VM: Optimized code for all of [External]{One|Two}ByteString::codeUnitAt.

runtime/lib/string_patch.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.
 
 const int _maxAscii = 0x7f;
 const int _maxLatin1 = 0xff;
 const int _maxUtf16 = 0xffff;
 const int _maxUnicode = 0x10ffff;
 
 patch class String {
@@ skipping 212 matching lines @@
     // TODO(lrn): Create string without scanning charCodes again - all values
     // in the [start..end] range are uint16 values.
     return _createFromCodePoints(charCodes, start, end);
   }
 
   static String _createFromCodePoints(List<int> codePoints, int start, int end)
       native "StringBase_createFromCodePoints";
 
   String operator [](int index) native "String_charAt";
 
-  int codeUnitAt(int index) native "String_codeUnitAt";
+  int codeUnitAt(int index);  // Implemented in the subclasses.
 
   int get length native "String_getLength";
 
   bool get isEmpty {
     return this.length == 0;
   }
 
   bool get isNotEmpty => !isEmpty;
 
   String operator +(String other) native "String_concat";
@@ skipping 686 matching lines @@
 
 class _OneByteString extends _StringBase implements String {
 
   factory _OneByteString._uninstantiable() {
     throw new UnsupportedError(
         "_OneByteString can only be allocated by the VM");
   }
 
   int get hashCode native "String_getHashCode";
 
+  int codeUnitAt(int index) native "String_codeUnitAt";
+
   bool _isWhitespace(int codeUnit) {
     return _StringBase._isOneByteWhitespace(codeUnit);
   }
 
   bool operator ==(Object other) {
     return super == other;
   }
 
   String _substringUncheckedNative(int startIndex, int endIndex)
       native "OneByteString_substringUnchecked";
@@ skipping 283 matching lines @@
         "_TwoByteString can only be allocated by the VM");
   }
 
   static String _allocateFromTwoByteList(List list, int start, int end)
       native "TwoByteString_allocateFromTwoByteList";
 
   bool _isWhitespace(int codeUnit) {
     return _StringBase._isTwoByteWhitespace(codeUnit);
   }
 
+  int codeUnitAt(int index) native "String_codeUnitAt";
+
   bool operator ==(Object other) {
     return super == other;
   }
 }
 
 
 class _ExternalOneByteString extends _StringBase implements String {
   factory _ExternalOneByteString._uninstantiable() {
     throw new UnsupportedError(
         "_ExternalOneByteString can only be allocated by the VM");
   }
 
   bool _isWhitespace(int codeUnit) {
     return _StringBase._isOneByteWhitespace(codeUnit);
   }
 
+  int codeUnitAt(int index) native "String_codeUnitAt";
+
   bool operator ==(Object other) {
     return super == other;
   }
 
   static int _getCid() native "ExternalOneByteString_getCid";
 }
 
 
 class _ExternalTwoByteString extends _StringBase implements String {
   factory _ExternalTwoByteString._uninstantiable() {
     throw new UnsupportedError(
         "_ExternalTwoByteString can only be allocated by the VM");
   }
 
   bool _isWhitespace(int codeUnit) {
     return _StringBase._isTwoByteWhitespace(codeUnit);
   }
 
+  int codeUnitAt(int index) native "String_codeUnitAt";
+
   bool operator ==(Object other) {
     return super == other;
   }
 }
 
 
 class _StringMatch implements Match {
   const _StringMatch(int this.start,
                      String this.input,
                      String this.pattern);
@@ skipping 64 matching lines @@
     int end = index + _pattern.length;
     _current = new _StringMatch(index, _input, _pattern);
     // Empty match, don't start at same location again.
     if (end == _index) end++;
     _index = end;
     return true;
   }
 
   Match get current => _current;
 }