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      1 /*
      2  * Copyright (C) 2009 Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
     14  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
     15  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
     17  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     18  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     19  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     20  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     21  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     22  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
     23  * THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 #ifndef V8ValueCache_h
     27 #define V8ValueCache_h
     28 
     29 #include "bindings/v8/UnsafePersistent.h"
     30 #include <v8.h>
     31 #include "wtf/HashMap.h"
     32 #include "wtf/RefPtr.h"
     33 #include "wtf/text/AtomicString.h"
     34 #include "wtf/text/WTFString.h"
     35 
     36 namespace WebCore {
     37 
     38 class StringCache {
     39 public:
     40     StringCache() { }
     41 
     42     v8::Handle<v8::String> v8ExternalString(StringImpl* stringImpl, v8::Isolate* isolate)
     43     {
     44         ASSERT(stringImpl);
     45         if (m_lastStringImpl.get() == stringImpl)
     46             return m_lastV8String.newLocal(isolate);
     47         return v8ExternalStringSlow(stringImpl, isolate);
     48     }
     49 
     50     void setReturnValueFromString(v8::ReturnValue<v8::Value> returnValue, StringImpl* stringImpl)
     51     {
     52         ASSERT(stringImpl);
     53         if (m_lastStringImpl.get() == stringImpl)
     54             returnValue.Set(*m_lastV8String.persistent());
     55         else
     56             setReturnValueFromStringSlow(returnValue, stringImpl);
     57     }
     58 
     59 private:
     60     static void setWeakCallback(const v8::WeakCallbackData<v8::String, StringImpl>&);
     61 
     62     v8::Handle<v8::String> v8ExternalStringSlow(StringImpl*, v8::Isolate*);
     63     void setReturnValueFromStringSlow(v8::ReturnValue<v8::Value>, StringImpl*);
     64     v8::Local<v8::String> createStringAndInsertIntoCache(StringImpl*, v8::Isolate*);
     65 
     66     HashMap<StringImpl*, UnsafePersistent<v8::String> > m_stringCache;
     67     UnsafePersistent<v8::String> m_lastV8String;
     68     // Note: RefPtr is a must as we cache by StringImpl* equality, not identity
     69     // hence lastStringImpl might be not a key of the cache (in sense of identity)
     70     // and hence it's not refed on addition.
     71     RefPtr<StringImpl> m_lastStringImpl;
     72 };
     73 
     74 } // namespace WebCore
     75 
     76 #endif // V8ValueCache_h
     77