Added implementation of String.codeUnits.

sdk/lib/core/string.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.core;
 
 /**
  * The String class represents sequences of characters. Strings are
  * immutable. A string is represented by a sequence of Unicode UTF-16
  * code units accessible through the [codeUnitAt] or the
@@ skipping 431 matching lines @@
    * a two-character String.
    *
    * Returns null if [current] is null.
    */
   String get currentAsString {
     if (_position == _nextPosition) return null;
     if (_position + 1 == _nextPosition) return string[_position];
     return string.substring(_position, _nextPosition);
   }
 
-
   bool moveNext() {
     _position = _nextPosition;
     if (_position == string.length) {
       _currentCodePoint = null;
       return false;
     }
     int codeUnit = string.charCodeAt(_position);
     int nextPosition = _position + 1;
     if (_isLeadSurrogate(codeUnit) && nextPosition < string.length) {
       int nextCodeUnit = string.charCodeAt(nextPosition);
@@ skipping 22 matching lines @@
         _position = position - 1;
         _currentCodePoint = _combineSurrogatePair(prevCodeUnit, codeUnit);
         return true;
       }
     }
     _position = position;
     _currentCodePoint = codeUnit;
     return true;
   }
 }
+
+/**
+ * An [Iterable] of the UTF-16 code units of a [String] in index order.
+ */
+class CodeUnits extends ListIterable<int> {
+  /** The string that this is the code units of. */
+  String string;
+
+  CodeUnits(this.string);
+
+  int get length => string.length;
+  int elementAt(int i) => string.codeUnitAt(i);
+}