Improve performance of String.fromCharCodes by implementing it in Dart. Add tow internal natives to…

runtime/lib/string.cc

 // Copyright (c) 2011, 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.
 
 #include "vm/bootstrap_natives.h"
 
 #include "vm/exceptions.h"
 #include "vm/native_entry.h"
 #include "vm/object.h"
 #include "vm/symbols.h"
@@ skipping 103 matching lines @@
   }
   str = OneByteString::SubStringUnchecked(receiver,
                                           start,
                                           (i - start),
                                           Heap::kNew);
   result.Add(str);
   return result.raw();
 }
 
 
+DEFINE_NATIVE_ENTRY(OneByteString_allocate, 1) {
+  GET_NON_NULL_NATIVE_ARGUMENT(Smi, length_obj, arguments->NativeArgAt(0));
+  return OneByteString::New(length_obj.Value(), Heap::kNew);
+}
+
+
+DEFINE_NATIVE_ENTRY(OneByteString_setAt, 3) {
+  const String& receiver = String::CheckedHandle(arguments->NativeArgAt(0));

[siva, 2013/05/03 23:05:01]

May be do a GET_NON_NULL_NATIVE_ARGUMENT(...)

[srdjan, 2013/05/03 23:36:37]

Done.

+  ASSERT(receiver.IsOneByteString());
+  GET_NON_NULL_NATIVE_ARGUMENT(Smi, index_obj, arguments->NativeArgAt(1));
+  GET_NON_NULL_NATIVE_ARGUMENT(Smi, code_point_obj, arguments->NativeArgAt(2));
+  ASSERT((0 <= code_point_obj.Value()) && (code_point_obj.Value() <= 0xFF);
+  OneByteString::SetCharAt(receiver, index_obj.Value(), code_point_obj.Value());
+  return Object::null();
+}
+
+
 DEFINE_NATIVE_ENTRY(String_getHashCode, 1) {
   const String& receiver = String::CheckedHandle(arguments->NativeArgAt(0));
   intptr_t hash_val = receiver.Hash();
   ASSERT(hash_val > 0);
   ASSERT(Smi::IsValid(hash_val));
   return Smi::New(hash_val);
 }
 
 
 DEFINE_NATIVE_ENTRY(String_getLength, 1) {
@@ skipping 94 matching lines @@
       ? String::Handle(OneByteString::New(length_value, Heap::kNew))
       : String::Handle(TwoByteString::New(length_value, Heap::kNew));
   NoGCScope no_gc;
 
   uint16_t* data_position = reinterpret_cast<uint16_t*>(codeUnits.DataAddr(0));
   String::Copy(result, 0, data_position, length_value);
   return result.raw();
 }
 
 }  // namespace dart