add logical assignment operators

Author: mysticatea

acorn/src/tokenize.js

@@ -233,7 +233,13 @@ pp.readToken_mult_modulo_exp = function(code) { // '%*'
 
 pp.readToken_pipe_amp = function(code) { // '|&'
   let next = this.input.charCodeAt(this.pos + 1)
-  if (next === code) return this.finishOp(code === 124 ? tt.logicalOR : tt.logicalAND, 2)
+  if (next === code) {
+    if (this.options.ecmaVersion >= 12) {
+      let next2 = this.input.charCodeAt(this.pos + 2)
+      if (next2 === 61) return this.finishOp(tt.assign, 3)
+    }
+    return this.finishOp(code === 124 ? tt.logicalOR : tt.logicalAND, 2)
+  }
   if (next === 61) return this.finishOp(tt.assign, 2)
   return this.finishOp(code === 124 ? tt.bitwiseOR : tt.bitwiseAND, 1)
 }
@@ -290,13 +296,20 @@ pp.readToken_eq_excl = function(code) { // '=!'
 }
 
 pp.readToken_question = function() { // '?'
-  if (this.options.ecmaVersion >= 11) {
+  const ecmaVersion = this.options.ecmaVersion
+  if (ecmaVersion >= 11) {
     let next = this.input.charCodeAt(this.pos + 1)
     if (next === 46) {
       let next2 = this.input.charCodeAt(this.pos + 2)
       if (next2 < 48 || next2 > 57) return this.finishOp(tt.questionDot, 2)
     }
-    if (next === 63) return this.finishOp(tt.coalesce, 2)
+    if (next === 63) {
+      if (ecmaVersion >= 12) {
+        let next2 = this.input.charCodeAt(this.pos + 2)
+        if (next2 === 61) return this.finishOp(tt.assign, 3)
+      }
+      return this.finishOp(tt.coalesce, 2)
+    }
   }
   return this.finishOp(tt.question, 1)
 }

bin/run_test262.js

@@ -11,11 +11,10 @@ const unsupportedFeatures = [
   "class-static-fields-public",
   "class-static-methods-private",
   "numeric-separator-literal",
-  "logical-assignment-operators",
 ];
 
 run(
-  (content, {sourceType}) => parse(content, {sourceType, ecmaVersion: 11, allowHashBang: true, allowAwaitOutsideFunction: true}),
+  (content, {sourceType}) => parse(content, {sourceType, ecmaVersion: 12, allowHashBang: true, allowAwaitOutsideFunction: true}),
   {
     testsDirectory: path.dirname(require.resolve("test262/package.json")),
     skip: test => (test.attrs.features && unsupportedFeatures.some(f => test.attrs.features.includes(f))),

test/run.js

@@ -21,6 +21,7 @@
   require("./tests-import-meta.js");
   require("./tests-nullish-coalescing.js");
   require("./tests-optional-chaining.js");
+  require("./tests-logical-assignment-operators.js");
   var acorn = require("../acorn")
   var acorn_loose = require("../acorn-loose")
 

test/tests-logical-assignment-operators.js

@@ -0,0 +1,182 @@
+// Tests for ECMAScript 2021 `&&=`, `||=`, `??=`
+
+if (typeof exports != 'undefined') {
+  var test = require('./driver.js').test;
+  var testFail = require('./driver.js').testFail;
+}
+
+test(
+  "a &&= b",
+  {
+    "type": "Program",
+    "start": 0,
+    "end": 7,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start": 0,
+        "end": 7,
+        "expression": {
+          "type": "AssignmentExpression",
+          "start": 0,
+          "end": 7,
+          "operator": "&&=",
+          "left": {
+            "type": "Identifier",
+            "start": 0,
+            "end": 1,
+            "name": "a"
+          },
+          "right": {
+            "type": "Identifier",
+            "start": 6,
+            "end": 7,
+            "name": "b"
+          }
+        }
+      }
+    ],
+    "sourceType": "script"
+  },
+  { ecmaVersion: 12 }
+);
+
+test(
+  "a ||= b",
+  {
+    "type": "Program",
+    "start": 0,
+    "end": 7,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start": 0,
+        "end": 7,
+        "expression": {
+          "type": "AssignmentExpression",
+          "start": 0,
+          "end": 7,
+          "operator": "||=",
+          "left": {
+            "type": "Identifier",
+            "start": 0,
+            "end": 1,
+            "name": "a"
+          },
+          "right": {
+            "type": "Identifier",
+            "start": 6,
+            "end": 7,
+            "name": "b"
+          }
+        }
+      }
+    ],
+    "sourceType": "script"
+  },
+  { ecmaVersion: 12 }
+);
+
+test(
+  "a ??= b",
+  {
+    "type": "Program",
+    "start": 0,
+    "end": 7,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start": 0,
+        "end": 7,
+        "expression": {
+          "type": "AssignmentExpression",
+          "start": 0,
+          "end": 7,
+          "operator": "??=",
+          "left": {
+            "type": "Identifier",
+            "start": 0,
+            "end": 1,
+            "name": "a"
+          },
+          "right": {
+            "type": "Identifier",
+            "start": 6,
+            "end": 7,
+            "name": "b"
+          }
+        }
+      }
+    ],
+    "sourceType": "script"
+  },
+  { ecmaVersion: 12 }
+);
+
+test(
+  "a &&= b ||= c ??= d",
+  {
+    "type": "Program",
+    "start": 0,
+    "end": 19,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start": 0,
+        "end": 19,
+        "expression": {
+          "type": "AssignmentExpression",
+          "start": 0,
+          "end": 19,
+          "operator": "&&=",
+          "left": {
+            "type": "Identifier",
+            "start": 0,
+            "end": 1,
+            "name": "a"
+          },
+          "right": {
+            "type": "AssignmentExpression",
+            "start": 6,
+            "end": 19,
+            "operator": "||=",
+            "left": {
+              "type": "Identifier",
+              "start": 6,
+              "end": 7,
+              "name": "b"
+            },
+            "right": {
+              "type": "AssignmentExpression",
+              "start": 12,
+              "end": 19,
+              "operator": "??=",
+              "left": {
+                "type": "Identifier",
+                "start": 12,
+                "end": 13,
+                "name": "c"
+              },
+              "right": {
+                "type": "Identifier",
+                "start": 18,
+                "end": 19,
+                "name": "d"
+              }
+            }
+          }
+        }
+      }
+    ],
+    "sourceType": "script"
+  },
+  { ecmaVersion: 12 }
+);
+
+testFail("a &&= b", "Unexpected token (1:4)", { ecmaVersion: 11 });
+testFail("a ||= b", "Unexpected token (1:4)", { ecmaVersion: 11 });
+testFail("a ??= b", "Unexpected token (1:4)", { ecmaVersion: 11 });
+
+testFail("({a} &&= b)", "Assigning to rvalue (1:1)", { ecmaVersion: 12 });
+testFail("({a} ||= b)", "Assigning to rvalue (1:1)", { ecmaVersion: 12 });
+testFail("({a} ??= b)", "Assigning to rvalue (1:1)", { ecmaVersion: 12 });