Improve scanner performance by remembering string's CharAt function as the string type does not cha…

runtime/vm/object.h

 // 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.
 
 #ifndef VM_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 5286 matching lines @@
   }
 
   static intptr_t hash_offset() { return OFFSET_OF(RawString, hash_); }
   static intptr_t Hash(const String& str, intptr_t begin_index, intptr_t len);
   static intptr_t Hash(const uint8_t* characters, intptr_t len);
   static intptr_t Hash(const uint16_t* characters, intptr_t len);
   static intptr_t Hash(const int32_t* characters, intptr_t len);
 
   int32_t CharAt(intptr_t index) const;
 
+  Scanner::CharAtFunc CharAtFunc() const;
+
   intptr_t CharSize() const;
 
   inline bool Equals(const String& str) const;
   inline bool Equals(const String& str,
                      intptr_t begin_index,  // begin index on 'str'.
                      intptr_t len) const;  // len on 'str'.
 
   // Compares to a '\0' terminated array of UTF-8 encoded characters.
   bool Equals(const char* cstr) const;
 
@@ skipping 1789 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_