Refactor array construction for map, filter

src/js/array.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.
 
 (function(global, utils, extrasUtils) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
@@ skipping 1178 matching lines @@
   for (var i = 0; i < length; i++) {
     if (HAS_INDEX(array, i, is_array)) {
       var element = array[i];
       // Prepare break slots for debugger step in.
       if (stepping) %DebugPrepareStepInIfStepping(f);
       if (%_Call(f, receiver, element, i, array)) {
         accumulator[accumulator_length++] = element;
       }
     }
   }
-  return accumulator;
+  var result = new GlobalArray();
+  %MoveArrayContents(accumulator, result);
+  return result;
 }
 
 function ArrayFilter(f, receiver) {
   CHECK_OBJECT_COERCIBLE(this, "Array.prototype.filter");
 
   // Pull out the length so that modifications to the length in the
   // loop will not affect the looping and side effects are visible.
   var array = TO_OBJECT(this);
   var length = TO_LENGTH_OR_UINT32(array.length);
-  var accumulator = InnerArrayFilter(f, receiver, array, length);
-  var result = new GlobalArray();
-  %MoveArrayContents(accumulator, result);
-  return result;
+  return InnerArrayFilter(f, receiver, array, length);
 }
 
 function InnerArrayForEach(f, receiver, array, length) {
   if (!IS_CALLABLE(f)) throw MakeTypeError(kCalledNonCallable, f);
 
   var is_array = IS_ARRAY(array);
   var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
   for (var i = 0; i < length; i++) {
     if (HAS_INDEX(array, i, is_array)) {
       var element = array[i];
@@ skipping 79 matching lines @@
   var is_array = IS_ARRAY(array);
   var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
   for (var i = 0; i < length; i++) {
     if (HAS_INDEX(array, i, is_array)) {
       var element = array[i];
       // Prepare break slots for debugger step in.
       if (stepping) %DebugPrepareStepInIfStepping(f);
       accumulator[i] = %_Call(f, receiver, element, i, array);
     }
   }
-  return accumulator;
+  var result = new GlobalArray();
+  %MoveArrayContents(accumulator, result);
+  return result;
 }
 
 
 function ArrayMap(f, receiver) {
   CHECK_OBJECT_COERCIBLE(this, "Array.prototype.map");
 
   // Pull out the length so that modifications to the length in the
   // loop will not affect the looping and side effects are visible.
   var array = TO_OBJECT(this);
   var length = TO_LENGTH_OR_UINT32(array.length);
-  var accumulator = InnerArrayMap(f, receiver, array, length);
-  var result = new GlobalArray();
-  %MoveArrayContents(accumulator, result);
-  return result;
+  return InnerArrayMap(f, receiver, array, length);
 }
 
 
 // For .indexOf, we don't need to pass in the number of arguments
 // at the callsite since ToInteger(undefined) == 0; however, for
 // .lastIndexOf, we need to pass it, since the behavior for passing
 // undefined is 0 but for not including the argument is length-1.
 function InnerArrayIndexOf(array, element, index, length) {
   if (length == 0) return -1;
   if (IS_UNDEFINED(index)) {
@@ skipping 330 matching lines @@
 %InstallToContext([
   "array_pop", ArrayPop,
   "array_push", ArrayPush,
   "array_shift", ArrayShift,
   "array_splice", ArraySplice,
   "array_slice", ArraySlice,
   "array_unshift", ArrayUnshift,
 ]);
 
 });