Use for-of loops in collection constructors

src/weak-collection.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 "use strict";
 
 // This file relies on the fact that the following declaration has been made
 // in runtime.js:
 // var $Array = global.Array;
 
 var $WeakMap = global.WeakMap;
 var $WeakSet = global.WeakSet;
 
 
 // -------------------------------------------------------------------
 // Harmony WeakMap
 
 function WeakMapConstructor(iterable) {
   if (!%_IsConstructCall()) {
     throw MakeTypeError('constructor_not_function', ['WeakMap']);
   }
 
-  var iter, adder;
-
-  if (!IS_NULL_OR_UNDEFINED(iterable)) {
-    adder = this.set;
-    if (!IS_SPEC_FUNCTION(adder)) {
-      throw MakeTypeError('property_not_function', ['set', this]);
-    }
-    iter = GetIterator(iterable);
-  }
-
   %WeakCollectionInitialize(this);
 
-  if (IS_UNDEFINED(iter)) return;
-
-  var next, done, nextItem;
-  while (!(next = iter.next()).done) {
-    if (!IS_SPEC_OBJECT(next)) {
-      throw MakeTypeError('iterator_result_not_an_object', [next]);
+  if (!IS_NULL_OR_UNDEFINED(iterable)) {
+    var adder = this.set;
+    if (!IS_SPEC_FUNCTION(adder)) {
+      throw MakeTypeError('property_not_function', ['set', this]);
     }
-    nextItem = next.value;
-    if (!IS_SPEC_OBJECT(nextItem)) {
-      throw MakeTypeError('iterator_value_not_an_object', [nextItem]);
+    for (var nextItem of iterable) {
+      if (!IS_SPEC_OBJECT(nextItem)) {
+        throw MakeTypeError('iterator_value_not_an_object', [nextItem]);
+      }
+      %_CallFunction(this, nextItem[0], nextItem[1], adder);
     }
-    %_CallFunction(this, nextItem[0], nextItem[1], adder);
   }
 }
 
 
 function WeakMapGet(key) {
   if (!IS_WEAKMAP(this)) {
     throw MakeTypeError('incompatible_method_receiver',
                         ['WeakMap.prototype.get', this]);
   }
   if (!(IS_SPEC_OBJECT(key) || IS_SYMBOL(key))) {
@@ skipping 63 matching lines @@
 
 
 // -------------------------------------------------------------------
 // Harmony WeakSet
 
 function WeakSetConstructor(iterable) {
   if (!%_IsConstructCall()) {
     throw MakeTypeError('constructor_not_function', ['WeakSet']);
   }
 
-  var iter, adder;
-
-  if (!IS_NULL_OR_UNDEFINED(iterable)) {
-    adder = this.add;
-    if (!IS_SPEC_FUNCTION(adder)) {
-      throw MakeTypeError('property_not_function', ['add', this]);
-    }
-    iter = GetIterator(iterable);
-  }
-
   %WeakCollectionInitialize(this);
 
-  if (IS_UNDEFINED(iter)) return;
-
-  var next, done;
-  while (!(next = iter.next()).done) {
-    if (!IS_SPEC_OBJECT(next)) {
-      throw MakeTypeError('iterator_result_not_an_object', [next]);
+  if (!IS_NULL_OR_UNDEFINED(iterable)) {
+    var adder = this.add;
+    if (!IS_SPEC_FUNCTION(adder)) {
+      throw MakeTypeError('property_not_function', ['add', this]);
     }
-    %_CallFunction(this, next.value, adder);
+    for (var value of iterable) {
+      %_CallFunction(this, value, adder);
+    }
   }
 }
 
 
 function WeakSetAdd(value) {
   if (!IS_WEAKSET(this)) {
     throw MakeTypeError('incompatible_method_receiver',
                         ['WeakSet.prototype.add', this]);
   }
   if (!(IS_SPEC_OBJECT(value) || IS_SYMBOL(value))) {
@@ skipping 40 matching lines @@
 
   // Set up the non-enumerable functions on the WeakSet prototype object.
   InstallFunctions($WeakSet.prototype, DONT_ENUM, $Array(
     "add", WeakSetAdd,
     "has", WeakSetHas,
     "delete", WeakSetDelete
   ));
 }
 
 SetUpWeakSet();