cmd: Add debugging support

go.mod

@@ -4,6 +4,7 @@ go 1.14
 
 require (
 	github.com/antlr/antlr4 v0.0.0-20200209180723-1177c0b58d07
+	github.com/davecgh/go-spew v1.1.1
 	github.com/google/go-cmp v0.4.0
 	github.com/jinzhu/inflection v1.0.0
 	github.com/lfittl/pg_query_go v1.0.0

internal/cmd/generate.go

@@ -91,6 +91,12 @@ func Generate(e Env, dir string, stderr io.Writer) (map[string]string, error) {
 		return nil, err
 	}
 
+	debug, err := opts.DebugFromEnv()
+	if err != nil {
+		fmt.Fprintf(stderr, "error parsing SQLCDEBUG: %s\n", err)
+		return nil, err
+	}
+
 	output := map[string]string{}
 	errored := false
 
@@ -127,7 +133,9 @@ func Generate(e Env, dir string, stderr io.Writer) (map[string]string, error) {
 		sql.Queries = joined
 
 		var name string
-		parseOpts := opts.Parser{}
+		parseOpts := opts.Parser{
+			Debug: debug,
+		}
 		if sql.Gen.Go != nil {
 			name = combo.Go.Package
 		} else if sql.Gen.Kotlin != nil {

internal/compiler/compile.go

@@ -104,7 +104,7 @@ func parseQueries(p Parser, c *catalog.Catalog, queries []string, o opts.Parser)
 			continue
 		}
 		for _, stmt := range stmts {
-			query, err := parseQuery(p, c, stmt.Raw, src, o.UsePositionalParameters)
+			query, err := parseQuery(p, c, stmt.Raw, src, o)
 			if err == ErrUnsupportedStatementType {
 				continue
 			}

internal/compiler/parse.go

@@ -6,7 +6,9 @@ import (
 	"sort"
 	"strings"
 
+	"github.com/kyleconroy/sqlc/internal/debug"
 	"github.com/kyleconroy/sqlc/internal/metadata"
+	"github.com/kyleconroy/sqlc/internal/opts"
 	"github.com/kyleconroy/sqlc/internal/source"
 	"github.com/kyleconroy/sqlc/internal/sql/ast"
 	"github.com/kyleconroy/sqlc/internal/sql/ast/pg"
@@ -30,7 +32,10 @@ func rewriteNumberedParameters(refs []paramRef, raw *ast.RawStmt, sql string) ([
 	return edits, nil
 }
 
-func parseQuery(p Parser, c *catalog.Catalog, stmt ast.Node, src string, rewriteParameters bool) (*Query, error) {
+func parseQuery(p Parser, c *catalog.Catalog, stmt ast.Node, src string, o opts.Parser) (*Query, error) {
+	if o.Debug.DumpAST {
+		debug.Dump(stmt)
+	}
 	if err := validate.ParamStyle(stmt); err != nil {
 		return nil, err
 	}
@@ -75,7 +80,7 @@ func parseQuery(p Parser, c *catalog.Catalog, stmt ast.Node, src string, rewrite
 	raw, namedParams, edits := rewrite.NamedParameters(raw)
 	rvs := rangeVars(raw.Stmt)
 	refs := findParameters(raw.Stmt)
-	if rewriteParameters {
+	if o.UsePositionalParameters {
 		edits, err = rewriteNumberedParameters(refs, raw, rawSQL)
 		if err != nil {
 			return nil, err

internal/debug/dump.go

@@ -0,0 +1,9 @@
+package debug
+
+import (
+	"github.com/davecgh/go-spew/spew"
+)
+
+func Dump(n interface{}) {
+	spew.Dump(n)
+}

internal/opts/debug.go

@@ -0,0 +1,29 @@
+package opts
+
+import (
+	"os"
+	"strings"
+)
+
+// The SQLCDEBUG variable controls debugging variables within the runtime. It
+// is a comma-separated list of name=val pairs setting these named variables:
+//
+//     dumpast: setting dumpast=1 will print the AST of every SQL statement
+
+type Debug struct {
+	DumpAST bool
+}
+
+func DebugFromEnv() (Debug, error) {
+	d := Debug{}
+	val := os.Getenv("SQLCDEBUG")
+	if val == "" {
+		return d, nil
+	}
+	for _, pair := range strings.Split(val, ",") {
+		if pair == "dumpast=1" {
+			d.DumpAST = true
+		}
+	}
+	return d, nil
+}

internal/opts/parser.go

@@ -2,4 +2,5 @@ package opts
 
 type Parser struct {
 	UsePositionalParameters bool
+	Debug                   Debug
 }