Implement .forEach() on typed arrays

src/harmony-typedarray.js

+// Copyright 2013 the V8 project authors. All rights reserved.

[wingo, 2014/09/19 10:24:26]

2014

+// 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;
+
+// -------------------------------------------------------------------
+
+macro TYPED_ARRAYS(FUNCTION)
+// arrayIds below should be synchronized with Runtime_TypedArrayInitialize.
+FUNCTION(1, Uint8Array, 1)
+FUNCTION(2, Int8Array, 1)
+FUNCTION(3, Uint16Array, 2)
+FUNCTION(4, Int16Array, 2)
+FUNCTION(5, Uint32Array, 4)
+FUNCTION(6, Int32Array, 4)
+FUNCTION(7, Float32Array, 4)
+FUNCTION(8, Float64Array, 8)
+FUNCTION(9, Uint8ClampedArray, 1)
+endmacro
+
+
+macro TYPED_ARRAY_CONSTRUCTOR(ARRAY_ID, NAME, ELEMENT_SIZE)

[wingo, 2014/09/19 10:24:26]

need a link to the spec in a comment:
http://people.mozilla.org/~jorendorff/es6-draft.html#sec-%typedarray%.prototy...

+  function NAMEForEach(f, receiver) {
+    CHECK_OBJECT_COERCIBLE(this, "NAME.prototype.forEach");
+
+    var array = ToObject(this);
+    var length = ToLength(array.length);

[wingo, 2014/09/19 10:24:26]

This is incorrect.  The spec says:

%TypedArray%.prototype.indexOf is a distinct function that implements the same
algorithm as Array.prototype.indexOf as defined in 22.1.3.11 except that the
this object’s [[ArrayLength]] internal slot is accessed in place of performing a
[[Get]] of "length". 

+
+    if (!IS_SPEC_FUNCTION(f)) {
+      throw MakeTypeError('called_non_callable', [ f ]);
+    }
+    if (IS_NULL_OR_UNDEFINED(receiver)) {
+      receiver = %GetDefaultReceiver(f) || receiver;
+    } else if (!IS_SPEC_OBJECT(receiver) && %IsSloppyModeFunction(f)) {
+      receiver = ToObject(receiver);

[wingo, 2014/09/19 10:24:26]

If we have to create a wrapper object, it probably has to be done anew for each
call to "f".  See http://code.google.com/p/v8/issues/detail?id=3536.

+    }
+
+    var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
+    for (var i = 0; i < length; i++) {
+      var element = array[i];
+      // Prepare break slots for debugger step in.
+      if (stepping) %DebugPrepareStepInIfStepping(f);
+      %_CallFunction(receiver, element, i, array, f);
+    }
+  }
+endmacro
+
+TYPED_ARRAYS(TYPED_ARRAY_CONSTRUCTOR)
+
+
+function HarmonyTypedArrayExtendPrototypes() {
+macro EXTEND_TYPED_ARRAY(ARRAY_ID, NAME, ELEMENT_SIZE)
+  %CheckIsBootstrapping();
+
+  // Set up non-enumerable functions on the prototype object.
+  InstallFunctions(global.NAME.prototype, DONT_ENUM, $Array(
+    "forEach", NAMEForEach
+  ));
+endmacro
+
+  TYPED_ARRAYS(EXTEND_TYPED_ARRAY)
+}
+
+HarmonyTypedArrayExtendPrototypes();