            // exports.name = expr OR module.exports.name = expr OR exports["name"] = expr ...
            return AssignmentDeclarationKind.ExportsProperty;
        }
        if (isBindableStaticNameExpression(lhs, /*excludeThisKeyword*/ true) || (isElementAccessExpression(lhs) && isDynamicName(lhs))) {
            // F.G...x = expr
            return AssignmentDeclarationKind.Property;
        }
    }

    return AssignmentDeclarationKind.None;
}

/** @internal */
export function getInitializerOfBinaryExpression(expr: BinaryExpression): Expression {
    while (isBinaryExpression(expr.right)) {
        expr = expr.right;
    }
    return expr.right;
}

/** @internal */
export interface PrototypePropertyAssignment extends AssignmentExpression<EqualsToken> {
    _prototypePropertyAssignmentBrand: any;
    readonly left: AccessExpression;
}

/** @internal */
export function isPrototypePropertyAssignment(node: Node): node is PrototypePropertyAssignment {
    return isBinaryExpression(node) && getAssignmentDeclarationKind(node) === AssignmentDeclarationKind.PrototypeProperty;
}

/** @internal */
export function isSpecialPropertyDeclaration(expr: PropertyAccessExpression | ElementAccessExpression): expr is PropertyAccessExpression | LiteralLikeElementAccessExpression {
    return isInJSFile(expr) &&
        expr.parent && expr.parent.kind === SyntaxKind.ExpressionStatement &&
        (!isElementAccessExpression(expr) || isLiteralLikeElementAccess(expr)) &&
        !!getJSDocTypeTag(expr.parent);
}

/** @internal */
export function setValueDeclaration(symbol: Symbol, node: Declaration): void {
    const { valueDeclaration } = symbol;
    if (
        !valueDeclaration ||
        !(node.flags & NodeFlags.Ambient && !isInJSFile(node) && !(valueDeclaration.flags & NodeFlags.Ambient)) &&
            (isAssignmentDeclaration(valueDeclaration) && !isAssignmentDeclaration(node)) ||
        (valueDeclaration.kind !== node.kind && isEffectiveModuleDeclaration(valueDeclaration))
    ) {
        // other kinds of value declarations take precedence over modules and assignment declarations
        symbol.valueDeclaration = node;
    }
}

/** @internal */
export function isFunctionSymbol(symbol: Symbol | undefined): boolean | undefined {
    if (!symbol || !symbol.valueDeclaration) {
        return false;
    }
    const decl = symbol.valueDeclaration;
    return decl.kind === SyntaxKind.FunctionDeclaration || isVariableDeclaration(decl) && decl.initializer && isFunctionLike(decl.initializer);
}

/** @internal */
export function canHaveModuleSpecifier(node: Node | undefined): node is CanHaveModuleSpecifier {
    switch (node?.kind) {
        case SyntaxKind.VariableDeclaration:
        case SyntaxKind.BindingElement:
        case SyntaxKind.ImportDeclaration:
        case SyntaxKind.ExportDeclaration:
        case SyntaxKind.ImportEqualsDeclaration:
        case SyntaxKind.ImportClause:
        case SyntaxKind.NamespaceExport:
        case SyntaxKind.NamespaceImport:
        case SyntaxKind.ExportSpecifier:
        case SyntaxKind.ImportSpecifier:
        case SyntaxKind.ImportType:
            return true;
    }
    return false;
}

/** @internal */
export function tryGetModuleSpecifierFromDeclaration(node: CanHaveModuleSpecifier | JSDocImportTag): StringLiteralLike | undefined {
    switch (node.kind) {
        case SyntaxKind.VariableDeclaration:
        case SyntaxKind.BindingElement:
            return findAncestor(node.initializer, (node): node is RequireOrImportCall => isRequireCall(node, /*requireStringLiteralLikeArgument*/ true))?.arguments[0];
        case SyntaxKind.ImportDeclaration:
        case SyntaxKind.ExportDeclaration:
        case SyntaxKind.JSDocImportTag:
            return tryCast(node.moduleSpecifier, isStringLiteralLike);
        case SyntaxKind.ImportEqualsDeclaration:
            return tryCast(tryCast(node.moduleReference, isExternalModuleReference)?.expression, isStringLiteralLike);
        case SyntaxKind.ImportClause:
        case SyntaxKind.NamespaceExport:
            return tryCast(node.parent.moduleSpecifier, isStringLiteralLike);
        case SyntaxKind.NamespaceImport:
        case SyntaxKind.ExportSpecifier:
            return tryCast(node.parent.parent.moduleSpecifier, isStringLiteralLike);
        case SyntaxKind.ImportSpecifier:
            return tryCast(node.parent.parent.parent.moduleSpecifier, isStringLiteralLike);
        case SyntaxKind.ImportType:
            return isLiteralImportTypeNode(node) ? node.argument.literal : undefined;
        default:
            Debug.assertNever(node);
    }
}

/** @internal */
export function importFromModuleSpecifier(node: StringLiteralLike): AnyValidImportOrReExport {
    return tryGetImportFromModuleSpecifier(node) || Debug.failBadSyntaxKind(node.parent);
}

/** @internal */
export function tryGetImportFromModuleSpecifier(node: StringLiteralLike): AnyValidImportOrReExport | undefined {
    switch (node.parent.kind) {
        case SyntaxKind.ImportDeclaration:
        case SyntaxKind.ExportDeclaration:
        case SyntaxKind.JSDocImportTag:
            return node.parent as AnyValidImportOrReExport;
        case SyntaxKind.ExternalModuleReference:
            return (node.parent as ExternalModuleReference).parent as AnyValidImportOrReExport;
        case SyntaxKind.CallExpression:
            return isImportCall(node.parent) || isRequireCall(node.parent, /*requireStringLiteralLikeArgument*/ false) ? node.parent as RequireOrImportCall : undefined;
        case SyntaxKind.LiteralType:
            if (!isStringLiteral(node)) {
                break;
            }
            return tryCast(node.parent.parent, isImportTypeNode) as ValidImportTypeNode | undefined;
        default:
            return undefined;
    }
}

/** @internal */
export function shouldRewriteModuleSpecifier(specifier: string, compilerOptions: CompilerOptions): boolean {
    return !!compilerOptions.rewriteRelativeImportExtensions && pathIsRelative(specifier) && !isDeclarationFileName(specifier) && hasTSFileExtension(specifier);
}

/** @internal */
export function getExternalModuleName(node: AnyImportOrReExport | ImportTypeNode | ImportCall | ModuleDeclaration | JSDocImportTag): Expression | undefined {
    switch (node.kind) {
        case SyntaxKind.ImportDeclaration:
        case SyntaxKind.ExportDeclaration:
        case SyntaxKind.JSDocImportTag:
            return node.moduleSpecifier;
        case SyntaxKind.ImportEqualsDeclaration:
            return node.moduleReference.kind === SyntaxKind.ExternalModuleReference ? node.moduleReference.expression : undefined;
        case SyntaxKind.ImportType:
            return isLiteralImportTypeNode(node) ? node.argument.literal : undefined;
        case SyntaxKind.CallExpression:
            return node.arguments[0];
        case SyntaxKind.ModuleDeclaration:
            return node.name.kind === SyntaxKind.StringLiteral ? node.name : undefined;
        default:
            return Debug.assertNever(node);
    }
}

/** @internal */
export function getNamespaceDeclarationNode(node: ImportDeclaration | ImportEqualsDeclaration | ExportDeclaration): ImportEqualsDeclaration | NamespaceImport | NamespaceExport | undefined {
    switch (node.kind) {
        case SyntaxKind.ImportDeclaration:
            return node.importClause && tryCast(node.importClause.namedBindings, isNamespaceImport);
        case SyntaxKind.ImportEqualsDeclaration:
            return node;
        case SyntaxKind.ExportDeclaration:
            return node.exportClause && tryCast(node.exportClause, isNamespaceExport);
        default:
            return Debug.assertNever(node);
    }
}

/** @internal */
export function isDefaultImport(node: ImportDeclaration | ImportEqualsDeclaration | ExportDeclaration | JSDocImportTag): boolean {
    return (node.kind === SyntaxKind.ImportDeclaration || node.kind === SyntaxKind.JSDocImportTag) && !!node.importClause && !!node.importClause.name;
}

/** @internal */
export function forEachImportClauseDeclaration<T>(node: ImportClause, action: (declaration: ImportClause | NamespaceImport | ImportSpecifier) => T | undefined): T | undefined {
    if (node.name) {
        const result = action(node);
        if (result) return result;
    }
    if (node.namedBindings) {
        const result = isNamespaceImport(node.namedBindings)
            ? action(node.namedBindings)
            : forEach(node.namedBindings.elements, action);
        if (result) return result;
    }
}

/** @internal */
export function hasQuestionToken(node: Node): boolean {
    switch (node.kind) {
        case SyntaxKind.Parameter:
        case SyntaxKind.MethodDeclaration:
        case SyntaxKind.MethodSignature:
        case SyntaxKind.ShorthandPropertyAssignment:
        case SyntaxKind.PropertyAssignment:
        case SyntaxKind.PropertyDeclaration:
        case SyntaxKind.PropertySignature:
            return (node as ParameterDeclaration | MethodDeclaration | PropertyDeclaration).questionToken !== undefined;
    }
    return false;
}

/** @internal */
export function isJSDocConstructSignature(node: Node): boolean {
    const param = isJSDocFunctionType(node) ? firstOrUndefined(node.parameters) : undefined;
    const name = tryCast(param && param.name, isIdentifier);
    return !!name && name.escapedText === "new";
}

/** @internal */
export function isJSDocTypeAlias(node: Node): node is JSDocTypedefTag | JSDocCallbackTag | JSDocEnumTag {
    return node.kind === SyntaxKind.JSDocTypedefTag || node.kind === SyntaxKind.JSDocCallbackTag || node.kind === SyntaxKind.JSDocEnumTag;
}

/** @internal */
export function isTypeAlias(node: Node): node is JSDocTypedefTag | JSDocCallbackTag | JSDocEnumTag | TypeAliasDeclaration {
    return isJSDocTypeAlias(node) || isTypeAliasDeclaration(node);
}

function getSourceOfAssignment(node: Node): Node | undefined {
    return isExpressionStatement(node) &&
            isBinaryExpression(node.expression) &&
            node.expression.operatorToken.kind === SyntaxKind.EqualsToken
        ? getRightMostAssignedExpression(node.expression)
        : undefined;
}

function getSourceOfDefaultedAssignment(node: Node): Node | undefined {
    return isExpressionStatement(node) &&
            isBinaryExpression(node.expression) &&
            getAssignmentDeclarationKind(node.expression) !== AssignmentDeclarationKind.None &&
            isBinaryExpression(node.expression.right) &&
            (node.expression.right.operatorToken.kind === SyntaxKind.BarBarToken || node.expression.right.operatorToken.kind === SyntaxKind.QuestionQuestionToken)
        ? node.expression.right.right
        : undefined;
}

function getSingleInitializerOfVariableStatementOrPropertyDeclaration(node: Node): Expression | undefined {
    switch (node.kind) {
        case SyntaxKind.VariableStatement:
            const v = getSingleVariableOfVariableStatement(node);
            return v && v.initializer;
        case SyntaxKind.PropertyDeclaration:
            return (node as PropertyDeclaration).initializer;
        case SyntaxKind.PropertyAssignment:
            return (node as PropertyAssignment).initializer;
    }
}

/** @internal */
export function getSingleVariableOfVariableStatement(node: Node): VariableDeclaration | undefined {
    return isVariableStatement(node) ? firstOrUndefined(node.declarationList.declarations) : undefined;
}

function getNestedModuleDeclaration(node: Node): Node | undefined {
    return isModuleDeclaration(node) &&
            node.body &&
            node.body.kind === SyntaxKind.ModuleDeclaration
        ? node.body
        : undefined;
}

/** @internal */
export function canHaveFlowNode(node: Node): node is HasFlowNode {
    if (node.kind >= SyntaxKind.FirstStatement && node.kind <= SyntaxKind.LastStatement) {
        return true;
    }

    switch (node.kind) {
        case SyntaxKind.Identifier:
        case SyntaxKind.ThisKeyword:
        case SyntaxKind.SuperKeyword:
        case SyntaxKind.QualifiedName:
        case SyntaxKind.MetaProperty:
        case SyntaxKind.ElementAccessExpression:
        case SyntaxKind.PropertyAccessExpression:
        case SyntaxKind.BindingElement:
        case SyntaxKind.FunctionExpression:
        case SyntaxKind.ArrowFunction:
        case SyntaxKind.MethodDeclaration:
        case SyntaxKind.GetAccessor:
        case SyntaxKind.SetAccessor:
            return true;
        default:
            return false;
    }
}

/** @internal */
export function canHaveJSDoc(node: Node): node is HasJSDoc {
    switch (node.kind) {
        case SyntaxKind.ArrowFunction:
        case SyntaxKind.BinaryExpression:
        case SyntaxKind.Block:
        case SyntaxKind.BreakStatement:
        case SyntaxKind.CallSignature:
        case SyntaxKind.CaseClause:
        case SyntaxKind.ClassDeclaration:
        case SyntaxKind.ClassExpression:
        case SyntaxKind.ClassStaticBlockDeclaration:
        case SyntaxKind.Constructor:
        case SyntaxKind.ConstructorType:
        case SyntaxKind.ConstructSignature:
        case SyntaxKind.ContinueStatement:
        case SyntaxKind.DebuggerStatement:
        case SyntaxKind.DoStatement:
        case SyntaxKind.ElementAccessExpression:
        case SyntaxKind.EmptyStatement:
        case SyntaxKind.EndOfFileToken:
        case SyntaxKind.EnumDeclaration:
        case SyntaxKind.EnumMember:
        case SyntaxKind.ExportAssignment:
        case SyntaxKind.ExportDeclaration:
        case SyntaxKind.ExportSpecifier:
        case SyntaxKind.ExpressionStatement:
        case SyntaxKind.ForInStatement:
        case SyntaxKind.ForOfStatement:
        case SyntaxKind.ForStatement:
        case SyntaxKind.FunctionDeclaration:
        case SyntaxKind.FunctionExpression:
        case SyntaxKind.FunctionType:
        case SyntaxKind.GetAccessor:
        case SyntaxKind.Identifier:
        case SyntaxKind.IfStatement:
        case SyntaxKind.ImportDeclaration:
        case SyntaxKind.ImportEqualsDeclaration:
        case SyntaxKind.IndexSignature:
        case SyntaxKind.InterfaceDeclaration:
        case SyntaxKind.JSDocFunctionType:
        case SyntaxKind.JSDocSignature:
        case SyntaxKind.LabeledStatement:
        case SyntaxKind.MethodDeclaration:
        case SyntaxKind.MethodSignature:
        case SyntaxKind.ModuleDeclaration:
        case SyntaxKind.NamedTupleMember:
        case SyntaxKind.NamespaceExportDeclaration:
        case SyntaxKind.ObjectLiteralExpression:
        case SyntaxKind.Parameter:
        case SyntaxKind.ParenthesizedExpression:
        case SyntaxKind.PropertyAccessExpression:
        case SyntaxKind.PropertyAssignment:
        case SyntaxKind.PropertyDeclaration:
        case SyntaxKind.PropertySignature:
        case SyntaxKind.ReturnStatement:
        case SyntaxKind.SemicolonClassElement:
        case SyntaxKind.SetAccessor:
        case SyntaxKind.ShorthandPropertyAssignment:
        case SyntaxKind.SpreadAssignment:
        case SyntaxKind.SwitchStatement:
        case SyntaxKind.ThrowStatement:
        case SyntaxKind.TryStatement:
        case SyntaxKind.TypeAliasDeclaration:
        case SyntaxKind.TypeParameter:
        case SyntaxKind.VariableDeclaration:
        case SyntaxKind.VariableStatement:
        case SyntaxKind.WhileStatement:
        case SyntaxKind.WithStatement:
            return true;
        default:
            return false;
    }
}

/**
 * This function checks multiple locations for JSDoc comments that apply to a host node.
 * At each location, the whole comment may apply to the node, or only a specific tag in
 * the comment. In the first case, location adds the entire {@link JSDoc} object. In the
 * second case, it adds the applicable {@link JSDocTag}.
 *
 * For example, a JSDoc comment before a parameter adds the entire {@link JSDoc}. But a
 * `@param` tag on the parent function only adds the {@link JSDocTag} for the `@param`.
 *
 * ```ts
 * /** JSDoc will be returned for `a` *\/
 * const a = 0
 * /**
 *  * Entire JSDoc will be returned for `b`
 *  * @param c JSDocTag will be returned for `c`
 *  *\/
 * function b(/** JSDoc will be returned for `c` *\/ c) {}
 * ```
 */
export function getJSDocCommentsAndTags(hostNode: Node): readonly (JSDoc | JSDocTag)[];
/** @internal separate signature so that stripInternal can remove noCache from the public API */
// eslint-disable-next-line @typescript-eslint/unified-signatures
export function getJSDocCommentsAndTags(hostNode: Node, noCache?: boolean): readonly (JSDoc | JSDocTag)[];
export function getJSDocCommentsAndTags(hostNode: Node, noCache?: boolean): readonly (JSDoc | JSDocTag)[] {
    let result: (JSDoc | JSDocTag)[] | undefined;
    // Pull parameter comments from declaring function as well
    if (isVariableLike(hostNode) && hasInitializer(hostNode) && hasJSDocNodes(hostNode.initializer!)) {
        result = addRange(result, filterOwnedJSDocTags(hostNode, hostNode.initializer.jsDoc!));
    }

    let node: Node | undefined = hostNode;
    while (node && node.parent) {
        if (hasJSDocNodes(node)) {
            result = addRange(result, filterOwnedJSDocTags(hostNode, node.jsDoc!));
        }

        if (node.kind === SyntaxKind.Parameter) {
            result = addRange(result, (noCache ? getJSDocParameterTagsNoCache : getJSDocParameterTags)(node as ParameterDeclaration));
            break;
        }
        if (node.kind === SyntaxKind.TypeParameter) {
            result = addRange(result, (noCache ? getJSDocTypeParameterTagsNoCache : getJSDocTypeParameterTags)(node as TypeParameterDeclaration));
            break;
        }
        node = getNextJSDocCommentLocation(node);
    }
    return result || emptyArray;
}

function filterOwnedJSDocTags(hostNode: Node, comments: JSDocArray) {
    const lastJsDoc = last(comments);
    return flatMap<JSDoc, JSDoc | JSDocTag>(comments, jsDoc => {
        if (jsDoc === lastJsDoc) {
            const ownedTags = filter(jsDoc.tags, tag => ownsJSDocTag(hostNode, tag));
            return jsDoc.tags === ownedTags ? [jsDoc] : ownedTags;
        }
        else {
            return filter(jsDoc.tags, isJSDocOverloadTag);
        }
    });
}

/**
 * Determines whether a host node owns a jsDoc tag. A `@type`/`@satisfies` tag attached to a
 * a ParenthesizedExpression belongs only to the ParenthesizedExpression.
 */
function ownsJSDocTag(hostNode: Node, tag: JSDocTag) {
    return !(isJSDocTypeTag(tag) || isJSDocSatisfiesTag(tag))
        || !tag.parent
        || !isJSDoc(tag.parent)
        || !isParenthesizedExpression(tag.parent.parent)
        || tag.parent.parent === hostNode;
}

/** @internal */
export function getNextJSDocCommentLocation(node: Node): Node | undefined {
    const parent = node.parent;
    if (
        parent.kind === SyntaxKind.PropertyAssignment ||
        parent.kind === SyntaxKind.ExportAssignment ||
        parent.kind === SyntaxKind.PropertyDeclaration ||
        parent.kind === SyntaxKind.ExpressionStatement && node.kind === SyntaxKind.PropertyAccessExpression ||
        parent.kind === SyntaxKind.ReturnStatement ||
        getNestedModuleDeclaration(parent) ||
        isAssignmentExpression(node)
    ) {
        return parent;
    }
    // Try to recognize this pattern when node is initializer of variable declaration and JSDoc comments are on containing variable statement.
    // /**
    //   * @param {number} name
    //   * @returns {number}
    //   */
    // var x = function(name) { return name.length; }
    else if (
        parent.parent &&
        (getSingleVariableOfVariableStatement(parent.parent) === node || isAssignmentExpression(parent))
    ) {
        return parent.parent;
    }
    else if (
        parent.parent && parent.parent.parent &&
        (getSingleVariableOfVariableStatement(parent.parent.parent) ||
            getSingleInitializerOfVariableStatementOrPropertyDeclaration(parent.parent.parent) === node ||
            getSourceOfDefaultedAssignment(parent.parent.parent))
    ) {
        return parent.parent.parent;
    }
}

/**
 * Does the opposite of `getJSDocParameterTags`: given a JSDoc parameter, finds the parameter corresponding to it.
 *
 * @internal
 */
export function getParameterSymbolFromJSDoc(node: JSDocParameterTag): Symbol | undefined {
    if (node.symbol) {
        return node.symbol;
    }
    if (!isIdentifier(node.name)) {
        return undefined;
    }
    const name = node.name.escapedText;
    const decl = getHostSignatureFromJSDoc(node);
    if (!decl) {
        return undefined;
    }
    const parameter = find(decl.parameters, p => p.name.kind === SyntaxKind.Identifier && p.name.escapedText === name);
    return parameter && parameter.symbol;
}

/** @internal */
export function getEffectiveContainerForJSDocTemplateTag(node: JSDocTemplateTag): SignatureDeclaration | JSDocTypedefTag | JSDocCallbackTag | JSDocEnumTag | undefined {
    if (isJSDoc(node.parent) && node.parent.tags) {
        // A @template tag belongs to any @typedef, @callback, or @enum tags in the same comment block, if they exist.
        const typeAlias = find(node.parent.tags, isJSDocTypeAlias);
        if (typeAlias) {
            return typeAlias;
        }
    }
    // otherwise it belongs to the host it annotates
    return getHostSignatureFromJSDoc(node);
}

/** @internal */
export function getJSDocOverloadTags(node: Node): readonly JSDocOverloadTag[] {
    return getAllJSDocTags(node, isJSDocOverloadTag);
}

/** @internal */
export function getHostSignatureFromJSDoc(node: Node): SignatureDeclaration | undefined {
    const host = getEffectiveJSDocHost(node);
    if (host) {
        return isPropertySignature(host) && host.type && isFunctionLike(host.type) ? host.type :
            isFunctionLike(host) ? host : undefined;
    }
    return undefined;
}

/** @internal */
export function getEffectiveJSDocHost(node: Node): Node | undefined {
    const host = getJSDocHost(node);
    if (host) {
        return getSourceOfDefaultedAssignment(host)
            || getSourceOfAssignment(host)
            || getSingleInitializerOfVariableStatementOrPropertyDeclaration(host)
            || getSingleVariableOfVariableStatement(host)
            || getNestedModuleDeclaration(host)
            || host;
    }
}

/**
 * Use getEffectiveJSDocHost if you additionally need to look for jsdoc on parent nodes, like assignments.
 *
 * @internal
 */
export function getJSDocHost(node: Node): HasJSDoc | undefined {
    const jsDoc = getJSDocRoot(node);
    if (!jsDoc) {
        return undefined;
    }

    const host = jsDoc.parent;
    if (host && host.jsDoc && jsDoc === lastOrUndefined(host.jsDoc)) {
        return host;
    }
}

/** @internal */
export function getJSDocRoot(node: Node): JSDoc | undefined {
    return findAncestor(node.parent, isJSDoc);
}

/** @internal */
export function getTypeParameterFromJsDoc(node: TypeParameterDeclaration & { parent: JSDocTemplateTag; }): TypeParameterDeclaration | undefined {
    const name = node.name.escapedText;
    const { typeParameters } = node.parent.parent.parent as SignatureDeclaration | InterfaceDeclaration | ClassDeclaration;
    return typeParameters && find(typeParameters, p => p.name.escapedText === name);
}

/** @internal */
export function hasTypeArguments(node: Node): node is HasTypeArguments {
    return !!(node as HasTypeArguments).typeArguments;
}

/** @internal */
export const enum AssignmentKind {
    None,
    Definite,
    Compound,
}

type AssignmentTarget =
    | BinaryExpression
    | PrefixUnaryExpression
    | PostfixUnaryExpression
    | ForInOrOfStatement;

function getAssignmentTarget(node: Node): AssignmentTarget | undefined {
    let parent = node.parent;
    while (true) {
        switch (parent.kind) {
            case SyntaxKind.BinaryExpression:
                const binaryExpression = parent as BinaryExpression;
                const binaryOperator = binaryExpression.operatorToken.kind;
                return isAssignmentOperator(binaryOperator) && binaryExpression.left === node ? binaryExpression : undefined;
            case SyntaxKind.PrefixUnaryExpression:
            case SyntaxKind.PostfixUnaryExpression:
                const unaryExpression = parent as PrefixUnaryExpression | PostfixUnaryExpression;
                const unaryOperator = unaryExpression.operator;
                return unaryOperator === SyntaxKind.PlusPlusToken || unaryOperator === SyntaxKind.MinusMinusToken ? unaryExpression : undefined;
            case SyntaxKind.ForInStatement:
            case SyntaxKind.ForOfStatement:
                const forInOrOfStatement = parent as ForInOrOfStatement;
                return forInOrOfStatement.initializer === node ? forInOrOfStatement : undefined;
            case SyntaxKind.ParenthesizedExpression:
            case SyntaxKind.ArrayLiteralExpression:
            case SyntaxKind.SpreadElement:
            case SyntaxKind.NonNullExpression:
                node = parent;
                break;
            case SyntaxKind.SpreadAssignment:
                node = parent.parent;
                break;
            case SyntaxKind.ShorthandPropertyAssignment:
                if ((parent as ShorthandPropertyAssignment).name !== node) {
                    return undefined;
                }
                node = parent.parent;
                break;
            case SyntaxKind.PropertyAssignment:
                if ((parent as PropertyAssignment).name === node) {
                    return undefined;
                }
                node = parent.parent;
                break;
            default:
                return undefined;
        }
        parent = node.parent;
    }
}

/** @internal */
export function getAssignmentTargetKind(node: Node): AssignmentKind {
    const target = getAssignmentTarget(node);
    if (!target) {
        return AssignmentKind.None;
    }
    switch (target.kind) {
        case SyntaxKind.BinaryExpression:
            const binaryOperator = target.operatorToken.kind;
            return binaryOperator === SyntaxKind.EqualsToken || isLogicalOrCoalescingAssignmentOperator(binaryOperator) ?
                AssignmentKind.Definite :
                AssignmentKind.Compound;
        case SyntaxKind.PrefixUnaryExpression:
        case SyntaxKind.PostfixUnaryExpression:
            return AssignmentKind.Compound;
        case SyntaxKind.ForInStatement:
        case SyntaxKind.ForOfStatement:
            return AssignmentKind.Definite;
    }
}

// A node is an assignment target if it is on the left hand side of an '=' token, if it is parented by a property
// assignment in an object literal that is an assignment target, or if it is parented by an array literal that is
// an assignment target. Examples include 'a = xxx', '{ p: a } = xxx', '[{ a }] = xxx'.
// (Note that `p` is not a target in the above examples, only `a`.)
/** @internal */
export function isAssignmentTarget(node: Node): boolean {
    return !!getAssignmentTarget(node);
}

function isCompoundLikeAssignment(assignment: AssignmentExpression<EqualsToken>): boolean {
    const right = skipParentheses(assignment.right);
    return right.kind === SyntaxKind.BinaryExpression && isShiftOperatorOrHigher((right as BinaryExpression).operatorToken.kind);
}

/** @internal */
export function isInCompoundLikeAssignment(node: Node): boolean {
    const target = getAssignmentTarget(node);
    return !!target && isAssignmentExpression(target, /*excludeCompoundAssignment*/ true) && isCompoundLikeAssignment(target);
}

/** @internal */
export type NodeWithPossibleHoistedDeclaration =
    | Block
    | VariableStatement
    | WithStatement
    | IfStatement
    | SwitchStatement
    | CaseBlock
    | CaseClause
    | DefaultClause
    | LabeledStatement
    | ForStatement
    | ForInOrOfStatement
    | DoStatement
    | WhileStatement
    | TryStatement
    | CatchClause;

/**
 * Indicates whether a node could contain a `var` VariableDeclarationList that contributes to
 * the same `var` declaration scope as the node's parent.
 *
 * @internal
 */
export function isNodeWithPossibleHoistedDeclaration(node: Node): node is NodeWithPossibleHoistedDeclaration {
    switch (node.kind) {
        case SyntaxKind.Block:
        case SyntaxKind.VariableStatement:
        case SyntaxKind.WithStatement:
        case SyntaxKind.IfStatement:
        case SyntaxKind.SwitchStatement:
        case SyntaxKind.CaseBlock:
        case SyntaxKind.CaseClause:
        case SyntaxKind.DefaultClause:
        case SyntaxKind.LabeledStatement:
        case SyntaxKind.ForStatement:
        case SyntaxKind.ForInStatement:
        case SyntaxKind.ForOfStatement:
        case SyntaxKind.DoStatement:
        case SyntaxKind.WhileStatement:
        case SyntaxKind.TryStatement:
        case SyntaxKind.CatchClause:
            return true;
    }
    return false;
}

/** @internal */
export type ValueSignatureDeclaration =
    | FunctionDeclaration
    | MethodDeclaration
    | ConstructorDeclaration
    | AccessorDeclaration
    | FunctionExpression
    | ArrowFunction;

/** @internal */
export function isValueSignatureDeclaration(node: Node): node is ValueSignatureDeclaration {
    return isFunctionExpression(node) || isArrowFunction(node) || isMethodOrAccessor(node) || isFunctionDeclaration(node) || isConstructorDeclaration(node);
}

function walkUp(node: Node, kind: SyntaxKind) {
    while (node && node.kind === kind) {
        node = node.parent;
    }
    return node;
}

/** @internal */
export function walkUpParenthesizedTypes(node: Node): Node {
    return walkUp(node, SyntaxKind.ParenthesizedType);
}

/** @internal */
export function walkUpParenthesizedExpressions(node: Node): Node {
    return walkUp(node, SyntaxKind.ParenthesizedExpression);
}

/**
 * Walks up parenthesized types.
 * It returns both the outermost parenthesized type and its parent.
 * If given node is not a parenthesiezd type, undefined is return as the former.
 *
 * @internal
 */
export function walkUpParenthesizedTypesAndGetParentAndChild(node: Node): [ParenthesizedTypeNode | undefined, Node] {
    let child: ParenthesizedTypeNode | undefined;
    while (node && node.kind === SyntaxKind.ParenthesizedType) {
        child = node as ParenthesizedTypeNode;
        node = node.parent;
    }
    return [child, node];
}

/** @internal */
export function skipTypeParentheses(node: TypeNode): TypeNode {
    while (isParenthesizedTypeNode(node)) node = node.type;
    return node;
}

/** @internal */
export function skipParentheses(node: Expression, excludeJSDocTypeAssertions?: boolean): Expression;
/** @internal */
export function skipParentheses(node: Node, excludeJSDocTypeAssertions?: boolean): Node;
/** @internal */
export function skipParentheses(node: Node, excludeJSDocTypeAssertions?: boolean): Node {
    const flags = excludeJSDocTypeAssertions ?
        OuterExpressionKinds.Parentheses | OuterExpressionKinds.ExcludeJSDocTypeAssertion :
        OuterExpressionKinds.Parentheses;
    return skipOuterExpressions(node, flags);
}

// a node is delete target iff. it is PropertyAccessExpression/ElementAccessExpression with parentheses skipped
/** @internal */
export function isDeleteTarget(node: Node): boolean {
    if (node.kind !== SyntaxKind.PropertyAccessExpression && node.kind !== SyntaxKind.ElementAccessExpression) {
        return false;
    }
    node = walkUpParenthesizedExpressions(node.parent);
    return node && node.kind === SyntaxKind.DeleteExpression;
}

/** @internal */
export function isNodeDescendantOf(node: Node, ancestor: Node | undefined): boolean {
    while (node) {
        if (node === ancestor) return true;
        node = node.parent;
    }
    return false;
}

// True if `name` is the name of a declaration node
/** @internal */
export function isDeclarationName(name: Node): boolean {
    return !isSourceFile(name) && !isBindingPattern(name) && isDeclaration(name.parent) && name.parent.name === name;
}

// See GH#16030
/** @internal */
export function getDeclarationFromName(name: Node): Declaration | undefined {
    const parent = name.parent;
    switch (name.kind) {
        case SyntaxKind.StringLiteral:
        case SyntaxKind.NoSubstitutionTemplateLiteral:
        case SyntaxKind.NumericLiteral:
            if (isComputedPropertyName(parent)) return parent.parent;
            // falls through
        case SyntaxKind.Identifier:
            if (isDeclaration(parent)) {
                return parent.name === name ? parent : undefined;
            }
            else if (isQualifiedName(parent)) {
                const tag = parent.parent;
                return isJSDocParameterTag(tag) && tag.name === parent ? tag : undefined;
            }
            else {
                const binExp = parent.parent;
                return isBinaryExpression(binExp) &&
                        getAssignmentDeclarationKind(binExp) !== AssignmentDeclarationKind.None &&
                        ((binExp.left as BindableStaticNameExpression).symbol || binExp.symbol) &&
                        getNameOfDeclaration(binExp) === name
                    ? binExp
                    : undefined;
            }
        case SyntaxKind.PrivateIdentifier:
            return isDeclaration(parent) && parent.name === name ? parent : undefined;
        default:
            return undefined;
    }
}

/** @internal */
export function isLiteralComputedPropertyDeclarationName(node: Node): boolean {
    return isStringOrNumericLiteralLike(node) &&
        node.parent.kind === SyntaxKind.ComputedPropertyName &&
        isDeclaration(node.parent.parent);
}

// Return true if the given identifier is classified as an IdentifierName
/** @internal */
export function isIdentifierName(node: Identifier): boolean {
    const parent = node.parent;
    switch (parent.kind) {
        case SyntaxKind.PropertyDeclaration:
        case SyntaxKind.PropertySignature:
        case SyntaxKind.MethodDeclaration:
        case SyntaxKind.MethodSignature:
        case SyntaxKind.GetAccessor:
        case SyntaxKind.SetAccessor:
        case SyntaxKind.EnumMember:
        case SyntaxKind.PropertyAssignment:
        case SyntaxKind.PropertyAccessExpression:
            // Name in member declaration or property name in property access
            return (parent as NamedDeclaration | PropertyAccessExpression).name === node;
        case SyntaxKind.QualifiedName:
            // Name on right hand side of dot in a type query or type reference
            return (parent as QualifiedName).right === node;
        case SyntaxKind.BindingElement:
        case SyntaxKind.ImportSpecifier:
            // Property name in binding element or import specifier
            return (parent as BindingElement | ImportSpecifier).propertyName === node;
        case SyntaxKind.ExportSpecifier:
        case SyntaxKind.JsxAttribute:
        case SyntaxKind.JsxSelfClosingElement:
        case SyntaxKind.JsxOpeningElement:
        case SyntaxKind.JsxClosingElement:
            // Any name in an export specifier or JSX Attribute or Jsx Element
            return true;
    }
    return false;
}

/** @internal */
export function getAliasDeclarationFromName(node: EntityName): Declaration | undefined {
    switch (node.parent.kind) {
        case SyntaxKind.ImportClause:
        case SyntaxKind.ImportSpecifier:
        case SyntaxKind.NamespaceImport:
        case SyntaxKind.ExportSpecifier:
        case SyntaxKind.ExportAssignment:
        case SyntaxKind.ImportEqualsDeclaration:
        case SyntaxKind.NamespaceExport:
            return node.parent as Declaration;
        case SyntaxKind.QualifiedName:
            do {
                node = node.parent as QualifiedName;
            }
            while (node.parent.kind === SyntaxKind.QualifiedName);
            return getAliasDeclarationFromName(node);
    }
}

/** @internal */
export function isAliasableExpression(e: Expression): boolean {
    return isEntityNameExpression(e) || isClassExpression(e);
}

/** @internal */
export function exportAssignmentIsAlias(node: ExportAssignment | BinaryExpression): boolean {
    const e = getExportAssignmentExpression(node);
    return isAliasableExpression(e);
}

/** @internal */
export function getExportAssignmentExpression(node: ExportAssignment | BinaryExpression): Expression {
    return isExportAssignment(node) ? node.expression : node.right;
}

/** @internal */
export function getPropertyAssignmentAliasLikeExpression(node: PropertyAssignment | ShorthandPropertyAssignment | PropertyAccessExpression): Expression {
    return node.kind === SyntaxKind.ShorthandPropertyAssignment ? node.name : node.kind === SyntaxKind.PropertyAssignment ? node.initializer :
        (node.parent as BinaryExpression).right;
}

/** @internal */
export function getEffectiveBaseTypeNode(node: ClassLikeDeclaration | InterfaceDeclaration): ExpressionWithTypeArguments | undefined {
    const baseType = getClassExtendsHeritageElement(node);
    if (baseType && isInJSFile(node)) {
        // Prefer an @augments tag because it may have type parameters.
        const tag = getJSDocAugmentsTag(node);
        if (tag) {
            return tag.class;
        }
    }
    return baseType;
}

/** @internal */
export function getClassExtendsHeritageElement(node: ClassLikeDeclaration | InterfaceDeclaration): ExpressionWithTypeArguments | undefined {
    const heritageClause = getHeritageClause(node.heritageClauses, SyntaxKind.ExtendsKeyword);
    return heritageClause && heritageClause.types.length > 0 ? heritageClause.types[0] : undefined;
}

/** @internal */
export function getEffectiveImplementsTypeNodes(node: ClassLikeDeclaration): undefined | readonly ExpressionWithTypeArguments[] {
    if (isInJSFile(node)) {
        return getJSDocImplementsTags(node).map(n => n.class);
    }
    else {
        const heritageClause = getHeritageClause(node.heritageClauses, SyntaxKind.ImplementsKeyword);
        return heritageClause?.types;
    }
}

/**
 * Returns the node in an `extends` or `implements` clause of a class or interface.
 *
 * @internal
 */
export function getAllSuperTypeNodes(node: Node): readonly TypeNode[] {
    return isInterfaceDeclaration(node) ? getInterfaceBaseTypeNodes(node) || emptyArray :
        isClassLike(node) ? concatenate(singleElementArray(getEffectiveBaseTypeNode(node)), getEffectiveImplementsTypeNodes(node)) || emptyArray :
        emptyArray;
}

/** @internal */
export function getInterfaceBaseTypeNodes(node: InterfaceDeclaration): NodeArray<ExpressionWithTypeArguments> | undefined {
    const heritageClause = getHeritageClause(node.heritageClauses, SyntaxKind.ExtendsKeyword);
    return heritageClause ? heritageClause.types : undefined;
}

/** @internal */
export function getHeritageClause(clauses: NodeArray<HeritageClause> | undefined, kind: SyntaxKind): HeritageClause | undefined {
    if (clauses) {
        for (const clause of clauses) {
            if (clause.token === kind) {
                return clause;
            }
        }
    }

    return undefined;
}

/** @internal */
export function getAncestor(node: Node | undefined, kind: SyntaxKind): Node | undefined {
    while (node) {
        if (node.kind === kind) {
            return node;
        }
        node = node.parent;
    }
    return undefined;
}

/** @internal */
export function isKeyword(token: SyntaxKind): token is KeywordSyntaxKind {
    return SyntaxKind.FirstKeyword <= token && token <= SyntaxKind.LastKeyword;
}

/** @internal */
export function isPunctuation(token: SyntaxKind): token is PunctuationSyntaxKind {
    return SyntaxKind.FirstPunctuation <= token && token <= SyntaxKind.LastPunctuation;
}

/** @internal */
export function isKeywordOrPunctuation(token: SyntaxKind): token is PunctuationOrKeywordSyntaxKind {
    return isKeyword(token) || isPunctuation(token);
}

/** @internal */
export function isContextualKeyword(token: SyntaxKind): boolean {
    return SyntaxKind.FirstContextualKeyword <= token && token <= SyntaxKind.LastContextualKeyword;
}

/** @internal */
export function isNonContextualKeyword(token: SyntaxKind): boolean {
    return isKeyword(token) && !isContextualKeyword(token);
}

/** @internal */
export function isStringANonContextualKeyword(name: string): boolean {
    const token = stringToToken(name);
    return token !== undefined && isNonContextualKeyword(token);
}

/** @internal */
export function isIdentifierANonContextualKeyword(node: Identifier): boolean {
    const originalKeywordKind = identifierToKeywordKind(node);
    return !!originalKeywordKind && !isContextualKeyword(originalKeywordKind);
}

/** @internal */
export function isTrivia(token: SyntaxKind): token is TriviaSyntaxKind {
    return SyntaxKind.FirstTriviaToken <= token && token <= SyntaxKind.LastTriviaToken;
}

// dprint-ignore
/** @internal */
export const enum FunctionFlags {
    Normal = 0,             // Function is a normal function
    Generator = 1 << 0,     // Function is a generator function or async generator function
    Async = 1 << 1,         // Function is an async function or an async generator function
    Invalid = 1 << 2,       // Function is a signature or overload and does not have a body.
    AsyncGenerator = Async | Generator, // Function is an async generator function
}

/** @internal */
export function getFunctionFlags(node: SignatureDeclaration | undefined): FunctionFlags {
    if (!node) {
        return FunctionFlags.Invalid;
    }

    let flags = FunctionFlags.Normal;
    switch (node.kind) {
        case SyntaxKind.FunctionDeclaration:
        case SyntaxKind.FunctionExpression:
        case SyntaxKind.MethodDeclaration:
            if (node.asteriskToken) {
                flags |= FunctionFlags.Generator;
            }
            // falls through

        case SyntaxKind.ArrowFunction:
            if (hasSyntacticModifier(node, ModifierFlags.Async)) {
                flags |= FunctionFlags.Async;
            }
            break;
    }

    if (!(node as FunctionLikeDeclaration).body) {
        flags |= FunctionFlags.Invalid;
    }

    return flags;
}

/** @internal */
export function isAsyncFunction(node: Node): boolean {
    switch (node.kind) {
        case SyntaxKind.FunctionDeclaration:
        case SyntaxKind.FunctionExpression:
        case SyntaxKind.ArrowFunction:
        case SyntaxKind.MethodDeclaration:
            return (node as FunctionLikeDeclaration).body !== undefined
                && (node as FunctionLikeDeclaration).asteriskToken === undefined
                && hasSyntacticModifier(node, ModifierFlags.Async);
    }
    return false;
}

/** @internal */
export function isStringOrNumericLiteralLike(node: Node): node is StringLiteralLike | NumericLiteral {
    return isStringLiteralLike(node) || isNumericLiteral(node);
}

/** @internal */
export function isSignedNumericLiteral(node: Node): node is PrefixUnaryExpression & { operand: NumericLiteral; } {
    return isPrefixUnaryExpression(node) && (node.operator === SyntaxKind.PlusToken || node.operator === SyntaxKind.MinusToken) && isNumericLiteral(node.operand);
}

/**
 * A declaration has a dynamic name if all of the following are true:
 *   1. The declaration has a computed property name.
 *   2. The computed name is *not* expressed as a StringLiteral.
 *   3. The computed name is *not* expressed as a NumericLiteral.
 *   4. The computed name is *not* expressed as a PlusToken or MinusToken
 *      immediately followed by a NumericLiteral.
 *
 * @internal
 */
export function hasDynamicName(declaration: Declaration): declaration is DynamicNamedDeclaration | DynamicNamedBinaryExpression {
    const name = getNameOfDeclaration(declaration);
    return !!name && isDynamicName(name);
}

/** @internal */
export function isDynamicName(name: DeclarationName): boolean {
    if (!(name.kind === SyntaxKind.ComputedPropertyName || name.kind === SyntaxKind.ElementAccessExpression)) {
        return false;
    }
    const expr = isElementAccessExpression(name) ? skipParentheses(name.argumentExpression) : name.expression;
    return !isStringOrNumericLiteralLike(expr) &&
        !isSignedNumericLiteral(expr);
}

/** @internal */
export function getPropertyNameForPropertyNameNode(name: PropertyName | JsxAttributeName): __String | undefined {
    switch (name.kind) {
        case SyntaxKind.Identifier:
        case SyntaxKind.PrivateIdentifier:
            return name.escapedText;
        case SyntaxKind.StringLiteral:
        case SyntaxKind.NoSubstitutionTemplateLiteral:
        case SyntaxKind.NumericLiteral:
        case SyntaxKind.BigIntLiteral:
            return escapeLeadingUnderscores(name.text);
        case SyntaxKind.ComputedPropertyName:
            const nameExpression = name.expression;
            if (isStringOrNumericLiteralLike(nameExpression)) {
                return escapeLeadingUnderscores(nameExpression.text);
            }
            else if (isSignedNumericLiteral(nameExpression)) {
                if (nameExpression.operator === SyntaxKind.MinusToken) {
                    return tokenToString(nameExpression.operator) + nameExpression.operand.text as __String;
                }
                return nameExpression.operand.text as __String;
            }
            return undefined;
        case SyntaxKind.JsxNamespacedName:
            return getEscapedTextOfJsxNamespacedName(name);
        default:
            return Debug.assertNever(name);
    }
}

/** @internal */
export function isPropertyNameLiteral(node: Node): node is PropertyNameLiteral {
    switch (node.kind) {
        case SyntaxKind.Identifier:
        case SyntaxKind.StringLiteral:
        case SyntaxKind.NoSubstitutionTemplateLiteral:
        case SyntaxKind.NumericLiteral:
            return true;
        default:
            return false;
    }
}
/** @internal */
export function getTextOfIdentifierOrLiteral(node: PropertyNameLiteral | PrivateIdentifier): string {
    return isMemberName(node) ? idText(node) : isJsxNamespacedName(node) ? getTextOfJsxNamespacedName(node) : node.text;
}

/** @internal */
export function getEscapedTextOfIdentifierOrLiteral(node: PropertyNameLiteral): __String {
    return isMemberName(node) ? node.escapedText : isJsxNamespacedName(node) ? getEscapedTextOfJsxNamespacedName(node) : escapeLeadingUnderscores(node.text);
}

/** @internal */
export function getSymbolNameForPrivateIdentifier(containingClassSymbol: Symbol, description: __String): __String {
    return `__#${getSymbolId(containingClassSymbol)}@${description}` as __String;
}

/** @internal */
export function isKnownSymbol(symbol: Symbol): boolean {
    return startsWith(symbol.escapedName as string, "__@");
}

/** @internal */
export function isPrivateIdentifierSymbol(symbol: Symbol): boolean {
    return startsWith(symbol.escapedName as string, "__#");
}

/**
 * Indicates whether a property name is the special `__proto__` property.
 * Per the ECMA-262 spec, this only matters for property assignments whose name is
 * the Identifier `__proto__`, or the string literal `"__proto__"`, but not for
 * computed property names.
 */
function isProtoSetter(node: PropertyName) {
    return isIdentifier(node) ? idText(node) === "__proto__" :
        isStringLiteral(node) && node.text === "__proto__";
}

/** @internal */
export type AnonymousFunctionDefinition =
    | ClassExpression & { readonly name?: undefined; }
    | FunctionExpression & { readonly name?: undefined; }
    | ArrowFunction;

/**
 * Indicates whether an expression is an anonymous function definition.
 *
 * @see https://tc39.es/ecma262/#sec-isanonymousfunctiondefinition
 */
function isAnonymousFunctionDefinition(node: Expression, cb?: (node: AnonymousFunctionDefinition) => boolean): node is WrappedExpression<AnonymousFunctionDefinition> {
    node = skipOuterExpressions(node);
    switch (node.kind) {
        case SyntaxKind.ClassExpression:
            if (classHasDeclaredOrExplicitlyAssignedName(node as ClassExpression)) {
                return false;
            }
            break;
        case SyntaxKind.FunctionExpression:
            if ((node as FunctionExpression).name) {
                return false;
            }
            break;
        case SyntaxKind.ArrowFunction:
            break;
        default:
            return false;
    }
    return typeof cb === "function" ? cb(node as AnonymousFunctionDefinition) : true;
}

/** @internal */
export type NamedEvaluationSource =
    | PropertyAssignment & { readonly name: Identifier; }
    | ShorthandPropertyAssignment & { readonly objectAssignmentInitializer: Expression; }
    | VariableDeclaration & { readonly name: Identifier; readonly initializer: Expression; }
    | ParameterDeclaration & { readonly name: Identifier; readonly initializer: Expression; readonly dotDotDotToken: undefined; }
    | BindingElement & { readonly name: Identifier; readonly initializer: Expression; readonly dotDotDotToken: undefined; }
    | PropertyDeclaration & { readonly initializer: Expression; }
    | AssignmentExpression<EqualsToken | AmpersandAmpersandEqualsToken | BarBarEqualsToken | QuestionQuestionEqualsToken> & { readonly left: Identifier; }
    | ExportAssignment;

/**
 * Indicates whether a node is a potential source of an assigned name for a class, function, or arrow function.
 *
 * @internal
 */
export function isNamedEvaluationSource(node: Node): node is NamedEvaluationSource {
    switch (node.kind) {
        case SyntaxKind.PropertyAssignment:
            return !isProtoSetter((node as PropertyAssignment).name);
        case SyntaxKind.ShorthandPropertyAssignment:
            return !!(node as ShorthandPropertyAssignment).objectAssignmentInitializer;
        case SyntaxKind.VariableDeclaration:
            return isIdentifier((node as VariableDeclaration).name) && !!(node as VariableDeclaration).initializer;
        case SyntaxKind.Parameter:
            return isIdentifier((node as ParameterDeclaration).name) && !!(node as VariableDeclaration).initializer && !(node as BindingElement).dotDotDotToken;
        case SyntaxKind.BindingElement:
            return isIdentifier((node as BindingElement).name) && !!(node as VariableDeclaration).initializer && !(node as BindingElement).dotDotDotToken;
        case SyntaxKind.PropertyDeclaration:
            return !!(node as PropertyDeclaration).initializer;
        case SyntaxKind.BinaryExpression:
            switch ((node as BinaryExpression).operatorToken.kind) {
                case SyntaxKind.EqualsToken:
                case SyntaxKind.AmpersandAmpersandEqualsToken:
                case SyntaxKind.BarBarEqualsToken:
                case SyntaxKind.QuestionQuestionEqualsToken:
                    return isIdentifier((node as BinaryExpression).left);
            }
            break;
        case SyntaxKind.ExportAssignment:
            return true;
    }
    return false;
}

/** @internal */
export type NamedEvaluation =
    | PropertyAssignment & { readonly name: Identifier; readonly initializer: WrappedExpression<AnonymousFunctionDefinition>; }
    | ShorthandPropertyAssignment & { readonly objectAssignmentInitializer: WrappedExpression<AnonymousFunctionDefinition>; }
    | VariableDeclaration & { readonly name: Identifier; readonly initializer: WrappedExpression<AnonymousFunctionDefinition>; }
    | ParameterDeclaration & { readonly name: Identifier; readonly dotDotDotToken: undefined; readonly initializer: WrappedExpression<AnonymousFunctionDefinition>; }
    | BindingElement & { readonly name: Identifier; readonly dotDotDotToken: undefined; readonly initializer: WrappedExpression<AnonymousFunctionDefinition>; }
    | PropertyDeclaration & { readonly initializer: WrappedExpression<AnonymousFunctionDefinition>; }
    | AssignmentExpression<EqualsToken> & { readonly left: Identifier; readonly right: WrappedExpression<AnonymousFunctionDefinition>; }
    | AssignmentExpression<AmpersandAmpersandEqualsToken | BarBarEqualsToken | QuestionQuestionEqualsToken> & { readonly left: Identifier; readonly right: WrappedExpression<AnonymousFunctionDefinition>; }
    | ExportAssignment & { readonly expression: WrappedExpression<AnonymousFunctionDefinition>; };

/** @internal */
export function isNamedEvaluation(node: Node, cb?: (node: AnonymousFunctionDefinition) => boolean): node is NamedEvaluation {
    if (!isNamedEvaluationSource(node)) return false;
    switch (node.kind) {
        case SyntaxKind.PropertyAssignment:
            return isAnonymousFunctionDefinition(node.initializer, cb);
        case SyntaxKind.ShorthandPropertyAssignment:
            return isAnonymousFunctionDefinition(node.objectAssignmentInitializer, cb);
        case SyntaxKind.VariableDeclaration:
        case SyntaxKind.Parameter:
        case SyntaxKind.BindingElement:
        case SyntaxKind.PropertyDeclaration:
            return isAnonymousFunctionDefinition(node.initializer, cb);
        case SyntaxKind.BinaryExpression:
            return isAnonymousFunctionDefinition(node.right, cb);
        case SyntaxKind.ExportAssignment:
            return isAnonymousFunctionDefinition(node.expression, cb);
    }
}

/** @internal */
export function isPushOrUnshiftIdentifier(node: Identifier): boolean {
    return node.escapedText === "push" || node.escapedText === "unshift";
}

/**
 * This function returns true if the this node's root declaration is a parameter.
 * For example, passing a `ParameterDeclaration` will return true, as will passing a
 * binding element that is a child of a `ParameterDeclaration`.
 *
 * If you are looking to test that a `Node` is a `ParameterDeclaration`, use `isParameter`.
 *
 * @internal
 */
export function isPartOfParameterDeclaration(node: Declaration): boolean {
    const root = getRootDeclaration(node);
    return root.kind === SyntaxKind.Parameter;
}

/** @internal */
export function getRootDeclaration(node: Node): Node {
    while (node.kind === SyntaxKind.BindingElement) {
        node = node.parent.parent;
    }
    return node;
}

/** @internal */
export function nodeStartsNewLexicalEnvironment(node: Node): boolean {
    const kind = node.kind;
    return kind === SyntaxKind.Constructor
        || kind === SyntaxKind.FunctionExpression
        || kind === SyntaxKind.FunctionDeclaration
        || kind === SyntaxKind.ArrowFunction
        || kind === SyntaxKind.MethodDeclaration
        || kind === SyntaxKind.GetAccessor
        || kind === SyntaxKind.SetAccessor
        || kind === SyntaxKind.ModuleDeclaration
        || kind === SyntaxKind.SourceFile;
}

/** @internal */
export function nodeIsSynthesized(range: TextRange): boolean {
    return positionIsSynthesized(range.pos)
        || positionIsSynthesized(range.end);
}

/** @internal */
export const enum Associativity {
    Left,
    Right,
}

/** @internal */
export function getExpressionAssociativity(expression: Expression): Associativity {
    const operator = getOperator(expression);
    const hasArguments = expression.kind === SyntaxKind.NewExpression && (expression as NewExpression).arguments !== undefined;
    return getOperatorAssociativity(expression.kind, operator, hasArguments);
}

/** @internal */
export function getOperatorAssociativity(kind: SyntaxKind, operator: SyntaxKind, hasArguments?: boolean): Associativity {
    switch (kind) {
        case SyntaxKind.NewExpression:
            return hasArguments ? Associativity.Left : Associativity.Right;

        case SyntaxKind.PrefixUnaryExpression:
        case SyntaxKind.TypeOfExpression:
        case SyntaxKind.VoidExpression:
        case SyntaxKind.DeleteExpression:
        case SyntaxKind.AwaitExpression:
        case SyntaxKind.ConditionalExpression:
        case SyntaxKind.YieldExpression:
            return Associativity.Right;

        case SyntaxKind.BinaryExpression:
            switch (operator) {
                case SyntaxKind.AsteriskAsteriskToken:
                case SyntaxKind.EqualsToken:
                case SyntaxKind.PlusEqualsToken:
                case SyntaxKind.MinusEqualsToken:
                case SyntaxKind.AsteriskAsteriskEqualsToken:
                case SyntaxKind.AsteriskEqualsToken:
                case SyntaxKind.SlashEqualsToken:
                case SyntaxKind.PercentEqualsToken:
                case SyntaxKind.LessThanLessThanEqualsToken:
                case SyntaxKind.GreaterThanGreaterThanEqualsToken:
                case SyntaxKind.GreaterThanGreaterThanGreaterThanEqualsToken:
                case SyntaxKind.AmpersandEqualsToken:
                case SyntaxKind.CaretEqualsToken:
                case SyntaxKind.BarEqualsToken:
                case SyntaxKind.BarBarEqualsToken:
                case SyntaxKind.AmpersandAmpersandEqualsToken:
                case SyntaxKind.QuestionQuestionEqualsToken:
                    return Associativity.Right;
            }
    }
    return Associativity.Left;
}

/** @internal */
export function getExpressionPrecedence(expression: Expression): OperatorPrecedence {
    const operator = getOperator(expression);
    const hasArguments = expression.kind === SyntaxKind.NewExpression && (expression as NewExpression).arguments !== undefined;
    return getOperatorPrecedence(expression.kind, operator, hasArguments);
}

function getOperator(expression: Expression): SyntaxKind {
    if (expression.kind === SyntaxKind.BinaryExpression) {
        return (expression as BinaryExpression).operatorToken.kind;
    }
    else if (expression.kind === SyntaxKind.PrefixUnaryExpression || expression.kind === SyntaxKind.PostfixUnaryExpression) {
        return (expression as PrefixUnaryExpression | PostfixUnaryExpression).operator;
    }
    else {
        return expression.kind;
    }
}

/** @internal */
export const enum OperatorPrecedence {
    // Expression:
    //     AssignmentExpression
    //     Expression `,` AssignmentExpression
    Comma,

    // NOTE: `Spread` is higher than `Comma` due to how it is parsed in |ElementList|
    // SpreadElement:
    //     `...` AssignmentExpression
    Spread,

    // AssignmentExpression:
    //     ConditionalExpression
    //     YieldExpression
    //     ArrowFunction
    //     AsyncArrowFunction
    //     LeftHandSideExpression `=` AssignmentExpression
    //     LeftHandSideExpression AssignmentOperator AssignmentExpression
    //
    // NOTE: AssignmentExpression is broken down into several precedences due to the requirements
    //       of the parenthesizer rules.

    // AssignmentExpression: YieldExpression
    // YieldExpression:
    //     `yield`
    //     `yield` AssignmentExpression
    //     `yield` `*` AssignmentExpression
    Yield,

    // AssignmentExpression: LeftHandSideExpression `=` AssignmentExpression
    // AssignmentExpression: LeftHandSideExpression AssignmentOperator AssignmentExpression
    // AssignmentOperator: one of
    //     `*=` `/=` `%=` `+=` `-=` `<<=` `>>=` `>>>=` `&=` `^=` `|=` `**=`
    Assignment,

    // NOTE: `Conditional` is considered higher than `Assignment` here, but in reality they have
    //       the same precedence.
    // AssignmentExpression: ConditionalExpression
    // ConditionalExpression:
    //     ShortCircuitExpression
    //     ShortCircuitExpression `?` AssignmentExpression `:` AssignmentExpression
    // ShortCircuitExpression:
    //     LogicalORExpression
    //     CoalesceExpression
    Conditional,

    // LogicalORExpression:
    //     LogicalANDExpression
    //     LogicalORExpression `||` LogicalANDExpression
    LogicalOR,

    // CoalesceExpression:
    //     CoalesceExpressionHead `??` BitwiseORExpression
    // CoalesceExpressionHead:
    //     CoalesceExpression
    //     BitwiseORExpression
    Coalesce = LogicalOR,

    // LogicalANDExpression:
    //     BitwiseORExpression
    //     LogicalANDExprerssion `&&` BitwiseORExpression
    LogicalAND,

    // BitwiseORExpression:
    //     BitwiseXORExpression
    //     BitwiseORExpression `^` BitwiseXORExpression
    BitwiseOR,

    // BitwiseXORExpression:
    //     BitwiseANDExpression
    //     BitwiseXORExpression `^` BitwiseANDExpression
    BitwiseXOR,

    // BitwiseANDExpression:
    //     EqualityExpression
    //     BitwiseANDExpression `^` EqualityExpression
    BitwiseAND,

    // EqualityExpression:
    //     RelationalExpression
    //     EqualityExpression `==` RelationalExpression
    //     EqualityExpression `!=` RelationalExpression
    //     EqualityExpression `===` RelationalExpression
    //     EqualityExpression `!==` RelationalExpression
    Equality,

    // RelationalExpression:
    //     ShiftExpression
    //     RelationalExpression `<` ShiftExpression
    //     RelationalExpression `>` ShiftExpression
    //     RelationalExpression `<=` ShiftExpression
    //     RelationalExpression `>=` ShiftExpression
    //     RelationalExpression `instanceof` ShiftExpression
    //     RelationalExpression `in` ShiftExpression
    //     [+TypeScript] RelationalExpression `as` Type
    Relational,

    // ShiftExpression:
    //     AdditiveExpression
    //     ShiftExpression `<<` AdditiveExpression
    //     ShiftExpression `>>` AdditiveExpression
    //     ShiftExpression `>>>` AdditiveExpression
    Shift,

    // AdditiveExpression:
    //     MultiplicativeExpression
    //     AdditiveExpression `+` MultiplicativeExpression
    //     AdditiveExpression `-` MultiplicativeExpression
    Additive,

    // MultiplicativeExpression:
    //     ExponentiationExpression
    //     MultiplicativeExpression MultiplicativeOperator ExponentiationExpression
    // MultiplicativeOperator: one of `*`, `/`, `%`
    Multiplicative,

    // ExponentiationExpression:
    //     UnaryExpression
    //     UpdateExpression `**` ExponentiationExpression
    Exponentiation,

    // UnaryExpression:
    //     UpdateExpression
    //     `delete` UnaryExpression
    //     `void` UnaryExpression
    //     `typeof` UnaryExpression
    //     `+` UnaryExpression
    //     `-` UnaryExpression
    //     `~` UnaryExpression
    //     `!` UnaryExpression
    //     AwaitExpression
    // UpdateExpression:            // TODO: Do we need to investigate the precedence here?
    //     `++` UnaryExpression
    //     `--` UnaryExpression
    Unary,

    // UpdateExpression:
    //     LeftHandSideExpression
    //     LeftHandSideExpression `++`
    //     LeftHandSideExpression `--`
    Update,

    // LeftHandSideExpression:
    //     NewExpression
    //     CallExpression
    // NewExpression:
    //     MemberExpression
    //     `new` NewExpression
    LeftHandSide,

    // CallExpression:
    //     CoverCallExpressionAndAsyncArrowHead
    //     SuperCall
    //     ImportCall
    //     CallExpression Arguments
    //     CallExpression `[` Expression `]`
    //     CallExpression `.` IdentifierName
    //     CallExpression TemplateLiteral
    // MemberExpression:
    //     PrimaryExpression
    //     MemberExpression `[` Expression `]`
    //     MemberExpression `.` IdentifierName
    //     MemberExpression TemplateLiteral
    //     SuperProperty
    //     MetaProperty
    //     `new` MemberExpression Arguments
    Member,

    // TODO: JSXElement?
    // PrimaryExpression:
    //     `this`
    //     IdentifierReference
    //     Literal
    //     ArrayLiteral
    //     ObjectLiteral
    //     FunctionExpression
    //     ClassExpression
    //     GeneratorExpression
    //     AsyncFunctionExpression
    //     AsyncGeneratorExpression
    //     RegularExpressionLiteral
    //     TemplateLiteral
    //     CoverParenthesizedExpressionAndArrowParameterList
    Primary,

    Highest = Primary,
    Lowest = Comma,
    // -1 is lower than all other precedences. Returning it will cause binary expression
    // parsing to stop.
    Invalid = -1,
}

/** @internal */
export function getOperatorPrecedence(nodeKind: SyntaxKind, operatorKind: SyntaxKind, hasArguments?: boolean): OperatorPrecedence {
    switch (nodeKind) {
        case SyntaxKind.CommaListExpression:
            return OperatorPrecedence.Comma;

        case SyntaxKind.SpreadElement:
            return OperatorPrecedence.Spread;

        case SyntaxKind.YieldExpression:
            return OperatorPrecedence.Yield;

        case SyntaxKind.ConditionalExpression:
            return OperatorPrecedence.Conditional;

        case SyntaxKind.BinaryExpression:
            switch (operatorKind) {
                case SyntaxKind.CommaToken:
                    return OperatorPrecedence.Comma;

                case SyntaxKind.EqualsToken:
                case SyntaxKind.PlusEqualsToken:
                case SyntaxKind.MinusEqualsToken:
                case SyntaxKind.AsteriskAsteriskEqualsToken:
                case SyntaxKind.AsteriskEqualsToken:
                case SyntaxKind.SlashEqualsToken:
                case SyntaxKind.PercentEqualsToken:
                case SyntaxKind.LessThanLessThanEqualsToken:
                case SyntaxKind.GreaterThanGreaterThanEqualsToken:
                case SyntaxKind.GreaterThanGreaterThanGreaterThanEqualsToken:
                case SyntaxKind.AmpersandEqualsToken:
                case SyntaxKind.CaretEqualsToken:
                case SyntaxKind.BarEqualsToken:
                case SyntaxKind.BarBarEqualsToken:
                case SyntaxKind.AmpersandAmpersandEqualsToken:
                case SyntaxKind.QuestionQuestionEqualsToken:
                    return OperatorPrecedence.Assignment;

                default:
                    return getBinaryOperatorPrecedence(operatorKind);
            }

        // TODO: Should prefix `++` and `--` be moved to the `Update` precedence?
        case SyntaxKind.TypeAssertionExpression:
        case SyntaxKind.NonNullExpression:
        case SyntaxKind.PrefixUnaryExpression:
        case SyntaxKind.TypeOfExpression:
        case SyntaxKind.VoidExpression:
        case SyntaxKind.DeleteExpression:
        case SyntaxKind.AwaitExpression:
            return OperatorPrecedence.Unary;

        case SyntaxKind.PostfixUnaryExpression:
            return OperatorPrecedence.Update;

        case SyntaxKind.CallExpression:
            return OperatorPrecedence.LeftHandSide;

        case SyntaxKind.NewExpression:
            return hasArguments ? OperatorPrecedence.Member : OperatorPrecedence.LeftHandSide;

        case SyntaxKind.TaggedTemplateExpression:
        case SyntaxKind.PropertyAccessExpression:
        case SyntaxKind.ElementAccessExpression:
        case SyntaxKind.MetaProperty:
            return OperatorPrecedence.Member;

        case SyntaxKind.AsExpression:
        case SyntaxKind.SatisfiesExpression:
            return OperatorPrecedence.Relational;

        case SyntaxKind.ThisKeyword:
        case SyntaxKind.SuperKeyword:
        case SyntaxKind.Identifier:
        case SyntaxKind.PrivateIdentifier:
        case SyntaxKind.NullKeyword:
        case SyntaxKind.TrueKeyword:
        case SyntaxKind.FalseKeyword:
        case SyntaxKind.NumericLiteral:
        case SyntaxKind.BigIntLiteral:
        case SyntaxKind.StringLiteral:
        case SyntaxKind.ArrayLiteralExpression:
        case SyntaxKind.ObjectLiteralExpression:
        case SyntaxKind.FunctionExpression:
        case SyntaxKind.ArrowFunction:
        case SyntaxKind.ClassExpression:
        case SyntaxKind.RegularExpressionLiteral:
        case SyntaxKind.NoSubstitutionTemplateLiteral:
        case SyntaxKind.TemplateExpression:
        case SyntaxKind.ParenthesizedExpression:
        case SyntaxKind.OmittedExpression:
        case SyntaxKind.JsxElement:
        case SyntaxKind.JsxSelfClosingElement:
        case SyntaxKind.JsxFragment:
            return OperatorPrecedence.Primary;

        default:
            return OperatorPrecedence.Invalid;
    }
}

/** @internal */
export function getBinaryOperatorPrecedence(kind: SyntaxKind): OperatorPrecedence {
    switch (kind) {
        case SyntaxKind.QuestionQuestionToken:
            return OperatorPrecedence.Coalesce;
        case SyntaxKind.BarBarToken:
            return OperatorPrecedence.LogicalOR;
        case SyntaxKind.AmpersandAmpersandToken:
            return OperatorPrecedence.LogicalAND;
        case SyntaxKind.BarToken:
            return OperatorPrecedence.BitwiseOR;
        case SyntaxKind.CaretToken:
            return OperatorPrecedence.BitwiseXOR;
        case SyntaxKind.AmpersandToken:
            return OperatorPrecedence.BitwiseAND;
        case SyntaxKind.EqualsEqualsToken:
        case SyntaxKind.ExclamationEqualsToken:
        case SyntaxKind.EqualsEqualsEqualsToken:
        case SyntaxKind.ExclamationEqualsEqualsToken:
            return OperatorPrecedence.Equality;
        case SyntaxKind.LessThanToken:
        case SyntaxKind.GreaterThanToken:
        case SyntaxKind.LessThanEqualsToken:
        case SyntaxKind.GreaterThanEqualsToken:
        case SyntaxKind.InstanceOfKeyword:
        case SyntaxKind.InKeyword:
        case SyntaxKind.AsKeyword:
        case SyntaxKind.SatisfiesKeyword:
            return OperatorPrecedence.Relational;
        case SyntaxKind.LessThanLessThanToken:
        case SyntaxKind.GreaterThanGreaterThanToken:
        case SyntaxKind.GreaterThanGreaterThanGreaterThanToken:
            return OperatorPrecedence.Shift;
        case SyntaxKind.PlusToken:
        case SyntaxKind.MinusToken:
            return OperatorPrecedence.Additive;
        case SyntaxKind.AsteriskToken:
        case SyntaxKind.SlashToken:
        case SyntaxKind.PercentToken:
            return OperatorPrecedence.Multiplicative;
        case SyntaxKind.AsteriskAsteriskToken:
            return OperatorPrecedence.Exponentiation;
    }

    // -1 is lower than all other precedences.  Returning it will cause binary expression
    // parsing to stop.
    return -1;
}

/** @internal */
export function getSemanticJsxChildren(children: readonly JsxChild[]): readonly JsxChild[] {
    return filter(children, i => {
        switch (i.kind) {
            case SyntaxKind.JsxExpression:
                return !!i.expression;
            case SyntaxKind.JsxText:
                return !i.containsOnlyTriviaWhiteSpaces;
            default:
                return true;
        }
    });
}

/** @internal */
export function createDiagnosticCollection(): DiagnosticCollection {
    let nonFileDiagnostics = [] as Diagnostic[] as SortedArray<Diagnostic>; // See GH#19873
    const filesWithDiagnostics = [] as string[] as SortedArray<string>;
    const fileDiagnostics = new Map<string, SortedArray<DiagnosticWithLocation>>();
    let hasReadNonFileDiagnostics = false;

    return {
        add,
        lookup,
        getGlobalDiagnostics,
        getDiagnostics,
    };

    function lookup(diagnostic: Diagnostic): Diagnostic | undefined {
        let diagnostics: SortedArray<Diagnostic> | undefined;
        if (diagnostic.file) {
            diagnostics = fileDiagnostics.get(diagnostic.file.fileName);
        }
        else {
            diagnostics = nonFileDiagnostics;
        }
        if (!diagnostics) {
            return undefined;
        }
        const result = binarySearch(diagnostics, diagnostic, identity, compareDiagnosticsSkipRelatedInformation);
        if (result >= 0) {
            return diagnostics[result];
        }
        if (~result > 0 && diagnosticsEqualityComparer(diagnostic, diagnostics[~result - 1])) {
            return diagnostics[~result - 1];
        }
        return undefined;
    }

    function add(diagnostic: Diagnostic): void {
        let diagnostics: SortedArray<Diagnostic> | undefined;
        if (diagnostic.file) {
            diagnostics = fileDiagnostics.get(diagnostic.file.fileName);
            if (!diagnostics) {
                diagnostics = [] as Diagnostic[] as SortedArray<DiagnosticWithLocation>; // See GH#19873
                fileDiagnostics.set(diagnostic.file.fileName, diagnostics as SortedArray<DiagnosticWithLocation>);
                insertSorted(filesWithDiagnostics, diagnostic.file.fileName, compareStringsCaseSensitive);
            }
        }
        else {
            // If we've already read the non-file diagnostics, do not modify the existing array.
            if (hasReadNonFileDiagnostics) {
                hasReadNonFileDiagnostics = false;
                nonFileDiagnostics = nonFileDiagnostics.slice() as SortedArray<Diagnostic>;
            }

            diagnostics = nonFileDiagnostics;
        }

        insertSorted(diagnostics, diagnostic, compareDiagnosticsSkipRelatedInformation, diagnosticsEqualityComparer);
    }

    function getGlobalDiagnostics(): Diagnostic[] {
        hasReadNonFileDiagnostics = true;
        return nonFileDiagnostics;
    }

    function getDiagnostics(fileName: string): DiagnosticWithLocation[];
    function getDiagnostics(): Diagnostic[];
    function getDiagnostics(fileName?: string): Diagnostic[] {
        if (fileName) {
            return fileDiagnostics.get(fileName) || [];
        }

        const fileDiags: Diagnostic[] = flatMapToMutable(filesWithDiagnostics, f => fileDiagnostics.get(f));
        if (!nonFileDiagnostics.length) {
            return fileDiags;
        }
        fileDiags.unshift(...nonFileDiagnostics);
        return fileDiags;
    }
}

const templateSubstitutionRegExp = /\$\{/g;
/** @internal */
export function escapeTemplateSubstitution(str: string): string {
    return str.replace(templateSubstitutionRegExp, "\\${");
}

function containsInvalidEscapeFlag(node: TemplateLiteralToken): boolean {
    return !!((node.templateFlags || 0) & TokenFlags.ContainsInvalidEscape);
}

/** @internal */
export function hasInvalidEscape(template: TemplateLiteral): boolean {
    return template && !!(isNoSubstitutionTemplateLiteral(template)
        ? containsInvalidEscapeFlag(template)
        : (containsInvalidEscapeFlag(template.head) || some(template.templateSpans, span => containsInvalidEscapeFlag(span.literal))));
}

// This consists of the first 19 unprintable ASCII characters, canonical escapes, lineSeparator,
// paragraphSeparator, and nextLine. The latter three are just desirable to suppress new lines in
// the language service. These characters should be escaped when printing, and if any characters are added,
// the map below must be updated. Note that this regexp *does not* include the 'delete' character.
// There is no reason for this other than that JSON.stringify does not handle it either.
const doubleQuoteEscapedCharsRegExp = /[\\"\u0000-\u001f\u2028\u2029\u0085]/g;
const singleQuoteEscapedCharsRegExp = /[\\'\u0000-\u001f\u2028\u2029\u0085]/g;
// Template strings preserve simple LF newlines, still encode CRLF (or CR)
const backtickQuoteEscapedCharsRegExp = /\r\n|[\\`\u0000-\u0009\u000b-\u001f\u2028\u2029\u0085]/g;
const escapedCharsMap = new Map(Object.entries({
    "\t": "\\t",
    "\v": "\\v",
    "\f": "\\f",
    "\b": "\\b",
    "\r": "\\r",
    "\n": "\\n",
    "\\": "\\\\",
    '"': '\\"',
    "'": "\\'",
    "`": "\\`",
    "\u2028": "\\u2028", // lineSeparator
    "\u2029": "\\u2029", // paragraphSeparator
    "\u0085": "\\u0085", // nextLine
    "\r\n": "\\r\\n", // special case for CRLFs in backticks
}));

function encodeUtf16EscapeSequence(charCode: number): string {
    const hexCharCode = charCode.toString(16).toUpperCase();
    const paddedHexCode = ("0000" + hexCharCode).slice(-4);
    return "\\u" + paddedHexCode;
}

function getReplacement(c: string, offset: number, input: string) {
    if (c.charCodeAt(0) === CharacterCodes.nullCharacter) {
        const lookAhead = input.charCodeAt(offset + c.length);
        if (lookAhead >= CharacterCodes._0 && lookAhead <= CharacterCodes._9) {
            // If the null character is followed by digits, print as a hex escape to prevent the result from parsing as an octal (which is forbidden in strict mode)
            return "\\x00";
        }
        // Otherwise, keep printing a literal \0 for the null character
        return "\\0";
    }
    return escapedCharsMap.get(c) || encodeUtf16EscapeSequence(c.charCodeAt(0));
}

/**
 * Based heavily on the abstract 'Quote'/'QuoteJSONString' operation from ECMA-262 (24.3.2.2),
 * but augmented for a few select characters (e.g. lineSeparator, paragraphSeparator, nextLine)
 * Note that this doesn't actually wrap the input in double quotes.
 *
 * @internal
 */
export function escapeString(s: string, quoteChar?: CharacterCodes.doubleQuote | CharacterCodes.singleQuote | CharacterCodes.backtick): string {
    const escapedCharsRegExp = quoteChar === CharacterCodes.backtick ? backtickQuoteEscapedCharsRegExp :
        quoteChar === CharacterCodes.singleQuote ? singleQuoteEscapedCharsRegExp :
        doubleQuoteEscapedCharsRegExp;
    return s.replace(escapedCharsRegExp, getReplacement);
}

const nonAsciiCharacters = /[^\u0000-\u007F]/g;
/** @internal */
export function escapeNonAsciiString(s: string, quoteChar?: CharacterCodes.doubleQuote | CharacterCodes.singleQuote | CharacterCodes.backtick): string {
    s = escapeString(s, quoteChar);
    // Replace non-ASCII characters with '\uNNNN' escapes if any exist.
    // Otherwise just return the original string.
    return nonAsciiCharacters.test(s) ?
        s.replace(nonAsciiCharacters, c => encodeUtf16EscapeSequence(c.charCodeAt(0))) :
        s;
}

// This consists of the first 19 unprintable ASCII characters, JSX canonical escapes, lineSeparator,
// paragraphSeparator, and nextLine. The latter three are just desirable to suppress new lines in
// the language service. These characters should be escaped when printing, and if any characters are added,
// the map below must be updated.
const jsxDoubleQuoteEscapedCharsRegExp = /["\u0000-\u001f\u2028\u2029\u0085]/g;
const jsxSingleQuoteEscapedCharsRegExp = /['\u0000-\u001f\u2028\u2029\u0085]/g;
const jsxEscapedCharsMap = new Map(Object.entries({
    '"': "&quot;",
    "'": "&apos;",
}));

function encodeJsxCharacterEntity(charCode: number): string {
    const hexCharCode = charCode.toString(16).toUpperCase();
    return "&#x" + hexCharCode + ";";
}

function getJsxAttributeStringReplacement(c: string) {
    if (c.charCodeAt(0) === CharacterCodes.nullCharacter) {
        return "&#0;";
    }
    return jsxEscapedCharsMap.get(c) || encodeJsxCharacterEntity(c.charCodeAt(0));
}

/** @internal */
export function escapeJsxAttributeString(s: string, quoteChar?: CharacterCodes.doubleQuote | CharacterCodes.singleQuote): string {
    const escapedCharsRegExp = quoteChar === CharacterCodes.singleQuote ? jsxSingleQuoteEscapedCharsRegExp :
        jsxDoubleQuoteEscapedCharsRegExp;
    return s.replace(escapedCharsRegExp, getJsxAttributeStringReplacement);
}

/**
 * Strip off existed surrounding single quotes, double quotes, or backticks from a given string
 *
 * @return non-quoted string
 *
 * @internal
 */
export function stripQuotes(name: string): string {
    const length = name.length;
    if (length >= 2 && name.charCodeAt(0) === name.charCodeAt(length - 1) && isQuoteOrBacktick(name.charCodeAt(0))) {
        return name.substring(1, length - 1);
    }
    return name;
}

function isQuoteOrBacktick(charCode: number) {
    return charCode === CharacterCodes.singleQuote ||
        charCode === CharacterCodes.doubleQuote ||
        charCode === CharacterCodes.backtick;
}

/** @internal */
export function isIntrinsicJsxName(name: __String | string): boolean {
    const ch = (name as string).charCodeAt(0);
    return (ch >= CharacterCodes.a && ch <= CharacterCodes.z) || (name as string).includes("-");
}

const indentStrings: string[] = ["", "    "];
/** @internal */
export function getIndentString(level: number): string {
    // prepopulate cache
    const singleLevel = indentStrings[1];
    for (let current = indentStrings.length; current <= level; current++) {
        indentStrings.push(indentStrings[current - 1] + singleLevel);
    }
    return indentStrings[level];
}

function getIndentSize() {
    return indentStrings[1].length;
}

/** @internal */
export function createTextWriter(newLine: string): EmitTextWriter {
    // Why var? It avoids TDZ checks in the runtime which can be costly.
    // See: https://github.com/microsoft/TypeScript/issues/52924
    /* eslint-disable no-var */
    var output: string;
    var indent: number;
    var lineStart: boolean;
    var lineCount: number;
    var linePos: number;
    var hasTrailingComment = false;
    /* eslint-enable no-var */

    function updateLineCountAndPosFor(s: string) {
        const lineStartsOfS = computeLineStarts(s);
        if (lineStartsOfS.length > 1) {
            lineCount = lineCount + lineStartsOfS.length - 1;
            linePos = output.length - s.length + last(lineStartsOfS);
            lineStart = (linePos - output.length) === 0;
        }
        else {
            lineStart = false;
        }
    }

    function writeText(s: string) {
        if (s && s.length) {
            if (lineStart) {
                s = getIndentString(indent) + s;
                lineStart = false;
            }
            output += s;
            updateLineCountAndPosFor(s);
        }
    }

    function write(s: string) {
        if (s) hasTrailingComment = false;
        writeText(s);
    }

    function writeComment(s: string) {
        if (s) hasTrailingComment = true;
        writeText(s);
    }

    function reset(): void {
        output = "";
        indent = 0;
        lineStart = true;
        lineCount = 0;
        linePos = 0;
        hasTrailingComment = false;
    }

    function rawWrite(s: string) {
        if (s !== undefined) {
            output += s;
            updateLineCountAndPosFor(s);
            hasTrailingComment = false;
        }
    }

    function writeLiteral(s: string) {
        if (s && s.length) {
            write(s);
        }
    }

    function writeLine(force?: boolean) {
        if (!lineStart || force) {
            output += newLine;
            lineCount++;
            linePos = output.length;
            lineStart = true;
            hasTrailingComment = false;
        }
    }

    reset();

    return {
        write,
        rawWrite,
        writeLiteral,
        writeLine,
        increaseIndent: () => {
            indent++;
        },
        decreaseIndent: () => {
            indent--;
        },
        getIndent: () => indent,
        getTextPos: () => output.length,
        getLine: () => lineCount,
        getColumn: () => lineStart ? indent * getIndentSize() : output.length - linePos,
        getText: () => output,
        isAtStartOfLine: () => lineStart,
        hasTrailingComment: () => hasTrailingComment,
        hasTrailingWhitespace: () => !!output.length && isWhiteSpaceLike(output.charCodeAt(output.length - 1)),
        clear: reset,
        writeKeyword: write,
        writeOperator: write,
        writeParameter: write,
        writeProperty: write,
        writePunctuation: write,
        writeSpace: write,
        writeStringLiteral: write,
        writeSymbol: (s, _) => write(s),
        writeTrailingSemicolon: write,
        writeComment,
    };
}

/** @internal */
export function getTrailingSemicolonDeferringWriter(writer: EmitTextWriter): EmitTextWriter {
    let pendingTrailingSemicolon = false;

    function commitPendingTrailingSemicolon() {
        if (pendingTrailingSemicolon) {
            writer.writeTrailingSemicolon(";");
            pendingTrailingSemicolon = false;
        }
    }

    return {
        ...writer,
        writeTrailingSemicolon() {
            pendingTrailingSemicolon = true;
        },
        writeLiteral(s) {
            commitPendingTrailingSemicolon();
            writer.writeLiteral(s);
        },
        writeStringLiteral(s) {
            commitPendingTrailingSemicolon();
            writer.writeStringLiteral(s);
        },
        writeSymbol(s, sym) {
            commitPendingTrailingSemicolon();
            writer.writeSymbol(s, sym);
        },
        writePunctuation(s) {
            commitPendingTrailingSemicolon();
            writer.writePunctuation(s);
        },
        writeKeyword(s) {
            commitPendingTrailingSemicolon();
            writer.writeKeyword(s);
        },
        writeOperator(s) {
            commitPendingTrailingSemicolon();
            writer.writeOperator(s);
        },
        writeParameter(s) {
            commitPendingTrailingSemicolon();
            writer.writeParameter(s);
        },
        writeSpace(s) {
            commitPendingTrailingSemicolon();
            writer.writeSpace(s);
        },
        writeProperty(s) {
            commitPendingTrailingSemicolon();
            writer.writeProperty(s);
        },
        writeComment(s) {
            commitPendingTrailingSemicolon();
            writer.writeComment(s);
        },
        writeLine() {
            commitPendingTrailingSemicolon();
            writer.writeLine();
        },
        increaseIndent() {
            commitPendingTrailingSemicolon();
            writer.increaseIndent();
        },
        decreaseIndent() {
            commitPendingTrailingSemicolon();
            writer.decreaseIndent();
        },
    };
}

/** @internal */
export function hostUsesCaseSensitiveFileNames(host: { useCaseSensitiveFileNames?(): boolean; }): boolean {
    return host.useCaseSensitiveFileNames ? host.useCaseSensitiveFileNames() : false;
}

/** @internal */
export function hostGetCanonicalFileName(host: { useCaseSensitiveFileNames?(): boolean; }): GetCanonicalFileName {
    return createGetCanonicalFileName(hostUsesCaseSensitiveFileNames(host));
}

/** @internal */
export interface ResolveModuleNameResolutionHost {
    getCanonicalFileName(p: string): string;
    getCommonSourceDirectory(): string;
    getCurrentDirectory(): string;
}

/** @internal */
export function getResolvedExternalModuleName(host: ResolveModuleNameResolutionHost, file: SourceFile, referenceFile?: SourceFile): string {
    return file.moduleName || getExternalModuleNameFromPath(host, file.fileName, referenceFile && referenceFile.fileName);
}

function getCanonicalAbsolutePath(host: ResolveModuleNameResolutionHost, path: string) {
    return host.getCanonicalFileName(getNormalizedAbsolutePath(path, host.getCurrentDirectory()));
}

/** @internal */
export function getExternalModuleNameFromDeclaration(host: ResolveModuleNameResolutionHost, resolver: EmitResolver, declaration: ImportEqualsDeclaration | ImportDeclaration | ExportDeclaration | ModuleDeclaration | ImportTypeNode): string | undefined {
    const file = resolver.getExternalModuleFileFromDeclaration(declaration);
    if (!file || file.isDeclarationFile) {
        return undefined;
    }
    // If the declaration already uses a non-relative name, and is outside the common source directory, continue to use it
    const specifier = getExternalModuleName(declaration);
    if (
        specifier && isStringLiteralLike(specifier) && !pathIsRelative(specifier.text) &&
        !getCanonicalAbsolutePath(host, file.path).includes(getCanonicalAbsolutePath(host, ensureTrailingDirectorySeparator(host.getCommonSourceDirectory())))
    ) {
        return undefined;
    }
    return getResolvedExternalModuleName(host, file);
}

/**
 * Resolves a local path to a path which is absolute to the base of the emit
 *
 * @internal
 */
export function getExternalModuleNameFromPath(host: ResolveModuleNameResolutionHost, fileName: string, referencePath?: string): string {
    const getCanonicalFileName = (f: string) => host.getCanonicalFileName(f);
    const dir = toPath(referencePath ? getDirectoryPath(referencePath) : host.getCommonSourceDirectory(), host.getCurrentDirectory(), getCanonicalFileName);
    const filePath = getNormalizedAbsolutePath(fileName, host.getCurrentDirectory());
    const relativePath = getRelativePathToDirectoryOrUrl(dir, filePath, dir, getCanonicalFileName, /*isAbsolutePathAnUrl*/ false);
    const extensionless = removeFileExtension(relativePath);
    return referencePath ? ensurePathIsNonModuleName(extensionless) : extensionless;
}

/** @internal */
export function getOwnEmitOutputFilePath(fileName: string, host: EmitHost, extension: string): string {
    const compilerOptions = host.getCompilerOptions();
    let emitOutputFilePathWithoutExtension: string;
    if (compilerOptions.outDir) {
        emitOutputFilePathWithoutExtension = removeFileExtension(getSourceFilePathInNewDir(fileName, host, compilerOptions.outDir));
    }
    else {
        emitOutputFilePathWithoutExtension = removeFileExtension(fileName);
    }

    return emitOutputFilePathWithoutExtension + extension;
}

/** @internal */
export function getDeclarationEmitOutputFilePath(fileName: string, host: EmitHost): string {
    return getDeclarationEmitOutputFilePathWorker(fileName, host.getCompilerOptions(), host);
}

/** @internal */
export function getDeclarationEmitOutputFilePathWorker(fileName: string, options: CompilerOptions, host: Pick<EmitHost, "getCommonSourceDirectory" | "getCurrentDirectory" | "getCanonicalFileName">): string {
    const outputDir = options.declarationDir || options.outDir; // Prefer declaration folder if specified

    const path = outputDir
        ? getSourceFilePathInNewDirWorker(fileName, outputDir, host.getCurrentDirectory(), host.getCommonSourceDirectory(), f => host.getCanonicalFileName(f))
        : fileName;
    const declarationExtension = getDeclarationEmitExtensionForPath(path);
    return removeFileExtension(path) + declarationExtension;
}

/** @internal */
export function getDeclarationEmitExtensionForPath(path: string): Extension.Dts | Extension.Dmts | Extension.Dcts | ".d.json.ts" {
    return fileExtensionIsOneOf(path, [Extension.Mjs, Extension.Mts]) ? Extension.Dmts :
        fileExtensionIsOneOf(path, [Extension.Cjs, Extension.Cts]) ? Extension.Dcts :
        fileExtensionIsOneOf(path, [Extension.Json]) ? `.d.json.ts` : // Drive-by redefinition of json declaration file output name so if it's ever enabled, it behaves well
        Extension.Dts;
}

/**
 * This function is an inverse of `getDeclarationEmitExtensionForPath`.
 *
 * @internal
 */
export function getPossibleOriginalInputExtensionForExtension(path: string): Extension[] {
    return fileExtensionIsOneOf(path, [Extension.Dmts, Extension.Mjs, Extension.Mts]) ? [Extension.Mts, Extension.Mjs] :
        fileExtensionIsOneOf(path, [Extension.Dcts, Extension.Cjs, Extension.Cts]) ? [Extension.Cts, Extension.Cjs] :
        fileExtensionIsOneOf(path, [`.d.json.ts`]) ? [Extension.Json] :
        [Extension.Tsx, Extension.Ts, Extension.Jsx, Extension.Js];
}

/** @internal */
export function getPossibleOriginalInputPathWithoutChangingExt(
    filePath: string,
    ignoreCase: boolean,
    outputDir: string | undefined,
    getCommonSourceDirectory: () => string,
): string {
    return outputDir ?
        resolvePath(
            getCommonSourceDirectory(),
            getRelativePathFromDirectory(outputDir, filePath, ignoreCase),
        ) :
        filePath;
}

/**
 * Returns 'undefined' if and only if 'options.paths' is undefined.
 *
 * @internal
 */
export function getPathsBasePath(options: CompilerOptions, host: { getCurrentDirectory?(): string; }): string | undefined {
    if (!options.paths) return undefined;
    return options.baseUrl ?? Debug.checkDefined(options.pathsBasePath || host.getCurrentDirectory?.(), "Encountered 'paths' without a 'baseUrl', config file, or host 'getCurrentDirectory'.");
}

/** @internal */
export interface EmitFileNames {
    jsFilePath?: string | undefined;
    sourceMapFilePath?: string | undefined;
    declarationFilePath?: string | undefined;
    declarationMapPath?: string | undefined;
    buildInfoPath?: string | undefined;
}

/**
 * Gets the source files that are expected to have an emit output.
 *
 * Originally part of `forEachExpectedEmitFile`, this functionality was extracted to support
 * transformations.
 *
 * @param host An EmitHost.
 * @param targetSourceFile An optional target source file to emit.
 *
 * @internal
 */
export function getSourceFilesToEmit(host: EmitHost, targetSourceFile?: SourceFile, forceDtsEmit?: boolean): readonly SourceFile[] {
    const options = host.getCompilerOptions();
    if (options.outFile) {
        const moduleKind = getEmitModuleKind(options);
        const moduleEmitEnabled = options.emitDeclarationOnly || moduleKind === ModuleKind.AMD || moduleKind === ModuleKind.System;
        // Can emit only sources that are not declaration file and are either non module code or module with --module or --target es6 specified
        return filter(
            host.getSourceFiles(),
            sourceFile =>
                (moduleEmitEnabled || !isExternalModule(sourceFile)) &&
                sourceFileMayBeEmitted(sourceFile, host, forceDtsEmit),
        );
    }
    else {
        const sourceFiles = targetSourceFile === undefined ? host.getSourceFiles() : [targetSourceFile];
        return filter(
            sourceFiles,
            sourceFile => sourceFileMayBeEmitted(sourceFile, host, forceDtsEmit),
        );
    }
}

/**
 * Don't call this for `--outFile`, just for `--outDir` or plain emit. `--outFile` needs additional checks.
 *
 * @internal
 */
export function sourceFileMayBeEmitted(sourceFile: SourceFile, host: SourceFileMayBeEmittedHost, forceDtsEmit?: boolean): boolean {
    const options = host.getCompilerOptions();
    // Js files are emitted only if option is enabled
    if (options.noEmitForJsFiles && isSourceFileJS(sourceFile)) return false;
    // Declaration files are not emitted
    if (sourceFile.isDeclarationFile) return false;
    // Source file from node_modules are not emitted
    if (host.isSourceFileFromExternalLibrary(sourceFile)) return false;
    // forcing dts emit => file needs to be emitted
    if (forceDtsEmit) return true;
    // Check other conditions for file emit
    // Source files from referenced projects are not emitted
    if (host.isSourceOfProjectReferenceRedirect(sourceFile.fileName)) return false;
    // Any non json file should be emitted
    if (!isJsonSourceFile(sourceFile)) return true;
    if (host.getRedirectFromSourceFile(sourceFile.fileName)) return false;
    // Emit json file if outFile is specified
    if (options.outFile) return true;
    // Json file is not emitted if outDir is not specified
    if (!options.outDir) return false;
    // Otherwise if rootDir or composite config file, we know common sourceDir and can check if file would be emitted in same location
    if (options.rootDir || options.configFilePath) {
        const commonDir = getNormalizedAbsolutePath(getCommonSourceDirectory(options, () => [], host.getCurrentDirectory(), host.getCanonicalFileName), host.getCurrentDirectory());
        const outputPath = getSourceFilePathInNewDirWorker(sourceFile.fileName, options.outDir, host.getCurrentDirectory(), commonDir, host.getCanonicalFileName);
        if (comparePaths(sourceFile.fileName, outputPath, host.getCurrentDirectory(), !host.useCaseSensitiveFileNames()) === Comparison.EqualTo) return false;
    }
    return true;
}

/** @internal */
export function getSourceFilePathInNewDir(fileName: string, host: EmitHost, newDirPath: string): string {
    return getSourceFilePathInNewDirWorker(fileName, newDirPath, host.getCurrentDirectory(), host.getCommonSourceDirectory(), f => host.getCanonicalFileName(f));
}

function getSourceFilePathInNewDirWorker(fileName: string, newDirPath: string, currentDirectory: string, commonSourceDirectory: string, getCanonicalFileName: GetCanonicalFileName): string {
    let sourceFilePath = getNormalizedAbsolutePath(fileName, currentDirectory);
    const isSourceFileInCommonSourceDirectory = getCanonicalFileName(sourceFilePath).indexOf(getCanonicalFileName(commonSourceDirectory)) === 0;
    sourceFilePath = isSourceFileInCommonSourceDirectory ? sourceFilePath.substring(commonSourceDirectory.length) : sourceFilePath;
    return combinePaths(newDirPath, sourceFilePath);
}

/** @internal */
export function writeFile(host: { writeFile: WriteFileCallback; }, diagnostics: DiagnosticCollection, fileName: string, text: string, writeByteOrderMark: boolean, sourceFiles?: readonly SourceFile[], data?: WriteFileCallbackData): void {
    host.writeFile(
        fileName,
        text,
        writeByteOrderMark,
        hostErrorMessage => {
            diagnostics.add(createCompilerDiagnostic(Diagnostics.Could_not_write_file_0_Colon_1, fileName, hostErrorMessage));
        },
        sourceFiles,
        data,
    );
}

function ensureDirectoriesExist(
    directoryPath: string,
    createDirectory: (path: string) => void,
    directoryExists: (path: string) => boolean,
): void {
    if (directoryPath.length > getRootLength(directoryPath) && !directoryExists(directoryPath)) {
        const parentDirectory = getDirectoryPath(directoryPath);
        ensureDirectoriesExist(parentDirectory, createDirectory, directoryExists);
        createDirectory(directoryPath);
    }
}

/** @internal */
export function writeFileEnsuringDirectories(
    path: string,
    data: string,
    writeByteOrderMark: boolean,
    writeFile: (path: string, data: string, writeByteOrderMark: boolean) => void,
    createDirectory: (path: string) => void,
    directoryExists: (path: string) => boolean,
): void {
    // PERF: Checking for directory existence is expensive.  Instead, assume the directory exists
    // and fall back to creating it if the file write fails.
    try {
        writeFile(path, data, writeByteOrderMark);
    }
    catch {
        ensureDirectoriesExist(getDirectoryPath(normalizePath(path)), createDirectory, directoryExists);
        writeFile(path, data, writeByteOrderMark);
    }
}

/** @internal */
export function getLineOfLocalPosition(sourceFile: SourceFile, pos: number): number {
    const lineStarts = getLineStarts(sourceFile);
    return computeLineOfPosition(lineStarts, pos);
}

function getLineOfLocalPositionFromLineMap(lineMap: readonly number[], pos: number) {
    return computeLineOfPosition(lineMap, pos);
}

/** @internal */
export function getFirstConstructorWithBody(node: ClassLikeDeclaration): ConstructorDeclaration & { body: FunctionBody; } | undefined {
    return find(node.members, (member): member is ConstructorDeclaration & { body: FunctionBody; } => isConstructorDeclaration(member) && nodeIsPresent(member.body));
}

/** @internal */
export function getSetAccessorValueParameter(accessor: SetAccessorDeclaration): ParameterDeclaration | undefined {
    if (accessor && accessor.parameters.length > 0) {
        const hasThis = accessor.parameters.length === 2 && parameterIsThisKeyword(accessor.parameters[0]);
        return accessor.parameters[hasThis ? 1 : 0];
    }
}

/**
 * Get the type annotation for the value parameter.
 *
 * @internal
 */
export function getSetAccessorTypeAnnotationNode(accessor: SetAccessorDeclaration): TypeNode | undefined {
    const parameter = getSetAccessorValueParameter(accessor);
    return parameter && parameter.type;
}

/** @internal */
export function getThisParameter(signature: SignatureDeclaration | JSDocSignature): ParameterDeclaration | undefined {
    // callback tags do not currently support this parameters
    if (signature.parameters.length && !isJSDocSignature(signature)) {
        const thisParameter = signature.parameters[0];
        if (parameterIsThisKeyword(thisParameter)) {
            return thisParameter;
        }
    }
}

/** @internal */
export function parameterIsThisKeyword(parameter: ParameterDeclaration): boolean {
    return isThisIdentifier(parameter.name);
}

/** @internal */
export function isThisIdentifier(node: Node | undefined): boolean {
    return !!node && node.kind === SyntaxKind.Identifier && identifierIsThisKeyword(node as Identifier);
}

/** @internal */
export function isInTypeQuery(node: Node): boolean {
    // TypeScript 1.0 spec (April 2014): 3.6.3
    // A type query consists of the keyword typeof followed by an expression.
    // The expression is restricted to a single identifier or a sequence of identifiers separated by periods
    return !!findAncestor(
        node,
        n => n.kind === SyntaxKind.TypeQuery ? true : n.kind === SyntaxKind.Identifier || n.kind === SyntaxKind.QualifiedName ? false : "quit",
    );
}

/** @internal */
export function isThisInTypeQuery(node: Node): boolean {
    if (!isThisIdentifier(node)) {
        return false;
    }

    while (isQualifiedName(node.parent) && node.parent.left === node) {
        node = node.parent;
    }

    return node.parent.kind === SyntaxKind.TypeQuery;
}

/** @internal */
export function identifierIsThisKeyword(id: Identifier): boolean {
    return id.escapedText === "this";
}

/** @internal */
export function getAllAccessorDeclarations(declarations: readonly Declaration[] | undefined, accessor: AccessorDeclaration): AllAccessorDeclarations {
    // TODO: GH#18217
    let firstAccessor!: AccessorDeclaration;
    let secondAccessor!: AccessorDeclaration;
    let getAccessor!: GetAccessorDeclaration;
    let setAccessor!: SetAccessorDeclaration;
    if (hasDynamicName(accessor)) {
        firstAccessor = accessor;
        if (accessor.kind === SyntaxKind.GetAccessor) {
            getAccessor = accessor;
        }
        else if (accessor.kind === SyntaxKind.SetAccessor) {
            setAccessor = accessor;
        }
        else {
            Debug.fail("Accessor has wrong kind");
        }
    }
    else {
        forEach(declarations, member => {
            if (
                isAccessor(member)
                && isStatic(member) === isStatic(accessor)
            ) {
                const memberName = getPropertyNameForPropertyNameNode(member.name);
                const accessorName = getPropertyNameForPropertyNameNode(accessor.name);
                if (memberName === accessorName) {
                    if (!firstAccessor) {
                        firstAccessor = member;
                    }
                    else if (!secondAccessor) {
                        secondAccessor = member;
                    }

                    if (member.kind === SyntaxKind.GetAccessor && !getAccessor) {
                        getAccessor = member;
                    }

                    if (member.kind === SyntaxKind.SetAccessor && !setAccessor) {
                        setAccessor = member;
                    }
                }
            }
        });
    }
    return {
        firstAccessor,
        secondAccessor,
        getAccessor,
        setAccessor,
    };
}

/**
 * Gets the effective type annotation of a variable, parameter, or property. If the node was
 * parsed in a JavaScript file, gets the type annotation from JSDoc.  Also gets the type of
 * functions only the JSDoc case.
 *
 * @internal
 */
export function getEffectiveTypeAnnotationNode(node: Node): TypeNode | undefined {
    if (!isInJSFile(node) && isFunctionDeclaration(node)) return undefined;
    if (isTypeAliasDeclaration(node)) return undefined; // has a .type, is not a type annotation
    const type = (node as HasType).type;
    if (type || !isInJSFile(node)) return type;
    return isJSDocPropertyLikeTag(node) ? node.typeExpression && node.typeExpression.type : getJSDocType(node);
}

/** @internal */
export function getTypeAnnotationNode(node: Node): TypeNode | undefined {
    return (node as HasType).type;
}

/**
 * Gets the effective return type annotation of a signature. If the node was parsed in a
 * JavaScript file, gets the return type annotation from JSDoc.
 *
 * @internal
 */
export function getEffectiveReturnTypeNode(node: SignatureDeclaration | JSDocSignature): TypeNode | undefined {
    return isJSDocSignature(node) ?
        node.type && node.type.typeExpression && node.type.typeExpression.type :
        node.type || (isInJSFile(node) ? getJSDocReturnType(node) : undefined);
}

/** @internal */
export function getJSDocTypeParameterDeclarations(node: DeclarationWithTypeParameters): readonly TypeParameterDeclaration[] {
    return flatMap(getJSDocTags(node), tag => isNonTypeAliasTemplate(tag) ? tag.typeParameters : undefined);
}

/** template tags are only available when a typedef isn't already using them */
function isNonTypeAliasTemplate(tag: JSDocTag): tag is JSDocTemplateTag {
    return isJSDocTemplateTag(tag) && !(tag.parent.kind === SyntaxKind.JSDoc && (tag.parent.tags!.some(isJSDocTypeAlias) || tag.parent.tags!.some(isJSDocOverloadTag)));
}

/**
 * Gets the effective type annotation of the value parameter of a set accessor. If the node
 * was parsed in a JavaScript file, gets the type annotation from JSDoc.
 *
 * @internal
 */
export function getEffectiveSetAccessorTypeAnnotationNode(node: SetAccessorDeclaration): TypeNode | undefined {
    const parameter = getSetAccessorValueParameter(node);
    return parameter && getEffectiveTypeAnnotationNode(parameter);
}

function emitNewLineBeforeLeadingComments(lineMap: readonly number[], writer: EmitTextWriter, node: TextRange, leadingComments: readonly CommentRange[] | undefined) {
    emitNewLineBeforeLeadingCommentsOfPosition(lineMap, writer, node.pos, leadingComments);
}

function emitNewLineBeforeLeadingCommentsOfPosition(lineMap: readonly number[], writer: EmitTextWriter, pos: number, leadingComments: readonly CommentRange[] | undefined) {
    // If the leading comments start on different line than the start of node, write new line
    if (
        leadingComments && leadingComments.length && pos !== leadingComments[0].pos &&
        getLineOfLocalPositionFromLineMap(lineMap, pos) !== getLineOfLocalPositionFromLineMap(lineMap, leadingComments[0].pos)
    ) {
        writer.writeLine();
    }
}

/** @internal */
export function emitNewLineBeforeLeadingCommentOfPosition(lineMap: readonly number[], writer: EmitTextWriter, pos: number, commentPos: number): void {
    // If the leading comments start on different line than the start of node, write new line
    if (
        pos !== commentPos &&
        getLineOfLocalPositionFromLineMap(lineMap, pos) !== getLineOfLocalPositionFromLineMap(lineMap, commentPos)
    ) {
        writer.writeLine();
    }
}

function emitComments(
    text: string,
    lineMap: readonly number[],
    writer: EmitTextWriter,
    comments: readonly CommentRange[] | undefined,
    leadingSeparator: boolean,
    trailingSeparator: boolean,
    newLine: string,
    writeComment: (text: string, lineMap: readonly number[], writer: EmitTextWriter, commentPos: number, commentEnd: number, newLine: string) => void,
) {
    if (comments && comments.length > 0) {
        if (leadingSeparator) {
            writer.writeSpace(" ");
        }

        let emitInterveningSeparator = false;
        for (const comment of comments) {
            if (emitInterveningSeparator) {
                writer.writeSpace(" ");
                emitInterveningSeparator = false;
            }

            writeComment(text, lineMap, writer, comment.pos, comment.end, newLine);
            if (comment.hasTrailingNewLine) {
                writer.writeLine();
            }
            else {
                emitInterveningSeparator = true;
            }
        }

        if (emitInterveningSeparator && trailingSeparator) {
            writer.writeSpace(" ");
        }
    }
}

/** @internal */
export interface DetachedCommentInfo {
    nodePos: number;
    detachedCommentEndPos: number;
}

/**
 * Detached comment is a comment at the top of file or function body that is separated from
 * the next statement by space.
 *
 * @internal
 */
export function emitDetachedComments(
    text: string,
    lineMap: readonly number[],
    writer: EmitTextWriter,
    writeComment: (text: string, lineMap: readonly number[], writer: EmitTextWriter, commentPos: number, commentEnd: number, newLine: string) => void,
    node: TextRange,
    newLine: string,
    removeComments: boolean,
): DetachedCommentInfo | undefined {
    let leadingComments: CommentRange[] | undefined;
    let currentDetachedCommentInfo: { nodePos: number; detachedCommentEndPos: number; } | undefined;
    if (removeComments) {
        // removeComments is true, only reserve pinned comment at the top of file
        // For example:
        //      /*! Pinned Comment */
        //
        //      var x = 10;
        if (node.pos === 0) {
            leadingComments = filter(getLeadingCommentRanges(text, node.pos), isPinnedCommentLocal);
        }
    }
    else {
        // removeComments is false, just get detached as normal and bypass the process to filter comment
        leadingComments = getLeadingCommentRanges(text, node.pos);
    }

    if (leadingComments) {
        const detachedComments: CommentRange[] = [];
        let lastComment: CommentRange | undefined;

        for (const comment of leadingComments) {
            if (lastComment) {
                const lastCommentLine = getLineOfLocalPositionFromLineMap(lineMap, lastComment.end);
                const commentLine = getLineOfLocalPositionFromLineMap(lineMap, comment.pos);

                if (commentLine >= lastCommentLine + 2) {
                    // There was a blank line between the last comment and this comment.  This
                    // comment is not part of the copyright comments.  Return what we have so
                    // far.
                    break;
                }
            }

            detachedComments.push(comment);
            lastComment = comment;
        }

        if (detachedComments.length) {
            // All comments look like they could have been part of the copyright header.  Make
            // sure there is at least one blank line between it and the node.  If not, it's not
            // a copyright header.
            const lastCommentLine = getLineOfLocalPositionFromLineMap(lineMap, last(detachedComments).end);
            const nodeLine = getLineOfLocalPositionFromLineMap(lineMap, skipTrivia(text, node.pos));
            if (nodeLine >= lastCommentLine + 2) {
                // Valid detachedComments
                emitNewLineBeforeLeadingComments(lineMap, writer, node, leadingComments);
                emitComments(text, lineMap, writer, detachedComments, /*leadingSeparator*/ false, /*trailingSeparator*/ true, newLine, writeComment);
                currentDetachedCommentInfo = { nodePos: node.pos, detachedCommentEndPos: last(detachedComments).end };
            }
        }
    }

    return currentDetachedCommentInfo;

    function isPinnedCommentLocal(comment: CommentRange) {
        return isPinnedComment(text, comment.pos);
    }
}

/** @internal */
export function writeCommentRange(text: string, lineMap: readonly number[], writer: EmitTextWriter, commentPos: number, commentEnd: number, newLine: string): void {
    if (text.charCodeAt(commentPos + 1) === CharacterCodes.asterisk) {
        const firstCommentLineAndCharacter = computeLineAndCharacterOfPosition(lineMap, commentPos);
        const lineCount = lineMap.length;
        let firstCommentLineIndent: number | undefined;
        for (let pos = commentPos, currentLine = firstCommentLineAndCharacter.line; pos < commentEnd; currentLine++) {
            const nextLineStart = (currentLine + 1) === lineCount
                ? text.length + 1
                : lineMap[currentLine + 1];

            if (pos !== commentPos) {
                // If we are not emitting first line, we need to write the spaces to adjust the alignment
                if (firstCommentLineIndent === undefined) {
                    firstCommentLineIndent = calculateIndent(text, lineMap[firstCommentLineAndCharacter.line], commentPos);
                }

                // These are number of spaces writer is going to write at current indent
                const currentWriterIndentSpacing = writer.getIndent() * getIndentSize();

                // Number of spaces we want to be writing
                // eg: Assume writer indent
                // module m {
                //         /* starts at character 9 this is line 1
                //    * starts at character pos 4 line                        --1  = 8 - 8 + 3
                //   More left indented comment */                            --2  = 8 - 8 + 2
                //     class c { }
                // }
                // module m {
                //     /* this is line 1 -- Assume current writer indent 8
                //      * line                                                --3 = 8 - 4 + 5
                //            More right indented comment */                  --4 = 8 - 4 + 11
                //     class c { }
                // }
                const spacesToEmit = currentWriterIndentSpacing - firstCommentLineIndent + calculateIndent(text, pos, nextLineStart);
                if (spacesToEmit > 0) {
                    let numberOfSingleSpacesToEmit = spacesToEmit % getIndentSize();
                    const indentSizeSpaceString = getIndentString((spacesToEmit - numberOfSingleSpacesToEmit) / getIndentSize());

                    // Write indent size string ( in eg 1: = "", 2: "" , 3: string with 8 spaces 4: string with 12 spaces
                    writer.rawWrite(indentSizeSpaceString);

                    // Emit the single spaces (in eg: 1: 3 spaces, 2: 2 spaces, 3: 1 space, 4: 3 spaces)
                    while (numberOfSingleSpacesToEmit) {
                        writer.rawWrite(" ");
                        numberOfSingleSpacesToEmit--;
                    }
                }
                else {
                    // No spaces to emit write empty string
                    writer.rawWrite("");
                }
            }

            // Write the comment line text
            writeTrimmedCurrentLine(text, commentEnd, writer, newLine, pos, nextLineStart);

            pos = nextLineStart;
        }
    }
    else {
        // Single line comment of style //....
        writer.writeComment(text.substring(commentPos, commentEnd));
    }
}

function writeTrimmedCurrentLine(text: string, commentEnd: number, writer: EmitTextWriter, newLine: string, pos: number, nextLineStart: number) {
    const end = Math.min(commentEnd, nextLineStart - 1);
    const currentLineText = text.substring(pos, end).trim();
    if (currentLineText) {
        // trimmed forward and ending spaces text
        writer.writeComment(currentLineText);
        if (end !== commentEnd) {
            writer.writeLine();
        }
    }
    else {
        // Empty string - make sure we write empty line
        writer.rawWrite(newLine);
    }
}

function calculateIndent(text: string, pos: number, end: number) {
    let currentLineIndent = 0;
    for (; pos < end && isWhiteSpaceSingleLine(text.charCodeAt(pos)); pos++) {
        if (text.charCodeAt(pos) === CharacterCodes.tab) {
            // Tabs = TabSize = indent size and go to next tabStop
            currentLineIndent += getIndentSize() - (currentLineIndent % getIndentSize());
        }
        else {
            // Single space
            currentLineIndent++;
        }
    }

    return currentLineIndent;
}

/** @internal */
export function hasEffectiveModifiers(node: Node): boolean {
    return getEffectiveModifierFlags(node) !== ModifierFlags.None;
}

/** @internal */
export function hasSyntacticModifiers(node: Node): boolean {
    return getSyntacticModifierFlags(node) !== ModifierFlags.None;
}

/** @internal */
export function hasEffectiveModifier(node: Node, flags: ModifierFlags): boolean {
    return !!getSelectedEffectiveModifierFlags(node, flags);
}

/** @internal */
export function hasSyntacticModifier(node: Node, flags: ModifierFlags): boolean {
    return !!getSelectedSyntacticModifierFlags(node, flags);
}

/** @internal */
export function isStatic(node: Node): boolean {
    // https://tc39.es/ecma262/#sec-static-semantics-isstatic
    return isClassElement(node) && hasStaticModifier(node) || isClassStaticBlockDeclaration(node);
}

/** @internal */
export function hasStaticModifier(node: Node): boolean {
    return hasSyntacticModifier(node, ModifierFlags.Static);
}

/** @internal */
export function hasOverrideModifier(node: Node): boolean {
    return hasEffectiveModifier(node, ModifierFlags.Override);
}

/** @internal */
export function hasAbstractModifier(node: Node): boolean {
    return hasSyntacticModifier(node, ModifierFlags.Abstract);
}

/** @internal */
export function hasAmbientModifier(node: Node): boolean {
    return hasSyntacticModifier(node, ModifierFlags.Ambient);
}

/** @internal */
export function hasAccessorModifier(node: Node): boolean {
    return hasSyntacticModifier(node, ModifierFlags.Accessor);
}

/** @internal */
export function hasEffectiveReadonlyModifier(node: Node): boolean {
    return hasEffectiveModifier(node, ModifierFlags.Readonly);
}

/** @internal */
export function hasDecorators(node: Node): boolean {
    return hasSyntacticModifier(node, ModifierFlags.Decorator);
}

/** @internal */
export function getSelectedEffectiveModifierFlags(node: Node, flags: ModifierFlags): ModifierFlags {
    return getEffectiveModifierFlags(node) & flags;
}

/** @internal @knipignore */
export function getSelectedSyntacticModifierFlags(node: Node, flags: ModifierFlags): ModifierFlags {
    return getSyntacticModifierFlags(node) & flags;
}

function getModifierFlagsWorker(node: Node, includeJSDoc: boolean, alwaysIncludeJSDoc?: boolean): ModifierFlags {
    if (node.kind >= SyntaxKind.FirstToken && node.kind <= SyntaxKind.LastToken) {
        return ModifierFlags.None;
    }

    if (!(node.modifierFlagsCache & ModifierFlags.HasComputedFlags)) {
        node.modifierFlagsCache = getSyntacticModifierFlagsNoCache(node) | ModifierFlags.HasComputedFlags;
    }

    if (alwaysIncludeJSDoc || includeJSDoc && isInJSFile(node)) {
        if (!(node.modifierFlagsCache & ModifierFlags.HasComputedJSDocModifiers) && node.parent) {
            node.modifierFlagsCache |= getRawJSDocModifierFlagsNoCache(node) | ModifierFlags.HasComputedJSDocModifiers;
        }
        return selectEffectiveModifierFlags(node.modifierFlagsCache);
    }

    return selectSyntacticModifierFlags(node.modifierFlagsCache);
}

/**
 * Gets the effective ModifierFlags for the provided node, including JSDoc modifiers. The modifiers will be cached on the node to improve performance.
 *
 * NOTE: This function may use `parent` pointers.
 *
 * @internal
 */
export function getEffectiveModifierFlags(node: Node): ModifierFlags {
    return getModifierFlagsWorker(node, /*includeJSDoc*/ true);
}

/** @internal */
export function getEffectiveModifierFlagsAlwaysIncludeJSDoc(node: Node): ModifierFlags {
    return getModifierFlagsWorker(node, /*includeJSDoc*/ true, /*alwaysIncludeJSDoc*/ true);
}

/**
 * Gets the ModifierFlags for syntactic modifiers on the provided node. The modifiers will be cached on the node to improve performance.
 *
 * NOTE: This function does not use `parent` pointers and will not include modifiers from JSDoc.
 *
 * @internal
 */
export function getSyntacticModifierFlags(node: Node): ModifierFlags {
    return getModifierFlagsWorker(node, /*includeJSDoc*/ false);
}

function getRawJSDocModifierFlagsNoCache(node: Node): ModifierFlags {
    let flags = ModifierFlags.None;
    if (!!node.parent && !isParameter(node)) {
        if (isInJSFile(node)) {
            if (getJSDocPublicTagNoCache(node)) flags |= ModifierFlags.JSDocPublic;
            if (getJSDocPrivateTagNoCache(node)) flags |= ModifierFlags.JSDocPrivate;
            if (getJSDocProtectedTagNoCache(node)) flags |= ModifierFlags.JSDocProtected;
            if (getJSDocReadonlyTagNoCache(node)) flags |= ModifierFlags.JSDocReadonly;
            if (getJSDocOverrideTagNoCache(node)) flags |= ModifierFlags.JSDocOverride;
        }
        if (getJSDocDeprecatedTagNoCache(node)) flags |= ModifierFlags.Deprecated;
    }

    return flags;
}

function selectSyntacticModifierFlags(flags: ModifierFlags) {
    return flags & ModifierFlags.SyntacticModifiers;
}

function selectEffectiveModifierFlags(flags: ModifierFlags) {
    return (flags & ModifierFlags.NonCacheOnlyModifiers) |
        ((flags & ModifierFlags.JSDocCacheOnlyModifiers) >>> 23); // shift ModifierFlags.JSDoc* to match ModifierFlags.*
}

function getJSDocModifierFlagsNoCache(node: Node): ModifierFlags {
    return selectEffectiveModifierFlags(getRawJSDocModifierFlagsNoCache(node));
}

/**
 * Gets the effective ModifierFlags for the provided node, including JSDoc modifiers. The modifier flags cache on the node is ignored.
 *
 * NOTE: This function may use `parent` pointers.
 *
 * @internal
 */
export function getEffectiveModifierFlagsNoCache(node: Node): ModifierFlags {
    return getSyntacticModifierFlagsNoCache(node) | getJSDocModifierFlagsNoCache(node);
}

/**
 * Gets the ModifierFlags for syntactic modifiers on the provided node. The modifier flags cache on the node is ignored.
 *
 * NOTE: This function does not use `parent` pointers and will not include modifiers from JSDoc.
 *
 * @internal
 * @knipignore
 */
export function getSyntacticModifierFlagsNoCache(node: Node): ModifierFlags {
    let flags = canHaveModifiers(node) ? modifiersToFlags(node.modifiers) : ModifierFlags.None;
    if (node.flags & NodeFlags.NestedNamespace || node.kind === SyntaxKind.Identifier && node.flags & NodeFlags.IdentifierIsInJSDocNamespace) {
        flags |= ModifierFlags.Export;
    }
    return flags;
}

/** @internal */
export function modifiersToFlags(modifiers: readonly ModifierLike[] | undefined): ModifierFlags {
    let flags = ModifierFlags.None;
    if (modifiers) {
        for (const modifier of modifiers) {
            flags |= modifierToFlag(modifier.kind);
        }
    }
    return flags;
}

/** @internal */
export function modifierToFlag(token: SyntaxKind): ModifierFlags {
    switch (token) {
        case SyntaxKind.StaticKeyword:
            return ModifierFlags.Static;
        case SyntaxKind.PublicKeyword:
            return ModifierFlags.Public;
        case SyntaxKind.ProtectedKeyword:
            return ModifierFlags.Protected;
        case SyntaxKind.PrivateKeyword:
            return ModifierFlags.Private;
        case SyntaxKind.AbstractKeyword:
            return ModifierFlags.Abstract;
        case SyntaxKind.AccessorKeyword:
            return ModifierFlags.Accessor;
        case SyntaxKind.ExportKeyword:
            return ModifierFlags.Export;
        case SyntaxKind.DeclareKeyword:
            return ModifierFlags.Ambient;
        case SyntaxKind.ConstKeyword:
            return ModifierFlags.Const;
        case SyntaxKind.DefaultKeyword:
            return ModifierFlags.Default;
        case SyntaxKind.AsyncKeyword:
            return ModifierFlags.Async;
        case SyntaxKind.ReadonlyKeyword:
            return ModifierFlags.Readonly;
        case SyntaxKind.OverrideKeyword:
            return ModifierFlags.Override;
        case SyntaxKind.InKeyword:
            return ModifierFlags.In;
        case SyntaxKind.OutKeyword:
            return ModifierFlags.Out;
        case SyntaxKind.Decorator:
            return ModifierFlags.Decorator;
    }
    return ModifierFlags.None;
}

/** @internal */
export function isBinaryLogicalOperator(token: SyntaxKind): boolean {
    return token === SyntaxKind.BarBarToken || token === SyntaxKind.AmpersandAmpersandToken;
}

/** @internal */
export function isLogicalOperator(token: SyntaxKind): boolean {
    return isBinaryLogicalOperator(token) || token === SyntaxKind.ExclamationToken;
}

/** @internal */
export function isLogicalOrCoalescingAssignmentOperator(token: SyntaxKind): token is LogicalOrCoalescingAssignmentOperator {
    return token === SyntaxKind.BarBarEqualsToken
        || token === SyntaxKind.AmpersandAmpersandEqualsToken
        || token === SyntaxKind.QuestionQuestionEqualsToken;
}

/** @internal */
export function isLogicalOrCoalescingAssignmentExpression(expr: Node): expr is AssignmentExpression<Token<LogicalOrCoalescingAssignmentOperator>> {
    return isBinaryExpression(expr) && isLogicalOrCoalescingAssignmentOperator(expr.operatorToken.kind);
}

/** @internal */
export function isLogicalOrCoalescingBinaryOperator(token: SyntaxKind): token is LogicalOperator | SyntaxKind.QuestionQuestionToken {
    return isBinaryLogicalOperator(token) || token === SyntaxKind.QuestionQuestionToken;
}

/** @internal */
export function isLogicalOrCoalescingBinaryExpression(expr: Node): expr is BinaryExpression {
    return isBinaryExpression(expr) && isLogicalOrCoalescingBinaryOperator(expr.operatorToken.kind);
}

/** @internal */
export function isAssignmentOperator(token: SyntaxKind): boolean {
    return token >= SyntaxKind.FirstAssignment && token <= SyntaxKind.LastAssignment;
}

/**
 * Get `C` given `N` if `N` is in the position `class C extends N` where `N` is an ExpressionWithTypeArguments.
 *
 * @internal
 */
export function tryGetClassExtendingExpressionWithTypeArguments(node: Node): ClassLikeDeclaration | undefined {
    const cls = tryGetClassImplementingOrExtendingExpressionWithTypeArguments(node);
    return cls && !cls.isImplements ? cls.class : undefined;
}

/** @internal */
export interface ClassImplementingOrExtendingExpressionWithTypeArguments {
    readonly class: ClassLikeDeclaration;
    readonly isImplements: boolean;
}
/** @internal */
export function tryGetClassImplementingOrExtendingExpressionWithTypeArguments(node: Node): ClassImplementingOrExtendingExpressionWithTypeArguments | undefined {
    if (isExpressionWithTypeArguments(node)) {
        if (isHeritageClause(node.parent) && isClassLike(node.parent.parent)) {
            return { class: node.parent.parent, isImplements: node.parent.token === SyntaxKind.ImplementsKeyword };
        }
        if (isJSDocAugmentsTag(node.parent)) {
            const host = getEffectiveJSDocHost(node.parent);
            if (host && isClassLike(host)) {
                return { class: host, isImplements: false };
            }
        }
    }
    return undefined;
}

/** @internal */
export function isAssignmentExpression(node: Node, excludeCompoundAssignment: true): node is AssignmentExpression<EqualsToken>;
/** @internal */
export function isAssignmentExpression(node: Node, excludeCompoundAssignment?: false): node is AssignmentExpression<AssignmentOperatorToken>;
/** @internal */
export function isAssignmentExpression(node: Node, excludeCompoundAssignment?: boolean): node is AssignmentExpression<AssignmentOperatorToken> {
    return isBinaryExpression(node)
        && (excludeCompoundAssignment
            ? node.operatorToken.kind === SyntaxKind.EqualsToken
            : isAssignmentOperator(node.operatorToken.kind))
        && isLeftHandSideExpression(node.left);
}

/** @internal */
export function isDestructuringAssignment(node: Node): node is DestructuringAssignment {
    if (isAssignmentExpression(node, /*excludeCompoundAssignment*/ true)) {
        const kind = node.left.kind;
        return kind === SyntaxKind.ObjectLiteralExpression
            || kind === SyntaxKind.ArrayLiteralExpression;
    }

    return false;
}

/** @internal */
export function isExpressionWithTypeArgumentsInClassExtendsClause(node: Node): node is ExpressionWithTypeArguments {
    return tryGetClassExtendingExpressionWithTypeArguments(node) !== undefined;
}

/** @internal */
export function isEntityNameExpression(node: Node): node is EntityNameExpression {
    return node.kind === SyntaxKind.Identifier || isPropertyAccessEntityNameExpression(node);
}

/** @internal */
export function getFirstIdentifier(node: EntityNameOrEntityNameExpression): Identifier {
    switch (node.kind) {
        case SyntaxKind.Identifier:
            return node;
        case SyntaxKind.QualifiedName:
            do {
                node = node.left;
            }
            while (node.kind !== SyntaxKind.Identifier);
            return node;
        case SyntaxKind.PropertyAccessExpression:
            do {
                node = node.expression;
            }
            while (node.kind !== SyntaxKind.Identifier);
            return node;
    }
}

/** @internal */
export function isDottedName(node: Expression): boolean {
    return node.kind === SyntaxKind.Identifier
        || node.kind === SyntaxKind.ThisKeyword
        || node.kind === SyntaxKind.SuperKeyword
        || node.kind === SyntaxKind.MetaProperty
        || node.kind === SyntaxKind.PropertyAccessExpression && isDottedName((node as PropertyAccessExpression).expression)
        || node.kind === SyntaxKind.ParenthesizedExpression && isDottedName((node as ParenthesizedExpression).expression);
}

/** @internal */
export function isPropertyAccessEntityNameExpression(node: Node): node is PropertyAccessEntityNameExpression {
    return isPropertyAccessExpression(node) && isIdentifier(node.name) && isEntityNameExpression(node.expression);
}

/** @internal */
export function tryGetPropertyAccessOrIdentifierToString(expr: Expression | JsxTagNameExpression): string | undefined {
    if (isPropertyAccessExpression(expr)) {
        const baseStr = tryGetPropertyAccessOrIdentifierToString(expr.expression);
        if (baseStr !== undefined) {
            return baseStr + "." + entityNameToString(expr.name);
        }
    }
    else if (isElementAccessExpression(expr)) {
        const baseStr = tryGetPropertyAccessOrIdentifierToString(expr.expression);
        if (baseStr !== undefined && isPropertyName(expr.argumentExpression)) {
            return baseStr + "." + getPropertyNameForPropertyNameNode(expr.argumentExpression);
        }
    }
    else if (isIdentifier(expr)) {
        return unescapeLeadingUnderscores(expr.escapedText);
    }
    else if (isJsxNamespacedName(expr)) {
        return getTextOfJsxNamespacedName(expr);
    }
    return undefined;
}

/** @internal */
export function isPrototypeAccess(node: Node): node is BindableStaticAccessExpression {
    return isBindableStaticAccessExpression(node) && getElementOrPropertyAccessName(node) === "prototype";
}

/** @internal */
export function isRightSideOfQualifiedNameOrPropertyAccess(node: Node): boolean {
    return (node.parent.kind === SyntaxKind.QualifiedName && (node.parent as QualifiedName).right === node) ||
        (node.parent.kind === SyntaxKind.PropertyAccessExpression && (node.parent as PropertyAccessExpression).name === node) ||
        (node.parent.kind === SyntaxKind.MetaProperty && (node.parent as MetaProperty).name === node);
}

/** @internal */
export function isRightSideOfAccessExpression(node: Node): boolean {
    return !!node.parent && (isPropertyAccessExpression(node.parent) && node.parent.name === node
        || isElementAccessExpression(node.parent) && node.parent.argumentExpression === node);
}

/** @internal */
export function isRightSideOfQualifiedNameOrPropertyAccessOrJSDocMemberName(node: Node): boolean {
    return isQualifiedName(node.parent) && node.parent.right === node
        || isPropertyAccessExpression(node.parent) && node.parent.name === node
        || isJSDocMemberName(node.parent) && node.parent.right === node;
}
/** @internal */
export function isInstanceOfExpression(node: Node): node is InstanceofExpression {
    return isBinaryExpression(node) && node.operatorToken.kind === SyntaxKind.InstanceOfKeyword;
}

/** @internal */
export function isRightSideOfInstanceofExpression(node: Node): boolean {
    return isInstanceOfExpression(node.parent) && node === node.parent.right;
}

/** @internal */
export function isEmptyObjectLiteral(expression: Node): boolean {
    return expression.kind === SyntaxKind.ObjectLiteralExpression &&
        (expression as ObjectLiteralExpression).properties.length === 0;
}

/** @internal */
export function isEmptyArrayLiteral(expression: Node): boolean {
    return expression.kind === SyntaxKind.ArrayLiteralExpression &&
        (expression as ArrayLiteralExpression).elements.length === 0;
}

/** @internal */
export function getLocalSymbolForExportDefault(symbol: Symbol): Symbol | undefined {
    if (!isExportDefaultSymbol(symbol) || !symbol.declarations) return undefined;
    for (const decl of symbol.declarations) {
        if (decl.localSymbol) return decl.localSymbol;
    }
    return undefined;
}

function isExportDefaultSymbol(symbol: Symbol): boolean {
    return symbol && length(symbol.declarations) > 0 && hasSyntacticModifier(symbol.declarations![0], ModifierFlags.Default);
}

/**
 * Return ".ts", ".d.ts", or ".tsx", if that is the extension.
 *
 * @internal
 */
export function tryExtractTSExtension(fileName: string): string | undefined {
    return find(supportedTSExtensionsForExtractExtension, extension => fileExtensionIs(fileName, extension));
}
/**
 * Replace each instance of non-ascii characters by one, two, three, or four escape sequences
 * representing the UTF-8 encoding of the character, and return the expanded char code list.
 */
function getExpandedCharCodes(input: string): number[] {
    const output: number[] = [];
    const length = input.length;

    for (let i = 0; i < length; i++) {
        const charCode = input.charCodeAt(i);

        // handle utf8
        if (charCode < 0x80) {
            output.push(charCode);
        }
        else if (charCode < 0x800) {
            output.push((charCode >> 6) | 0B11000000);
            output.push((charCode & 0B00111111) | 0B10000000);
        }
        else if (charCode < 0x10000) {
            output.push((charCode >> 12) | 0B11100000);
            output.push(((charCode >> 6) & 0B00111111) | 0B10000000);
            output.push((charCode & 0B00111111) | 0B10000000);
        }
        else if (charCode < 0x20000) {
            output.push((charCode >> 18) | 0B11110000);
            output.push(((charCode >> 12) & 0B00111111) | 0B10000000);
            output.push(((charCode >> 6) & 0B00111111) | 0B10000000);
            output.push((charCode & 0B00111111) | 0B10000000);
        }
        else {
            Debug.assert(false, "Unexpected code point");
        }
    }

    return output;
}

const base64Digits = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

/**
 * Converts a string to a base-64 encoded ASCII string.
 *
 * @internal
 */
export function convertToBase64(input: string): string {
    let result = "";
    const charCodes = getExpandedCharCodes(input);
    let i = 0;
    const length = charCodes.length;
    let byte1: number, byte2: number, byte3: number, byte4: number;

    while (i < length) {
        // Convert every 6-bits in the input 3 character points
        // into a base64 digit
        byte1 = charCodes[i] >> 2;
        byte2 = (charCodes[i] & 0B00000011) << 4 | charCodes[i + 1] >> 4;
        byte3 = (charCodes[i + 1] & 0B00001111) << 2 | charCodes[i + 2] >> 6;
        byte4 = charCodes[i + 2] & 0B00111111;

        // We are out of characters in the input, set the extra
        // digits to 64 (padding character).
        if (i + 1 >= length) {
            byte3 = byte4 = 64;
        }
        else if (i + 2 >= length) {
            byte4 = 64;
        }

        // Write to the output
        result += base64Digits.charAt(byte1) + base64Digits.charAt(byte2) + base64Digits.charAt(byte3) + base64Digits.charAt(byte4);

        i += 3;
    }

    return result;
}

function getStringFromExpandedCharCodes(codes: number[]): string {
    let output = "";
    let i = 0;
    const length = codes.length;
    while (i < length) {
        const charCode = codes[i];

        if (charCode < 0x80) {
            output += String.fromCharCode(charCode);
            i++;
        }
        else if ((charCode & 0B11000000) === 0B11000000) {
            let value = charCode & 0B00111111;
            i++;
            let nextCode: number = codes[i];
            while ((nextCode & 0B11000000) === 0B10000000) {
                value = (value << 6) | (nextCode & 0B00111111);
                i++;
                nextCode = codes[i];
            }
            // `value` may be greater than 10FFFF (the maximum unicode codepoint) - JS will just make this into an invalid character for us
            output += String.fromCharCode(value);
        }
        else {
            // We don't want to kill the process when decoding fails (due to a following char byte not
            // following a leading char), so we just print the (bad) value
            output += String.fromCharCode(charCode);
            i++;
        }
    }
    return output;
}

/** @internal */
export function base64encode(host: { base64encode?(input: string): string; } | undefined, input: string): string {
    if (host && host.base64encode) {
        return host.base64encode(input);
    }
    return convertToBase64(input);
}

/** @internal */
export function base64decode(host: { base64decode?(input: string): string; } | undefined, input: string): string {
    if (host && host.base64decode) {
        return host.base64decode(input);
    }
    const length = input.length;
    const expandedCharCodes: number[] = [];
    let i = 0;
    while (i < length) {
        // Stop decoding once padding characters are present
        if (input.charCodeAt(i) === base64Digits.charCodeAt(64)) {
            break;
        }
        // convert 4 input digits into three characters, ignoring padding characters at the end
        const ch1 = base64Digits.indexOf(input[i]);
        const ch2 = base64Digits.indexOf(input[i + 1]);
        const ch3 = base64Digits.indexOf(input[i + 2]);
        const ch4 = base64Digits.indexOf(input[i + 3]);

        const code1 = ((ch1 & 0B00111111) << 2) | ((ch2 >> 4) & 0B00000011);
        const code2 = ((ch2 & 0B00001111) << 4) | ((ch3 >> 2) & 0B00001111);
        const code3 = ((ch3 & 0B00000011) << 6) | (ch4 & 0B00111111);

        if (code2 === 0 && ch3 !== 0) { // code2 decoded to zero, but ch3 was padding - elide code2 and code3
            expandedCharCodes.push(code1);
        }
        else if (code3 === 0 && ch4 !== 0) { // code3 decoded to zero, but ch4 was padding, elide code3
            expandedCharCodes.push(code1, code2);
        }
        else {
            expandedCharCodes.push(code1, code2, code3);
        }
        i += 4;
    }
    return getStringFromExpandedCharCodes(expandedCharCodes);
}

/** @internal */
export function readJsonOrUndefined(path: string, hostOrText: { readFile(fileName: string): string | undefined; } | string): object | undefined {
    const jsonText = isString(hostOrText) ? hostOrText : hostOrText.readFile(path);
    if (!jsonText) return undefined;
    // Try strictly parsing first, then fall back to our (slower)
    // parser that is resilient to comments/trailing commas.
    // package.json files should never have these, but we
    // have no way to communicate these issues in the first place.
    let result = tryParseJson(jsonText);
    if (result === undefined) {
        const looseResult = parseConfigFileTextToJson(path, jsonText);
        if (!looseResult.error) {
            result = looseResult.config;
        }
    }
    return result;
}

/** @internal */
export function readJson(path: string, host: { readFile(fileName: string): string | undefined; }): object {
    return readJsonOrUndefined(path, host) || {};
}

/** @internal */
export function tryParseJson(text: string): any {
    try {
        return JSON.parse(text);
    }
    catch {
        return undefined;
    }
}

/** @internal */
export function directoryProbablyExists(directoryName: string, host: { directoryExists?: (directoryName: string) => boolean; }): boolean {
    // if host does not support 'directoryExists' assume that directory will exist
    return !host.directoryExists || host.directoryExists(directoryName);
}

const carriageReturnLineFeed = "\r\n";
const lineFeed = "\n";
/** @internal */
export function getNewLineCharacter(options: CompilerOptions | PrinterOptions): string {
    switch (options.newLine) {
        case NewLineKind.CarriageReturnLineFeed:
            return carriageReturnLineFeed;
        case NewLineKind.LineFeed:
        case undefined:
            return lineFeed;
    }
}

/**
 * Creates a new TextRange from the provided pos and end.
 *
 * @param pos The start position.
 * @param end The end position.
 *
 * @internal
 */
export function createRange(pos: number, end: number = pos): TextRange {
    Debug.assert(end >= pos || end === -1);
    return { pos, end };
}

/**
 * Creates a new TextRange from a provided range with a new end position.
 *
 * @param range A TextRange.
 * @param end The new end position.
 *
 * @internal
 */
export function moveRangeEnd(range: TextRange, end: number): TextRange {
    return createRange(range.pos, end);
}

/**
 * Creates a new TextRange from a provided range with a new start position.
 *
 * @param range A TextRange.
 * @param pos The new Start position.
 *
 * @internal
 */
export function moveRangePos(range: TextRange, pos: number): TextRange {
    return createRange(pos, range.end);
}

/**
 * Moves the start position of a range past any decorators.
 *
 * @internal
 */
export function moveRangePastDecorators(node: Node): TextRange {
    const lastDecorator = canHaveModifiers(node) ? findLast(node.modifiers, isDecorator) : undefined;
    return lastDecorator && !positionIsSynthesized(lastDecorator.end)
        ? moveRangePos(node, lastDecorator.end)
        : node;
}

/**
 * Moves the start position of a range past any decorators or modifiers.
 *
 * @internal
 */
export function moveRangePastModifiers(node: Node): TextRange {
    if (isPropertyDeclaration(node) || isMethodDeclaration(node)) {
        return moveRangePos(node, node.name.pos);
    }

    const lastModifier = canHaveModifiers(node) ? lastOrUndefined(node.modifiers) : undefined;
    return lastModifier && !positionIsSynthesized(lastModifier.end)
        ? moveRangePos(node, lastModifier.end)
        : moveRangePastDecorators(node);
}

/**
 * Creates a new TextRange for a token at the provides start position.
 *
 * @param pos The start position.
 * @param token The token.
 *
 * @internal
 */
export function createTokenRange(pos: number, token: SyntaxKind): TextRange {
    return createRange(pos, pos + tokenToString(token)!.length);
}

/** @internal */
export function rangeIsOnSingleLine(range: TextRange, sourceFile: SourceFile): boolean {
    return rangeStartIsOnSameLineAsRangeEnd(range, range, sourceFile);
}

/** @internal */
export function rangeStartPositionsAreOnSameLine(range1: TextRange, range2: TextRange, sourceFile: SourceFile): boolean {
    return positionsAreOnSameLine(
        getStartPositionOfRange(range1, sourceFile, /*includeComments*/ false),
        getStartPositionOfRange(range2, sourceFile, /*includeComments*/ false),
        sourceFile,
    );
}

/** @internal */
export function rangeEndPositionsAreOnSameLine(range1: TextRange, range2: TextRange, sourceFile: SourceFile): boolean {
    return positionsAreOnSameLine(range1.end, range2.end, sourceFile);
}

/** @internal @knipignore */
export function rangeStartIsOnSameLineAsRangeEnd(range1: TextRange, range2: TextRange, sourceFile: SourceFile): boolean {
    return positionsAreOnSameLine(getStartPositionOfRange(range1, sourceFile, /*includeComments*/ false), range2.end, sourceFile);
}

/** @internal */
export function rangeEndIsOnSameLineAsRangeStart(range1: TextRange, range2: TextRange, sourceFile: SourceFile): boolean {
    return positionsAreOnSameLine(range1.end, getStartPositionOfRange(range2, sourceFile, /*includeComments*/ false), sourceFile);
}

/** @internal */
export function getLinesBetweenRangeEndAndRangeStart(range1: TextRange, range2: TextRange, sourceFile: SourceFile, includeSecondRangeComments: boolean): number {
    const range2Start = getStartPositionOfRange(range2, sourceFile, includeSecondRangeComments);
    return getLinesBetweenPositions(sourceFile, range1.end, range2Start);
}

/** @internal @knipignore */
export function getLinesBetweenRangeEndPositions(range1: TextRange, range2: TextRange, sourceFile: SourceFile): number {
    return getLinesBetweenPositions(sourceFile, range1.end, range2.end);
}

/** @internal */
export function isNodeArrayMultiLine(list: NodeArray<Node>, sourceFile: SourceFile): boolean {
    return !positionsAreOnSameLine(list.pos, list.end, sourceFile);
}

/** @internal */
export function positionsAreOnSameLine(pos1: number, pos2: number, sourceFile: SourceFile): boolean {
    return getLinesBetweenPositions(sourceFile, pos1, pos2) === 0;
}

/** @internal @knipignore */
export function getStartPositionOfRange(range: TextRange, sourceFile: SourceFile, includeComments: boolean): number {
    return positionIsSynthesized(range.pos) ? -1 : skipTrivia(sourceFile.text, range.pos, /*stopAfterLineBreak*/ false, includeComments);
}

/** @internal */
export function getLinesBetweenPositionAndPrecedingNonWhitespaceCharacter(pos: number, stopPos: number, sourceFile: SourceFile, includeComments?: boolean): number {
    const startPos = skipTrivia(sourceFile.text, pos, /*stopAfterLineBreak*/ false, includeComments);
    const prevPos = getPreviousNonWhitespacePosition(startPos, stopPos, sourceFile);
    return getLinesBetweenPositions(sourceFile, prevPos ?? stopPos, startPos);
}

/** @internal */
export function getLinesBetweenPositionAndNextNonWhitespaceCharacter(pos: number, stopPos: number, sourceFile: SourceFile, includeComments?: boolean): number {
    const nextPos = skipTrivia(sourceFile.text, pos, /*stopAfterLineBreak*/ false, includeComments);
    return getLinesBetweenPositions(sourceFile, pos, Math.min(stopPos, nextPos));
}

/** @internal */
export function rangeContainsRange(r1: TextRange, r2: TextRange): boolean {
    return startEndContainsRange(r1.pos, r1.end, r2);
}

/** @internal */
export function startEndContainsRange(start: number, end: number, range: TextRange): boolean {
    return start <= range.pos && end >= range.end;
}

function getPreviousNonWhitespacePosition(pos: number, stopPos = 0, sourceFile: SourceFile) {
    while (pos-- > stopPos) {
        if (!isWhiteSpaceLike(sourceFile.text.charCodeAt(pos))) {
            return pos;
        }
    }
}

/**
 * Determines whether a name was originally the declaration name of an enum or namespace
 * declaration.
 *
 * @internal
 */
export function isDeclarationNameOfEnumOrNamespace(node: Identifier): boolean {
    const parseNode = getParseTreeNode(node);
    if (parseNode) {
        switch (parseNode.parent.kind) {
            case SyntaxKind.EnumDeclaration:
            case SyntaxKind.ModuleDeclaration:
                return parseNode === (parseNode.parent as EnumDeclaration | ModuleDeclaration).name;
        }
    }
    return false;
}

/** @internal */
export function getInitializedVariables(node: VariableDeclarationList): readonly InitializedVariableDeclaration[] {
    return filter(node.declarations, isInitializedVariable);
}

/** @internal */
export function isInitializedVariable(node: Node): node is InitializedVariableDeclaration {
    return isVariableDeclaration(node) && node.initializer !== undefined;
}

/** @internal */
export function isWatchSet(options: CompilerOptions): boolean | undefined {
    // Firefox has Object.prototype.watch
    return options.watch && hasProperty(options, "watch");
}

/** @internal */
export function closeFileWatcher(watcher: FileWatcher): void {
    watcher.close();
}

/** @internal */
export function getCheckFlags(symbol: Symbol): CheckFlags {
    return symbol.flags & SymbolFlags.Transient ? (symbol as TransientSymbol).links.checkFlags : 0;
}

/** @internal */
export function getDeclarationModifierFlagsFromSymbol(s: Symbol, isWrite = false): ModifierFlags {
    if (s.valueDeclaration) {
        const declaration = (isWrite && s.declarations && find(s.declarations, isSetAccessorDeclaration))
            || (s.flags & SymbolFlags.GetAccessor && find(s.declarations, isGetAccessorDeclaration)) || s.valueDeclaration;
        const flags = getCombinedModifierFlags(declaration);
        return s.parent && s.parent.flags & SymbolFlags.Class ? flags : flags & ~ModifierFlags.AccessibilityModifier;
    }
    if (getCheckFlags(s) & CheckFlags.Synthetic) {
        // NOTE: potentially unchecked cast to TransientSymbol
        const checkFlags = (s as TransientSymbol).links.checkFlags;
        const accessModifier = checkFlags & CheckFlags.ContainsPrivate ? ModifierFlags.Private :
            checkFlags & CheckFlags.ContainsPublic ? ModifierFlags.Public :
            ModifierFlags.Protected;
        const staticModifier = checkFlags & CheckFlags.ContainsStatic ? ModifierFlags.Static : 0;
        return accessModifier | staticModifier;
    }
    if (s.flags & SymbolFlags.Prototype) {
        return ModifierFlags.Public | ModifierFlags.Static;
    }
    return 0;
}

/** @internal */
export function skipAlias(symbol: Symbol, checker: TypeChecker): Symbol {
    return symbol.flags & SymbolFlags.Alias ? checker.getAliasedSymbol(symbol) : symbol;
}

/**
 * See comment on `declareModuleMember` in `binder.ts`.
 *
 * @internal
 */
export function getCombinedLocalAndExportSymbolFlags(symbol: Symbol): SymbolFlags {
    return symbol.exportSymbol ? symbol.exportSymbol.flags | symbol.flags : symbol.flags;
}

/** @internal */
export function isWriteOnlyAccess(node: Node): boolean {
    return accessKind(node) === AccessKind.Write;
}

/** @internal */
export function isWriteAccess(node: Node): boolean {
    return accessKind(node) !== AccessKind.Read;
}

const enum AccessKind {
    /** Only reads from a variable. */
    Read,
    /** Only writes to a variable without ever reading it. E.g.: `x=1;`. */
    Write,
    /** Reads from and writes to a variable. E.g.: `f(x++);`, `x/=1`. */
    ReadWrite,
}
function accessKind(node: Node): AccessKind {
    const { parent } = node;

    switch (parent?.kind) {
        case SyntaxKind.ParenthesizedExpression:
            return accessKind(parent);
        case SyntaxKind.PostfixUnaryExpression:
        case SyntaxKind.PrefixUnaryExpression:
            const { operator } = parent as PrefixUnaryExpression | PostfixUnaryExpression;
            return operator === SyntaxKind.PlusPlusToken || operator === SyntaxKind.MinusMinusToken ? AccessKind.ReadWrite : AccessKind.Read;
        case SyntaxKind.BinaryExpression:
            const { left, operatorToken } = parent as BinaryExpression;
            return left === node && isAssignmentOperator(operatorToken.kind) ?
                operatorToken.kind === SyntaxKind.EqualsToken ? AccessKind.Write : AccessKind.ReadWrite
                : AccessKind.Read;
        case SyntaxKind.PropertyAccessExpression:
            return (parent as PropertyAccessExpression).name !== node ? AccessKind.Read : accessKind(parent);
        case SyntaxKind.PropertyAssignment: {
            const parentAccess = accessKind(parent.parent);
            // In `({ x: varname }) = { x: 1 }`, the left `x` is a read, the right `x` is a write.
            return node === (parent as PropertyAssignment).name ? reverseAccessKind(parentAccess) : parentAccess;
        }
        case SyntaxKind.ShorthandPropertyAssignment:
            // Assume it's the local variable being accessed, since we don't check public properties for --noUnusedLocals.
            return node === (parent as ShorthandPropertyAssignment).objectAssignmentInitializer ? AccessKind.Read : accessKind(parent.parent);
        case SyntaxKind.ArrayLiteralExpression:
            return accessKind(parent);
        case SyntaxKind.ForInStatement:
        case SyntaxKind.ForOfStatement:
            return node === (parent as ForInStatement | ForOfStatement).initializer ? AccessKind.Write : AccessKind.Read;
        default:
            return AccessKind.Read;
    }
}
function reverseAccessKind(a: AccessKind): AccessKind {
    switch (a) {
        case AccessKind.Read:
            return AccessKind.Write;
        case AccessKind.Write:
            return AccessKind.Read;
        case AccessKind.ReadWrite:
            return AccessKind.ReadWrite;
        default:
            return Debug.assertNever(a);
    }
}

/** @internal */
export function compareDataObjects(dst: any, src: any): boolean {
    if (!dst || !src || Object.keys(dst).length !== Object.keys(src).length) {
        return false;
    }

    for (const e in dst) {
        if (typeof dst[e] === "object") {
            if (!compareDataObjects(dst[e], src[e])) {
                return false;
            }
        }
        else if (typeof dst[e] !== "function") {
            if (dst[e] !== src[e]) {
                return false;
            }
        }
    }
    return true;
}

/**
 * clears already present map by calling onDeleteExistingValue callback before deleting that key/value
 *
 * @internal
 */
export function clearMap<K, T>(map: { forEach: Map<K, T>["forEach"]; clear: Map<K, T>["clear"]; }, onDeleteValue: (valueInMap: T, key: K) => void): void {
    // Remove all
    map.forEach(onDeleteValue);
    map.clear();
}

/** @internal */
export interface MutateMapSkippingNewValuesDelete<K, T> {
    onDeleteValue(existingValue: T, key: K): void;
}

/** @internal */
export interface MutateMapSkippingNewValuesOptions<K, T, U> extends MutateMapSkippingNewValuesDelete<K, T> {
    /**
     * If present this is called with the key when there is value for that key both in new map as well as existing map provided
     * Caller can then decide to update or remove this key.
     * If the key is removed, caller will get callback of createNewValue for that key.
     * If this callback is not provided, the value of such keys is not updated.
     */
    onExistingValue?(existingValue: T, valueInNewMap: U, key: K): void;
}

/**
 * Mutates the map with newMap such that keys in map will be same as newMap.
 *
 * @internal
 */
export function mutateMapSkippingNewValues<K, T>(
    map: Map<K, T>,
    newMap: ReadonlySet<K> | undefined,
    options: MutateMapSkippingNewValuesDelete<K, T>,
): void;
/** @internal */
export function mutateMapSkippingNewValues<K, T, U>(
    map: Map<K, T>,
    newMap: ReadonlyMap<K, U> | undefined,
    options: MutateMapSkippingNewValuesOptions<K, T, U>,
): void;
export function mutateMapSkippingNewValues<K, T, U>(
    map: Map<K, T>,
    newMap: ReadonlyMap<K, U> | ReadonlySet<K> | undefined,
    options: MutateMapSkippingNewValuesOptions<K, T, U>,
) {
    const { onDeleteValue, onExistingValue } = options;
    // Needs update
    map.forEach((existingValue, key) => {
        // Not present any more in new map, remove it
        if (!newMap?.has(key)) {
            map.delete(key);
            onDeleteValue(existingValue, key);
        }
        // If present notify about existing values
        else if (onExistingValue) {
            onExistingValue(existingValue, (newMap as Map<K, U>).get?.(key)!, key);
        }
    });
}

/** @internal */
export interface MutateMapOptionsCreate<K, T, U> {
    createNewValue(key: K, valueInNewMap: U): T;
}

/** @internal */
export interface MutateMapWithNewSetOptions<K, T> extends MutateMapSkippingNewValuesDelete<K, T>, MutateMapOptionsCreate<K, T, K> {
}

/** @internal */
export interface MutateMapOptions<K, T, U> extends MutateMapSkippingNewValuesOptions<K, T, U>, MutateMapOptionsCreate<K, T, U> {
}

/**
 * Mutates the map with newMap such that keys in map will be same as newMap.
 *
 * @internal
 */
export function mutateMap<K, T>(map: Map<K, T>, newMap: ReadonlySet<K> | undefined, options: MutateMapWithNewSetOptions<K, T>): void;
/** @internal */
export function mutateMap<K, T, U>(map: Map<K, T>, newMap: ReadonlyMap<K, U> | undefined, options: MutateMapOptions<K, T, U>): void;
export function mutateMap<K, T, U>(map: Map<K, T>, newMap: ReadonlyMap<K, U> | ReadonlySet<K> | undefined, options: MutateMapOptions<K, T, U>) {
    // Needs update
    mutateMapSkippingNewValues(map, newMap as ReadonlyMap<K, U>, options);

    const { createNewValue } = options;
    // Add new values that are not already present
    newMap?.forEach((valueInNewMap, key) => {
        if (!map.has(key)) {
            // New values
            map.set(key, createNewValue(key, valueInNewMap as U & K));
        }
    });
}

/** @internal */
export function isAbstractConstructorSymbol(symbol: Symbol): boolean {
    if (symbol.flags & SymbolFlags.Class) {
        const declaration = getClassLikeDeclarationOfSymbol(symbol);
        return !!declaration && hasSyntacticModifier(declaration, ModifierFlags.Abstract);
    }
    return false;
}

/** @internal */
export function getClassLikeDeclarationOfSymbol(symbol: Symbol): ClassLikeDeclaration | undefined {
    return symbol.declarations?.find(isClassLike);
}

/** @internal */
export function getObjectFlags(type: Type): ObjectFlags {
    return type.flags & TypeFlags.ObjectFlagsType ? (type as ObjectFlagsType).objectFlags : 0;
}

/** @internal */
export function isUMDExportSymbol(symbol: Symbol | undefined): boolean {
    return !!symbol && !!symbol.declarations && !!symbol.declarations[0] && isNamespaceExportDeclaration(symbol.declarations[0]);
}

/** @internal */
export function showModuleSpecifier({ moduleSpecifier }: ImportDeclaration): string {
    return isStringLiteral(moduleSpecifier) ? moduleSpecifier.text : getTextOfNode(moduleSpecifier);
}

/** @internal */
export function getLastChild(node: Node): Node | undefined {
    let lastChild: Node | undefined;
    forEachChild(node, child => {
        if (nodeIsPresent(child)) lastChild = child;
    }, children => {
        // As an optimization, jump straight to the end of the list.
        for (let i = children.length - 1; i >= 0; i--) {
            if (nodeIsPresent(children[i])) {
                lastChild = children[i];
                break;
            }
        }
    });
    return lastChild;
}

/**
 * Add a value to a set, and return true if it wasn't already present.
 *
 * @internal
 */
export function addToSeen<K>(seen: Set<K>, key: K): boolean {
    if (seen.has(key)) {
        return false;
    }
    seen.add(key);
    return true;
}

/** @internal */
export function isObjectTypeDeclaration(node: Node): node is ObjectTypeDeclaration {
    return isClassLike(node) || isInterfaceDeclaration(node) || isTypeLiteralNode(node);
}

/** @internal */
export function isTypeNodeKind(kind: SyntaxKind): kind is TypeNodeSyntaxKind {
    return (kind >= SyntaxKind.FirstTypeNode && kind <= SyntaxKind.LastTypeNode)
        || kind === SyntaxKind.AnyKeyword
        || kind === SyntaxKind.UnknownKeyword
        || kind === SyntaxKind.NumberKeyword
        || kind === SyntaxKind.BigIntKeyword
        || kind === SyntaxKind.ObjectKeyword
        || kind === SyntaxKind.BooleanKeyword
        || kind === SyntaxKind.StringKeyword
        || kind === SyntaxKind.SymbolKeyword
        || kind === SyntaxKind.VoidKeyword
        || kind === SyntaxKind.UndefinedKeyword
        || kind === SyntaxKind.NeverKeyword
        || kind === SyntaxKind.IntrinsicKeyword
        || kind === SyntaxKind.ExpressionWithTypeArguments
        || kind === SyntaxKind.JSDocAllType
        || kind === SyntaxKind.JSDocUnknownType
        || kind === SyntaxKind.JSDocNullableType
        || kind === SyntaxKind.JSDocNonNullableType
        || kind === SyntaxKind.JSDocOptionalType
        || kind === SyntaxKind.JSDocFunctionType
        || kind === SyntaxKind.JSDocVariadicType;
}

/** @internal */
export function isAccessExpression(node: Node): node is AccessExpression {
    return node.kind === SyntaxKind.PropertyAccessExpression || node.kind === SyntaxKind.ElementAccessExpression;
}

/** @internal */
export function getNameOfAccessExpression(node: AccessExpression): Expression {
    if (node.kind === SyntaxKind.PropertyAccessExpression) {
        return node.name;
    }
    Debug.assert(node.kind === SyntaxKind.ElementAccessExpression);
    return node.argumentExpression;
}

/** @internal */
export function isNamedImportsOrExports(node: Node): node is NamedImportsOrExports {
    return node.kind === SyntaxKind.NamedImports || node.kind === SyntaxKind.NamedExports;
}

/** @internal */
export function getLeftmostAccessExpression(expr: Expression): Expression {
    while (isAccessExpression(expr)) {
        expr = expr.expression;
    }
    return expr;
}

/** @internal */
export function forEachNameInAccessChainWalkingLeft<T>(name: MemberName | StringLiteralLike, action: (name: MemberName | StringLiteralLike) => T | undefined): T | undefined {
    if (isAccessExpression(name.parent) && isRightSideOfAccessExpression(name)) {
        return walkAccessExpression(name.parent);
    }

    function walkAccessExpression(access: AccessExpression): T | undefined {
        if (access.kind === SyntaxKind.PropertyAccessExpression) {
            const res = action(access.name);
            if (res !== undefined) {
                return res;
            }
        }
        else if (access.kind === SyntaxKind.ElementAccessExpression) {
            if (isIdentifier(access.argumentExpression) || isStringLiteralLike(access.argumentExpression)) {
                const res = action(access.argumentExpression);
                if (res !== undefined) {
                    return res;
                }
            }
            else {
                // Chain interrupted by non-static-name access 'x[expr()].y.z'
                return undefined;
            }
        }

        if (isAccessExpression(access.expression)) {
            return walkAccessExpression(access.expression);
        }
        if (isIdentifier(access.expression)) {
            // End of chain at Identifier 'x.y.z'
            return action(access.expression);
        }
        // End of chain at non-Identifier 'x().y.z'
        return undefined;
    }
}

/** @internal */
export function getLeftmostExpression(node: Expression, stopAtCallExpressions: boolean): Expression {
    while (true) {
        switch (node.kind) {
            case SyntaxKind.PostfixUnaryExpression:
                node = (node as PostfixUnaryExpression).operand;
                continue;

            case SyntaxKind.BinaryExpression:
                node = (node as BinaryExpression).left;
                continue;

            case SyntaxKind.ConditionalExpression:
                node = (node as ConditionalExpression).condition;
                continue;

            case SyntaxKind.TaggedTemplateExpression:
                node = (node as TaggedTemplateExpression).tag;
                continue;

            case SyntaxKind.CallExpression:
                if (stopAtCallExpressions) {
                    return node;
                }
                // falls through
            case SyntaxKind.AsExpression:
            case SyntaxKind.ElementAccessExpression:
            case SyntaxKind.PropertyAccessExpression:
            case SyntaxKind.NonNullExpression:
            case SyntaxKind.PartiallyEmittedExpression:
            case SyntaxKind.SatisfiesExpression:
                node = (node as CallExpression | PropertyAccessExpression | ElementAccessExpression | AsExpression | NonNullExpression | PartiallyEmittedExpression | SatisfiesExpression).expression;
                continue;
        }

        return node;
    }
}

/** @internal */
export interface ObjectAllocator {
    getNodeConstructor(): new (kind: SyntaxKind, pos: number, end: number) => Node;
    getTokenConstructor(): new <TKind extends SyntaxKind>(kind: TKind, pos: number, end: number) => Token<TKind>;
    getIdentifierConstructor(): new (kind: SyntaxKind.Identifier, pos: number, end: number) => Identifier;
    getPrivateIdentifierConstructor(): new (kind: SyntaxKind.PrivateIdentifier, pos: number, end: number) => PrivateIdentifier;
    getSourceFileConstructor(): new (kind: SyntaxKind.SourceFile, pos: number, end: number) => SourceFile;
    getSymbolConstructor(): new (flags: SymbolFlags, name: __String) => Symbol;
    getTypeConstructor(): new (checker: TypeChecker, flags: TypeFlags) => Type;
    getSignatureConstructor(): new (checker: TypeChecker, flags: SignatureFlags) => Signature;
    getSourceMapSourceConstructor(): new (fileName: string, text: string, skipTrivia?: (pos: number) => number) => SourceMapSource;
}

function Symbol(this: Symbol, flags: SymbolFlags, name: __String): void {
    // Note: if modifying this, be sure to update SymbolObject in src/services/services.ts
    this.flags = flags;
    this.escapedName = name;
    this.declarations = undefined;
    this.valueDeclaration = undefined;
    this.id = 0;
    this.mergeId = 0;
    this.parent = undefined;
    this.members = undefined;
    this.exports = undefined;
    this.exportSymbol = undefined;
    this.constEnumOnlyModule = undefined;
    this.isReferenced = undefined;
    this.lastAssignmentPos = undefined;
    (this as any).links = undefined; // used by TransientSymbol
}

function Type(this: Type, checker: TypeChecker, flags: TypeFlags): void {
    // Note: if modifying this, be sure to update TypeObject in src/services/services.ts
    this.flags = flags;
    if (Debug.isDebugging || tracing) {
        this.checker = checker;
    }
}

function Signature(this: Signature, checker: TypeChecker, flags: SignatureFlags): void {
    // Note: if modifying this, be sure to update SignatureObject in src/services/services.ts
    this.flags = flags;
    if (Debug.isDebugging) {
        this.checker = checker;
    }
}

function Node(this: Mutable<Node>, kind: SyntaxKind, pos: number, end: number): void {
    // Note: if modifying this, be sure to update NodeObject in src/services/services.ts
    this.pos = pos;
    this.end = end;
    this.kind = kind;
    this.id = 0;
    this.flags = NodeFlags.None;
    this.modifierFlagsCache = ModifierFlags.None;
    this.transformFlags = TransformFlags.None;
    this.parent = undefined!;
    this.original = undefined;
    this.emitNode = undefined;
}

function Token(this: Mutable<Node>, kind: SyntaxKind, pos: number, end: number): void {
    // Note: if modifying this, be sure to update TokenOrIdentifierObject in src/services/services.ts
    this.pos = pos;
    this.end = end;
    this.kind = kind;
    this.id = 0;
    this.flags = NodeFlags.None;
    this.transformFlags = TransformFlags.None;
    this.parent = undefined!;
    this.emitNode = undefined;
}

function Identifier(this: Mutable<Node>, kind: SyntaxKind, pos: number, end: number): void {
    // Note: if modifying this, be sure to update TokenOrIdentifierObject in src/services/services.ts
    this.pos = pos;
    this.end = end;
    this.kind = kind;
    this.id = 0;
    this.flags = NodeFlags.None;
    this.transformFlags = TransformFlags.None;
    this.parent = undefined!;
    this.original = undefined;
    this.emitNode = undefined;
}

function SourceMapSource(this: SourceMapSource, fileName: string, text: string, skipTrivia?: (pos: number) => number): void {
    // Note: if modifying this, be sure to update SourceMapSourceObject in src/services/services.ts
    this.fileName = fileName;
    this.text = text;
    this.skipTrivia = skipTrivia || (pos => pos);
}

/** @internal */
export const objectAllocator: ObjectAllocator = {
    getNodeConstructor: () => Node as any,
    getTokenConstructor: () => Token as any,
    getIdentifierConstructor: () => Identifier as any,
    getPrivateIdentifierConstructor: () => Node as any,
    getSourceFileConstructor: () => Node as any,
    getSymbolConstructor: () => Symbol as any,
    getTypeConstructor: () => Type as any,
    getSignatureConstructor: () => Signature as any,
    getSourceMapSourceConstructor: () => SourceMapSource as any,
};

const objectAllocatorPatchers: ((objectAllocator: ObjectAllocator) => void)[] = [];

/**
 * Used by `deprecatedCompat` to patch the object allocator to apply deprecations.
 * @internal
 * @knipignore
 */
export function addObjectAllocatorPatcher(fn: (objectAllocator: ObjectAllocator) => void): void {
    objectAllocatorPatchers.push(fn);
    fn(objectAllocator);
}

/** @internal */
export function setObjectAllocator(alloc: ObjectAllocator): void {
    Object.assign(objectAllocator, alloc);
    forEach(objectAllocatorPatchers, fn => fn(objectAllocator));
}

/** @internal */
export function formatStringFromArgs(text: string, args: DiagnosticArguments): string {
    return text.replace(/\{(\d+)\}/g, (_match, index: string) => "" + Debug.checkDefined(args[+index]));
}

let localizedDiagnosticMessages: MapLike<string> | undefined;

/** @internal */
export function setLocalizedDiagnosticMessages(messages: MapLike<string> | undefined): void {
    localizedDiagnosticMessages = messages;
}

/** @internal */
// If the localized messages json is unset, and if given function use it to set the json

export function maybeSetLocalizedDiagnosticMessages(getMessages: undefined | (() => MapLike<string> | undefined)): void {
    if (!localizedDiagnosticMessages && getMessages) {
        localizedDiagnosticMessages = getMessages();
    }
}

/** @internal */
export function getLocaleSpecificMessage(message: DiagnosticMessage): string {
    return localizedDiagnosticMessages && localizedDiagnosticMessages[message.key] || message.message;
}

/** @internal */
export function createDetachedDiagnostic(fileName: string, sourceText: string, start: number, length: number, message: DiagnosticMessage, ...args: DiagnosticArguments): DiagnosticWithDetachedLocation {
    if ((start + length) > sourceText.length) {
        length = sourceText.length - start;
    }

    assertDiagnosticLocation(sourceText, start, length);
    let text = getLocaleSpecificMessage(message);

    if (some(args)) {
        text = formatStringFromArgs(text, args);
    }

    return {
        file: undefined,
        start,
        length,

        messageText: text,
        category: message.category,
        code: message.code,
        reportsUnnecessary: message.reportsUnnecessary,
        fileName,
    };
}

function isDiagnosticWithDetachedLocation(diagnostic: DiagnosticRelatedInformation | DiagnosticWithDetachedLocation): diagnostic is DiagnosticWithDetachedLocation {
    return diagnostic.file === undefined
        && diagnostic.start !== undefined
        && diagnostic.length !== undefined
        && typeof (diagnostic as DiagnosticWithDetachedLocation).fileName === "string";
}

function attachFileToDiagnostic(diagnostic: DiagnosticWithDetachedLocation, file: SourceFile): DiagnosticWithLocation {
    const fileName = file.fileName || "";
    const length = file.text.length;
    Debug.assertEqual(diagnostic.fileName, fileName);
    Debug.assertLessThanOrEqual(diagnostic.start, length);
    Debug.assertLessThanOrEqual(diagnostic.start + diagnostic.length, length);
    const diagnosticWithLocation: DiagnosticWithLocation = {
        file,
        start: diagnostic.start,
        length: diagnostic.length,
        messageText: diagnostic.messageText,
        category: diagnostic.category,
        code: diagnostic.code,
        reportsUnnecessary: diagnostic.reportsUnnecessary,
    };
    if (diagnostic.relatedInformation) {
        diagnosticWithLocation.relatedInformation = [];
        for (const related of diagnostic.relatedInformation) {
            if (isDiagnosticWithDetachedLocation(related) && related.fileName === fileName) {
                Debug.assertLessThanOrEqual(related.start, length);
                Debug.assertLessThanOrEqual(related.start + related.length, length);
                diagnosticWithLocation.relatedInformation.push(attachFileToDiagnostic(related, file));
            }
            else {
                diagnosticWithLocation.relatedInformation.push(related);
            }
        }
    }
    return diagnosticWithLocation;
}

/** @internal */
export function attachFileToDiagnostics(diagnostics: DiagnosticWithDetachedLocation[], file: SourceFile): DiagnosticWithLocation[] {
    const diagnosticsWithLocation: DiagnosticWithLocation[] = [];
    for (const diagnostic of diagnostics) {
        diagnosticsWithLocation.push(attachFileToDiagnostic(diagnostic, file));
    }
    return diagnosticsWithLocation;
}

/** @internal */
export function createFileDiagnostic(file: SourceFile, start: number, length: number, message: DiagnosticMessage, ...args: DiagnosticArguments): DiagnosticWithLocation {
    assertDiagnosticLocation(file.text, start, length);

    let text = getLocaleSpecificMessage(message);

    if (some(args)) {
        text = formatStringFromArgs(text, args);
    }

    return {
        file,
        start,
        length,

        messageText: text,
        category: message.category,
        code: message.code,
        reportsUnnecessary: message.reportsUnnecessary,
        reportsDeprecated: message.reportsDeprecated,
    };
}

/** @internal */
export function formatMessage(message: DiagnosticMessage, ...args: DiagnosticArguments): string {
    let text = getLocaleSpecificMessage(message);

    if (some(args)) {
        text = formatStringFromArgs(text, args);
    }

    return text;
}

/** @internal */
export function createCompilerDiagnostic(message: DiagnosticMessage, ...args: DiagnosticArguments): Diagnostic {
    let text = getLocaleSpecificMessage(message);

    if (some(args)) {
        text = formatStringFromArgs(text, args);
    }

    return {
        file: undefined,
        start: undefined,
        length: undefined,

        messageText: text,
        category: message.category,
        code: message.code,
        reportsUnnecessary: message.reportsUnnecessary,
        reportsDeprecated: message.reportsDeprecated,
    };
}

/** @internal */
export function createCompilerDiagnosticFromMessageChain(chain: DiagnosticMessageChain, relatedInformation?: DiagnosticRelatedInformation[]): Diagnostic {
    return {
        file: undefined,
        start: undefined,
        length: undefined,

        code: chain.code,
        category: chain.category,
        messageText: chain.next ? chain : chain.messageText,
        relatedInformation,
    };
}

/** @internal */
export function chainDiagnosticMessages(details: DiagnosticMessageChain | DiagnosticMessageChain[] | undefined, message: DiagnosticMessage, ...args: DiagnosticArguments): DiagnosticMessageChain {
    let text = getLocaleSpecificMessage(message);

    if (some(args)) {
        text = formatStringFromArgs(text, args);
    }
    return {
        messageText: text,
        category: message.category,
        code: message.code,

        next: details === undefined || Array.isArray(details) ? details : [details],
    };
}

/** @internal */
export function concatenateDiagnosticMessageChains(headChain: DiagnosticMessageChain, tailChain: DiagnosticMessageChain): void {
    let lastChain = headChain;
    while (lastChain.next) {
        lastChain = lastChain.next[0];
    }

    lastChain.next = [tailChain];
}

function getDiagnosticFilePath(diagnostic: Diagnostic): string | undefined {
    return diagnostic.file ? diagnostic.file.path : undefined;
}

/** @internal */
export function compareDiagnostics(d1: Diagnostic, d2: Diagnostic): Comparison {
    return compareDiagnosticsSkipRelatedInformation(d1, d2) ||
        compareRelatedInformation(d1, d2) ||
        Comparison.EqualTo;
}

function compareDiagnosticsSkipRelatedInformation(d1: Diagnostic, d2: Diagnostic): Comparison {
    const code1 = getDiagnosticCode(d1);
    const code2 = getDiagnosticCode(d2);
    return compareStringsCaseSensitive(getDiagnosticFilePath(d1), getDiagnosticFilePath(d2)) ||
        compareValues(d1.start, d2.start) ||
        compareValues(d1.length, d2.length) ||
        compareValues(code1, code2) ||
        compareMessageText(d1, d2) ||
        Comparison.EqualTo;
}

// A diagnostic with more elaboration should be considered *less than* a diagnostic
// with less elaboration that is otherwise similar.
function compareRelatedInformation(d1: Diagnostic, d2: Diagnostic): Comparison {
    if (!d1.relatedInformation && !d2.relatedInformation) {
        return Comparison.EqualTo;
    }
    if (d1.relatedInformation && d2.relatedInformation) {
        return compareValues(d2.relatedInformation.length, d1.relatedInformation.length) || forEach(d1.relatedInformation, (d1i, index) => {
            const d2i = d2.relatedInformation![index];
            return compareDiagnostics(d1i, d2i); // EqualTo is 0, so falsy, and will cause the next item to be compared
        }) || Comparison.EqualTo;
    }
    return d1.relatedInformation ? Comparison.LessThan : Comparison.GreaterThan;
}

// An diagnostic message with more elaboration should be considered *less than* a diagnostic message
// with less elaboration that is otherwise similar.
function compareMessageText(
    d1: Diagnostic,
    d2: Diagnostic,
): Comparison {
    let headMsg1 = getDiagnosticMessage(d1);
    let headMsg2 = getDiagnosticMessage(d2);
    if (typeof headMsg1 !== "string") {
        headMsg1 = headMsg1.messageText;
    }
    if (typeof headMsg2 !== "string") {
        headMsg2 = headMsg2.messageText;
    }
    const chain1 = typeof d1.messageText !== "string" ? d1.messageText.next : undefined;
    const chain2 = typeof d2.messageText !== "string" ? d2.messageText.next : undefined;

    let res = compareStringsCaseSensitive(headMsg1, headMsg2);
    if (res) {
        return res;
    }

    res = compareMessageChain(chain1, chain2);
    if (res) {
        return res;
    }

    if (d1.canonicalHead && !d2.canonicalHead) {
        return Comparison.LessThan;
    }
    if (d2.canonicalHead && !d1.canonicalHead) {
        return Comparison.GreaterThan;
    }

    return Comparison.EqualTo;
}

// First compare by size of the message chain,
// then compare by content of the message chain.
function compareMessageChain(
    c1: DiagnosticMessageChain[] | undefined,
    c2: DiagnosticMessageChain[] | undefined,
): Comparison {
    if (c1 === undefined && c2 === undefined) {
        return Comparison.EqualTo;
    }
    if (c1 === undefined) {
        return Comparison.GreaterThan;
    }
    if (c2 === undefined) {
        return Comparison.LessThan;
    }

    return compareMessageChainSize(c1, c2) || compareMessageChainContent(c1, c2);
}

function compareMessageChainSize(
    c1: DiagnosticMessageChain[] | undefined,
    c2: DiagnosticMessageChain[] | undefined,
): Comparison {
    if (c1 === undefined && c2 === undefined) {
        return Comparison.EqualTo;
    }
    if (c1 === undefined) {
        return Comparison.GreaterThan;
    }
    if (c2 === undefined) {
        return Comparison.LessThan;
    }

    let res = compareValues(c2.length, c1.length);
    if (res) {
        return res;
    }

    for (let i = 0; i < c2.length; i++) {
        res = compareMessageChainSize(c1[i].next, c2[i].next);
        if (res) {
            return res;
        }
    }

    return Comparison.EqualTo;
}

// Assumes the two chains have the same shape.
function compareMessageChainContent(
    c1: DiagnosticMessageChain[],
    c2: DiagnosticMessageChain[],
): Comparison {
    let res;
    for (let i = 0; i < c2.length; i++) {
        res = compareStringsCaseSensitive(c1[i].messageText, c2[i].messageText);
        if (res) {
            return res;
        }
        if (c1[i].next === undefined) {
            continue;
        }
        res = compareMessageChainContent(c1[i].next!, c2[i].next!);
        if (res) {
            return res;
        }
    }
    return Comparison.EqualTo;
}

/** @internal */
export function diagnosticsEqualityComparer(d1: Diagnostic, d2: Diagnostic): boolean {
    const code1 = getDiagnosticCode(d1);
    const code2 = getDiagnosticCode(d2);
    const msg1 = getDiagnosticMessage(d1);
    const msg2 = getDiagnosticMessage(d2);
    return compareStringsCaseSensitive(getDiagnosticFilePath(d1), getDiagnosticFilePath(d2)) === Comparison.EqualTo &&
        compareValues(d1.start, d2.start) === Comparison.EqualTo &&
        compareValues(d1.length, d2.length) === Comparison.EqualTo &&
        compareValues(code1, code2) === Comparison.EqualTo &&
        messageTextEqualityComparer(msg1, msg2);
}

function getDiagnosticCode(d: Diagnostic): number {
    return d.canonicalHead?.code || d.code;
}

function getDiagnosticMessage(d: Diagnostic): string | DiagnosticMessageChain {
    return d.canonicalHead?.messageText || d.messageText;
}

function messageTextEqualityComparer(m1: string | DiagnosticMessageChain, m2: string | DiagnosticMessageChain): boolean {
    const t1 = typeof m1 === "string" ? m1 : m1.messageText;
    const t2 = typeof m2 === "string" ? m2 : m2.messageText;
    return compareStringsCaseSensitive(t1, t2) === Comparison.EqualTo;
}

/** @internal */
export function getLanguageVariant(scriptKind: ScriptKind): LanguageVariant {
    // .tsx and .jsx files are treated as jsx language variant.
    return scriptKind === ScriptKind.TSX || scriptKind === ScriptKind.JSX || scriptKind === ScriptKind.JS || scriptKind === ScriptKind.JSON ? LanguageVariant.JSX : LanguageVariant.Standard;
}

/**
 * This is a somewhat unavoidable full tree walk to locate a JSX tag - `import.meta` requires the same,
 * but we avoid that walk (or parts of it) if at all possible using the `PossiblyContainsImportMeta` node flag.
 * Unfortunately, there's no `NodeFlag` space to do the same for JSX.
 */
function walkTreeForJSXTags(node: Node): Node | undefined {
    if (!(node.transformFlags & TransformFlags.ContainsJsx)) return undefined;
    return isJsxOpeningLikeElement(node) || isJsxFragment(node) ? node : forEachChild(node, walkTreeForJSXTags);
}

function isFileModuleFromUsingJSXTag(file: SourceFile): Node | undefined {
    // Excludes declaration files - they still require an explicit `export {}` or the like
    // for back compat purposes. (not that declaration files should contain JSX tags!)
    return !file.isDeclarationFile ? walkTreeForJSXTags(file) : undefined;
}

/**
 * Note that this requires file.impliedNodeFormat be set already; meaning it must be set very early on
 * in SourceFile construction.
 */
function isFileForcedToBeModuleByFormat(file: SourceFile, options: CompilerOptions): true | undefined {
    // Excludes declaration files - they still require an explicit `export {}` or the like
    // for back compat purposes. The only non-declaration files _not_ forced to be a module are `.js` files
    // that aren't esm-mode (meaning not in a `type: module` scope).
    return (getImpliedNodeFormatForEmitWorker(file, options) === ModuleKind.ESNext || (fileExtensionIsOneOf(file.fileName, [Extension.Cjs, Extension.Cts, Extension.Mjs, Extension.Mts]))) && !file.isDeclarationFile ? true : undefined;
}

/** @internal */
export function getSetExternalModuleIndicator(options: CompilerOptions): (file: SourceFile) => void {
    // TODO: Should this callback be cached?
    switch (getEmitModuleDetectionKind(options)) {
        case ModuleDetectionKind.Force:
            // All non-declaration files are modules, declaration files still do the usual isFileProbablyExternalModule
            return (file: SourceFile) => {
                file.externalModuleIndicator = isFileProbablyExternalModule(file) || !file.isDeclarationFile || undefined;
            };
        case ModuleDetectionKind.Legacy:
            // Files are modules if they have imports, exports, or import.meta
            return (file: SourceFile) => {
                file.externalModuleIndicator = isFileProbablyExternalModule(file);
            };
        case ModuleDetectionKind.Auto:
            // If module is nodenext or node16, all esm format files are modules
            // If jsx is react-jsx or react-jsxdev then jsx tags force module-ness
            // otherwise, the presence of import or export statments (or import.meta) implies module-ness
            const checks: ((file: SourceFile, options: CompilerOptions) => Node | true | undefined)[] = [isFileProbablyExternalModule];
            if (options.jsx === JsxEmit.ReactJSX || options.jsx === JsxEmit.ReactJSXDev) {
                checks.push(isFileModuleFromUsingJSXTag);
            }
            checks.push(isFileForcedToBeModuleByFormat);
            const combined = or(...checks);
            const callback = (file: SourceFile) => void (file.externalModuleIndicator = combined(file, options));
            return callback;
    }
}

/**
 * @internal
 * Returns true if an `import` and a `require` of the same module specifier
 * can resolve to a different file.
 */
export function importSyntaxAffectsModuleResolution(options: CompilerOptions): boolean {
    const moduleResolution = getEmitModuleResolutionKind(options);
    return ModuleResolutionKind.Node16 <= moduleResolution && moduleResolution <= ModuleResolutionKind.NodeNext
        || getResolvePackageJsonExports(options)
        || getResolvePackageJsonImports(options);
}

/**
 * @internal
 * Returns true if this option's types array includes "*"
 */
export function usesWildcardTypes(options: CompilerOptions): options is CompilerOptions & { types: string[]; } {
    return some(options.types, t => t === "*");
}

type CompilerOptionKeys = keyof { [K in keyof CompilerOptions as string extends K ? never : K]: any; };
function createComputedCompilerOptions<T extends Record<string, CompilerOptionKeys[]>>(
    options: {
        [K in keyof T & CompilerOptionKeys | StrictOptionName]: {
            dependencies: T[K];
            computeValue: (compilerOptions: Pick<CompilerOptions, K | T[K][number]>) => Exclude<CompilerOptions[K], undefined>;
        };
    },
) {
    return options;
}

const _computedOptions = createComputedCompilerOptions({
    allowImportingTsExtensions: {
        dependencies: ["rewriteRelativeImportExtensions"],
        computeValue: compilerOptions => {
            return !!(compilerOptions.allowImportingTsExtensions || compilerOptions.rewriteRelativeImportExtensions);
        },
    },
    target: {
        dependencies: [],
        computeValue: compilerOptions => {
            const target = compilerOptions.target === ScriptTarget.ES3 ? undefined : compilerOptions.target;
            return target ?? ScriptTarget.LatestStandard;
        },
    },
    module: {
        dependencies: ["target"],
        computeValue: (compilerOptions): ModuleKind => {
            if (typeof compilerOptions.module === "number") {
                return compilerOptions.module;
            }
            const target = _computedOptions.target.computeValue(compilerOptions);
            if (target === ScriptTarget.ESNext) {
                return ModuleKind.ESNext;
            }
            if (target >= ScriptTarget.ES2022) {
                return ModuleKind.ES2022;
            }
            if (target >= ScriptTarget.ES2020) {
                return ModuleKind.ES2020;
            }
            if (target >= ScriptTarget.ES2015) {
                return ModuleKind.ES2015;
            }
            return ModuleKind.CommonJS;
        },
    },
    moduleResolution: {
        dependencies: ["module", "target"],
        computeValue: (compilerOptions): ModuleResolutionKind => {
            if (compilerOptions.moduleResolution !== undefined) {
                return compilerOptions.moduleResolution;
            }
            const moduleKind = _computedOptions.module.computeValue(compilerOptions);
            switch (moduleKind) {
                case ModuleKind.None:
                case ModuleKind.AMD:
                case ModuleKind.UMD:
                case ModuleKind.System:
                    return ModuleResolutionKind.Classic;
                case ModuleKind.NodeNext:
                    return ModuleResolutionKind.NodeNext;
            }
            if (ModuleKind.Node16 <= moduleKind && moduleKind < ModuleKind.NodeNext) {
                return ModuleResolutionKind.Node16;
            }
            return ModuleResolutionKind.Bundler;
        },
    },
    moduleDetection: {
        dependencies: ["module", "target"],
        computeValue: (compilerOptions): ModuleDetectionKind => {
            if (compilerOptions.moduleDetection !== undefined) {
                return compilerOptions.moduleDetection;
            }
            const moduleKind = _computedOptions.module.computeValue(compilerOptions);
            return ModuleKind.Node16 <= moduleKind && moduleKind <= ModuleKind.NodeNext
                ? ModuleDetectionKind.Force
                : ModuleDetectionKind.Auto;
        },
    },
    isolatedModules: {
        dependencies: ["verbatimModuleSyntax"],
        computeValue: compilerOptions => {
            return !!(compilerOptions.isolatedModules || compilerOptions.verbatimModuleSyntax);
        },
    },
    esModuleInterop: {
        dependencies: [],
        computeValue: (compilerOptions): boolean => {
            if (compilerOptions.esModuleInterop !== undefined) {
                return compilerOptions.esModuleInterop;
            }
            return true;
        },
    },
    allowSyntheticDefaultImports: {
        dependencies: [],
        computeValue: (compilerOptions): boolean => {
            if (compilerOptions.allowSyntheticDefaultImports !== undefined) {
                return compilerOptions.allowSyntheticDefaultImports;
            }
            return true;
        },
    },
    resolvePackageJsonExports: {
        dependencies: ["moduleResolution", "module", "target"],
        computeValue: (compilerOptions): boolean => {
            const moduleResolution = _computedOptions.moduleResolution.computeValue(compilerOptions);
            if (!moduleResolutionSupportsPackageJsonExportsAndImports(moduleResolution)) {
                return false;
            }
            if (compilerOptions.resolvePackageJsonExports !== undefined) {
                return compilerOptions.resolvePackageJsonExports;
            }
            switch (moduleResolution) {
                case ModuleResolutionKind.Node16:
                case ModuleResolutionKind.NodeNext:
                case ModuleResolutionKind.Bundler:
                    return true;
            }
            return false;
        },
    },
    resolvePackageJsonImports: {
        dependencies: ["moduleResolution", "resolvePackageJsonExports", "module", "target"],
        computeValue: (compilerOptions): boolean => {
            const moduleResolution = _computedOptions.moduleResolution.computeValue(compilerOptions);
            if (!moduleResolutionSupportsPackageJsonExportsAndImports(moduleResolution)) {
                return false;
            }
            if (compilerOptions.resolvePackageJsonImports !== undefined) {
                return compilerOptions.resolvePackageJsonImports;
            }
            switch (moduleResolution) {
                case ModuleResolutionKind.Node16:
                case ModuleResolutionKind.NodeNext:
                case ModuleResolutionKind.Bundler:
                    return true;
            }
            return false;
        },
    },
    resolveJsonModule: {
        dependencies: ["moduleResolution", "module", "target"],
        computeValue: (compilerOptions): boolean => {
            if (compilerOptions.resolveJsonModule !== undefined) {
                return compilerOptions.resolveJsonModule;
            }
            switch (_computedOptions.module.computeValue(compilerOptions)) {
                // TODO in 6.0: uncomment
                // case ModuleKind.Node16:
                // case ModuleKind.Node18:
                case ModuleKind.Node20:
                case ModuleKind.NodeNext:
                    return true;
            }
            return _computedOptions.moduleResolution.computeValue(compilerOptions) === ModuleResolutionKind.Bundler;
        },
    },
    declaration: {
        dependencies: ["composite"],
        computeValue: compilerOptions => {
            return !!(compilerOptions.declaration || compilerOptions.composite);
        },
    },
    preserveConstEnums: {
        dependencies: ["isolatedModules", "verbatimModuleSyntax"],
        computeValue: (compilerOptions): boolean => {
            return !!(compilerOptions.preserveConstEnums || _computedOptions.isolatedModules.computeValue(compilerOptions));
        },
    },
    incremental: {
        dependencies: ["composite"],
        computeValue: compilerOptions => {
            return !!(compilerOptions.incremental || compilerOptions.composite);
        },
    },
    declarationMap: {
        dependencies: ["declaration", "composite"],
        computeValue: (compilerOptions): boolean => {
            return !!(compilerOptions.declarationMap && _computedOptions.declaration.computeValue(compilerOptions));
        },
    },
    allowJs: {
        dependencies: ["checkJs"],
        computeValue: compilerOptions => {
            return compilerOptions.allowJs === undefined ? !!compilerOptions.checkJs : compilerOptions.allowJs;
        },
    },
    useDefineForClassFields: {
        dependencies: ["target", "module"],
        computeValue: (compilerOptions): boolean => {
            return compilerOptions.useDefineForClassFields === undefined
                ? _computedOptions.target.computeValue(compilerOptions) >= ScriptTarget.ES2022
                : compilerOptions.useDefineForClassFields;
        },
    },
    noImplicitAny: {
        dependencies: ["strict"],
        computeValue: compilerOptions => {
            return getStrictOptionValue(compilerOptions, "noImplicitAny");
        },
    },
    noImplicitThis: {
        dependencies: ["strict"],
        computeValue: compilerOptions => {
            return getStrictOptionValue(compilerOptions, "noImplicitThis");
        },
    },
    strictNullChecks: {
        dependencies: ["strict"],
        computeValue: compilerOptions => {
            return getStrictOptionValue(compilerOptions, "strictNullChecks");
        },
    },
    strictFunctionTypes: {
        dependencies: ["strict"],
        computeValue: compilerOptions => {
            return getStrictOptionValue(compilerOptions, "strictFunctionTypes");
        },
    },
    strictBindCallApply: {
        dependencies: ["strict"],
        computeValue: compilerOptions => {
            return getStrictOptionValue(compilerOptions, "strictBindCallApply");
        },
    },
    strictPropertyInitialization: {
        dependencies: ["strict"],
        computeValue: compilerOptions => {
            return getStrictOptionValue(compilerOptions, "strictPropertyInitialization");
        },
    },
    strictBuiltinIteratorReturn: {
        dependencies: ["strict"],
        computeValue: compilerOptions => {
            return getStrictOptionValue(compilerOptions, "strictBuiltinIteratorReturn");
        },
    },
    // Previously a strict-mode flag, but no longer.
    alwaysStrict: {
        dependencies: [],
        computeValue: compilerOptions => {
            return compilerOptions.alwaysStrict !== false;
        },
    },
    useUnknownInCatchVariables: {
        dependencies: ["strict"],
        computeValue: compilerOptions => {
            return getStrictOptionValue(compilerOptions, "useUnknownInCatchVariables");
        },
    },
});

/** @internal */
export const computedOptions: Record<string, { dependencies: readonly string[]; computeValue: (options: CompilerOptions) => CompilerOptionsValue; }> = _computedOptions;

/** @internal */
export const getAllowImportingTsExtensions: (compilerOptions: CompilerOptions) => boolean = _computedOptions.allowImportingTsExtensions.computeValue;
/** @internal */
export const getEmitScriptTarget: (compilerOptions: CompilerOptions) => ScriptTarget = _computedOptions.target.computeValue;
/** @internal */
export const getEmitModuleKind: (compilerOptions: Pick<CompilerOptions, "module" | "target">) => ModuleKind = _computedOptions.module.computeValue;
/** @internal */
export const getEmitModuleResolutionKind: (compilerOptions: CompilerOptions) => ModuleResolutionKind = _computedOptions.moduleResolution.computeValue;
/** @internal @knipignore */
export const getEmitModuleDetectionKind: (compilerOptions: CompilerOptions) => ModuleDetectionKind = _computedOptions.moduleDetection.computeValue;
/** @internal */
export const getIsolatedModules: (compilerOptions: CompilerOptions) => boolean = _computedOptions.isolatedModules.computeValue;
/** @internal */
export const getESModuleInterop: (compilerOptions: CompilerOptions) => boolean = _computedOptions.esModuleInterop.computeValue;
/** @internal */
export const getAllowSyntheticDefaultImports: (compilerOptions: CompilerOptions) => boolean = _computedOptions.allowSyntheticDefaultImports.computeValue;
/** @internal */
export const getResolvePackageJsonExports: (compilerOptions: CompilerOptions) => boolean = _computedOptions.resolvePackageJsonExports.computeValue;
/** @internal */
export const getResolvePackageJsonImports: (compilerOptions: CompilerOptions) => boolean = _computedOptions.resolvePackageJsonImports.computeValue;
/** @internal */
export const getResolveJsonModule: (compilerOptions: CompilerOptions) => boolean = _computedOptions.resolveJsonModule.computeValue;
/** @internal */
export const getEmitDeclarations: (compilerOptions: CompilerOptions) => boolean = _computedOptions.declaration.computeValue;
/** @internal */
export const shouldPreserveConstEnums: (compilerOptions: CompilerOptions) => boolean = _computedOptions.preserveConstEnums.computeValue;
/** @internal */
export const isIncrementalCompilation: (compilerOptions: CompilerOptions) => boolean = _computedOptions.incremental.computeValue;
/** @internal */
export const getAreDeclarationMapsEnabled: (compilerOptions: CompilerOptions) => boolean = _computedOptions.declarationMap.computeValue;
/** @internal */
export const getAllowJSCompilerOption: (compilerOptions: CompilerOptions) => boolean = _computedOptions.allowJs.computeValue;
/** @internal */
export const getUseDefineForClassFields: (compilerOptions: CompilerOptions) => boolean = _computedOptions.useDefineForClassFields.computeValue;
/** @internal */
export const getAlwaysStrict: (compilerOptions: CompilerOptions) => boolean = _computedOptions.alwaysStrict.computeValue;

/** @internal */
export function emitModuleKindIsNonNodeESM(moduleKind: ModuleKind): boolean {
    return moduleKind >= ModuleKind.ES2015 && moduleKind <= ModuleKind.ESNext;
}

/** @internal */
export function hasJsonModuleEmitEnabled(options: CompilerOptions): boolean {
    switch (getEmitModuleKind(options)) {
        case ModuleKind.None:
        case ModuleKind.System:
        case ModuleKind.UMD:
            return false;
    }
    return true;
}

/** @internal */
export function moduleResolutionSupportsPackageJsonExportsAndImports(moduleResolution: ModuleResolutionKind): boolean {
    return moduleResolution >= ModuleResolutionKind.Node16 && moduleResolution <= ModuleResolutionKind.NodeNext
        || moduleResolution === ModuleResolutionKind.Bundler;
}

/**
 * @internal
 * The same set of options also support import assertions.
 */
export function moduleSupportsImportAttributes(moduleKind: ModuleKind): boolean {
    return ModuleKind.Node18 <= moduleKind && moduleKind <= ModuleKind.NodeNext
        || moduleKind === ModuleKind.Preserve
        || moduleKind === ModuleKind.ESNext;
}

/** @internal */
export type StrictOptionName =
    | "noImplicitAny"
    | "noImplicitThis"
    | "strictNullChecks"
    | "strictFunctionTypes"
    | "strictBindCallApply"
    | "strictPropertyInitialization"
    | "strictBuiltinIteratorReturn"
    | "useUnknownInCatchVariables";

/** @internal */
export function getStrictOptionValue(compilerOptions: CompilerOptions, flag: StrictOptionName): boolean {
    return compilerOptions[flag] === undefined ? (compilerOptions.strict !== false) : !!compilerOptions[flag];
}

/** @internal */
export function getNameOfScriptTarget(scriptTarget: ScriptTarget): string | undefined {
    return forEachEntry(targetOptionDeclaration.type, (value, key) => value === scriptTarget ? key : undefined);
}

/** @internal */
export function getEmitStandardClassFields(compilerOptions: CompilerOptions): boolean {
    return compilerOptions.useDefineForClassFields !== false && getEmitScriptTarget(compilerOptions) >= ScriptTarget.ES2022;
}

/** @internal */
export function compilerOptionsAffectSemanticDiagnostics(newOptions: CompilerOptions, oldOptions: CompilerOptions): boolean {
    return optionsHaveChanges(oldOptions, newOptions, semanticDiagnosticsOptionDeclarations);
}

/** @internal */
export function compilerOptionsAffectEmit(newOptions: CompilerOptions, oldOptions: CompilerOptions): boolean {
    return optionsHaveChanges(oldOptions, newOptions, affectsEmitOptionDeclarations);
}

/** @internal */
export function compilerOptionsAffectDeclarationPath(newOptions: CompilerOptions, oldOptions: CompilerOptions): boolean {
    return optionsHaveChanges(oldOptions, newOptions, affectsDeclarationPathOptionDeclarations);
}

/** @internal */
export function getCompilerOptionValue(options: CompilerOptions, option: CommandLineOption): unknown {
    return option.strictFlag ? getStrictOptionValue(options, option.name as StrictOptionName) :
        option.allowJsFlag ? getAllowJSCompilerOption(options) :
        options[option.name];
}

/** @internal */
export function getJSXTransformEnabled(options: CompilerOptions): boolean {
    const jsx = options.jsx;
    return jsx === JsxEmit.React || jsx === JsxEmit.ReactJSX || jsx === JsxEmit.ReactJSXDev;
}

/** @internal */
export function getJSXImplicitImportBase(compilerOptions: CompilerOptions, file?: SourceFile): string | undefined {
    const jsxImportSourcePragmas = file?.pragmas.get("jsximportsource");
    const jsxImportSourcePragma = isArray(jsxImportSourcePragmas) ? jsxImportSourcePragmas[jsxImportSourcePragmas.length - 1] : jsxImportSourcePragmas;
    const jsxRuntimePragmas = file?.pragmas.get("jsxruntime");
    const jsxRuntimePragma = isArray(jsxRuntimePragmas) ? jsxRuntimePragmas[jsxRuntimePragmas.length - 1] : jsxRuntimePragmas;
    if (jsxRuntimePragma?.arguments.factory === "classic") {
        return undefined;
    }
    return compilerOptions.jsx === JsxEmit.ReactJSX ||
            compilerOptions.jsx === JsxEmit.ReactJSXDev ||
            compilerOptions.jsxImportSource ||
            jsxImportSourcePragma ||
            jsxRuntimePragma?.arguments.factory === "automatic" ?
        jsxImportSourcePragma?.arguments.factory || compilerOptions.jsxImportSource || "react" :
        undefined;
}

/** @internal */
export function getJSXRuntimeImport(base: string | undefined, options: CompilerOptions): string | undefined {
    return base ? `${base}/${options.jsx === JsxEmit.ReactJSXDev ? "jsx-dev-runtime" : "jsx-runtime"}` : undefined;
}

/** @internal */
export function hasZeroOrOneAsteriskCharacter(str: string): boolean {
    let seenAsterisk = false;
    for (let i = 0; i < str.length; i++) {
        if (str.charCodeAt(i) === CharacterCodes.asterisk) {
            if (!seenAsterisk) {
                seenAsterisk = true;
            }
            else {
                // have already seen asterisk
                return false;
            }
        }
    }
    return true;
}

/** @internal */
export interface SymlinkedDirectory {
    /**
     * Matches the casing returned by `realpath`.  Used to compute the `realpath` of children.
     * Always has trailing directory separator
     */
    real: string;
    /**
     * toPath(real).  Stored to avoid repeated recomputation.
     * Always has trailing directory separator
     */
    realPath: Path;
}

/** @internal */
export interface SymlinkCache {
    /** Gets a map from symlink to realpath. Keys have trailing directory separators. */
    getSymlinkedDirectories(): ReadonlyMap<Path, SymlinkedDirectory | false> | undefined;
    /** Gets a map from realpath to symlinks. Keys have trailing directory separators. */
    getSymlinkedDirectoriesByRealpath(): MultiMap<Path, string> | undefined;
    /** Gets a map from symlink to realpath */
    getSymlinkedFiles(): ReadonlyMap<Path, string> | undefined;
    setSymlinkedDirectory(symlink: string, real: SymlinkedDirectory | false): void;
    setSymlinkedFile(symlinkPath: Path, real: string): void;
    hasAnySymlinks(): boolean;
    /**
     * @internal
     * Uses resolvedTypeReferenceDirectives from program instead of from files, since files
     * don't include automatic type reference directives. Must be called only when
     * `hasProcessedResolutions` returns false (once per cache instance).
     */
    setSymlinksFromResolutions(
        forEachResolvedModule: (
            callback: (resolution: ResolvedModuleWithFailedLookupLocations, moduleName: string, mode: ResolutionMode, filePath: Path) => void,
        ) => void,
        forEachResolvedTypeReferenceDirective: (
            callback: (resolution: ResolvedTypeReferenceDirectiveWithFailedLookupLocations, moduleName: string, mode: ResolutionMode, filePath: Path) => void,
        ) => void,
        typeReferenceDirectives: ModeAwareCache<ResolvedTypeReferenceDirectiveWithFailedLookupLocations>,
    ): void;
    setSymlinksFromResolution(resolution: ResolvedModuleFull | undefined): void;
    /**
     * @internal
     * Whether `setSymlinksFromResolutions` has already been called.
     */
    hasProcessedResolutions(): boolean;
}

/** @internal */
export function createSymlinkCache(cwd: string, getCanonicalFileName: GetCanonicalFileName): SymlinkCache {
    let symlinkedDirectories: Map<Path, SymlinkedDirectory | false> | undefined;
    let symlinkedDirectoriesByRealpath: MultiMap<Path, string> | undefined;
    let symlinkedFiles: Map<Path, string> | undefined;
    let hasProcessedResolutions = false;
    return {
        getSymlinkedFiles: () => symlinkedFiles,
        getSymlinkedDirectories: () => symlinkedDirectories,
        getSymlinkedDirectoriesByRealpath: () => symlinkedDirectoriesByRealpath,
        setSymlinkedFile: (path, real) => (symlinkedFiles || (symlinkedFiles = new Map())).set(path, real),
        setSymlinkedDirectory: (symlink, real) => {
            // Large, interconnected dependency graphs in pnpm will have a huge number of symlinks
            // where both the realpath and the symlink path are inside node_modules/.pnpm. Since
            // this path is never a candidate for a module specifier, we can ignore it entirely.
            let symlinkPath = toPath(symlink, cwd, getCanonicalFileName);
            if (!containsIgnoredPath(symlinkPath)) {
                symlinkPath = ensureTrailingDirectorySeparator(symlinkPath);
                if (real !== false && !symlinkedDirectories?.has(symlinkPath)) {
                    (symlinkedDirectoriesByRealpath ||= createMultiMap()).add(real.realPath, symlink);
                }
                (symlinkedDirectories || (symlinkedDirectories = new Map())).set(symlinkPath, real);
            }
        },
        setSymlinksFromResolutions(forEachResolvedModule, forEachResolvedTypeReferenceDirective, typeReferenceDirectives) {
            Debug.assert(!hasProcessedResolutions);
            hasProcessedResolutions = true;
            forEachResolvedModule(resolution => processResolution(this, resolution.resolvedModule));
            forEachResolvedTypeReferenceDirective(resolution => processResolution(this, resolution.resolvedTypeReferenceDirective));
            typeReferenceDirectives.forEach(resolution => processResolution(this, resolution.resolvedTypeReferenceDirective));
        },
        hasProcessedResolutions: () => hasProcessedResolutions,
        setSymlinksFromResolution(resolution) {
            processResolution(this, resolution);
        },
        hasAnySymlinks,
    };

    function hasAnySymlinks() {
        return !!symlinkedFiles?.size || (!!symlinkedDirectories && !!forEachEntry(symlinkedDirectories, value => !!value));
    }

    function processResolution(cache: SymlinkCache, resolution: ResolvedModuleFull | ResolvedTypeReferenceDirective | undefined) {
        if (!resolution || !resolution.originalPath || !resolution.resolvedFileName) return;
        const { resolvedFileName, originalPath } = resolution;
        cache.setSymlinkedFile(toPath(originalPath, cwd, getCanonicalFileName), resolvedFileName);
        const [commonResolved, commonOriginal] = guessDirectorySymlink(resolvedFileName, originalPath, cwd, getCanonicalFileName) || emptyArray;
        if (commonResolved && commonOriginal) {
            cache.setSymlinkedDirectory(
                commonOriginal,
                {
                    real: ensureTrailingDirectorySeparator(commonResolved),
                    realPath: ensureTrailingDirectorySeparator(toPath(commonResolved, cwd, getCanonicalFileName)),
                },
            );
        }
    }
}

function guessDirectorySymlink(a: string, b: string, cwd: string, getCanonicalFileName: GetCanonicalFileName): [string, string] | undefined {
    const aParts = getPathComponents(getNormalizedAbsolutePath(a, cwd));
    const bParts = getPathComponents(getNormalizedAbsolutePath(b, cwd));
    let isDirectory = false;
    while (
        aParts.length >= 2 && bParts.length >= 2 &&
        !isNodeModulesOrScopedPackageDirectory(aParts[aParts.length - 2], getCanonicalFileName) &&
        !isNodeModulesOrScopedPackageDirectory(bParts[bParts.length - 2], getCanonicalFileName) &&
        getCanonicalFileName(aParts[aParts.length - 1]) === getCanonicalFileName(bParts[bParts.length - 1])
    ) {
        aParts.pop();
        bParts.pop();
        isDirectory = true;
    }
    return isDirectory ? [getPathFromPathComponents(aParts), getPathFromPathComponents(bParts)] : undefined;
}

// KLUDGE: Don't assume one 'node_modules' links to another. More likely a single directory inside the node_modules is the symlink.
// ALso, don't assume that an `@foo` directory is linked. More likely the contents of that are linked.
function isNodeModulesOrScopedPackageDirectory(s: string | undefined, getCanonicalFileName: GetCanonicalFileName): boolean {
    return s !== undefined && (getCanonicalFileName(s) === "node_modules" || startsWith(s, "@"));
}

function stripLeadingDirectorySeparator(s: string): string | undefined {
    return isAnyDirectorySeparator(s.charCodeAt(0)) ? s.slice(1) : undefined;
}

/** @internal */
export function tryRemoveDirectoryPrefix(path: string, dirPath: string, getCanonicalFileName: GetCanonicalFileName): string | undefined {
    const withoutPrefix = tryRemovePrefix(path, dirPath, getCanonicalFileName);
    return withoutPrefix === undefined ? undefined : stripLeadingDirectorySeparator(withoutPrefix);
}

// Reserved characters, forces escaping of any non-word (or digit), non-whitespace character.
// It may be inefficient (we could just match (/[-[\]{}()*+?.,\\^$|#\s]/g), but this is future
// proof.
const reservedCharacterPattern = /[^\w\s/]/g;

/** @internal */
export function regExpEscape(text: string): string {
    return text.replace(reservedCharacterPattern, escapeRegExpCharacter);
}

function escapeRegExpCharacter(match: string) {
    return "\\" + match;
}

const wildcardCharCodes = [CharacterCodes.asterisk, CharacterCodes.question];

const commonPackageFolders: readonly string[] = ["node_modules", "bower_components", "jspm_packages"];

const implicitExcludePathRegexPattern = `(?!(?:${commonPackageFolders.join("|")})(?:/|$))`;

/** @internal */
export interface WildcardMatcher {
    singleAsteriskRegexFragment: string;
    doubleAsteriskRegexFragment: string;
    replaceWildcardCharacter: (match: string) => string;
}

const filesMatcher: WildcardMatcher = {
    /**
     * Matches any single directory segment unless it is the last segment and a .min.js file
     * Breakdown:
     *  [^./]                   # matches everything up to the first . character (excluding directory separators)
     *  (\\.(?!min\\.js$))?     # matches . characters but not if they are part of the .min.js file extension
     */
    singleAsteriskRegexFragment: "(?:[^./]|(?:\\.(?!min\\.js$))?)*",
    /**
     * Regex for the ** wildcard. Matches any number of subdirectories. When used for including
     * files or directories, does not match subdirectories that start with a . character
     */
    doubleAsteriskRegexFragment: `(?:/${implicitExcludePathRegexPattern}[^/.][^/]*)*?`,
    replaceWildcardCharacter: match => replaceWildcardCharacter(match, filesMatcher.singleAsteriskRegexFragment),
};

const directoriesMatcher: WildcardMatcher = {
    singleAsteriskRegexFragment: "[^/]*",
    /**
     * Regex for the ** wildcard. Matches any number of subdirectories. When used for including
     * files or directories, does not match subdirectories that start with a . character
     */
    doubleAsteriskRegexFragment: `(?:/${implicitExcludePathRegexPattern}[^/.][^/]*)*?`,
    replaceWildcardCharacter: match => replaceWildcardCharacter(match, directoriesMatcher.singleAsteriskRegexFragment),
};

const excludeMatcher: WildcardMatcher = {
    singleAsteriskRegexFragment: "[^/]*",
    doubleAsteriskRegexFragment: "(?:/.+?)?",
    replaceWildcardCharacter: match => replaceWildcardCharacter(match, excludeMatcher.singleAsteriskRegexFragment),
};

const wildcardMatchers = {
    files: filesMatcher,
    directories: directoriesMatcher,
    exclude: excludeMatcher,
};

/** @internal */
export function getRegularExpressionForWildcard(specs: readonly string[] | undefined, basePath: string, usage: "files" | "directories" | "exclude"): string | undefined {
    const patterns = getRegularExpressionsForWildcards(specs, basePath, usage);
    if (!patterns || !patterns.length) {
        return undefined;
    }

    const pattern = patterns.map(pattern => `(?:${pattern})`).join("|");
    // If excluding, match "foo/bar/baz...", but if including, only allow "foo".
    const terminator = usage === "exclude" ? "(?:$|/)" : "$";
    return `^(?:${pattern})${terminator}`;
}

/** @internal */
export function getRegularExpressionsForWildcards(specs: readonly string[] | undefined, basePath: string, usage: "files" | "directories" | "exclude"): readonly string[] | undefined {
    if (specs === undefined || specs.length === 0) {
        return undefined;
    }

    return flatMap(specs, spec => spec && getSubPatternFromSpec(spec, basePath, usage, wildcardMatchers[usage]));
}

/**
 * An "includes" path "foo" is implicitly a glob "foo/** /*" (without the space) if its last component has no extension,
 * and does not contain any glob characters itself.
 *
 * @internal
 */
export function isImplicitGlob(lastPathComponent: string): boolean {
    return !/[.*?]/.test(lastPathComponent);
}

/** @internal */
export function getPatternFromSpec(spec: string, basePath: string, usage: "files" | "directories" | "exclude"): string | undefined {
    const pattern = spec && getSubPatternFromSpec(spec, basePath, usage, wildcardMatchers[usage]);
    return pattern && `^(?:${pattern})${usage === "exclude" ? "(?:$|/)" : "$"}`;
}

/** @internal */
export function getSubPatternFromSpec(
    spec: string,
    basePath: string,
    usage: "files" | "directories" | "exclude",
    { singleAsteriskRegexFragment, doubleAsteriskRegexFragment, replaceWildcardCharacter }: WildcardMatcher = wildcardMatchers[usage],
): string | undefined {
    let subpattern = "";
    let hasWrittenComponent = false;
    const components = getNormalizedPathComponents(spec, basePath);
    const lastComponent = last(components);
    if (usage !== "exclude" && lastComponent === "**") {
        return undefined;
    }

    // getNormalizedPathComponents includes the separator for the root component.
    // We need to remove to create our regex correctly.
    components[0] = removeTrailingDirectorySeparator(components[0]);

    if (isImplicitGlob(lastComponent)) {
        components.push("**", "*");
    }

    let optionalCount = 0;
    for (let component of components) {
        if (component === "**") {
            subpattern += doubleAsteriskRegexFragment;
        }
        else {
            if (usage === "directories") {
                subpattern += "(?:";
                optionalCount++;
            }

            if (hasWrittenComponent) {
                subpattern += directorySeparator;
            }

            if (usage !== "exclude") {
                let componentPattern = "";
                // The * and ? wildcards should not match directories or files that start with . if they
                // appear first in a component. Dotted directories and files can be included explicitly
                // like so: **/.*/.*
                if (component.charCodeAt(0) === CharacterCodes.asterisk) {
                    componentPattern += "(?:[^./]" + singleAsteriskRegexFragment + ")?";
                    component = component.substr(1);
                }
                else if (component.charCodeAt(0) === CharacterCodes.question) {
                    componentPattern += "[^./]";
                    component = component.substr(1);
                }

                componentPattern += component.replace(reservedCharacterPattern, replaceWildcardCharacter);

                // Patterns should not include subfolders like node_modules unless they are
                // explicitly included as part of the path.
                //
                // As an optimization, if the component pattern is the same as the component,
                // then there definitely were no wildcard characters and we do not need to
                // add the exclusion pattern.
                if (componentPattern !== component) {
                    subpattern += implicitExcludePathRegexPattern;
                }

                subpattern += componentPattern;
            }
            else {
                subpattern += component.replace(reservedCharacterPattern, replaceWildcardCharacter);
            }
        }

        hasWrittenComponent = true;
    }

    while (optionalCount > 0) {
        subpattern += ")?";
        optionalCount--;
    }

    return subpattern;
}

function replaceWildcardCharacter(match: string, singleAsteriskRegexFragment: string) {
    return match === "*" ? singleAsteriskRegexFragment : match === "?" ? "[^/]" : "\\" + match;
}

/** @internal */
export interface FileSystemEntries {
    readonly files: readonly string[];
    readonly directories: readonly string[];
}

/** @internal */
export interface FileMatcherPatterns {
    /** One pattern for each "include" spec. */
    includeFilePatterns: readonly string[] | undefined;
    /** One pattern matching one of any of the "include" specs. */
    includeFilePattern: string | undefined;
    includeDirectoryPattern: string | undefined;
    excludePattern: string | undefined;
    basePaths: readonly string[];
}

/**
 * @param path directory of the tsconfig.json
 *
 * @internal
 */
export function getFileMatcherPatterns(path: string, excludes: readonly string[] | undefined, includes: readonly string[] | undefined, useCaseSensitiveFileNames: boolean, currentDirectory: string): FileMatcherPatterns {
    path = normalizePath(path);
    currentDirectory = normalizePath(currentDirectory);
    const absolutePath = combinePaths(currentDirectory, path);

    return {
        includeFilePatterns: map(getRegularExpressionsForWildcards(includes, absolutePath, "files"), pattern => `^${pattern}$`),
        includeFilePattern: getRegularExpressionForWildcard(includes, absolutePath, "files"),
        includeDirectoryPattern: getRegularExpressionForWildcard(includes, absolutePath, "directories"),
        excludePattern: getRegularExpressionForWildcard(excludes, absolutePath, "exclude"),
        basePaths: getBasePaths(path, includes, useCaseSensitiveFileNames),
    };
}

/** @internal */
export function getRegexFromPattern(pattern: string, useCaseSensitiveFileNames: boolean): RegExp {
    return new RegExp(pattern, useCaseSensitiveFileNames ? "" : "i");
}

/**
 * @param path directory of the tsconfig.json
 *
 * @internal
 */
export function matchFiles(path: string, extensions: readonly string[] | undefined, excludes: readonly string[] | undefined, includes: readonly string[] | undefined, useCaseSensitiveFileNames: boolean, currentDirectory: string, depth: number | undefined, getFileSystemEntries: (path: string) => FileSystemEntries, realpath: (path: string) => string): string[] {
    path = normalizePath(path);
    currentDirectory = normalizePath(currentDirectory);

    const patterns = getFileMatcherPatterns(path, excludes, includes, useCaseSensitiveFileNames, currentDirectory);

    const includeFileRegexes = patterns.includeFilePatterns && patterns.includeFilePatterns.map(pattern => getRegexFromPattern(pattern, useCaseSensitiveFileNames));
    const includeDirectoryRegex = patterns.includeDirectoryPattern && getRegexFromPattern(patterns.includeDirectoryPattern, useCaseSensitiveFileNames);
    const excludeRegex = patterns.excludePattern && getRegexFromPattern(patterns.excludePattern, useCaseSensitiveFileNames);

    // Associate an array of results with each include regex. This keeps results in order of the "include" order.
    // If there are no "includes", then just put everything in results[0].
    const results: string[][] = includeFileRegexes ? includeFileRegexes.map(() => []) : [[]];
    const visited = new Map<string, true>();
    const toCanonical = createGetCanonicalFileName(useCaseSensitiveFileNames);
    for (const basePath of patterns.basePaths) {
        visitDirectory(basePath, combinePaths(currentDirectory, basePath), depth);
    }

    return flatten(results);

    function visitDirectory(path: string, absolutePath: string, depth: number | undefined) {
        const canonicalPath = toCanonical(realpath(absolutePath));
        if (visited.has(canonicalPath)) return;
        visited.set(canonicalPath, true);
        const { files, directories } = getFileSystemEntries(path);

        for (const current of toSorted<string>(files, compareStringsCaseSensitive)) {
            const name = combinePaths(path, current);
            const absoluteName = combinePaths(absolutePath, current);
            if (extensions && !fileExtensionIsOneOf(name, extensions)) continue;
            if (excludeRegex && excludeRegex.test(absoluteName)) continue;
            if (!includeFileRegexes) {
                results[0].push(name);
            }
            else {
                const includeIndex = findIndex(includeFileRegexes, re => re.test(absoluteName));
                if (includeIndex !== -1) {
                    results[includeIndex].push(name);
                }
            }
        }

        if (depth !== undefined) {
            depth--;
            if (depth === 0) {
                return;
            }
        }

        for (const current of toSorted<string>(directories, compareStringsCaseSensitive)) {
            const name = combinePaths(path, current);
            const absoluteName = combinePaths(absolutePath, current);
            if (
                (!includeDirectoryRegex || includeDirectoryRegex.test(absoluteName)) &&
                (!excludeRegex || !excludeRegex.test(absoluteName))
            ) {
                visitDirectory(name, absoluteName, depth);
            }
        }
    }
}

/**
 * Computes the unique non-wildcard base paths amongst the provided include patterns.
 */
function getBasePaths(path: string, includes: readonly string[] | undefined, useCaseSensitiveFileNames: boolean): string[] {
    // Storage for our results in the form of literal paths (e.g. the paths as written by the user).
    const basePaths: string[] = [path];

    if (includes) {
        // Storage for literal base paths amongst the include patterns.
        const includeBasePaths: string[] = [];
        for (const include of includes) {
            // We also need to check the relative paths by converting them to absolute and normalizing
            // in case they escape the base path (e.g "..\somedirectory")
            const absolute: string = isRootedDiskPath(include) ? include : normalizePath(combinePaths(path, include));
            // Append the literal and canonical candidate base paths.
            includeBasePaths.push(getIncludeBasePath(absolute));
        }

        // Sort the offsets array using either the literal or canonical path representations.
        includeBasePaths.sort(getStringComparer(!useCaseSensitiveFileNames));

        // Iterate over each include base path and include unique base paths that are not a
        // subpath of an existing base path
        for (const includeBasePath of includeBasePaths) {
            if (every(basePaths, basePath => !containsPath(basePath, includeBasePath, path, !useCaseSensitiveFileNames))) {
                basePaths.push(includeBasePath);
            }
        }
    }

    return basePaths;
}

function getIncludeBasePath(absolute: string): string {
    const wildcardOffset = indexOfAnyCharCode(absolute, wildcardCharCodes);
    if (wildcardOffset < 0) {
        // No "*" or "?" in the path
        return !hasExtension(absolute)
            ? absolute
            : removeTrailingDirectorySeparator(getDirectoryPath(absolute));
    }
    return absolute.substring(0, absolute.lastIndexOf(directorySeparator, wildcardOffset));
}

/** @internal */
export function ensureScriptKind(fileName: string, scriptKind: ScriptKind | undefined): ScriptKind {
    // Using scriptKind as a condition handles both:
    // - 'scriptKind' is unspecified and thus it is `undefined`
    // - 'scriptKind' is set and it is `Unknown` (0)
    // If the 'scriptKind' is 'undefined' or 'Unknown' then we attempt
    // to get the ScriptKind from the file name. If it cannot be resolved
    // from the file name then the default 'TS' script kind is returned.
    return scriptKind || getScriptKindFromFileName(fileName) || ScriptKind.TS;
}

/** @internal */
export function getScriptKindFromFileName(fileName: string): ScriptKind {
    const ext = fileName.substr(fileName.lastIndexOf("."));
    switch (ext.toLowerCase()) {
        case Extension.Js:
        case Extension.Cjs:
        case Extension.Mjs:
            return ScriptKind.JS;
        case Extension.Jsx:
            return ScriptKind.JSX;
        case Extension.Ts:
        case Extension.Cts:
        case Extension.Mts:
            return ScriptKind.TS;
        case Extension.Tsx:
            return ScriptKind.TSX;
        case Extension.Json:
            return ScriptKind.JSON;
        default:
            return ScriptKind.Unknown;
    }
}

/**
 *  Groups of supported extensions in order of file resolution precedence. (eg, TS > TSX > DTS and seperately, CTS > DCTS)
 */
const supportedTSExtensions: readonly Extension[][] = [[Extension.Ts, Extension.Tsx, Extension.Dts], [Extension.Cts, Extension.Dcts], [Extension.Mts, Extension.Dmts]];
/** @internal */
export const supportedTSExtensionsFlat: readonly Extension[] = flatten(supportedTSExtensions);
const supportedTSExtensionsWithJson: readonly Extension[][] = [...supportedTSExtensions, [Extension.Json]];
/** Must have ".d.ts" first because if ".ts" goes first, that will be detected as the extension instead of ".d.ts". */
const supportedTSExtensionsForExtractExtension: readonly Extension[] = [Extension.Dts, Extension.Dcts, Extension.Dmts, Extension.Cts, Extension.Mts, Extension.Ts, Extension.Tsx];
const supportedJSExtensions: readonly Extension[][] = [[Extension.Js, Extension.Jsx], [Extension.Mjs], [Extension.Cjs]];
/** @internal */
export const supportedJSExtensionsFlat: readonly Extension[] = flatten(supportedJSExtensions);
const allSupportedExtensions: readonly Extension[][] = [[Extension.Ts, Extension.Tsx, Extension.Dts, Extension.Js, Extension.Jsx], [Extension.Cts, Extension.Dcts, Extension.Cjs], [Extension.Mts, Extension.Dmts, Extension.Mjs]];
const allSupportedExtensionsWithJson: readonly Extension[][] = [...allSupportedExtensions, [Extension.Json]];
/** @internal */
export const supportedDeclarationExtensions: readonly Extension[] = [Extension.Dts, Extension.Dcts, Extension.Dmts];
/** @internal */
export const supportedTSImplementationExtensions: readonly Extension[] = [Extension.Ts, Extension.Cts, Extension.Mts, Extension.Tsx];
/** @internal */
export const extensionsNotSupportingExtensionlessResolution: readonly Extension[] = [Extension.Mts, Extension.Dmts, Extension.Mjs, Extension.Cts, Extension.Dcts, Extension.Cjs];

/** @internal */
export function getSupportedExtensions(options?: CompilerOptions): readonly Extension[][];
/** @internal */
export function getSupportedExtensions(options?: CompilerOptions, extraFileExtensions?: readonly FileExtensionInfo[]): readonly string[][];
/** @internal */
export function getSupportedExtensions(options?: CompilerOptions, extraFileExtensions?: readonly FileExtensionInfo[]): readonly string[][] {
    const needJsExtensions = options && getAllowJSCompilerOption(options);

    if (!extraFileExtensions || extraFileExtensions.length === 0) {
        return needJsExtensions ? allSupportedExtensions : supportedTSExtensions;
    }

    const builtins = needJsExtensions ? allSupportedExtensions : supportedTSExtensions;
    const flatBuiltins = flatten(builtins);
    const extensions = [
        ...builtins,
        ...mapDefined(extraFileExtensions, x => x.scriptKind === ScriptKind.Deferred || needJsExtensions && isJSLike(x.scriptKind) && !flatBuiltins.includes(x.extension as Extension) ? [x.extension] : undefined),
    ];

    return extensions;
}

/** @internal */
export function getSupportedExtensionsWithJsonIfResolveJsonModule(options: CompilerOptions | undefined, supportedExtensions: readonly Extension[][]): readonly Extension[][];
/** @internal */
export function getSupportedExtensionsWithJsonIfResolveJsonModule(options: CompilerOptions | undefined, supportedExtensions: readonly string[][]): readonly string[][];
/** @internal */
export function getSupportedExtensionsWithJsonIfResolveJsonModule(options: CompilerOptions | undefined, supportedExtensions: readonly string[][]): readonly string[][] {
    if (!options || !getResolveJsonModule(options)) return supportedExtensions;
    if (supportedExtensions === allSupportedExtensions) return allSupportedExtensionsWithJson;
    if (supportedExtensions === supportedTSExtensions) return supportedTSExtensionsWithJson;
    return [...supportedExtensions, [Extension.Json]];
}

function isJSLike(scriptKind: ScriptKind | undefined): boolean {
    return scriptKind === ScriptKind.JS || scriptKind === ScriptKind.JSX;
}

/** @internal */
export function hasJSFileExtension(fileName: string): boolean {
    return some(supportedJSExtensionsFlat, extension => fileExtensionIs(fileName, extension));
}

/** @internal */
export function hasTSFileExtension(fileName: string): boolean {
    return some(supportedTSExtensionsFlat, extension => fileExtensionIs(fileName, extension));
}

/** @internal */
export function hasImplementationTSFileExtension(fileName: string): boolean {
    return some(supportedTSImplementationExtensions, extension => fileExtensionIs(fileName, extension))
        && !isDeclarationFileName(fileName);
}

/**
 * @internal
 * Corresponds to UserPreferences#importPathEnding
 */
export const enum ModuleSpecifierEnding {
    Minimal,
    Index,
    JsExtension,
    TsExtension,
}

function usesExtensionsOnImports({ imports }: SourceFile, hasExtension: (text: string) => boolean = or(hasJSFileExtension, hasTSFileExtension)): boolean {
    return firstDefined(imports, ({ text }) =>
        pathIsRelative(text) && !fileExtensionIsOneOf(text, extensionsNotSupportingExtensionlessResolution)
            ? hasExtension(text)
            : undefined) || false;
}

/** @internal */
export function getModuleSpecifierEndingPreference(preference: UserPreferences["importModuleSpecifierEnding"], resolutionMode: ResolutionMode, compilerOptions: CompilerOptions, sourceFile?: SourceFile): ModuleSpecifierEnding {
    const moduleResolution = getEmitModuleResolutionKind(compilerOptions);
    const moduleResolutionIsNodeNext = ModuleResolutionKind.Node16 <= moduleResolution && moduleResolution <= ModuleResolutionKind.NodeNext;
    if (preference === "js" || resolutionMode === ModuleKind.ESNext && moduleResolutionIsNodeNext) {
        // Extensions are explicitly requested or required. Now choose between .js and .ts.
        if (!shouldAllowImportingTsExtension(compilerOptions)) {
            return ModuleSpecifierEnding.JsExtension;
        }
        // `allowImportingTsExtensions` is a strong signal, so use .ts unless the file
        // already uses .js extensions and no .ts extensions.
        return inferPreference() !== ModuleSpecifierEnding.JsExtension
            ? ModuleSpecifierEnding.TsExtension
            : ModuleSpecifierEnding.JsExtension;
    }
    if (preference === "minimal") {
        return ModuleSpecifierEnding.Minimal;
    }
    if (preference === "index") {
        return ModuleSpecifierEnding.Index;
    }

    // No preference was specified.
    // Look at imports and/or requires to guess whether .js, .ts, or extensionless imports are preferred.
    // N.B. that `Index` detection is not supported since it would require file system probing to do
    // accurately, and more importantly, literally nobody wants `Index` and its existence is a mystery.
    if (!shouldAllowImportingTsExtension(compilerOptions)) {
        // If .ts imports are not valid, we only need to see one .js import to go with that.
        return sourceFile && usesExtensionsOnImports(sourceFile) ? ModuleSpecifierEnding.JsExtension : ModuleSpecifierEnding.Minimal;
    }

    return inferPreference();

    function inferPreference() {
        let usesJsExtensions = false;
        const specifiers = sourceFile?.imports.length ? sourceFile.imports :
            sourceFile && isSourceFileJS(sourceFile) ? getRequiresAtTopOfFile(sourceFile).map(r => r.arguments[0]) :
            emptyArray;
        for (const specifier of specifiers) {
            if (pathIsRelative(specifier.text)) {
                if (
                    moduleResolutionIsNodeNext &&
                    resolutionMode === ModuleKind.CommonJS &&
                    getModeForUsageLocation(sourceFile!, specifier, compilerOptions) === ModuleKind.ESNext
                ) {
                    // We're trying to decide a preference for a CommonJS module specifier, but looking at an ESM import.
                    continue;
                }
                if (fileExtensionIsOneOf(specifier.text, extensionsNotSupportingExtensionlessResolution)) {
                    // These extensions are not optional, so do not indicate a preference.
                    continue;
                }
                if (hasTSFileExtension(specifier.text)) {
                    return ModuleSpecifierEnding.TsExtension;
                }
                if (hasJSFileExtension(specifier.text)) {
                    usesJsExtensions = true;
                }
            }
        }
        return usesJsExtensions ? ModuleSpecifierEnding.JsExtension : ModuleSpecifierEnding.Minimal;
    }
}

function getRequiresAtTopOfFile(sourceFile: SourceFile): readonly RequireOrImportCall[] {
    let nonRequireStatementCount = 0;
    let requires: RequireOrImportCall[] | undefined;
    for (const statement of sourceFile.statements) {
        if (nonRequireStatementCount > 3) {
            break;
        }
        if (isRequireVariableStatement(statement)) {
            requires = concatenate(requires, statement.declarationList.declarations.map(d => d.initializer));
        }
        else if (isExpressionStatement(statement) && isRequireCall(statement.expression, /*requireStringLiteralLikeArgument*/ true)) {
            requires = append(requires, statement.expression);
        }
        else {
            nonRequireStatementCount++;
        }
    }
    return requires || emptyArray;
}

/** @internal */
export function isSupportedSourceFileName(fileName: string, compilerOptions?: CompilerOptions, extraFileExtensions?: readonly FileExtensionInfo[]): boolean {
    if (!fileName) return false;

    const supportedExtensions = getSupportedExtensions(compilerOptions, extraFileExtensions);
    for (const extension of flatten(getSupportedExtensionsWithJsonIfResolveJsonModule(compilerOptions, supportedExtensions))) {
        if (fileExtensionIs(fileName, extension)) {
            return true;
        }
    }
    return false;
}

function numberOfDirectorySeparators(str: string) {
    const match = str.match(/\//g);
    return match ? match.length : 0;
}

/** @internal */
export function compareNumberOfDirectorySeparators(path1: string, path2: string): Comparison {
    return compareValues(
        numberOfDirectorySeparators(path1),
        numberOfDirectorySeparators(path2),
    );
}

const extensionsToRemove = [Extension.Dts, Extension.Dmts, Extension.Dcts, Extension.Mjs, Extension.Mts, Extension.Cjs, Extension.Cts, Extension.Ts, Extension.Js, Extension.Tsx, Extension.Jsx, Extension.Json];
/** @internal */
export function removeFileExtension(path: string): string {
    for (const ext of extensionsToRemove) {
        const extensionless = tryRemoveExtension(path, ext);
        if (extensionless !== undefined) {
            return extensionless;
        }
    }
    return path;
}

/** @internal @knipignore */
export function tryRemoveExtension(path: string, extension: string): string | undefined {
    return fileExtensionIs(path, extension) ? removeExtension(path, extension) : undefined;
}

/** @internal */
export function removeExtension(path: string, extension: string): string {
    return path.substring(0, path.length - extension.length);
}

/** @internal */
export function changeExtension<T extends string | Path>(path: T, newExtension: string): T {
    return changeAnyExtension(path, newExtension, extensionsToRemove, /*ignoreCase*/ false) as T;
}

/**
 * Returns the input if there are no stars, a pattern if there is exactly one,
 * and undefined if there are more.
 *
 * @internal
 */
export function tryParsePattern(pattern: string): string | Pattern | undefined {
    const indexOfStar = pattern.indexOf("*");
    if (indexOfStar === -1) {
        return pattern;
    }
    return pattern.indexOf("*", indexOfStar + 1) !== -1
        ? undefined
        : {
            prefix: pattern.substr(0, indexOfStar),
            suffix: pattern.substr(indexOfStar + 1),
        };
}

/** @internal */
export interface ParsedPatterns {
    matchableStringSet: ReadonlySet<string> | undefined;
    patterns: (readonly Pattern[]) | undefined;
}

const parsedPatternsCache = new WeakMap<MapLike<string[]>, ParsedPatterns>();

/**
 * Divides patterns into a set of exact specifiers and patterns.
 * NOTE that this function caches the result based on object identity.
 *
 * @internal
 */
export function tryParsePatterns(paths: MapLike<string[]>): ParsedPatterns {
    let result = parsedPatternsCache.get(paths);
    if (result !== undefined) {
        return result;
    }

    let matchableStringSet: Set<string> | undefined;
    let patterns: Pattern[] | undefined;

    const pathList = getOwnKeys(paths);
    for (const path of pathList) {
        const patternOrStr = tryParsePattern(path);
        if (patternOrStr === undefined) {
            continue;
        }
        else if (typeof patternOrStr === "string") {
            (matchableStringSet ??= new Set()).add(patternOrStr);
        }
        else {
            (patterns ??= []).push(patternOrStr);
        }
    }

    parsedPatternsCache.set(
        paths,
        result = {
            matchableStringSet,
            patterns,
        },
    );

    return result;
}

/** @internal */
export function positionIsSynthesized(pos: number): boolean {
    // This is a fast way of testing the following conditions:
    //  pos === undefined || pos === null || isNaN(pos) || pos < 0;
    return !(pos >= 0);
}

/**
 * True if an extension is one of the supported TypeScript extensions.
 *
 * @internal
 */
export function extensionIsTS(ext: string): boolean {
    return ext === Extension.Ts || ext === Extension.Tsx || ext === Extension.Dts || ext === Extension.Cts || ext === Extension.Mts || ext === Extension.Dmts || ext === Extension.Dcts || (startsWith(ext, ".d.") && endsWith(ext, ".ts"));
}

/** @internal */
export function resolutionExtensionIsTSOrJson(ext: string): boolean {
    return extensionIsTS(ext) || ext === Extension.Json;
}

/**
 * Gets the extension from a path.
 * Path must have a valid extension.
 *
 * @internal
 */
export function extensionFromPath(path: string): Extension {
    const ext = tryGetExtensionFromPath(path);
    return ext !== undefined ? ext : Debug.fail(`File ${path} has unknown extension.`);
}

/** @internal */
export function isAnySupportedFileExtension(path: string): boolean {
    return tryGetExtensionFromPath(path) !== undefined;
}

/** @internal */
export function tryGetExtensionFromPath(path: string): Extension | undefined {
    return find(extensionsToRemove, e => fileExtensionIs(path, e));
}

/** @internal */
export function isCheckJsEnabledForFile(sourceFile: SourceFile, compilerOptions: CompilerOptions): boolean | undefined {
    return sourceFile.checkJsDirective ? sourceFile.checkJsDirective.enabled : compilerOptions.checkJs;
}

/** @internal */
export const emptyFileSystemEntries: FileSystemEntries = {
    files: emptyArray,
    directories: emptyArray,
};

/**
 * `parsedPatterns` contains both patterns (containing "*") and regular strings.
 * Return an exact match if possible, or a pattern match, or undefined.
 * (These are verified by verifyCompilerOptions to have 0 or 1 "*" characters.)
 *
 * @internal
 */
export function matchPatternOrExact(parsedPatterns: ParsedPatterns, candidate: string): string | Pattern | undefined {
    const { matchableStringSet, patterns } = parsedPatterns;

    if (matchableStringSet?.has(candidate)) {
        return candidate;
    }

    if (patterns === undefined || patterns.length === 0) {
        return undefined;
    }

    return findBestPatternMatch(patterns, _ => _, candidate);
}

/** @internal */
export type Mutable<T extends object> = { -readonly [K in keyof T]: T[K]; };

/** @internal */
export function sliceAfter<T>(arr: readonly T[], value: T): readonly T[] {
    const index = arr.indexOf(value);
    Debug.assert(index !== -1);
    return arr.slice(index);
}

/** @internal */
export function addRelatedInfo<T extends Diagnostic>(diagnostic: T, ...relatedInformation: DiagnosticRelatedInformation[]): T {
    if (!relatedInformation.length) {
        return diagnostic;
    }
    if (!diagnostic.relatedInformation) {
        diagnostic.relatedInformation = [];
    }
    Debug.assert(diagnostic.relatedInformation !== emptyArray, "Diagnostic had empty array singleton for related info, but is still being constructed!");
    diagnostic.relatedInformation.push(...relatedInformation);
    return diagnostic;
}

/** @internal */
export function minAndMax<T>(arr: readonly T[], getValue: (value: T) => number): { readonly min: number; readonly max: number; } {
    Debug.assert(arr.length !== 0);
    let min = getValue(arr[0]);
    let max = min;
    for (let i = 1; i < arr.length; i++) {
        const value = getValue(arr[i]);
        if (value < min) {
            min = value;
        }
        else if (value > max) {
            max = value;
        }
    }
    return { min, max };
}

/** @internal */
export function rangeOfNode(node: Node): TextRange {
    return { pos: getTokenPosOfNode(node), end: node.end };
}

/** @internal */
export function rangeOfTypeParameters(sourceFile: SourceFile, typeParameters: NodeArray<TypeParameterDeclaration>): TextRange {
    // Include the `<>`
    const pos = typeParameters.pos - 1;
    const end = Math.min(sourceFile.text.length, skipTrivia(sourceFile.text, typeParameters.end) + 1);
    return { pos, end };
}

/** @internal */
export interface HostWithIsSourceOfProjectReferenceRedirect {
    isSourceOfProjectReferenceRedirect(fileName: string): boolean;
    isSourceFileDefaultLibrary(file: SourceFile): boolean;
}
/** @internal */
export function skipTypeChecking(
    sourceFile: SourceFile,
    options: CompilerOptions,
    host: HostWithIsSourceOfProjectReferenceRedirect,
): boolean {
    return skipTypeCheckingWorker(sourceFile, options, host, /*ignoreNoCheck*/ false);
}

/** @internal */
export function skipTypeCheckingIgnoringNoCheck(
    sourceFile: SourceFile,
    options: CompilerOptions,
    host: HostWithIsSourceOfProjectReferenceRedirect,
): boolean {
    return skipTypeCheckingWorker(sourceFile, options, host, /*ignoreNoCheck*/ true);
}

function skipTypeCheckingWorker(
    sourceFile: SourceFile,
    options: CompilerOptions,
    host: HostWithIsSourceOfProjectReferenceRedirect,
    ignoreNoCheck: boolean,
) {
    // If skipLibCheck is enabled, skip reporting errors if file is a declaration file.
    // If skipDefaultLibCheck is enabled, skip reporting errors if file is a lib.
    return (options.skipLibCheck && sourceFile.isDeclarationFile ||
        options.skipDefaultLibCheck && host.isSourceFileDefaultLibrary(sourceFile)) ||
        (!ignoreNoCheck && options.noCheck) ||
        host.isSourceOfProjectReferenceRedirect(sourceFile.fileName) ||
        !canIncludeBindAndCheckDiagnostics(sourceFile, options);
}

/** @internal */
export function canIncludeBindAndCheckDiagnostics(sourceFile: SourceFile, options: CompilerOptions): boolean {
    if (!!sourceFile.checkJsDirective && sourceFile.checkJsDirective.enabled === false) return false;
    if (
        sourceFile.scriptKind === ScriptKind.TS ||
        sourceFile.scriptKind === ScriptKind.TSX ||
        sourceFile.scriptKind === ScriptKind.External
    ) return true;

    const isJs = sourceFile.scriptKind === ScriptKind.JS || sourceFile.scriptKind === ScriptKind.JSX;
    const isCheckJs = isJs && isCheckJsEnabledForFile(sourceFile, options);
    const isPlainJs = isPlainJsFile(sourceFile, options.checkJs);

    // By default, only type-check .ts, .tsx, Deferred, plain JS, checked JS and External
    // - plain JS: .js files with no // ts-check and checkJs: undefined
    // - check JS: .js files with either // ts-check or checkJs: true
    // - external: files that are added by plugins
    return isPlainJs || isCheckJs || sourceFile.scriptKind === ScriptKind.Deferred;
}

/** @internal */
export function isJsonEqual(a: unknown, b: unknown): boolean {
    // eslint-disable-next-line no-restricted-syntax
    return a === b || typeof a === "object" && a !== null && typeof b === "object" && b !== null && equalOwnProperties(a as MapLike<unknown>, b as MapLike<unknown>, isJsonEqual);
}

/**
 * Converts a bigint literal string, e.g. `0x1234n`,
 * to its decimal string representation, e.g. `4660`.
 *
 * @internal
 */
export function parsePseudoBigInt(stringValue: string): string {
    let log2Base: number;
    switch (stringValue.charCodeAt(1)) { // "x" in "0x123"
        case CharacterCodes.b:
        case CharacterCodes.B: // 0b or 0B
            log2Base = 1;
            break;
        case CharacterCodes.o:
        case CharacterCodes.O: // 0o or 0O
            log2Base = 3;
            break;
        case CharacterCodes.x:
        case CharacterCodes.X: // 0x or 0X
            log2Base = 4;
            break;
        default: // already in decimal; omit trailing "n"
            const nIndex = stringValue.length - 1;
            // Skip leading 0s
            let nonZeroStart = 0;
            while (stringValue.charCodeAt(nonZeroStart) === CharacterCodes._0) {
                nonZeroStart++;
            }
            return stringValue.slice(nonZeroStart, nIndex) || "0";
    }

    // Omit leading "0b", "0o", or "0x", and trailing "n"
    const startIndex = 2, endIndex = stringValue.length - 1;
    const bitsNeeded = (endIndex - startIndex) * log2Base;
    // Stores the value specified by the string as a LE array of 16-bit integers
    // using Uint16 instead of Uint32 so combining steps can use bitwise operators
    const segments = new Uint16Array((bitsNeeded >>> 4) + (bitsNeeded & 15 ? 1 : 0));
    // Add the digits, one at a time
    for (let i = endIndex - 1, bitOffset = 0; i >= startIndex; i--, bitOffset += log2Base) {
        const segment = bitOffset >>> 4;
        const digitChar = stringValue.charCodeAt(i);
        // Find character range: 0-9 < A-F < a-f
        const digit = digitChar <= CharacterCodes._9
            ? digitChar - CharacterCodes._0
            : 10 + digitChar -
                (digitChar <= CharacterCodes.F ? CharacterCodes.A : CharacterCodes.a);
        const shiftedDigit = digit << (bitOffset & 15);
        segments[segment] |= shiftedDigit;
        const residual = shiftedDigit >>> 16;
        if (residual) segments[segment + 1] |= residual; // overflows segment
    }
    // Repeatedly divide segments by 10 and add remainder to base10Value
    let base10Value = "";
    let firstNonzeroSegment = segments.length - 1;
    let segmentsRemaining = true;
    while (segmentsRemaining) {
        let mod10 = 0;
        segmentsRemaining = false;
        for (let segment = firstNonzeroSegment; segment >= 0; segment--) {
            const newSegment = mod10 << 16 | segments[segment];
            const segmentValue = (newSegment / 10) | 0;
            segments[segment] = segmentValue;
            mod10 = newSegment - segmentValue * 10;
            if (segmentValue && !segmentsRemaining) {
                firstNonzeroSegment = segment;
                segmentsRemaining = true;
            }
        }
        base10Value = mod10 + base10Value;
    }
    return base10Value;
}

/** @internal */
export function pseudoBigIntToString({ negative, base10Value }: PseudoBigInt): string {
    return (negative && base10Value !== "0" ? "-" : "") + base10Value;
}

/** @internal */
export function parseBigInt(text: string): PseudoBigInt | undefined {
    if (!isValidBigIntString(text, /*roundTripOnly*/ false)) {
        return undefined;
    }
    return parseValidBigInt(text);
}

/**
 * @internal
 * @param text a valid bigint string excluding a trailing `n`, but including a possible prefix `-`. Use `isValidBigIntString(text, roundTripOnly)` before calling this function.
 */
export function parseValidBigInt(text: string): PseudoBigInt {
    const negative = text.startsWith("-");
    const base10Value = parsePseudoBigInt(`${negative ? text.slice(1) : text}n`);
    return { negative, base10Value };
}

/**
 * @internal
 * Tests whether the provided string can be parsed as a bigint.
 * @param s The string to test.
 * @param roundTripOnly Indicates the resulting bigint matches the input when converted back to a string.
 */
export function isValidBigIntString(s: string, roundTripOnly: boolean): boolean {
    if (s === "") return false;
    const scanner = createScanner(ScriptTarget.ESNext, /*skipTrivia*/ false);
    let success = true;
    scanner.setOnError(() => success = false);
    scanner.setText(s + "n");
    let result = scanner.scan();
    const negative = result === SyntaxKind.MinusToken;
    if (negative) {
        result = scanner.scan();
    }
    const flags = scanner.getTokenFlags();
    // validate that
    // * scanning proceeded without error
    // * a bigint can be scanned, and that when it is scanned, it is
    // * the full length of the input string (so the scanner is one character beyond the augmented input length)
    // * it does not contain a numeric seperator (the `BigInt` constructor does not accept a numeric seperator in its input)
    return success && result === SyntaxKind.BigIntLiteral && scanner.getTokenEnd() === (s.length + 1) && !(flags & TokenFlags.ContainsSeparator)
        && (!roundTripOnly || s === pseudoBigIntToString({ negative, base10Value: parsePseudoBigInt(scanner.getTokenValue()) }));
}

/** @internal */
export function isValidTypeOnlyAliasUseSite(useSite: Node): boolean {
    return !!(useSite.flags & NodeFlags.Ambient)
        || isInJSDoc(useSite)
        || isPartOfTypeQuery(useSite)
        || isIdentifierInNonEmittingHeritageClause(useSite)
        || isPartOfPossiblyValidTypeOrAbstractComputedPropertyName(useSite)
        || !(isExpressionNode(useSite) || isShorthandPropertyNameUseSite(useSite));
}

function isShorthandPropertyNameUseSite(useSite: Node) {
    return isIdentifier(useSite) && isShorthandPropertyAssignment(useSite.parent) && useSite.parent.name === useSite;
}

function isPartOfPossiblyValidTypeOrAbstractComputedPropertyName(node: Node) {
    while (node.kind === SyntaxKind.Identifier || node.kind === SyntaxKind.PropertyAccessExpression) {
        node = node.parent;
    }
    if (node.kind !== SyntaxKind.ComputedPropertyName) {
        return false;
    }
    if (hasSyntacticModifier(node.parent, ModifierFlags.Abstract)) {
        return true;
    }
    const containerKind = node.parent.parent.kind;
    return containerKind === SyntaxKind.InterfaceDeclaration || containerKind === SyntaxKind.TypeLiteral;
}

/** Returns true for an identifier in 1) an `implements` clause, and 2) an `extends` clause of an interface. */
function isIdentifierInNonEmittingHeritageClause(node: Node): boolean {
    if (node.kind !== SyntaxKind.Identifier) return false;
    const heritageClause = findAncestor(node.parent, parent => {
        switch (parent.kind) {
            case SyntaxKind.HeritageClause:
                return true;
            case SyntaxKind.PropertyAccessExpression:
            case SyntaxKind.ExpressionWithTypeArguments:
                return false;
            default:
                return "quit";
        }
    }) as HeritageClause | undefined;
    return heritageClause?.token === SyntaxKind.ImplementsKeyword || heritageClause?.parent.kind === SyntaxKind.InterfaceDeclaration;
}

/** @internal */
export function isIdentifierTypeReference(node: Node): node is TypeReferenceNode & { typeName: Identifier; } {
    return isTypeReferenceNode(node) && isIdentifier(node.typeName);
}

/** @internal */
export function arrayIsHomogeneous<T>(array: readonly T[], comparer: EqualityComparer<T> = equateValues): boolean {
    if (array.length < 2) return true;
    const first = array[0];
    for (let i = 1, length = array.length; i < length; i++) {
        const target = array[i];
        if (!comparer(first, target)) return false;
    }
    return true;
}

/**
 * Bypasses immutability and directly sets the `pos` property of a `TextRange` or `Node`.
 *
 * @internal
 */
export function setTextRangePos<T extends ReadonlyTextRange>(range: T, pos: number): T {
    (range as TextRange).pos = pos;
    return range;
}

/**
 * Bypasses immutability and directly sets the `end` property of a `TextRange` or `Node`.
 *
 * @internal
 */
export function setTextRangeEnd<T extends ReadonlyTextRange>(range: T, end: number): T {
    (range as TextRange).end = end;
    return range;
}

/**
 * Bypasses immutability and directly sets the `pos` and `end` properties of a `TextRange` or `Node`.
 *
 * @internal
 */
export function setTextRangePosEnd<T extends ReadonlyTextRange>(range: T, pos: number, end: number): T {
    return setTextRangeEnd(setTextRangePos(range, pos), end);
}

/**
 * Bypasses immutability and directly sets the `pos` and `end` properties of a `TextRange` or `Node` from the
 * provided position and width.
 *
 * @internal
 */
export function setTextRangePosWidth<T extends ReadonlyTextRange>(range: T, pos: number, width: number): T {
    return setTextRangePosEnd(range, pos, pos + width);
}

/**
 * Bypasses immutability and directly sets the `flags` property of a `Node`.
 *
 * @internal
 */
export function setNodeFlags<T extends Node>(node: T, newFlags: NodeFlags): T;
/** @internal */
export function setNodeFlags<T extends Node>(node: T | undefined, newFlags: NodeFlags): T | undefined;
/** @internal */
export function setNodeFlags<T extends Node>(node: T | undefined, newFlags: NodeFlags): T | undefined {
    if (node) {
        (node as Mutable<T>).flags = newFlags;
    }
    return node;
}

/**
 * Bypasses immutability and directly sets the `parent` property of a `Node`.
 *
 * @internal
 */
export function setParent<T extends Node>(child: T, parent: T["parent"] | undefined): T;
/** @internal */
export function setParent<T extends Node>(child: T | undefined, parent: T["parent"] | undefined): T | undefined;
/** @internal */
export function setParent<T extends Node>(child: T | undefined, parent: T["parent"] | undefined): T | undefined {
    if (child && parent) {
        (child as Mutable<T>).parent = parent;
    }
    return child;
}

/**
 * Bypasses immutability and directly sets the `parent` property of each `Node` recursively.
 * @param rootNode The root node from which to start the recursion.
 * @param incremental When `true`, only recursively descends through nodes whose `parent` pointers are incorrect.
 * This allows us to quickly bail out of setting `parent` for subtrees during incremental parsing.
 *
 * @internal
 */
export function setParentRecursive<T extends Node>(rootNode: T, incremental: boolean): T;
/** @internal */
export function setParentRecursive<T extends Node>(rootNode: T | undefined, incremental: boolean): T | undefined;
/** @internal */
export function setParentRecursive<T extends Node>(rootNode: T | undefined, incremental: boolean): T | undefined {
    if (!rootNode) return rootNode;
    forEachChildRecursively(rootNode, isJSDocNode(rootNode) ? bindParentToChildIgnoringJSDoc : bindParentToChild);
    return rootNode;

    function bindParentToChildIgnoringJSDoc(child: Node, parent: Node): void | "skip" {
        if (incremental && child.parent === parent) {
            return "skip";
        }
        setParent(child, parent);
    }

    function bindJSDoc(child: Node) {
        if (hasJSDocNodes(child)) {
            for (const doc of child.jsDoc!) {
                bindParentToChildIgnoringJSDoc(doc, child);
                forEachChildRecursively(doc, bindParentToChildIgnoringJSDoc);
            }
        }
    }

    function bindParentToChild(child: Node, parent: Node) {
        return bindParentToChildIgnoringJSDoc(child, parent) || bindJSDoc(child);
    }
}

function isPackedElement(node: Expression) {
    return !isOmittedExpression(node);
}

/**
 * Determines whether the provided node is an ArrayLiteralExpression that contains no missing elements.
 *
 * @internal
 */
export function isPackedArrayLiteral(node: Expression): boolean {
    return isArrayLiteralExpression(node) && every(node.elements, isPackedElement);
}

/**
 * Indicates whether the result of an `Expression` will be unused.
 *
 * NOTE: This requires a node with a valid `parent` pointer.
 *
 * @internal
 */
export function expressionResultIsUnused(node: Expression): boolean {
    Debug.assertIsDefined(node.parent);
    while (true) {
        const parent: Node = node.parent;
        // walk up parenthesized expressions, but keep a pointer to the top-most parenthesized expression
        if (isParenthesizedExpression(parent)) {
            node = parent;
            continue;
        }
        // result is unused in an expression statement, `void` expression, or the initializer or incrementer of a `for` loop
        if (
            isExpressionStatement(parent) ||
            isVoidExpression(parent) ||
            isForStatement(parent) && (parent.initializer === node || parent.incrementor === node)
        ) {
            return true;
        }
        if (isCommaListExpression(parent)) {
            // left side of comma is always unused
            if (node !== last(parent.elements)) return true;
            // right side of comma is unused if parent is unused
            node = parent;
            continue;
        }
        if (isBinaryExpression(parent) && parent.operatorToken.kind === SyntaxKind.CommaToken) {
            // left side of comma is always unused
            if (node === parent.left) return true;
            // right side of comma is unused if parent is unused
            node = parent;
            continue;
        }
        return false;
    }
}

/** @internal */
export function containsIgnoredPath(path: string): boolean {
    return some(ignoredPaths, p => path.includes(p));
}

/** @internal */
export function getContainingNodeArray(node: Node): NodeArray<Node> | undefined {
    if (!node.parent) return undefined;
    switch (node.kind) {
        case SyntaxKind.TypeParameter:
            const { parent } = node as TypeParameterDeclaration;
            return parent.kind === SyntaxKind.InferType ? undefined : parent.typeParameters;
        case SyntaxKind.Parameter:
            return (node as ParameterDeclaration).parent.parameters;
        case SyntaxKind.TemplateLiteralTypeSpan:
            return (node as TemplateLiteralTypeSpan).parent.templateSpans;
        case SyntaxKind.TemplateSpan:
            return (node as TemplateSpan).parent.templateSpans;
        case SyntaxKind.Decorator: {
            const { parent } = node as Decorator;
            return canHaveDecorators(parent) ? parent.modifiers :
                undefined;
        }
        case SyntaxKind.HeritageClause:
            return (node as HeritageClause).parent.heritageClauses;
    }

    const { parent } = node;
    if (isJSDocTag(node)) {
        return isJSDocTypeLiteral(node.parent) ? undefined : node.parent.tags;
    }

    switch (parent.kind) {
        case SyntaxKind.TypeLiteral:
        case SyntaxKind.InterfaceDeclaration:
            return isTypeElement(node) ? (parent as TypeLiteralNode | InterfaceDeclaration).members : undefined;
        case SyntaxKind.UnionType:
        case SyntaxKind.IntersectionType:
            return (parent as UnionOrIntersectionTypeNode).types;
        case SyntaxKind.TupleType:
        case SyntaxKind.ArrayLiteralExpression:
        case SyntaxKind.CommaListExpression:
        case SyntaxKind.NamedImports:
        case SyntaxKind.NamedExports:
            return (parent as TupleTypeNode | ArrayLiteralExpression | CommaListExpression | NamedImports | NamedExports).elements;
        case SyntaxKind.ObjectLiteralExpression:
        case SyntaxKind.JsxAttributes:
            return (parent as ObjectLiteralExpressionBase<ObjectLiteralElement>).properties;
        case SyntaxKind.CallExpression:
        case SyntaxKind.NewExpression:
            return isTypeNode(node) ? (parent as CallExpression | NewExpression).typeArguments :
                (parent as CallExpression | NewExpression).expression === node ? undefined :
                (parent as CallExpression | NewExpression).arguments;
        case SyntaxKind.JsxElement:
        case SyntaxKind.JsxFragment:
            return isJsxChild(node) ? (parent as JsxElement | JsxFragment).children : undefined;
        case SyntaxKind.JsxOpeningElement:
        case SyntaxKind.JsxSelfClosingElement:
            return isTypeNode(node) ? (parent as JsxOpeningElement | JsxSelfClosingElement).typeArguments : undefined;
        case SyntaxKind.Block:
        case SyntaxKind.CaseClause:
        case SyntaxKind.DefaultClause:
        case SyntaxKind.ModuleBlock:
            return (parent as Block | CaseOrDefaultClause | ModuleBlock).statements;
        case SyntaxKind.CaseBlock:
            return (parent as CaseBlock).clauses;
        case SyntaxKind.ClassDeclaration:
        case SyntaxKind.ClassExpression:
            return isClassElement(node) ? (parent as ClassLikeDeclaration).members : undefined;
        case SyntaxKind.EnumDeclaration:
            return isEnumMember(node) ? (parent as EnumDeclaration).members : undefined;
        case SyntaxKind.SourceFile:
            return (parent as SourceFile).statements;
    }
}

/** @internal */
export function hasContextSensitiveParameters(node: FunctionLikeDeclaration): boolean {
    // Functions with type parameters are not context sensitive.
    if (!node.typeParameters) {
        // Functions with any parameters that lack type annotations are context sensitive.
        if (some(node.parameters, p => !getEffectiveTypeAnnotationNode(p))) {
            return true;
        }
        if (node.kind !== SyntaxKind.ArrowFunction) {
            // If the first parameter is not an explicit 'this' parameter, then the function has
            // an implicit 'this' parameter which is subject to contextual typing.
            const parameter = firstOrUndefined(node.parameters);
            if (!(parameter && parameterIsThisKeyword(parameter))) {
                return !!(node.flags & NodeFlags.ContainsThis);
            }
        }
    }
    return false;
}

/** @internal */
export function isInfinityOrNaNString(name: string | __String): boolean {
    return name === "Infinity" || name === "-Infinity" || name === "NaN";
}

/** @internal */
export function isCatchClauseVariableDeclaration(node: Node): boolean {
    return node.kind === SyntaxKind.VariableDeclaration && node.parent.kind === SyntaxKind.CatchClause;
}

/** @internal */
export function isFunctionExpressionOrArrowFunction(node: Node): node is FunctionExpression | ArrowFunction {
    return node.kind === SyntaxKind.FunctionExpression || node.kind === SyntaxKind.ArrowFunction;
}

/** @internal */
export function escapeSnippetText(text: string): string {
    return text.replace(/\$/g, () => "\\$");
}

/** @internal */
export function isNumericLiteralName(name: string | __String): boolean {
    // The intent of numeric names is that
    //     - they are names with text in a numeric form, and that
    //     - setting properties/indexing with them is always equivalent to doing so with the numeric literal 'numLit',
    //         acquired by applying the abstract 'ToNumber' operation on the name's text.
    //
    // The subtlety is in the latter portion, as we cannot reliably say that anything that looks like a numeric literal is a numeric name.
    // In fact, it is the case that the text of the name must be equal to 'ToString(numLit)' for this to hold.
    //
    // Consider the property name '"0xF00D"'. When one indexes with '0xF00D', they are actually indexing with the value of 'ToString(0xF00D)'
    // according to the ECMAScript specification, so it is actually as if the user indexed with the string '"61453"'.
    // Thus, the text of all numeric literals equivalent to '61543' such as '0xF00D', '0xf00D', '0170015', etc. are not valid numeric names
    // because their 'ToString' representation is not equal to their original text.
    // This is motivated by ECMA-262 sections 9.3.1, 9.8.1, 11.1.5, and 11.2.1.
    //
    // Here, we test whether 'ToString(ToNumber(name))' is exactly equal to 'name'.
    // The '+' prefix operator is equivalent here to applying the abstract ToNumber operation.
    // Applying the 'toString()' method on a number gives us the abstract ToString operation on a number.
    //
    // Note that this accepts the values 'Infinity', '-Infinity', and 'NaN', and that this is intentional.
    // This is desired behavior, because when indexing with them as numeric entities, you are indexing
    // with the strings '"Infinity"', '"-Infinity"', and '"NaN"' respectively.
    return (+name).toString() === name;
}

/** @internal */
export function createPropertyNameNodeForIdentifierOrLiteral(name: string, target: ScriptTarget, singleQuote: boolean, stringNamed: boolean, isMethod: boolean): Identifier | StringLiteral | NumericLiteral {
    const isMethodNamedNew = isMethod && name === "new";
    return !isMethodNamedNew && isIdentifierText(name, target) ? factory.createIdentifier(name) :
        !stringNamed && !isMethodNamedNew && isNumericLiteralName(name) && +name >= 0 ? factory.createNumericLiteral(+name) :
        factory.createStringLiteral(name, !!singleQuote);
}

/** @internal */
export function isThisTypeParameter(type: Type): boolean {
    return !!(type.flags & TypeFlags.TypeParameter && (type as TypeParameter).isThisType);
}

/** @internal */
export interface NodeModulePathParts {
    readonly topLevelNodeModulesIndex: number;
    readonly topLevelPackageNameIndex: number;
    readonly packageRootIndex: number;
    readonly fileNameIndex: number;
}
/** @internal */
export function getNodeModulePathParts(fullPath: string): NodeModulePathParts | undefined {
    // If fullPath can't be valid module file within node_modules, returns undefined.
    // Example of expected pattern: /base/path/node_modules/[@scope/otherpackage/@otherscope/node_modules/]package/[subdirectory/]file.js
    // Returns indices:                       ^            ^                                                      ^             ^

    let topLevelNodeModulesIndex = 0;
    let topLevelPackageNameIndex = 0;
    let packageRootIndex = 0;
    let fileNameIndex = 0;

    const enum States {
        BeforeNodeModules,
        NodeModules,
        Scope,
        PackageContent,
    }

    let partStart = 0;
    let partEnd = 0;
    let state = States.BeforeNodeModules;

    while (partEnd >= 0) {
        partStart = partEnd;
        partEnd = fullPath.indexOf("/", partStart + 1);
        switch (state) {
            case States.BeforeNodeModules:
                if (fullPath.indexOf(nodeModulesPathPart, partStart) === partStart) {
                    topLevelNodeModulesIndex = partStart;
                    topLevelPackageNameIndex = partEnd;
                    state = States.NodeModules;
                }
                break;
            case States.NodeModules:
            case States.Scope:
                if (state === States.NodeModules && fullPath.charAt(partStart + 1) === "@") {
                    state = States.Scope;
                }
                else {
                    packageRootIndex = partEnd;
                    state = States.PackageContent;
                }
                break;
            case States.PackageContent:
                if (fullPath.indexOf(nodeModulesPathPart, partStart) === partStart) {
                    state = States.NodeModules;
                }
                else {
                    state = States.PackageContent;
                }
                break;
        }
    }

    fileNameIndex = partStart;

    return state > States.NodeModules ? { topLevelNodeModulesIndex, topLevelPackageNameIndex, packageRootIndex, fileNameIndex } : undefined;
}

/** @internal */
export function isTypeDeclaration(node: Node): node is TypeParameterDeclaration | ClassDeclaration | InterfaceDeclaration | TypeAliasDeclaration | JSDocTypedefTag | JSDocCallbackTag | JSDocEnumTag | EnumDeclaration | ImportClause | ImportSpecifier | ExportSpecifier {
    switch (node.kind) {
        case SyntaxKind.TypeParameter:
        case SyntaxKind.ClassDeclaration:
        case SyntaxKind.InterfaceDeclaration:
        case SyntaxKind.TypeAliasDeclaration:
        case SyntaxKind.EnumDeclaration:
        case SyntaxKind.JSDocTypedefTag:
        case SyntaxKind.JSDocCallbackTag:
        case SyntaxKind.JSDocEnumTag:
            return true;
        case SyntaxKind.ImportClause:
            return (node as ImportClause).phaseModifier === SyntaxKind.TypeKeyword;
        case SyntaxKind.ImportSpecifier:
            return (node as ImportSpecifier).parent.parent.phaseModifier === SyntaxKind.TypeKeyword;
        case SyntaxKind.ExportSpecifier:
            return (node as ExportSpecifier).parent.parent.isTypeOnly;
        default:
            return false;
    }
}

/** @internal */
export function canHaveExportModifier(node: Node): node is Extract<HasModifiers, Statement> {
    return isEnumDeclaration(node) || isVariableStatement(node) || isFunctionDeclaration(node) || isClassDeclaration(node)
        || isInterfaceDeclaration(node) || isTypeDeclaration(node) || (isModuleDeclaration(node) && !isExternalModuleAugmentation(node) && !isGlobalScopeAugmentation(node));
}

/** @internal */
export function isOptionalJSDocPropertyLikeTag(node: Node): boolean {
    if (!isJSDocPropertyLikeTag(node)) {
        return false;
    }
    const { isBracketed, typeExpression } = node;
    return isBracketed || !!typeExpression && typeExpression.type.kind === SyntaxKind.JSDocOptionalType;
}

/** @internal */
export function canUsePropertyAccess(name: string, languageVersion: ScriptTarget): boolean {
    if (name.length === 0) {
        return false;
    }
    const firstChar = name.charCodeAt(0);
    return firstChar === CharacterCodes.hash ?
        name.length > 1 && isIdentifierStart(name.charCodeAt(1), languageVersion) :
        isIdentifierStart(firstChar, languageVersion);
}

/** @internal */
export function hasTabstop(node: Node): boolean {
    return getSnippetElement(node)?.kind === SnippetKind.TabStop;
}

/** @internal */
export function isJSDocOptionalParameter(node: ParameterDeclaration): boolean {
    return isInJSFile(node) && (
        // node.type should only be a JSDocOptionalType when node is a parameter of a JSDocFunctionType
        node.type && node.type.kind === SyntaxKind.JSDocOptionalType
        || getJSDocParameterTags(node).some(isOptionalJSDocPropertyLikeTag)
    );
}

/** @internal */
export function isOptionalDeclaration(declaration: Declaration): boolean {
    switch (declaration.kind) {
        case SyntaxKind.PropertyDeclaration:
        case SyntaxKind.PropertySignature:
            return !!(declaration as PropertyDeclaration | PropertySignature).questionToken;
        case SyntaxKind.Parameter:
            return !!(declaration as ParameterDeclaration).questionToken || isJSDocOptionalParameter(declaration as ParameterDeclaration);
        case SyntaxKind.JSDocPropertyTag:
        case SyntaxKind.JSDocParameterTag:
            return isOptionalJSDocPropertyLikeTag(declaration);
        default:
            return false;
    }
}

/** @internal */
export function isNonNullAccess(node: Node): node is AccessExpression {
    const kind = node.kind;
    return (kind === SyntaxKind.PropertyAccessExpression
        || kind === SyntaxKind.ElementAccessExpression) && isNonNullExpression((node as AccessExpression).expression);
}

/** @internal */
export function isJSDocSatisfiesExpression(node: Node): node is JSDocSatisfiesExpression {
    return isInJSFile(node) && isParenthesizedExpression(node) && hasJSDocNodes(node) && !!getJSDocSatisfiesTag(node);
}

/** @internal */
export function getJSDocSatisfiesExpressionType(node: JSDocSatisfiesExpression): TypeNode {
    return Debug.checkDefined(tryGetJSDocSatisfiesTypeNode(node));
}

/** @internal */
export function tryGetJSDocSatisfiesTypeNode(node: Node): TypeNode | undefined {
    const tag = getJSDocSatisfiesTag(node);
    return tag && tag.typeExpression && tag.typeExpression.type;
}

/** @internal */
export function getEscapedTextOfJsxAttributeName(node: JsxAttributeName): __String {
    return isIdentifier(node) ? node.escapedText : getEscapedTextOfJsxNamespacedName(node);
}

/** @internal */
export function getTextOfJsxAttributeName(node: JsxAttributeName): string {
    return isIdentifier(node) ? idText(node) : getTextOfJsxNamespacedName(node);
}

/** @internal */
export function isJsxAttributeName(node: Node): node is JsxAttributeName {
    const kind = node.kind;
    return kind === SyntaxKind.Identifier
        || kind === SyntaxKind.JsxNamespacedName;
}

/** @internal */
export function getEscapedTextOfJsxNamespacedName(node: JsxNamespacedName): __String {
    return `${node.namespace.escapedText}:${idText(node.name)}` as __String;
}

/** @internal */
export function getTextOfJsxNamespacedName(node: JsxNamespacedName) {
    return `${idText(node.namespace)}:${idText(node.name)}`;
}

/** @internal */
export function intrinsicTagNameToString(node: Identifier | JsxNamespacedName): string {
    return isIdentifier(node) ? idText(node) : getTextOfJsxNamespacedName(node);
}

/**
 * Indicates whether a type can be used as a property name.
 * @internal
 */
export function isTypeUsableAsPropertyName(type: Type): type is StringLiteralType | NumberLiteralType | UniqueESSymbolType {
    return !!(type.flags & TypeFlags.StringOrNumberLiteralOrUnique);
}

/**
 * Gets the symbolic name for a member from its type.
 * @internal
 */
export function getPropertyNameFromType(type: StringLiteralType | NumberLiteralType | UniqueESSymbolType): __String {
    if (type.flags & TypeFlags.UniqueESSymbol) {
        return (type as UniqueESSymbolType).escapedName;
    }
    if (type.flags & (TypeFlags.StringLiteral | TypeFlags.NumberLiteral)) {
        return escapeLeadingUnderscores("" + (type as StringLiteralType | NumberLiteralType).value);
    }
    return Debug.fail();
}

/** @internal */
export function isExpandoPropertyDeclaration(declaration: Declaration | undefined): declaration is PropertyAccessExpression | ElementAccessExpression | BinaryExpression {
    return !!declaration && (isPropertyAccessExpression(declaration) || isElementAccessExpression(declaration) || isBinaryExpression(declaration));
}

/** @internal */
export function hasResolutionModeOverride(node: ImportTypeNode | ImportDeclaration | ExportDeclaration | JSDocImportTag | undefined): boolean {
    if (node === undefined) {
        return false;
    }
    return !!getResolutionModeOverride(node.attributes);
}

const stringReplace = String.prototype.replace;

/** @internal */
export function replaceFirstStar(s: string, replacement: string): string {
    // `s.replace("*", replacement)` triggers CodeQL as they think it's a potentially incorrect string escaping.
    // See: https://codeql.github.com/codeql-query-help/javascript/js-incomplete-sanitization/
    // But, we really do want to replace only the first star.
    // Attempt to defeat this analysis by indirectly calling the method.
    return stringReplace.call(s, "*", replacement);
}

/** @internal */
export function getNameFromImportAttribute(node: ImportAttribute): __String {
    return isIdentifier(node.name) ? node.name.escapedText : escapeLeadingUnderscores(node.name.text);
}

/** @internal */
export function isSourceElement(node: Node): boolean {
    switch (node.kind) {
        case SyntaxKind.TypeParameter:
        case SyntaxKind.Parameter:
        case SyntaxKind.PropertyDeclaration:
        case SyntaxKind.PropertySignature:
        case SyntaxKind.ConstructorType:
        case SyntaxKind.FunctionType:
        case SyntaxKind.CallSignature:
        case SyntaxKind.ConstructSignature:
        case SyntaxKind.IndexSignature:
        case SyntaxKind.MethodDeclaration:
        case SyntaxKind.MethodSignature:
        case SyntaxKind.ClassStaticBlockDeclaration:
        case SyntaxKind.Constructor:
        case SyntaxKind.GetAccessor:
        case SyntaxKind.SetAccessor:
        case SyntaxKind.TypeReference:
        case SyntaxKind.TypePredicate:
        case SyntaxKind.TypeQuery:
        case SyntaxKind.TypeLiteral:
        case SyntaxKind.ArrayType:
        case SyntaxKind.TupleType:
        case SyntaxKind.UnionType:
        case SyntaxKind.IntersectionType:
        case SyntaxKind.ParenthesizedType:
        case SyntaxKind.OptionalType:
        case SyntaxKind.RestType:
        case SyntaxKind.ThisType:
        case SyntaxKind.TypeOperator:
        case SyntaxKind.ConditionalType:
        case SyntaxKind.InferType:
        case SyntaxKind.TemplateLiteralType:
        case SyntaxKind.ImportType:
        case SyntaxKind.NamedTupleMember:
        case SyntaxKind.JSDocAugmentsTag:
        case SyntaxKind.JSDocImplementsTag:
        case SyntaxKind.JSDocTypedefTag:
        case SyntaxKind.JSDocCallbackTag:
        case SyntaxKind.JSDocEnumTag:
        case SyntaxKind.JSDocTemplateTag:
        case SyntaxKind.JSDocTypeTag:
        case SyntaxKind.JSDocLink:
        case SyntaxKind.JSDocLinkCode:
        case SyntaxKind.JSDocLinkPlain:
        case SyntaxKind.JSDocParameterTag:
        case SyntaxKind.JSDocPropertyTag:
        case SyntaxKind.JSDocFunctionType:
        case SyntaxKind.JSDocNonNullableType:
        case SyntaxKind.JSDocNullableType:
        case SyntaxKind.JSDocAllType:
        case SyntaxKind.JSDocUnknownType:
        case SyntaxKind.JSDocTypeLiteral:
        case SyntaxKind.JSDocVariadicType:
        case SyntaxKind.JSDocTypeExpression:
        case SyntaxKind.JSDocPublicTag:
        case SyntaxKind.JSDocProtectedTag:
        case SyntaxKind.JSDocPrivateTag:
        case SyntaxKind.JSDocSatisfiesTag:
        case SyntaxKind.JSDocThisTag:
        case SyntaxKind.IndexedAccessType:
        case SyntaxKind.MappedType:
        case SyntaxKind.FunctionDeclaration:
        case SyntaxKind.Block:
        case SyntaxKind.ModuleBlock:
        case SyntaxKind.VariableStatement:
        case SyntaxKind.ExpressionStatement:
        case SyntaxKind.IfStatement:
        case SyntaxKind.DoStatement:
        case SyntaxKind.WhileStatement:
        case SyntaxKind.ForStatement:
        case SyntaxKind.ForInStatement:
        case SyntaxKind.ForOfStatement:
        case SyntaxKind.ContinueStatement:
        case SyntaxKind.BreakStatement:
        case SyntaxKind.ReturnStatement:
        case SyntaxKind.WithStatement:
        case SyntaxKind.SwitchStatement:
        case SyntaxKind.LabeledStatement:
        case SyntaxKind.ThrowStatement:
        case SyntaxKind.TryStatement:
        case SyntaxKind.VariableDeclaration:
        case SyntaxKind.BindingElement:
        case SyntaxKind.ClassDeclaration:
        case SyntaxKind.InterfaceDeclaration:
        case SyntaxKind.TypeAliasDeclaration:
        case SyntaxKind.EnumDeclaration:
        case SyntaxKind.ModuleDeclaration:
        case SyntaxKind.ImportDeclaration:
        case SyntaxKind.ImportEqualsDeclaration:
        case SyntaxKind.ExportDeclaration:
        case SyntaxKind.ExportAssignment:
        case SyntaxKind.EmptyStatement:
        case SyntaxKind.DebuggerStatement:
        case SyntaxKind.MissingDeclaration:
            return true;
    }
    return false;
}

/** @internal */
export function evaluatorResult<T extends string | number | undefined>(value: T, isSyntacticallyString = false, resolvedOtherFiles = false, hasExternalReferences = false): EvaluatorResult<T> {
    return { value, isSyntacticallyString, resolvedOtherFiles, hasExternalReferences };
}

/** @internal */
export function createEvaluator({ evaluateElementAccessExpression, evaluateEntityNameExpression }: EvaluationResolver): {
    (expr: TemplateExpression, location?: Declaration): EvaluatorResult<string | undefined>;
    (expr: Expression, location?: Declaration): EvaluatorResult;
} {
    function evaluate(expr: TemplateExpression, location?: Declaration): EvaluatorResult<string | undefined>;
    function evaluate(expr: Expression, location?: Declaration): EvaluatorResult;
    function evaluate(expr: Expression, location?: Declaration): EvaluatorResult {
        let isSyntacticallyString = false;
        let resolvedOtherFiles = false;
        let hasExternalReferences = false;
        // It's unclear when/whether we should consider skipping other kinds of outer expressions.
        // Type assertions intentionally break evaluation when evaluating literal types, such as:
        //     type T = `one ${"two" as any} three`; // string
        // But it's less clear whether such an assertion should break enum member evaluation:
        //     enum E {
        //       A = "one" as any
        //     }
        // SatisfiesExpressions and non-null assertions seem to have even less reason to break
        // emitting enum members as literals. However, these expressions also break Babel's
        // evaluation (but not esbuild's), and the isolatedModules errors we give depend on
        // our evaluation results, so we're currently being conservative so as to issue errors
        // on code that might break Babel.
        expr = skipParentheses(expr);
        switch (expr.kind) {
            case SyntaxKind.PrefixUnaryExpression:
                const result = evaluate((expr as PrefixUnaryExpression).operand, location);
                resolvedOtherFiles = result.resolvedOtherFiles;
                hasExternalReferences = result.hasExternalReferences;
                if (typeof result.value === "number") {
                    switch ((expr as PrefixUnaryExpression).operator) {
                        case SyntaxKind.PlusToken:
                            return evaluatorResult(result.value, isSyntacticallyString, resolvedOtherFiles, hasExternalReferences);
                        case SyntaxKind.MinusToken:
                            return evaluatorResult(-result.value, isSyntacticallyString, resolvedOtherFiles, hasExternalReferences);
                        case SyntaxKind.TildeToken:
                            return evaluatorResult(~result.value, isSyntacticallyString, resolvedOtherFiles, hasExternalReferences);
                    }
                }
                break;
            case SyntaxKind.BinaryExpression: {
                const left = evaluate((expr as BinaryExpression).left, location);
                const right = evaluate((expr as BinaryExpression).right, location);
                isSyntacticallyString = (left.isSyntacticallyString || right.isSyntacticallyString) && (expr as BinaryExpression).operatorToken.kind === SyntaxKind.PlusToken;
                resolvedOtherFiles = left.resolvedOtherFiles || right.resolvedOtherFiles;
                hasExternalReferences = left.hasExternalReferences || right.hasExternalReferences;
                if (typeof left.value === "number" && typeof right.value === "number") {
                    switch ((expr as BinaryExpression).operatorToken.kind) {
                        case SyntaxKind.BarToken:
                            return evaluatorResult(left.value | right.value, isSyntacticallyString, resolvedOtherFiles, hasExternalReferences);
                        case SyntaxKind.AmpersandToken:
                            return evaluatorResult(left.value & right.value, isSyntacticallyString, resolvedOtherFiles, hasExternalReferences);
                        case SyntaxKind.GreaterThanGreaterThanToken:
                            return evaluatorResult(left.value >> right.value, isSyntacticallyString, resolvedOtherFiles, hasExternalReferences);
                        case SyntaxKind.GreaterThanGreaterThanGreaterThanToken:
                            return evaluatorResult(left.value >>> right.value, isSyntacticallyString, resolvedOtherFiles, hasExternalReferences);
                        case SyntaxKind.LessThanLessThanToken:
                            return evaluatorResult(left.value << right.value, isSyntacticallyString, resolvedOtherFiles, hasExternalReferences);
                        case SyntaxKind.CaretToken:
                            return evaluatorResult(left.value ^ right.value, isSyntacticallyString, resolvedOtherFiles, hasExternalReferences);
                        case SyntaxKind.AsteriskToken:
                            return evaluatorResult(left.value * right.value, isSyntacticallyString, resolvedOtherFiles, hasExternalReferences);
                        case SyntaxKind.SlashToken:
                            return evaluatorResult(left.value / right.value, isSyntacticallyString, resolvedOtherFiles, hasExternalReferences);
                        case SyntaxKind.PlusToken:
                            return evaluatorResult(left.value + right.value, isSyntacticallyString, resolvedOtherFiles, hasExternalReferences);
                        case SyntaxKind.MinusToken:
                            return evaluatorResult(left.value - right.value, isSyntacticallyString, resolvedOtherFiles, hasExternalReferences);
                        case SyntaxKind.PercentToken:
                            return evaluatorResult(left.value % right.value, isSyntacticallyString, resolvedOtherFiles, hasExternalReferences);
                        case SyntaxKind.AsteriskAsteriskToken:
                            return evaluatorResult(left.value ** right.value, isSyntacticallyString, resolvedOtherFiles, hasExternalReferences);
                    }
                }
                else if (
                    (typeof left.value === "string" || typeof left.value === "number") &&
                    (typeof right.value === "string" || typeof right.value === "number") &&
                    (expr as BinaryExpression).operatorToken.kind === SyntaxKind.PlusToken
                ) {
                    return evaluatorResult(
                        "" + left.value + right.value,
                        isSyntacticallyString,
                        resolvedOtherFiles,
                        hasExternalReferences,
                    );
                }

                break;
            }
            case SyntaxKind.StringLiteral:
            case SyntaxKind.NoSubstitutionTemplateLiteral:
                return evaluatorResult((expr as StringLiteralLike).text, /*isSyntacticallyString*/ true);
            case SyntaxKind.TemplateExpression:
                return evaluateTemplateExpression(expr as TemplateExpression, location);
            case SyntaxKind.NumericLiteral:
                return evaluatorResult(+(expr as NumericLiteral).text);
            case SyntaxKind.Identifier:
                return evaluateEntityNameExpression(expr as Identifier, location);
            case SyntaxKind.PropertyAccessExpression:
                if (isEntityNameExpression(expr)) {
                    return evaluateEntityNameExpression(expr, location);
                }
                break;
            case SyntaxKind.ElementAccessExpression:
                return evaluateElementAccessExpression(expr as ElementAccessExpression, location);
        }
        return evaluatorResult(/*value*/ undefined, isSyntacticallyString, resolvedOtherFiles, hasExternalReferences);
    }

    function evaluateTemplateExpression(expr: TemplateExpression, location?: Declaration): EvaluatorResult<string | undefined> {
        let result = expr.head.text;
        let resolvedOtherFiles = false;
        let hasExternalReferences = false;
        for (const span of expr.templateSpans) {
            const spanResult = evaluate(span.expression, location);
            if (spanResult.value === undefined) {
                return evaluatorResult(/*value*/ undefined, /*isSyntacticallyString*/ true);
            }
            result += spanResult.value;
            result += span.literal.text;
            resolvedOtherFiles ||= spanResult.resolvedOtherFiles;
            hasExternalReferences ||= spanResult.hasExternalReferences;
        }
        return evaluatorResult(
            result,
            /*isSyntacticallyString*/ true,
            resolvedOtherFiles,
            hasExternalReferences,
        );
    }
    return evaluate;
}

/** @internal */
export function isConstAssertion(location: Node): boolean {
    return (isAssertionExpression(location) && isConstTypeReference(location.type))
        || (isJSDocTypeTag(location) && isConstTypeReference(location.typeExpression));
}

/** @internal */
export function findConstructorDeclaration(node: ClassLikeDeclaration): ConstructorDeclaration | undefined {
    const members = node.members;
    for (const member of members) {
        if (member.kind === SyntaxKind.Constructor && nodeIsPresent((member as ConstructorDeclaration).body)) {
            return member as ConstructorDeclaration;
        }
    }
}

/** @internal */
export interface NameResolverOptions {
    compilerOptions: CompilerOptions;
    getSymbolOfDeclaration: (node: Declaration) => Symbol;
    error: (location: Node | undefined, message: DiagnosticMessage, ...args: DiagnosticArguments) => void;
    globals: SymbolTable;
    argumentsSymbol: Symbol;
    requireSymbol: Symbol;
    lookup: (symbols: SymbolTable, name: __String, meaning: SymbolFlags) => Symbol | undefined;
    setRequiresScopeChangeCache: undefined | ((node: FunctionLikeDeclaration, value: boolean) => void);
    getRequiresScopeChangeCache: undefined | ((node: FunctionLikeDeclaration) => boolean | undefined);
    onPropertyWithInvalidInitializer?: (location: Node | undefined, name: __String, declaration: PropertyDeclaration, result: Symbol | undefined) => boolean;
    onFailedToResolveSymbol?: (location: Node | undefined, name: __String | Identifier, meaning: SymbolFlags, nameNotFoundMessage: DiagnosticMessage) => void;
    onSuccessfullyResolvedSymbol?: (location: Node | undefined, result: Symbol, meaning: SymbolFlags, lastLocation: Node | undefined, associatedDeclarationForContainingInitializerOrBindingName: ParameterDeclaration | BindingElement | undefined, withinDeferredContext: boolean) => void;
}

/** @internal */
export type NameResolver = (
    location: Node | undefined,
    nameArg: __String | Identifier,
    meaning: SymbolFlags,
    nameNotFoundMessage: DiagnosticMessage | undefined,
    isUse: boolean,
    excludeGlobals?: boolean,
) => Symbol | undefined;

/** @internal */
export function createNameResolver({
    compilerOptions,
    requireSymbol,
    argumentsSymbol,
    error,
    getSymbolOfDeclaration,
    globals,
    lookup,
    setRequiresScopeChangeCache = returnUndefined,
    getRequiresScopeChangeCache = returnUndefined,
    onPropertyWithInvalidInitializer = returnFalse,
    onFailedToResolveSymbol = returnUndefined,
    onSuccessfullyResolvedSymbol = returnUndefined,
}: NameResolverOptions): NameResolver {
    /* eslint-disable no-var */
    var isolatedModulesLikeFlagName = compilerOptions.verbatimModuleSyntax ? "verbatimModuleSyntax" : "isolatedModules";
    /* eslint-disable no-var */
    var emitStandardClassFields = getEmitStandardClassFields(compilerOptions);
    var emptySymbols = createSymbolTable();
    return resolveNameHelper;
    function resolveNameHelper(
        location: Node | undefined,
        nameArg: __String | Identifier,
        meaning: SymbolFlags,
        nameNotFoundMessage: DiagnosticMessage | undefined,
        isUse: boolean,
        excludeGlobals?: boolean,
    ): Symbol | undefined {
        const originalLocation = location; // needed for did-you-mean error reporting, which gathers candidates starting from the original location
        let result: Symbol | undefined;
        let lastLocation: Node | undefined;
        let lastSelfReferenceLocation: Declaration | undefined;
        let propertyWithInvalidInitializer: PropertyDeclaration | undefined;
        let associatedDeclarationForContainingInitializerOrBindingName: ParameterDeclaration | BindingElement | undefined;
        let withinDeferredContext = false;
        let grandparent: Node;
        const name = isString(nameArg) ? nameArg : (nameArg as Identifier).escapedText;
        loop:
        while (location) {
            if (name === "const" && isConstAssertion(location)) {
                // `const` in an `as const` has no symbol, but issues no error because there is no *actual* lookup of the type
                // (it refers to the constant type of the expression instead)
                return undefined;
            }
            if (isModuleOrEnumDeclaration(location) && lastLocation && location.name === lastLocation) {
                // If lastLocation is the name of a namespace or enum, skip the parent since it will have is own locals that could
                // conflict.
                lastLocation = location;
                location = location.parent;
            }
            // Locals of a source file are not in scope (because they get merged into the global symbol table)
            if (canHaveLocals(location) && location.locals && !isGlobalSourceFile(location)) {
                if (result = lookup(location.locals, name, meaning)) {
                    let useResult = true;
                    if (isFunctionLike(location) && lastLocation && lastLocation !== (location as FunctionLikeDeclaration).body) {
                        // symbol lookup restrictions for function-like declarations
                        // - Type parameters of a function are in scope in the entire function declaration, including the parameter
                        //   list and return type. However, local types are only in scope in the function body.
                        // - parameters are only in the scope of function body
                        // This restriction does not apply to JSDoc comment types because they are parented
                        // at a higher level than type parameters would normally be
                        if (meaning & result.flags & SymbolFlags.Type && lastLocation.kind !== SyntaxKind.JSDoc) {
                            useResult = result.flags & SymbolFlags.TypeParameter
                                // type parameters are visible in parameter list, return type and type parameter list
                                ? !!(lastLocation.flags & NodeFlags.Synthesized) || // Synthetic fake scopes are added for signatures so type parameters are accessible from them
                                    lastLocation === (location as FunctionLikeDeclaration).type ||
                                    lastLocation.kind === SyntaxKind.Parameter ||
                                    lastLocation.kind === SyntaxKind.JSDocParameterTag ||
                                    lastLocation.kind === SyntaxKind.JSDocReturnTag ||
                                    lastLocation.kind === SyntaxKind.TypeParameter
                                // local types not visible outside the function body
                                : false;
                        }
                        if (meaning & result.flags & SymbolFlags.Variable) {
                            // expression inside parameter will lookup as normal variable scope when targeting es2015+
                            if (useOuterVariableScopeInParameter(result, location, lastLocation)) {
                                useResult = false;
                            }
                            else if (result.flags & SymbolFlags.FunctionScopedVariable) {
                                // parameters are visible only inside function body, parameter list and return type
                                // technically for parameter list case here we might mix parameters and variables declared in function,
                                // however it is detected separately when checking initializers of parameters
                                // to make sure that they reference no variables declared after them.
                                useResult = lastLocation.kind === SyntaxKind.Parameter ||
                                    !!(lastLocation.flags & NodeFlags.Synthesized) || // Synthetic fake scopes are added for signatures so parameters are accessible from them
                                    (
                                        lastLocation === (location as FunctionLikeDeclaration).type &&
                                        !!findAncestor(result.valueDeclaration, isParameter)
                                    );
                            }
                        }
                    }
                    else if (location.kind === SyntaxKind.ConditionalType) {
                        // A type parameter declared using 'infer T' in a conditional type is visible only in
                        // the true branch of the conditional type.
                        useResult = lastLocation === location.trueType;
                    }

                    if (useResult) {
                        break loop;
                    }
                    else {
                        result = undefined;
                    }
                }
            }
            withinDeferredContext = withinDeferredContext || getIsDeferredContext(location, lastLocation);
            switch (location.kind) {
                case SyntaxKind.SourceFile:
                    if (!isExternalOrCommonJsModule(location as SourceFile)) break;
                    // falls through
                case SyntaxKind.ModuleDeclaration:
                    const moduleExports = getSymbolOfDeclaration(location as SourceFile | ModuleDeclaration)?.exports || emptySymbols;
                    if (location.kind === SyntaxKind.SourceFile || (isModuleDeclaration(location) && location.flags & NodeFlags.Ambient && !isGlobalScopeAugmentation(location))) {
                        // It's an external module. First see if the module has an export default and if the local
                        // name of that export default matches.
                        if (result = moduleExports.get(InternalSymbolName.Default)) {
                            const localSymbol = getLocalSymbolForExportDefault(result);
                            if (localSymbol && (result.flags & meaning) && localSymbol.escapedName === name) {
                                break loop;
                            }
                            result = undefined;
                        }

                        // Because of module/namespace merging, a module's exports are in scope,
                        // yet we never want to treat an export specifier as putting a member in scope.
                        // Therefore, if the name we find is purely an export specifier, it is not actually considered in scope.
                        // Two things to note about this:
                        //     1. We have to check this without calling getSymbol. The problem with calling getSymbol
                        //        on an export specifier is that it might find the export specifier itself, and try to
                        //        resolve it as an alias. This will cause the checker to consider the export specifier
                        //        a circular alias reference when it might not be.
                        //     2. We check === SymbolFlags.Alias in order to check that the symbol is *purely*
                        //        an alias. If we used &, we'd be throwing out symbols that have non alias aspects,
                        //        which is not the desired behavior.
                        const moduleExport = moduleExports.get(name);
                        if (
                            moduleExport &&
                            moduleExport.flags === SymbolFlags.Alias &&
                            (getDeclarationOfKind(moduleExport, SyntaxKind.ExportSpecifier) || getDeclarationOfKind(moduleExport, SyntaxKind.NamespaceExport))
                        ) {
                            break;
                        }
                    }

                    // ES6 exports are also visible locally (except for 'default'), but commonjs exports are not (except typedefs)
                    if (name !== InternalSymbolName.Default && (result = lookup(moduleExports, name, meaning & SymbolFlags.ModuleMember))) {
                        if (isSourceFile(location) && location.commonJsModuleIndicator && !result.declarations?.some(isJSDocTypeAlias)) {
                            result = undefined;
                        }
                        else {
                            break loop;
                        }
                    }
                    break;
                case SyntaxKind.EnumDeclaration:
                    if (result = lookup(getSymbolOfDeclaration(location as EnumDeclaration)?.exports || emptySymbols, name, meaning & SymbolFlags.EnumMember)) {
                        if (nameNotFoundMessage && getIsolatedModules(compilerOptions) && !(location.flags & NodeFlags.Ambient) && getSourceFileOfNode(location) !== getSourceFileOfNode(result.valueDeclaration)) {
                            error(
                                originalLocation,
                                Diagnostics.Cannot_access_0_from_another_file_without_qualification_when_1_is_enabled_Use_2_instead,
                                unescapeLeadingUnderscores(name),
                                isolatedModulesLikeFlagName,
                                `${unescapeLeadingUnderscores(getSymbolOfDeclaration(location as EnumDeclaration).escapedName)}.${unescapeLeadingUnderscores(name)}`,
                            );
                        }
                        break loop;
                    }
                    break;
                case SyntaxKind.PropertyDeclaration:
                    // TypeScript 1.0 spec (April 2014): 8.4.1
                    // Initializer expressions for instance member variables are evaluated in the scope
                    // of the class constructor body but are not permitted to reference parameters or
                    // local variables of the constructor. This effectively means that entities from outer scopes
                    // by the same name as a constructor parameter or local variable are inaccessible
                    // in initializer expressions for instance member variables.
                    if (!isStatic(location)) {
                        const ctor = findConstructorDeclaration(location.parent as ClassLikeDeclaration);
                        if (ctor && ctor.locals) {
                            if (lookup(ctor.locals, name, meaning & SymbolFlags.Value)) {
                                // Remember the property node, it will be used later to report appropriate error
                                Debug.assertNode(location, isPropertyDeclaration);
                                propertyWithInvalidInitializer = location;
                            }
                        }
                    }
                    break;
                case SyntaxKind.ClassDeclaration:
                case SyntaxKind.ClassExpression:
                case SyntaxKind.InterfaceDeclaration:
                    // The below is used to lookup type parameters within a class or interface, as they are added to the class/interface locals
                    // These can never be latebound, so the symbol's raw members are sufficient. `getMembersOfNode` cannot be used, as it would
                    // trigger resolving late-bound names, which we may already be in the process of doing while we're here!
                    if (result = lookup(getSymbolOfDeclaration(location as ClassLikeDeclaration | InterfaceDeclaration).members || emptySymbols, name, meaning & SymbolFlags.Type)) {
                        if (!isTypeParameterSymbolDeclaredInContainer(result, location)) {
                            // ignore type parameters not declared in this container
                            result = undefined;
                            break;
                        }
                        if (lastLocation && isStatic(lastLocation)) {
                            // TypeScript 1.0 spec (April 2014): 3.4.1
                            // The scope of a type parameter extends over the entire declaration with which the type
                            // parameter list is associated, with the exception of static member declarations in classes.
                            if (nameNotFoundMessage) {
                                error(originalLocation, Diagnostics.Static_members_cannot_reference_class_type_parameters);
                            }
                            return undefined;
                        }
                        break loop;
                    }
                    if (isClassExpression(location) && meaning & SymbolFlags.Class) {
                        const className = location.name;
                        if (className && name === className.escapedText) {
                            result = location.symbol;
                            break loop;
                        }
                    }
                    break;
                case SyntaxKind.ExpressionWithTypeArguments:
                    // The type parameters of a class are not in scope in the base class expression.
                    if (lastLocation === (location as ExpressionWithTypeArguments).expression && (location.parent as HeritageClause).token === SyntaxKind.ExtendsKeyword) {
                        const container = location.parent.parent;
                        if (isClassLike(container) && (result = lookup(getSymbolOfDeclaration(container).members!, name, meaning & SymbolFlags.Type))) {
                            if (nameNotFoundMessage) {
                                error(originalLocation, Diagnostics.Base_class_expressions_cannot_reference_class_type_parameters);
                            }
                            return undefined;
                        }
                    }
                    break;
                // It is not legal to reference a class's own type parameters from a computed property name that
                // belongs to the class. For example:
                //
                //   function foo<T>() { return '' }
                //   class C<T> { // <-- Class's own type parameter T
                //       [foo<T>()]() { } // <-- Reference to T from class's own computed property
                //   }
                //
                case SyntaxKind.ComputedPropertyName:
                    grandparent = location.parent.parent;
                    if (isClassLike(grandparent) || grandparent.kind === SyntaxKind.InterfaceDeclaration) {
                        // A reference to this grandparent's type parameters would be an error
                        if (result = lookup(getSymbolOfDeclaration(grandparent as ClassLikeDeclaration | InterfaceDeclaration).members!, name, meaning & SymbolFlags.Type)) {
                            if (nameNotFoundMessage) {
                                error(originalLocation, Diagnostics.A_computed_property_name_cannot_reference_a_type_parameter_from_its_containing_type);
                            }
                            return undefined;
                        }
                    }
                    break;
                case SyntaxKind.ArrowFunction:
                    // when targeting ES6 or higher there is no 'arguments' in an arrow function
                    // for lower compile targets the resolved symbol is used to emit an error
                    if (getEmitScriptTarget(compilerOptions) >= ScriptTarget.ES2015) {
                        break;
                    }
                    // falls through
                case SyntaxKind.MethodDeclaration:
                case SyntaxKind.Constructor:
                case SyntaxKind.GetAccessor:
                case SyntaxKind.SetAccessor:
                case SyntaxKind.FunctionDeclaration:
                    if (meaning & SymbolFlags.Variable && name === "arguments") {
                        result = argumentsSymbol;
                        break loop;
                    }
                    break;
                case SyntaxKind.FunctionExpression:
                    if (meaning & SymbolFlags.Variable && name === "arguments") {
                        result = argumentsSymbol;
                        break loop;
                    }

                    if (meaning & SymbolFlags.Function) {
                        const functionName = (location as FunctionExpression).name;
                        if (functionName && name === functionName.escapedText) {
                            result = (location as FunctionExpression).symbol;
                            break loop;
                        }
                    }
                    break;
                case SyntaxKind.Decorator:
                    // Decorators are resolved at the class declaration. Resolving at the parameter
                    // or member would result in looking up locals in the method.
                    //
                    //   function y() {}
                    //   class C {
                    //       method(@y x, y) {} // <-- decorator y should be resolved at the class declaration, not the parameter.
                    //   }
                    //
                    if (location.parent && location.parent.kind === SyntaxKind.Parameter) {
                        location = location.parent;
                    }
                    //
                    //   function y() {}
                    //   class C {
                    //       @y method(x, y) {} // <-- decorator y should be resolved at the class declaration, not the method.
                    //   }
                    //

                    // class Decorators are resolved outside of the class to avoid referencing type parameters of that class.
                    //
                    //   type T = number;
                    //   declare function y(x: T): any;
                    //   @param(1 as T) // <-- T should resolve to the type alias outside of class C
                    //   class C<T> {}
                    if (location.parent && (isClassElement(location.parent) || location.parent.kind === SyntaxKind.ClassDeclaration)) {
                        location = location.parent;
                    }
                    break;
                case SyntaxKind.JSDocTypedefTag:
                case SyntaxKind.JSDocCallbackTag:
                case SyntaxKind.JSDocEnumTag:
                case SyntaxKind.JSDocImportTag:
                    // js type aliases do not resolve names from their host, so skip past it
                    const root = getJSDocRoot(location);
                    if (root) {
                        location = root.parent;
                    }
                    break;
                case SyntaxKind.Parameter:
                    if (
                        lastLocation && (
                            lastLocation === (location as ParameterDeclaration).initializer ||
                            lastLocation === (location as ParameterDeclaration).name && isBindingPattern(lastLocation)
                        )
                    ) {
                        if (!associatedDeclarationForContainingInitializerOrBindingName) {
                            associatedDeclarationForContainingInitializerOrBindingName = location as ParameterDeclaration;
                        }
                    }
                    break;
                case SyntaxKind.BindingElement:
                    if (
                        lastLocation && (
                            lastLocation === (location as BindingElement).initializer ||
                            lastLocation === (location as BindingElement).name && isBindingPattern(lastLocation)
                        )
                    ) {
                        if (isPartOfParameterDeclaration(location as BindingElement) && !associatedDeclarationForContainingInitializerOrBindingName) {
                            associatedDeclarationForContainingInitializerOrBindingName = location as BindingElement;
                        }
                    }
                    break;
                case SyntaxKind.InferType:
                    if (meaning & SymbolFlags.TypeParameter) {
                        const parameterName = (location as InferTypeNode).typeParameter.name;
                        if (parameterName && name === parameterName.escapedText) {
                            result = (location as InferTypeNode).typeParameter.symbol;
                            break loop;
                        }
                    }
                    break;
                case SyntaxKind.ExportSpecifier:
                    // External module export bindings shouldn't be resolved to local symbols.
                    if (
                        lastLocation &&
                        lastLocation === (location as ExportSpecifier).propertyName &&
                        (location as ExportSpecifier).parent.parent.moduleSpecifier
                    ) {
                        location = location.parent.parent.parent;
                    }
                    break;
            }
            if (isSelfReferenceLocation(location, lastLocation)) {
                lastSelfReferenceLocation = location;
            }
            lastLocation = location;
            location = isJSDocTemplateTag(location) ? getEffectiveContainerForJSDocTemplateTag(location) || location.parent :
                isJSDocParameterTag(location) || isJSDocReturnTag(location) ? getHostSignatureFromJSDoc(location) || location.parent :
                location.parent;
        }

        // We just climbed up parents looking for the name, meaning that we started in a descendant node of `lastLocation`.
        // If `result === lastSelfReferenceLocation.symbol`, that means that we are somewhere inside `lastSelfReferenceLocation` looking up a name, and resolving to `lastLocation` itself.
        // That means that this is a self-reference of `lastLocation`, and shouldn't count this when considering whether `lastLocation` is used.
        if (isUse && result && (!lastSelfReferenceLocation || result !== lastSelfReferenceLocation.symbol)) {
            result.isReferenced! |= meaning;
        }

        if (!result) {
            if (lastLocation) {
                Debug.assertNode(lastLocation, isSourceFile);
                if (lastLocation.commonJsModuleIndicator && name === "exports" && meaning & lastLocation.symbol.flags) {
                    return lastLocation.symbol;
                }
            }

            if (!excludeGlobals) {
                result = lookup(globals, name, meaning);
            }
        }
        if (!result) {
            if (originalLocation && isInJSFile(originalLocation) && originalLocation.parent) {
                if (isRequireCall(originalLocation.parent, /*requireStringLiteralLikeArgument*/ false)) {
                    return requireSymbol;
                }
            }
        }

        if (nameNotFoundMessage) {
            if (propertyWithInvalidInitializer && onPropertyWithInvalidInitializer(originalLocation, name, propertyWithInvalidInitializer, result)) {
                return undefined;
            }
            if (!result) {
                onFailedToResolveSymbol(originalLocation, nameArg, meaning, nameNotFoundMessage);
            }
            else {
                onSuccessfullyResolvedSymbol(originalLocation, result, meaning, lastLocation, associatedDeclarationForContainingInitializerOrBindingName, withinDeferredContext);
            }
        }

        return result;
    }

    function useOuterVariableScopeInParameter(result: Symbol, location: Node, lastLocation: Node) {
        const target = getEmitScriptTarget(compilerOptions);
        const functionLocation = location as FunctionLikeDeclaration;
        if (
            isParameter(lastLocation)
            && functionLocation.body
            && result.valueDeclaration
            && result.valueDeclaration.pos >= functionLocation.body.pos
            && result.valueDeclaration.end <= functionLocation.body.end
        ) {
            // check for several cases where we introduce temporaries that require moving the name/initializer of the parameter to the body
            // - static field in a class expression
            // - optional chaining pre-es2020
            // - nullish coalesce pre-es2020
            // - spread assignment in binding pattern pre-es2017
            if (target >= ScriptTarget.ES2015) {
                let declarationRequiresScopeChange = getRequiresScopeChangeCache(functionLocation);
                if (declarationRequiresScopeChange === undefined) {
                    declarationRequiresScopeChange = forEach(functionLocation.parameters, requiresScopeChange) || false;
                    setRequiresScopeChangeCache(functionLocation, declarationRequiresScopeChange);
                }
                return !declarationRequiresScopeChange;
            }
        }
        return false;

        function requiresScopeChange(node: ParameterDeclaration): boolean {
            return requiresScopeChangeWorker(node.name)
                || !!node.initializer && requiresScopeChangeWorker(node.initializer);
        }

        function requiresScopeChangeWorker(node: Node): boolean {
            switch (node.kind) {
                case SyntaxKind.ArrowFunction:
                case SyntaxKind.FunctionExpression:
                case SyntaxKind.FunctionDeclaration:
                case SyntaxKind.Constructor:
                    // do not descend into these
                    return false;
                case SyntaxKind.MethodDeclaration:
                case SyntaxKind.GetAccessor:
                case SyntaxKind.SetAccessor:
                case SyntaxKind.PropertyAssignment:
                    return requiresScopeChangeWorker((node as MethodDeclaration | AccessorDeclaration | PropertyAssignment).name);
                case SyntaxKind.PropertyDeclaration:
                    // static properties in classes introduce temporary variables
                    if (hasStaticModifier(node)) {
                        return !emitStandardClassFields;
                    }
                    return requiresScopeChangeWorker((node as PropertyDeclaration).name);
                default:
                    // null coalesce and optional chain pre-es2020 produce temporary variables
                    if (isNullishCoalesce(node) || isOptionalChain(node)) {
                        return target < ScriptTarget.ES2020;
                    }
                    if (isBindingElement(node) && node.dotDotDotToken && isObjectBindingPattern(node.parent)) {
                        return target < ScriptTarget.ES2017;
                    }
                    if (isTypeNode(node)) return false;
                    return forEachChild(node, requiresScopeChangeWorker) || false;
            }
        }
    }

    function getIsDeferredContext(location: Node, lastLocation: Node | undefined): boolean {
        if (location.kind !== SyntaxKind.ArrowFunction && location.kind !== SyntaxKind.FunctionExpression) {
            // initializers in instance property declaration of class like entities are executed in constructor and thus deferred
            return isTypeQueryNode(location) || ((
                isFunctionLikeDeclaration(location) ||
                (location.kind === SyntaxKind.PropertyDeclaration && !isStatic(location))
            ) && (!lastLocation || lastLocation !== (location as SignatureDeclaration | PropertyDeclaration).name)); // A name is evaluated within the enclosing scope - so it shouldn't count as deferred
        }
        if (lastLocation && lastLocation === (location as FunctionExpression | ArrowFunction).name) {
            return false;
        }
        // generator functions and async functions are not inlined in control flow when immediately invoked
        if ((location as FunctionExpression | ArrowFunction).asteriskToken || hasSyntacticModifier(location, ModifierFlags.Async)) {
            return true;
        }
        return !getImmediatelyInvokedFunctionExpression(location);
    }

    type SelfReferenceLocation =
        | ParameterDeclaration
        | FunctionDeclaration
        | ClassDeclaration
        | InterfaceDeclaration
        | EnumDeclaration
        | TypeAliasDeclaration
        | ModuleDeclaration;

    function isSelfReferenceLocation(node: Node, lastLocation: Node | undefined): node is SelfReferenceLocation {
        switch (node.kind) {
            case SyntaxKind.Parameter:
                return !!lastLocation && lastLocation === (node as ParameterDeclaration).name;
            case SyntaxKind.FunctionDeclaration:
            case SyntaxKind.ClassDeclaration:
            case SyntaxKind.InterfaceDeclaration:
            case SyntaxKind.EnumDeclaration:
            case SyntaxKind.TypeAliasDeclaration:
            case SyntaxKind.ModuleDeclaration: // For `namespace N { N; }`
                return true;
            default:
                return false;
        }
    }

    function isTypeParameterSymbolDeclaredInContainer(symbol: Symbol, container: Node) {
        if (symbol.declarations) {
            for (const decl of symbol.declarations) {
                if (decl.kind === SyntaxKind.TypeParameter) {
                    const parent = isJSDocTemplateTag(decl.parent) ? getJSDocHost(decl.parent) : decl.parent;
                    if (parent === container) {
                        return !(isJSDocTemplateTag(decl.parent) && find((decl.parent.parent as JSDoc).tags, isJSDocTypeAlias));
                    }
                }
            }
        }

        return false;
    }
}

/** @internal */
export function isPrimitiveLiteralValue(node: Expression, includeBigInt = true): node is PrimitiveLiteral {
    Debug.type<PrimitiveLiteral>(node);
    switch (node.kind) {
        case SyntaxKind.TrueKeyword:
        case SyntaxKind.FalseKeyword:
        case SyntaxKind.NumericLiteral:
        case SyntaxKind.StringLiteral:
        case SyntaxKind.NoSubstitutionTemplateLiteral:
            return true;
        case SyntaxKind.BigIntLiteral:
            return includeBigInt;
        case SyntaxKind.PrefixUnaryExpression:
            if (node.operator === SyntaxKind.MinusToken) {
                return isNumericLiteral(node.operand) || (includeBigInt && isBigIntLiteral(node.operand));
            }
            if (node.operator === SyntaxKind.PlusToken) {
                return isNumericLiteral(node.operand);
            }
            return false;
        default:
            assertType<never>(node);
            return false;
    }
}

/** @internal */
export function unwrapParenthesizedExpression(o: Expression): Expression {
    while (o.kind === SyntaxKind.ParenthesizedExpression) {
        o = (o as ParenthesizedExpression).expression;
    }
    return o;
}

/** @internal */
export function hasInferredType(node: Node): node is HasInferredType {
    Debug.type<HasInferredType>(node);
    switch (node.kind) {
        case SyntaxKind.Parameter:
        case SyntaxKind.PropertySignature:
        case SyntaxKind.PropertyDeclaration:
        case SyntaxKind.BindingElement:
        case SyntaxKind.PropertyAccessExpression:
        case SyntaxKind.ElementAccessExpression:
        case SyntaxKind.BinaryExpression:
        case SyntaxKind.VariableDeclaration:
        case SyntaxKind.ExportAssignment:
        case SyntaxKind.PropertyAssignment:
        case SyntaxKind.ShorthandPropertyAssignment:
        case SyntaxKind.JSDocParameterTag:
        case SyntaxKind.JSDocPropertyTag:
            return true;
        default:
            assertType<never>(node);
            return false;
    }
}

/** @internal */
export function isSideEffectImport(node: Node): boolean {
    const ancestor = findAncestor(node, isImportDeclaration);
    return !!ancestor && !ancestor.importClause;
}

// require('module').builtinModules.filter(x => !x.match(/^(?:_|node:)/))
const unprefixedNodeCoreModulesList = [
    "assert",
    "assert/strict",
    "async_hooks",
    "buffer",
    "child_process",
    "cluster",
    "console",
    "constants",
    "crypto",
    "dgram",
    "diagnostics_channel",
    "dns",
    "dns/promises",
    "domain",
    "events",
    "fs",
    "fs/promises",
    "http",
    "http2",
    "https",
    "inspector",
    "inspector/promises",
    "module",
    "net",
    "os",
    "path",
    "path/posix",
    "path/win32",
    "perf_hooks",
    "process",
    "punycode",
    "querystring",
    "readline",
    "readline/promises",
    "repl",
    "stream",
    "stream/consumers",
    "stream/promises",
    "stream/web",
    "string_decoder",
    "sys",
    "timers",
    "timers/promises",
    "tls",
    "trace_events",
    "tty",
    "url",
    "util",
    "util/types",
    "v8",
    "vm",
    "wasi",
    "worker_threads",
    "zlib",
];

/** @internal */
export const unprefixedNodeCoreModules: Set<string> = new Set(unprefixedNodeCoreModulesList);

// require('module').builtinModules.filter(x => x.startsWith('node:'))
/** @internal */
export const exclusivelyPrefixedNodeCoreModules: Set<string> = new Set([
    "node:quic",
    "node:sea",
    "node:sqlite",
    "node:test",
    "node:test/reporters",
]);

/** @internal */
export const nodeCoreModules: Set<string> = new Set([
    ...unprefixedNodeCoreModulesList,
    ...unprefixedNodeCoreModulesList.map(name => `node:${name}`),
    ...exclusivelyPrefixedNodeCoreModules,
]);

/** @internal */
export function forEachDynamicImportOrRequireCall<IncludeTypeSpaceImports extends boolean, RequireStringLiteralLikeArgument extends boolean>(
    file: SourceFile,
    includeTypeSpaceImports: IncludeTypeSpaceImports,
    requireStringLiteralLikeArgument: RequireStringLiteralLikeArgument,
    cb: (node: CallExpression | (IncludeTypeSpaceImports extends false ? never : JSDocImportTag | ImportTypeNode), argument: RequireStringLiteralLikeArgument extends true ? StringLiteralLike : Expression) => void,
): void {
    const isJavaScriptFile = isInJSFile(file);
    const r = /import|require/g;
    while (r.exec(file.text) !== null) { // eslint-disable-line no-restricted-syntax
        const node = getNodeAtPosition(file, r.lastIndex, /*includeJSDoc*/ includeTypeSpaceImports);
        if (isJavaScriptFile && isRequireCall(node, requireStringLiteralLikeArgument)) {
            cb(node, node.arguments[0] as RequireStringLiteralLikeArgument extends true ? StringLiteralLike : Expression);
        }
        else if (isImportCall(node) && node.arguments.length >= 1 && (!requireStringLiteralLikeArgument || isStringLiteralLike(node.arguments[0]))) {
            cb(node, node.arguments[0] as RequireStringLiteralLikeArgument extends true ? StringLiteralLike : Expression);
        }
        else if (includeTypeSpaceImports && isLiteralImportTypeNode(node)) {
            (cb as (node: CallExpression | JSDocImportTag | ImportTypeNode, argument: StringLiteralLike) => void)(node, node.argument.literal);
        }
        else if (includeTypeSpaceImports && isJSDocImportTag(node)) {
            const moduleNameExpr = getExternalModuleName(node);
            if (moduleNameExpr && isStringLiteral(moduleNameExpr) && moduleNameExpr.text) {
                (cb as (node: CallExpression | JSDocImportTag | ImportTypeNode, argument: StringLiteralLike) => void)(node, moduleNameExpr);
            }
        }
    }
}

/** Returns a token if position is in [start-of-leading-trivia, end), includes JSDoc only in JS files */
function getNodeAtPosition(sourceFile: SourceFile, position: number, includeJSDoc: boolean): Node {
    const isJavaScriptFile = isInJSFile(sourceFile);
    let current: Node = sourceFile;
    const getContainingChild = (child: Node) => {
        if (child.pos <= position && (position < child.end || (position === child.end && (child.kind === SyntaxKind.EndOfFileToken)))) {
            return child;
        }
    };
    while (true) {
        const child = isJavaScriptFile && includeJSDoc && hasJSDocNodes(current) && forEach(current.jsDoc, getContainingChild) || forEachChild(current, getContainingChild);
        if (!child || isMetaProperty(child)) {
            return current;
        }
        current = child;
    }
}
/** @internal */
export function isNewScopeNode(node: Node): node is IntroducesNewScopeNode {
    return isFunctionLike(node)
        || isJSDocSignature(node)
        || isMappedTypeNode(node);
}

/** @internal */
export function getLibNameFromLibReference(libReference: FileReference): string {
    return toFileNameLowerCase(libReference.fileName);
}

/** @internal */
export function getLibFileNameFromLibReference(libReference: FileReference): string | undefined {
    const libName = getLibNameFromLibReference(libReference);
    return libMap.get(libName);
}

/** @internal */
export function forEachResolvedProjectReference<T>(
    resolvedProjectReferences: readonly (ResolvedProjectReference | undefined)[] | undefined,
    cb: (resolvedProjectReference: ResolvedProjectReference) => T | undefined,
): T | undefined {
    return forEachProjectReference(
        /*projectReferences*/ undefined,
        resolvedProjectReferences,
        resolvedRef => resolvedRef && cb(resolvedRef),
    );
}

/** @internal */
export function forEachProjectReference<T>(
    projectReferences: readonly ProjectReference[] | undefined,
    resolvedProjectReferences: readonly (ResolvedProjectReference | undefined)[] | undefined,
    cbResolvedRef: (resolvedRef: ResolvedProjectReference | undefined, parent: ResolvedProjectReference | undefined, index: number) => T | undefined,
    cbRef?: (projectReferences: readonly ProjectReference[] | undefined, parent: ResolvedProjectReference | undefined) => T | undefined,
): T | undefined {
    let seenResolvedRefs: Set<Path> | undefined;
    return worker(projectReferences, resolvedProjectReferences, /*parent*/ undefined);

    function worker(
        projectReferences: readonly ProjectReference[] | undefined,
        resolvedProjectReferences: readonly (ResolvedProjectReference | undefined)[] | undefined,
        parent: ResolvedProjectReference | undefined,
    ): T | undefined {
        // Visit project references first
        if (cbRef) {
            const result = cbRef(projectReferences, parent);
            if (result) return result;
        }
        let skipChildren: Set<ResolvedProjectReference> | undefined;
        return forEach(
            resolvedProjectReferences,
            (resolvedRef, index) => {
                if (resolvedRef && seenResolvedRefs?.has(resolvedRef.sourceFile.path)) {
                    (skipChildren ??= new Set()).add(resolvedRef);
                    // ignore recursives
                    return undefined;
                }
                const result = cbResolvedRef(resolvedRef, parent, index);
                if (result || !resolvedRef) return result;
                (seenResolvedRefs ||= new Set()).add(resolvedRef.sourceFile.path);
            },
        ) || forEach(
            resolvedProjectReferences,
            resolvedRef =>
                resolvedRef && !skipChildren?.has(resolvedRef) ?
                    worker(resolvedRef.commandLine.projectReferences, resolvedRef.references, resolvedRef) :
                    undefined,
        );
    }
}

/** @internal */
export function getOptionsSyntaxByArrayElementValue(optionsObject: ObjectLiteralExpression | undefined, name: string, value: string): StringLiteral | undefined {
    return optionsObject && getPropertyArrayElementValue(optionsObject, name, value);
}

function getPropertyArrayElementValue(objectLiteral: ObjectLiteralExpression, propKey: string, elementValue: string): StringLiteral | undefined {
    return forEachPropertyAssignment(objectLiteral, propKey, property =>
        isArrayLiteralExpression(property.initializer) ?
            find(property.initializer.elements, (element): element is StringLiteral => isStringLiteral(element) && element.text === elementValue) :
            undefined);
}

/** @internal */
export function getOptionsSyntaxByValue(optionsObject: ObjectLiteralExpression | undefined, name: string, value: string): StringLiteral | undefined {
    return forEachOptionsSyntaxByName(optionsObject, name, property => isStringLiteral(property.initializer) && property.initializer.text === value ? property.initializer : undefined);
}

/** @internal */
export function forEachOptionsSyntaxByName<T>(optionsObject: ObjectLiteralExpression | undefined, name: string, callback: (prop: PropertyAssignment) => T | undefined): T | undefined {
    return forEachPropertyAssignment(optionsObject, name, callback);
}

/**
 * Creates a deep, memberwise clone of a node with no source map location.
 *
 * WARNING: This is an expensive operation and is only intended to be used in refactorings
 * and code fixes (because those are triggered by explicit user actions).
 *
 * @internal
 */
// Moved here to compiler utilities for usage in node builder for quickinfo.
export function getSynthesizedDeepClone<T extends Node | undefined>(node: T, includeTrivia = true): T {
    const clone = node && getSynthesizedDeepCloneWorker(node);
    if (clone && !includeTrivia) suppressLeadingAndTrailingTrivia(clone);
    return setParentRecursive(clone, /*incremental*/ false);
}

/** @internal */
export function getSynthesizedDeepCloneWithReplacements<T extends Node>(
    node: T,
    includeTrivia: boolean,
    replaceNode: (node: Node) => Node | undefined,
): T {
    let clone = replaceNode(node);
    if (clone) {
        setOriginalNode(clone, node);
    }
    else {
        clone = getSynthesizedDeepCloneWorker(node as NonNullable<T>, replaceNode);
    }

    if (clone && !includeTrivia) suppressLeadingAndTrailingTrivia(clone);
    return clone as T;
}

function getSynthesizedDeepCloneWorker<T extends Node>(node: T, replaceNode?: (node: Node) => Node | undefined): T {
    const nodeClone: <T extends Node>(n: T) => T = replaceNode
        ? n => getSynthesizedDeepCloneWithReplacements(n, /*includeTrivia*/ true, replaceNode)
        : getSynthesizedDeepClone;
    const nodesClone: <T extends Node>(ns: NodeArray<T> | undefined) => NodeArray<T> | undefined = replaceNode
        ? ns => ns && getSynthesizedDeepClonesWithReplacements(ns, /*includeTrivia*/ true, replaceNode)
        : ns => ns && getSynthesizedDeepClones(ns);
    const visited = visitEachChild(node, nodeClone, /*context*/ undefined, nodesClone, nodeClone);

    if (visited === node) {
        // This only happens for leaf nodes - internal nodes always see their children change.
        const clone = isStringLiteral(node) ? setOriginalNode(factory.createStringLiteralFromNode(node), node) as Node as T :
            isNumericLiteral(node) ? setOriginalNode(factory.createNumericLiteral(node.text, node.numericLiteralFlags), node) as Node as T :
            factory.cloneNode(node);
        return setTextRange(clone, node);
    }

    // PERF: As an optimization, rather than calling factory.cloneNode, we'll update
    // the new node created by visitEachChild with the extra changes factory.cloneNode
    // would have made.
    (visited as Mutable<T>).parent = undefined!;
    return visited;
}

/** @internal */
export function getSynthesizedDeepClones<T extends Node>(nodes: NodeArray<T>, includeTrivia?: boolean): NodeArray<T>;
/** @internal */
export function getSynthesizedDeepClones<T extends Node>(nodes: NodeArray<T> | undefined, includeTrivia?: boolean): NodeArray<T> | undefined;
/** @internal */
export function getSynthesizedDeepClones<T extends Node>(nodes: NodeArray<T> | undefined, includeTrivia = true): NodeArray<T> | undefined {
    if (nodes) {
        const cloned = factory.createNodeArray(nodes.map(n => getSynthesizedDeepClone(n, includeTrivia)), nodes.hasTrailingComma);
        setTextRange(cloned, nodes);
        return cloned;
    }
    return nodes;
}

/** @internal */
export function getSynthesizedDeepClonesWithReplacements<T extends Node>(
    nodes: NodeArray<T>,
    includeTrivia: boolean,
    replaceNode: (node: Node) => Node | undefined,
): NodeArray<T> {
    return factory.createNodeArray(nodes.map(n => getSynthesizedDeepCloneWithReplacements(n, includeTrivia, replaceNode)), nodes.hasTrailingComma);
}

/**
 * Sets EmitFlags to suppress leading and trailing trivia on the node.
 *
 * @internal
 */
export function suppressLeadingAndTrailingTrivia(node: Node): void {
    suppressLeadingTrivia(node);
    suppressTrailingTrivia(node);
}

/**
 * Sets EmitFlags to suppress leading trivia on the node.
 *
 * @internal
 */
export function suppressLeadingTrivia(node: Node): void {
    addEmitFlagsRecursively(node, EmitFlags.NoLeadingComments, getFirstChild);
}

/**
 * Sets EmitFlags to suppress trailing trivia on the node.
 *
 * @internal @knipignore
 */
export function suppressTrailingTrivia(node: Node): void {
    addEmitFlagsRecursively(node, EmitFlags.NoTrailingComments, getLastChild);
}

function addEmitFlagsRecursively(node: Node, flag: EmitFlags, getChild: (n: Node) => Node | undefined) {
    addEmitFlags(node, flag);
    const child = getChild(node);
    if (child) addEmitFlagsRecursively(child, flag, getChild);
}

function getFirstChild(node: Node): Node | undefined {
    return forEachChild(node, child => child);
}

/** @internal */
export function canHaveStatements(node: Node): node is Block | ModuleBlock | SourceFile | CaseClause | DefaultClause {
    return isBlock(node) || isModuleBlock(node) || isSourceFile(node) || isCaseClause(node) || isDefaultClause(node);
}

/** @internal */
export function isPotentiallyExecutableNode(node: Node): boolean {
    if (SyntaxKind.FirstStatement <= node.kind && node.kind <= SyntaxKind.LastStatement) {
        if (isVariableStatement(node)) {
            if (getCombinedNodeFlags(node.declarationList) & NodeFlags.BlockScoped) {
                return true;
            }
            return some(node.declarationList.declarations, d => d.initializer !== undefined);
        }
        return true;
    }
    return isClassDeclaration(node) || isEnumDeclaration(node) || isModuleDeclaration(node);
}