initial sync*, part of #221

lib/src/js/nodes.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of js_ast;
 
 abstract class NodeVisitor<T> {
   T visitProgram(Program node);
 
   T visitBlock(Block node);
@@ skipping 23 matching lines @@
   T visitVariableDeclarationList(VariableDeclarationList node);
   T visitAssignment(Assignment node);
   T visitVariableInitialization(VariableInitialization node);
   T visitConditional(Conditional cond);
   T visitNew(New node);
   T visitCall(Call node);
   T visitBinary(Binary node);
   T visitPrefix(Prefix node);
   T visitPostfix(Postfix node);
   T visitSpread(Spread node);
+  T visitYield(Yield node);
 
   T visitIdentifier(Identifier node);
   T visitThis(This node);
   T visitSuper(Super node);
   T visitAccess(PropertyAccess node);
   T visitRestParameter(RestParameter node);
 
   T visitNamedFunction(NamedFunction node);
   T visitFun(Fun node);
   T visitArrowFun(ArrowFun node);
@@ skipping 79 matching lines @@
       return visitExpression(node);
     }
   }
   T visitConditional(Conditional node) => visitExpression(node);
   T visitNew(New node) => visitExpression(node);
   T visitCall(Call node) => visitExpression(node);
   T visitBinary(Binary node) => visitExpression(node);
   T visitPrefix(Prefix node) => visitExpression(node);
   T visitPostfix(Postfix node) => visitExpression(node);
   T visitSpread(Spread node) => visitPrefix(node);
+  T visitYield(Yield node) => visitExpression(node);
   T visitAccess(PropertyAccess node) => visitExpression(node);
 
   T visitIdentifier(Identifier node) => visitExpression(node);
   T visitThis(This node) => visitExpression(node);
   T visitSuper(Super node) => visitExpression(node);
 
   T visitRestParameter(RestParameter node) => visitNode(node);
 
   T visitNamedFunction(NamedFunction node) => visitExpression(node);
   T visitFunctionExpression(FunctionExpression node) => visitExpression(node);
@@ skipping 454 matching lines @@
     for (var node in exprs) {
       comma = (comma == null) ? node : new Binary(op, comma, node);
     }
     return comma;
   }
 
   int get precedenceLevel;
 
   Statement toStatement() => new ExpressionStatement(toVoidExpression());
   Statement toReturn() => new Return(this);
+  Statement toYieldStatement({bool star: false}) =>
+      new ExpressionStatement(new Yield(this, star: star));
 
   Expression toVoidExpression() => this;
   Expression toAssignExpression(Expression left) => new Assignment(left, this);
   Statement toVariableDeclaration(Identifier name) =>
       new VariableDeclarationList('let',
           [new VariableInitialization(name, this)]).toStatement();
 }
 
 class LiteralExpression extends Expression {
   final String template;
@@ skipping 157 matching lines @@
   Statement toStatement() {
     if (!isCommaOperator) return super.toStatement();
     return new Block([left.toStatement(), right.toStatement()]);
   }
 
   Statement toReturn() {
     if (!isCommaOperator) return super.toReturn();
     return new Block([left.toStatement(), right.toReturn()]);
   }
 
+  Statement toYieldStatement({bool star: false}) {
+    if (!isCommaOperator) return super.toYieldStatement(star: star);
+    return new Block([left.toStatement(), right.toYieldStatement(star: star)]);
+  }
+
   List<Expression> commaToExpressionList() {
     if (!isCommaOperator) throw new StateError('not a comma expression');
     var exprs = [];
     _flattenComma(exprs, left);
     _flattenComma(exprs, right);
     return exprs;
   }
 
   static void _flattenComma(List<Expression> exprs, Expression node) {
     if (node is Binary && node.isCommaOperator) {
@@ skipping 159 matching lines @@
 }
 
 abstract class FunctionExpression extends Expression {
   List<Parameter> get params;
   get body; // Expression or block
 }
 
 class Fun extends FunctionExpression {
   final List<Parameter> params;
   final Block body;
+  /** Whether this is a JS generator (`function*`) that may contain `yield`. */
+  final bool isGenerator;
+
   final AsyncModifier asyncModifier;
 
-  Fun(this.params, this.body, {this.asyncModifier: const AsyncModifier.sync()});
+  Fun(this.params, this.body, {this.isGenerator: false,
+      this.asyncModifier: const AsyncModifier.sync()});
 
   accept(NodeVisitor visitor) => visitor.visitFun(this);
 
   void visitChildren(NodeVisitor visitor) {
     for (Parameter param in params) param.accept(visitor);
     body.accept(visitor);
   }
 
-  Fun _clone() => new Fun(params, body, asyncModifier: asyncModifier);
+  Fun _clone() => new Fun(params, body,
+      isGenerator: isGenerator, asyncModifier: asyncModifier);
 
-  int get precedenceLevel => CALL;
+  int get precedenceLevel => ASSIGNMENT;
 }
 
 class ArrowFun extends FunctionExpression {
   final List<Parameter> params;
   final body; // Expression or Block
 
   ArrowFun(this.params, this.body);
 
   accept(NodeVisitor visitor) => visitor.visitArrowFun(this);
 
   void visitChildren(NodeVisitor visitor) {
     for (Parameter param in params) param.accept(visitor);
     body.accept(visitor);
   }
 
   ArrowFun _clone() => new ArrowFun(params, body);
 
   /// Ensure parens always get generated if necessary.
   // TODO(jmesserly): I'm not sure the printer is handling this correctly for
   // function() { ... } either.
   int get precedenceLevel => ASSIGNMENT;
 }
 
+/**
+ * The Dart sync, sync*, async, and async* modifier.
+ * See [DartYield].
+ *
+ * This is not used for JS functions.
+ */
 class AsyncModifier {
   final bool isAsync;
   final bool isYielding;
   final String description;
 
   const AsyncModifier.sync()
       : isAsync = false,
         isYielding = false,
         description = "sync";
   const AsyncModifier.async()
@@ skipping 210 matching lines @@
   void visitChildren(NodeVisitor visitor) {
     tag.accept(visitor);
     template.accept(visitor);
   }
 
   TaggedTemplate _clone() => new TaggedTemplate(tag, template);
 
   int get precedenceLevel => CALL;
 }
 
+// TODO(jmesserly): parser does not support this yet.
+class Yield extends Expression {
+  final Expression value;
+
+  /**
+   * Whether this yield expression is a `yield*` that iterates each item in
+   * [value].
+   */
+  final bool star;
+
+  Yield(this.value, {this.star: false});
+
+  accept(NodeVisitor visitor) => visitor.visitYield(this);
+
+  void visitChildren(NodeVisitor visitor) {
+    value.accept(visitor);
+  }
+
+  Yield _clone() => new Yield(value);
+
+  int get precedenceLevel => YIELD;
+}
+
 class ClassDeclaration extends Statement {
   final ClassExpression classExpr;
 
   ClassDeclaration(this.classExpr);
 
   accept(NodeVisitor visitor) => visitor.visitClassDeclaration(this);
   visitChildren(NodeVisitor visitor) => classExpr.accept(visitor);
   ClassDeclaration _clone() => new ClassDeclaration(classExpr);
 }
 
@@ skipping 20 matching lines @@
 class Method extends Property {
   final bool isGetter;
   final bool isSetter;
   final bool isStatic;
 
   Method(Expression name, Fun function,
       {this.isGetter: false, this.isSetter: false, this.isStatic: false})
       : super(name, function) {
     assert(!isGetter || function.params.length == 0);
     assert(!isSetter || function.params.length == 1);
+    assert(!isGetter && !isSetter || !function.isGenerator);
   }
 
   Fun get function => super.value;
 
   accept(NodeVisitor visitor) => visitor.visitMethod(this);
 
   void visitChildren(NodeVisitor visitor) {
     name.accept(visitor);
     function.accept(visitor);
   }
@@ skipping 172 matching lines @@
   final Expression expression;
 
   CommentExpression(this.comment, this.expression);
 
   int get precedenceLevel => PRIMARY;
   accept(NodeVisitor visitor) => visitor.visitCommentExpression(this);
   CommentExpression _clone() => new CommentExpression(comment, expression);
 
   void visitChildren(NodeVisitor visitor) => expression.accept(visitor);
 }