Add Array.prototype.reduce and .reduceRight.

src/array.js

 // Copyright 2006-2008 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
@@ skipping 861 matching lines @@
   for (var i = index; i >= 0; i--) {
     var current = this[i];
     if (!IS_UNDEFINED(current) || i in this) {
       if (current === element) return i;
     }
   }
   return -1;
 }
 
 
+function ArrayReduce(callback, current) {
+  if (!IS_FUNCTION(callback)) {
+    throw MakeTypeError('called_non_callable', [ callback ]);
+  }
+  // Pull out the length so that modifications to the length in the
+  // loop will not affect the looping.
+  var length = this.length;
+  var i = 0;
+
+  find_initial: if (%_ArgumentsLength() < 2) {

[Dean McNamee, 2009/04/21 09:19:50]

I am missing why you need the label.

[Christian Plesner Hansen, 2009/04/21 09:39:17]

I think the code style is

 find_initial:
  if (%_...)

[Lasse Reichstein, 2009/04/21 09:53:50]

I use the label to have a location to break to, to avoid executing the throw if
we don't find an element.

I preferred adding the label to the existing statement instead of creating
another block statement inside the if.

[Lasse Reichstein, 2009/04/21 09:53:50]

Done.

+    for (;i < length; i++) {

[Dean McNamee, 2009/04/21 09:19:50]

space after ;

[Lasse Reichstein, 2009/04/21 09:53:50]

Done.

+      current = this[i];
+      if (!IS_UNDEFINED(current) || i in this) {
+        i++;
+        break find_initial;
+      }
+    }
+    throw MakeTypeError('reduce_no_initial', []);
+  }
+
+  for (; i < length; i++) {
+    var element = this[i];
+    if (!IS_UNDEFINED(element) || i in this) {
+      current = callback.call(null, current, element, i, this);
+    }
+  }
+  return current;
+}
+
+function ArrayReduceRight(callback, current) {
+  if (!IS_FUNCTION(callback)) {
+    throw MakeTypeError('called_non_callable', [ callback ]);

[Dean McNamee, 2009/04/21 09:19:50]

no spaces around [ ] (consistency with [])

[Lasse Reichstein, 2009/04/21 09:53:50]

Done.

+  }
+  var i = this.length - 1;
+
+  find_initial: if (%_ArgumentsLength() < 2) {
+    for (;i >= 0; i--) {
+      current = this[i];
+      if (!IS_UNDEFINED(current) || i in this) {
+        i--;
+        break find_initial;
+      }
+    }
+    throw MakeTypeError('reduce_no_initial', []);
+  }
+
+  for (; i >= 0; i--) {
+    var element = this[i];
+    if (!IS_UNDEFINED(element) || i in this) {
+      current = callback.call(null, current, element, i, this);
+    }
+  }
+  return current;
+}
+
+
 // -------------------------------------------------------------------
 
 
 function UpdateFunctionLengths(lengths) {
   for (var key in lengths) {
     %FunctionSetLength(this[key], lengths[key]);
   }
 }
 
 
@@ skipping 18 matching lines @@
     "unshift", ArrayUnshift,
     "slice", ArraySlice,
     "splice", ArraySplice,
     "sort", ArraySort,
     "filter", ArrayFilter,
     "forEach", ArrayForEach,
     "some", ArraySome,
     "every", ArrayEvery,
     "map", ArrayMap,
     "indexOf", ArrayIndexOf,
-    "lastIndexOf", ArrayLastIndexOf
+    "lastIndexOf", ArrayLastIndexOf,
+    "reduce", ArrayReduce,
+    "reduceRight", ArrayReduceRight
   ));
 
   // Manipulate the length of some of the functions to meet
   // expectations set by ECMA-262 or Mozilla.
   UpdateFunctionLengths({
     ArrayFilter: 1,
     ArrayForEach: 1,
     ArraySome: 1,
     ArrayEvery: 1,
     ArrayMap: 1,
     ArrayIndexOf: 1,
     ArrayLastIndexOf: 1,
-    ArrayPush: 1
+    ArrayPush: 1,
+    ArrayReduce: 1,
+    ArrayReduceRight: 1
   });
 }
 
 
 SetupArray();