Support for-await-of (#1190)

Closes gh-2031
jquery · Sep 27, 2020 · 4f52923 · 4f52923
1 parent deaa653
commit 4f52923
Show file tree

Hide file tree

Showing 22 changed files with 453 additions and 753 deletions.
diff --git a/docs/syntax-tree-format.md b/docs/syntax-tree-format.md
@@ -546,6 +546,7 @@ interface ForInStatement {
 ```js
 interface ForOfStatement {
     type: 'ForOfStatement';
+    await: boolean;
     left: Expression | VariableDeclaration;
     right: Expression;
     body: Statement;

diff --git a/src/nodes.ts b/src/nodes.ts
@@ -381,11 +381,13 @@ export class ForInStatement {
 
 export class ForOfStatement {
     readonly type: string;
+    readonly await: boolean;
     readonly left: Expression;
     readonly right: Expression;
     readonly body: Statement;
-    constructor(left: Expression, right: Expression, body: Statement) {
+    constructor(left: Expression, right: Expression, body: Statement, _await: boolean) {
         this.type = Syntax.ForOfStatement;
+        this.await = _await;
         this.left = left;
         this.right = right;
         this.body = body;

diff --git a/src/parser.ts b/src/parser.ts
@@ -2248,9 +2248,18 @@ export class Parser {
         let update: Node.Expression | null = null;
         let forIn = true;
         let left, right;
+        let _await = false;
 
         const node = this.createNode();
         this.expectKeyword('for');
+        if (this.matchContextualKeyword('await')) {
+            if (!this.context.await) {
+                this.tolerateUnexpectedToken(this.lookahead);
+            }
+            _await = true;
+            this.nextToken();
+        }
+
         this.expect('(');
 
         if (this.match(';')) {
@@ -2265,7 +2274,7 @@ export class Parser {
                 const declarations = this.parseVariableDeclarationList({ inFor: true });
                 this.context.allowIn = previousAllowIn;
 
-                if (declarations.length === 1 && this.matchKeyword('in')) {
+                if (!_await && declarations.length === 1 && this.matchKeyword('in')) {
                     const decl = declarations[0];
                     if (decl.init && (decl.id.type === Syntax.ArrayPattern || decl.id.type === Syntax.ObjectPattern || this.context.strict)) {
                         this.tolerateError(Messages.ForInOfLoopInitializer, 'for-in');
@@ -2397,7 +2406,7 @@ export class Parser {
         return (typeof left === 'undefined') ?
             this.finalize(node, new Node.ForStatement(init, test, update, body)) :
             forIn ? this.finalize(node, new Node.ForInStatement(left, right, body)) :
-                this.finalize(node, new Node.ForOfStatement(left, right, body));
+                this.finalize(node, new Node.ForOfStatement(left, right, body, _await));
     }
 
     // https://tc39.github.io/ecma262/#sec-continue-statement

diff --git a/test/fixtures/ES6/for-of/for-of-array-pattern-let.tree.json b/test/fixtures/ES6/for-of/for-of-array-pattern-let.tree.json
@@ -17,6 +17,7 @@
                 }
             },
             "type": "ForOfStatement",
+            "await": false,
             "left": {
                 "range": [
                     5,

diff --git a/test/fixtures/ES6/for-of/for-of-array-pattern-var.tree.json b/test/fixtures/ES6/for-of/for-of-array-pattern-var.tree.json
@@ -17,6 +17,7 @@
                 }
             },
             "type": "ForOfStatement",
+            "await": false,
             "left": {
                 "range": [
                     5,

diff --git a/test/fixtures/ES6/for-of/for-of-array-pattern.tree.json b/test/fixtures/ES6/for-of/for-of-array-pattern.tree.json
@@ -17,6 +17,7 @@
                 }
             },
             "type": "ForOfStatement",
+            "await": false,
             "left": {
                 "range": [
                     5,

diff --git a/test/fixtures/ES6/for-of/for-of-let.tree.json b/test/fixtures/ES6/for-of/for-of-let.tree.json
@@ -31,6 +31,7 @@
                 }
             },
             "type": "ForOfStatement",
+            "await": false,
             "left": {
                 "range": [
                     5,

diff --git a/test/fixtures/ES6/for-of/for-of-object-pattern-const.tree.json b/test/fixtures/ES6/for-of/for-of-object-pattern-const.tree.json
@@ -17,6 +17,7 @@
                 }
             },
             "type": "ForOfStatement",
+            "await": false,
             "left": {
                 "range": [
                     5,

diff --git a/test/fixtures/ES6/for-of/for-of-object-pattern-var.tree.json b/test/fixtures/ES6/for-of/for-of-object-pattern-var.tree.json
@@ -17,6 +17,7 @@
                 }
             },
             "type": "ForOfStatement",
+            "await": false,
             "left": {
                 "range": [
                     5,

diff --git a/test/fixtures/ES6/for-of/for-of-object-pattern.tree.json b/test/fixtures/ES6/for-of/for-of-object-pattern.tree.json
@@ -17,6 +17,7 @@
                 }
             },
             "type": "ForOfStatement",
+            "await": false,
             "left": {
                 "range": [
                     5,

diff --git a/test/fixtures/ES6/for-of/for-of-with-const.tree.json b/test/fixtures/ES6/for-of/for-of-with-const.tree.json
@@ -17,6 +17,7 @@
                 }
             },
             "type": "ForOfStatement",
+            "await": false,
             "left": {
                 "range": [
                     5,

diff --git a/test/fixtures/ES6/for-of/for-of-with-let.tree.json b/test/fixtures/ES6/for-of/for-of-with-let.tree.json
@@ -17,6 +17,7 @@
                 }
             },
             "type": "ForOfStatement",
+            "await": false,
             "left": {
                 "range": [
                     5,

diff --git a/test/fixtures/ES6/for-of/for-of-with-var.tree.json b/test/fixtures/ES6/for-of/for-of-with-var.tree.json
@@ -17,6 +17,7 @@
                 }
             },
             "type": "ForOfStatement",
+            "await": false,
             "left": {
                 "range": [
                     5,

diff --git a/test/fixtures/ES6/for-of/for-of.tree.json b/test/fixtures/ES6/for-of/for-of.tree.json
@@ -17,6 +17,7 @@
                 }
             },
             "type": "ForOfStatement",
+            "await": false,
             "left": {
                 "range": [
                     5,

diff --git a/test/fixtures/ES6/for-of/let-of-of.tree.json b/test/fixtures/ES6/for-of/let-of-of.tree.json
@@ -17,6 +17,7 @@
                 }
             },
             "type": "ForOfStatement",
+            "await": false,
             "left": {
                 "range": [
                     5,

diff --git a/test/fixtures/es2018/for-await-of/for-await-of.js b/test/fixtures/es2018/for-await-of/for-await-of.js
@@ -0,0 +1 @@
+async function f() { for await (p of q); }