[destructuring] Implement spread binding patterns.

src/runtime.js

 // Copyright 2006-2008 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.
 
 // This files contains runtime support implemented in JavaScript.
 
 // CAUTION: Some of the functions specified in this file are called
 // directly from compiled code. These are the functions with names in
 // ALL CAPS. The compiled code passes the first argument in 'this'.
 
@@ skipping 711 matching lines @@
 
   // Return the length which is the number of arguments to copy to the
   // stack. It is guaranteed to be a small integer at this point.
   return length;
 }
 
 
 STACK_OVERFLOW = function STACK_OVERFLOW(length) {
   throw %MakeRangeError(kStackOverflow);
 }
 

[arv (Not doing code reviews), 2015/05/20 13:34:14]

undo this line removal... (it was probably from when you moved my function)

[Dmitry Lomov (no reviews), 2015/05/20 14:22:03]

Done.

-
 // Convert the receiver to an object - forward to ToObject.
 TO_OBJECT = function TO_OBJECT() {
   return %$toObject(this);
 }
 
 
 // Convert the receiver to a number - forward to ToNumber.
 TO_NUMBER = function TO_NUMBER() {
   return %$toNumber(this);
 }
@@ skipping 179 matching lines @@
 
 // ES6, section 7.2.4
 function SameValueZero(x, y) {
   if (typeof x != typeof y) return false;
   if (IS_NUMBER(x)) {
     if (NUMBER_IS_NAN(x) && NUMBER_IS_NAN(y)) return true;
   }
   return x === y;
 }
 
+function SpreadIntoArray(target, iterable) {

[rossberg, 2015/05/20 12:57:35]

Nit: ConcatIterableToArray

[arv (Not doing code reviews), 2015/05/20 13:34:14]

It is not to array... it adds it to an existing array. This is from my array
spread CL where we need to add the elements to an existing array.

For the rest destructuring we could skip passing an array and return a new
array. The only question is if we want to reuse this code or not?

[arv (Not doing code reviews), 2015/05/20 13:39:45]

There is also $spreadIterable which almost does this

https://code.google.com/p/chromium/codesearch#chromium/src/v8/src/harmony-spr...

(it returns an InternalArray)

[rossberg, 2015/05/20 13:49:39]

Hence Concat...ToArray ;)
It's good, as long as there is a simple way to make the array strong in strong
mode.

[Dmitry Lomov (no reviews), 2015/05/20 14:22:03]

Done.

+   var index = target.length;
+   for (var element of iterable) {
+     %AddElement(target, index++, element, NONE);
+   }
+   return target;
+}
+
 
 /* ---------------------------------
    - - -   U t i l i t i e s   - - -
    ---------------------------------
 */
 
 // Returns if the given x is a primitive value - not an object or a
 // function.
 function IsPrimitive(x) {
   // Even though the type of null is "object", null is still
@@ skipping 65 matching lines @@
 
 //----------------------------------------------------------------------------
 
 $defaultNumber = DefaultNumber;
 $defaultString = DefaultString;
 $NaN = %GetRootNaN();
 $nonNumberToNumber = NonNumberToNumber;
 $nonStringToString = NonStringToString;
 $sameValue = SameValue;
 $sameValueZero = SameValueZero;
+$spreadIntoArray = SpreadIntoArray;
 $toBoolean = ToBoolean;
 $toInt32 = ToInt32;
 $toInteger = ToInteger;
 $toLength = ToLength;
 $toName = ToName;
 $toNumber = ToNumber;
 $toObject = ToObject;
 $toPositiveInteger = ToPositiveInteger;
 $toPrimitive = ToPrimitive;
 $toString = ToString;
 $toUint32 = ToUint32;
 
 })