Add new Harmony methods to Array.prototype object.

src/harmony-array.js

+// Copyright 2013 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+'use strict';
+
+// This file relies on the fact that the following declaration has been made
+// in runtime.js:
+// var $Array = global.Array;
+
+// -------------------------------------------------------------------
+
+// ES6 draft 07-15-13, section 15.4.3.23
+function ArrayFind(predicate /* thisArg */) {  // length == 1
+  if (IS_NULL_OR_UNDEFINED(this) && !IS_UNDETECTABLE(this)) {
+    throw MakeTypeError("called_on_null_or_undefined",
+                        ["Array.prototype.find"]);
+  }
+
+  if (!IS_SPEC_FUNCTION(predicate)) {
+    throw MakeTypeError('called_non_callable', [predicate]);
+  }
+
+  var array = ToObject(this);
+  var length = ToUint32(array.length);

[Michael Starzinger, 2013/08/01 16:21:02]

The access to "array.length" is observable and needs to happen before checking
whether "predicate" is callable, let's move lines 47 and 48 up to before the
check.

Also I am not sure if that's an oversight in the spec draft or not, but the
draft currently specifies ToInteger to be used on the array length.

+  var thisArg;
+  if (%_ArgumentsLength() > 1) {
+    thisArg = %_Arguments(1);
+  }
+
+  for(var i = 0; i < length; i++) {
+    var key = %ToName(i);
+    if (%HasProperty(array, key)) {

[Michael Starzinger, 2013/08/01 16:21:02]

Better use the "in" keyword here, that's more efficient and doesn't require a
preceding %ToName() call either.

+      var element = array[key];
+      if (%_CallFunction(thisArg, element, i, array, predicate)) {

[Michael Starzinger, 2013/08/01 16:21:02]

When using the optimized %_CallFunction intrinsic we need to make sure that the
receiver is correct. If you take a look at some other Array functions (e.g.
ArraySome) you can see how that is done. In general you can these functions as a
good template as they have been thoroughly tested.

+        return element;
+      }
+    }
+  }
+
+  return;
+}
+
+
+// ES6 draft 07-15-13, section 15.4.3.24
+function ArrayFindIndex(predicate /* thisArg */) {  // length == 1

[Michael Starzinger, 2013/08/01 16:21:02]

Most comments from above apply to this function as well.

+  if (IS_NULL_OR_UNDEFINED(this) && !IS_UNDETECTABLE(this)) {
+    throw MakeTypeError("called_on_null_or_undefined",
+                        ["Array.prototype.findIndex"]);
+  }
+
+  if (!IS_SPEC_FUNCTION(predicate)) {
+    throw MakeTypeError('called_non_callable', [predicate]);
+  }
+
+  var array = ToObject(this);
+  var length = ToUint32(array.length);
+  var thisArg;
+  if (%_ArgumentsLength() > 1) {
+    thisArg = %_Arguments(1);
+  }
+
+  for(var i = 0; i < length; i++) {
+    var key = %ToName(i);
+    if (%HasProperty(array, key)) {
+      var element = array[key];
+      if (%_CallFunction(thisArg, element, i, array, predicate)) {
+        return i;
+      }
+    }
+  }
+
+  return -1;
+}
+
+
+// -------------------------------------------------------------------
+
+function HarmonyArrayExtendArrayPrototype() {
+  %CheckIsBootstrapping();
+
+  // Set up the non-enumerable functions on the Array prototype object.
+  InstallFunctions($Array.prototype, DONT_ENUM, $Array(
+    "find", ArrayFind,
+    "findIndex", ArrayFindIndex
+  ));
+}
+
+HarmonyArrayExtendArrayPrototype();