Support async generators

jquery · Aug 21, 2021 · a770bff · a770bff
1 parent 4e3b259
commit a770bff
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Showing 29 changed files with 1,818 additions and 6,062 deletions.
diff --git a/src/messages.ts b/src/messages.ts
@@ -1,5 +1,6 @@
 // Error messages should be identical to V8.
 export const Messages = {
+    AsyncFunctionInSingleStatementContext: 'Async functions can only be declared at the top level or inside a block.',
     BadImportCallArity: 'Unexpected token',
     BadGetterArity: 'Getter must not have any formal parameters',
     BadSetterArity: 'Setter must have exactly one formal parameter',
@@ -12,6 +13,7 @@ export const Messages = {
     DefaultRestProperty: 'Unexpected token =',
     DuplicateBinding: 'Duplicate binding %0',
     DuplicateConstructor: 'A class may only have one constructor',
+    DuplicateParameter: 'Duplicate parameter name not allowed in this context',
     DuplicateProtoProperty: 'Duplicate __proto__ fields are not allowed in object literals',
     ForInOfLoopInitializer: '%0 loop variable declaration may not have an initializer',
     GeneratorInLegacyContext: 'Generator declarations are not allowed in legacy contexts',

diff --git a/src/nodes.ts b/src/nodes.ts
@@ -115,12 +115,12 @@ export class AsyncFunctionDeclaration {
     readonly generator: boolean;
     readonly expression: boolean;
     readonly async: boolean;
-    constructor(id: Identifier | null, params: FunctionParameter[], body: BlockStatement) {
+    constructor(id: Identifier | null, params: FunctionParameter[], body: BlockStatement, generator: boolean) {
         this.type = Syntax.FunctionDeclaration;
         this.id = id;
         this.params = params;
         this.body = body;
-        this.generator = false;
+        this.generator = generator;
         this.expression = false;
         this.async = true;
     }
@@ -134,12 +134,12 @@ export class AsyncFunctionExpression {
     readonly generator: boolean;
     readonly expression: boolean;
     readonly async: boolean;
-    constructor(id: Identifier | null, params: FunctionParameter[], body: BlockStatement) {
+    constructor(id: Identifier | null, params: FunctionParameter[], body: BlockStatement, generator: boolean) {
         this.type = Syntax.FunctionExpression;
         this.id = id;
         this.params = params;
         this.body = body;
-        this.generator = false;
+        this.generator = generator;
         this.expression = false;
         this.async = true;
     }

diff --git a/src/parser.ts b/src/parser.ts
@@ -256,6 +256,12 @@ export class Parser {
         this.errorHandler.tolerate(this.unexpectedTokenError(token, message));
     }
 
+    tolerateInvalidLoopStatement() {
+        if (this.matchKeyword("class") || this.matchKeyword("function")) {
+            this.tolerateError(Messages.UnexpectedToken, this.lookahead);
+        }
+    }
+
     collectComments() {
         if (!this.config.comment) {
             this.scanner.scanComments();
@@ -772,8 +778,7 @@ export class Parser {
         return body;
     }
 
-    parsePropertyMethodFunction(): Node.FunctionExpression {
-        const isGenerator = false;
+    parsePropertyMethodFunction(isGenerator: boolean): Node.FunctionExpression {
         const node = this.createNode();
 
         const previousAllowYield = this.context.allowYield;
@@ -785,19 +790,24 @@ export class Parser {
         return this.finalize(node, new Node.FunctionExpression(null, params.params, method, isGenerator));
     }
 
-    parsePropertyMethodAsyncFunction(): Node.FunctionExpression {
+    parsePropertyMethodAsyncFunction(isGenerator: boolean): Node.FunctionExpression {
         const node = this.createNode();
 
         const previousAllowYield = this.context.allowYield;
         const previousAwait = this.context.await;
         this.context.allowYield = false;
         this.context.await = true;
+
         const params = this.parseFormalParameters();
+        if (params.message === Messages.StrictParamDupe) {
+            this.throwError(Messages.DuplicateParameter);
+        }
+
         const method = this.parsePropertyMethod(params);
         this.context.allowYield = previousAllowYield;
         this.context.await = previousAwait;
 
-        return this.finalize(node, new Node.AsyncFunctionExpression(null, params.params, method));
+        return this.finalize(node, new Node.AsyncFunctionExpression(null, params.params, method, isGenerator));
     }
 
     parseObjectPropertyKey(): Node.PropertyKey {
@@ -855,13 +865,18 @@ export class Parser {
         let method = false;
         let shorthand = false;
         let isAsync = false;
+        let isGenerator = false;
 
         if (token.type === Token.Identifier) {
             const id = token.value;
             this.nextToken();
             computed = this.match('[');
             isAsync = !this.hasLineTerminator && (id === 'async') &&
-                !this.match(':') && !this.match('(') && !this.match('*') && !this.match(',');
+                !this.match(':') && !this.match('(') && !this.match(',');
+            isGenerator = this.match('*');
+            if (isGenerator) {
+                this.nextToken();
+            }
             key = isAsync ? this.parseObjectPropertyKey() : this.finalize(node, new Node.Identifier(id));
         } else if (this.match('*')) {
             this.nextToken();
@@ -908,7 +923,7 @@ export class Parser {
                 value = this.inheritCoverGrammar(this.parseAssignmentExpression);
 
             } else if (this.match('(')) {
-                value = isAsync ? this.parsePropertyMethodAsyncFunction() : this.parsePropertyMethodFunction();
+                value = isAsync ? this.parsePropertyMethodAsyncFunction(isGenerator) : this.parsePropertyMethodFunction(isGenerator);
                 method = true;
 
             } else if (token.type === Token.Identifier) {
@@ -2125,7 +2140,7 @@ export class Parser {
         return this.finalize(node, new Node.Property('init', key, computed, value, method, shorthand));
     }
 
-    parseRestProperty(params, kind): Node.RestElement {
+    parseRestProperty(params): Node.RestElement {
         const node = this.createNode();
         this.expect('...');
         const arg = this.parsePattern(params);
@@ -2144,7 +2159,7 @@ export class Parser {
 
         this.expect('{');
         while (!this.match('}')) {
-            properties.push(this.match('...') ? this.parseRestProperty(params, kind) : this.parsePropertyPattern(params, kind));
+            properties.push(this.match('...') ? this.parseRestProperty(params) : this.parsePropertyPattern(params, kind));
             if (!this.match('}')) {
                 this.expect(',');
             }
@@ -2316,6 +2331,8 @@ export class Parser {
         const node = this.createNode();
         this.expectKeyword('do');
 
+        this.tolerateInvalidLoopStatement();
+
         const previousInIteration = this.context.inIteration;
         this.context.inIteration = true;
         const body = this.parseStatement();
@@ -2519,6 +2536,7 @@ export class Parser {
             body = this.finalize(this.createNode(), new Node.EmptyStatement());
         } else {
             this.expect(')');
+            this.tolerateInvalidLoopStatement();
 
             const previousInIteration = this.context.inIteration;
             this.context.inIteration = true;
@@ -3046,12 +3064,15 @@ export class Parser {
 
         const isAsync = this.matchContextualKeyword('async');
         if (isAsync) {
+            if (this.context.inIteration) {
+                this.tolerateError(Messages.AsyncFunctionInSingleStatementContext);
+            }
             this.nextToken();
         }
 
         this.expectKeyword('function');
 
-        const isGenerator = isAsync ? false : this.match('*');
+        const isGenerator = this.match('*');
         if (isGenerator) {
             this.nextToken();
         }
@@ -3084,6 +3105,10 @@ export class Parser {
         this.context.allowYield = !isGenerator;
 
         const formalParameters = this.parseFormalParameters(firstRestricted);
+        if (isGenerator && formalParameters.message === Messages.StrictParamDupe) {
+            this.throwError(Messages.DuplicateParameter);
+        }
+
         const params = formalParameters.params;
         const stricted = formalParameters.stricted;
         firstRestricted = formalParameters.firstRestricted;
@@ -3107,8 +3132,9 @@ export class Parser {
         this.context.await = previousAllowAwait;
         this.context.allowYield = previousAllowYield;
 
-        return isAsync ? this.finalize(node, new Node.AsyncFunctionDeclaration(id, params, body)) :
-            this.finalize(node, new Node.FunctionDeclaration(id, params, body, isGenerator));
+        return isAsync
+            ? this.finalize(node, new Node.AsyncFunctionDeclaration(id, params, body, isGenerator))
+            : this.finalize(node, new Node.FunctionDeclaration(id, params, body, isGenerator));
     }
 
     parseFunctionExpression(): Node.AsyncFunctionExpression | Node.FunctionExpression {
@@ -3121,7 +3147,7 @@ export class Parser {
 
         this.expectKeyword('function');
 
-        const isGenerator = isAsync ? false : this.match('*');
+        const isGenerator = this.match('*');
         if (isGenerator) {
             this.nextToken();
         }
@@ -3154,6 +3180,12 @@ export class Parser {
         }
 
         const formalParameters = this.parseFormalParameters(firstRestricted);
+        if (formalParameters.message === Messages.StrictParamDupe) {
+            if (isGenerator || isAsync) {
+                this.throwError(Messages.DuplicateParameter);
+            }
+        }
+
         const params = formalParameters.params;
         const stricted = formalParameters.stricted;
         firstRestricted = formalParameters.firstRestricted;
@@ -3176,8 +3208,9 @@ export class Parser {
         this.context.await = previousAllowAwait;
         this.context.allowYield = previousAllowYield;
 
-        return isAsync ? this.finalize(node, new Node.AsyncFunctionExpression(id, params, body)) :
-            this.finalize(node, new Node.FunctionExpression(id, params, body, isGenerator));
+        return isAsync
+            ? this.finalize(node, new Node.AsyncFunctionExpression(id, params, body, isGenerator))
+            : this.finalize(node, new Node.FunctionExpression(id, params, body, isGenerator));
     }
 
     // https://tc39.github.io/ecma262/#sec-directive-prologues-and-the-use-strict-directive
@@ -3360,6 +3393,7 @@ export class Parser {
         let method = false;
         let isStatic = false;
         let isAsync = false;
+        let isGenerator = false;
 
         if (this.match('*')) {
             this.nextToken();
@@ -3379,8 +3413,12 @@ export class Parser {
             }
             if ((token.type === Token.Identifier) && !this.hasLineTerminator && (token.value === 'async')) {
                 const punctuator = this.lookahead.value;
-                if (punctuator !== ':' && punctuator !== '(' && punctuator !== '*') {
+                if (punctuator !== ':' && punctuator !== '(') {
                     isAsync = true;
+                    isGenerator = this.match("*");
+                    if (isGenerator) {
+                        this.nextToken();
+                    }
                     token = this.lookahead;
                     computed = this.match('[');
                     key = this.parseObjectPropertyKey();
@@ -3415,7 +3453,7 @@ export class Parser {
 
         if (!kind && key && this.match('(')) {
             kind = 'init';
-            value = isAsync ? this.parsePropertyMethodAsyncFunction() : this.parsePropertyMethodFunction();
+            value = isAsync ? this.parsePropertyMethodAsyncFunction(isGenerator) : this.parsePropertyMethodFunction(isGenerator);
             method = true;
         }
 

diff --git a/test/fixtures/ES6/for-of/invalid-decl-cls.failure.json b/test/fixtures/ES6/for-of/invalid-decl-cls.failure.json
@@ -0,0 +1 @@
+{"index":17,"lineNumber":1,"column":18,"message":"Error: Line 1: Unexpected token [object Object]","description":"Unexpected token [object Object]"}
diff --git a/test/fixtures/ES6/for-of/invalid-decl-cls.js b/test/fixtures/ES6/for-of/invalid-decl-cls.js
@@ -0,0 +1 @@
+for (var x of []) class C {}
diff --git a/...unctions/invalid-generator-declaration.js → .../functions/async-generator-declaration.js b/...unctions/invalid-generator-declaration.js → .../functions/async-generator-declaration.js