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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/core/v8/V8PersistentValueMap.h"
     30 #include "wtf/HashMap.h"
     31 #include "wtf/RefPtr.h"
     32 #include "wtf/text/AtomicString.h"
     33 #include "wtf/text/WTFString.h"
     34 #include <v8.h>
     35 
     36 namespace blink {
     37 
     38 class StringCacheMapTraits : public V8PersistentValueMapTraits<StringImpl*, v8::String, true> {
     39 public:
     40     // Weak traits:
     41     typedef StringImpl WeakCallbackDataType;
     42     typedef v8::PersistentValueMap<StringImpl*, v8::String, StringCacheMapTraits> MapType;
     43 
     44     static WeakCallbackDataType* WeakCallbackParameter(
     45         MapType* map, StringImpl* key, v8::Local<v8::String>& value) { return key; }
     46     static void DisposeCallbackData(WeakCallbackDataType* callbackData) { }
     47 
     48     static MapType* MapFromWeakCallbackData(
     49         const v8::WeakCallbackData<v8::String, WeakCallbackDataType>&);
     50 
     51     static StringImpl* KeyFromWeakCallbackData(
     52         const v8::WeakCallbackData<v8::String, WeakCallbackDataType>& data)
     53     {
     54         return data.GetParameter();
     55     }
     56 
     57     static void Dispose(v8::Isolate*, v8::UniquePersistent<v8::String> value, StringImpl* key);
     58 };
     59 
     60 
     61 class StringCache {
     62 public:
     63     StringCache(v8::Isolate* isolate) : m_stringCache(isolate) { }
     64     ~StringCache();
     65 
     66     v8::Handle<v8::String> v8ExternalString(StringImpl* stringImpl, v8::Isolate* isolate)
     67     {
     68         ASSERT(stringImpl);
     69         if (m_lastStringImpl.get() == stringImpl)
     70             return m_lastV8String.NewLocal(isolate);
     71         return v8ExternalStringSlow(stringImpl, isolate);
     72     }
     73 
     74     void setReturnValueFromString(v8::ReturnValue<v8::Value> returnValue, StringImpl* stringImpl)
     75     {
     76         ASSERT(stringImpl);
     77         if (m_lastStringImpl.get() == stringImpl)
     78             m_lastV8String.SetReturnValue(returnValue);
     79         else
     80             setReturnValueFromStringSlow(returnValue, stringImpl);
     81     }
     82 
     83     friend class StringCacheMapTraits;
     84 
     85 private:
     86     v8::Handle<v8::String> v8ExternalStringSlow(StringImpl*, v8::Isolate*);
     87     void setReturnValueFromStringSlow(v8::ReturnValue<v8::Value>, StringImpl*);
     88     v8::Local<v8::String> createStringAndInsertIntoCache(StringImpl*, v8::Isolate*);
     89     void InvalidateLastString();
     90 
     91     StringCacheMapTraits::MapType m_stringCache;
     92     StringCacheMapTraits::MapType::PersistentValueReference m_lastV8String;
     93 
     94     // Note: RefPtr is a must as we cache by StringImpl* equality, not identity
     95     // hence lastStringImpl might be not a key of the cache (in sense of identity)
     96     // and hence it's not refed on addition.
     97     RefPtr<StringImpl> m_lastStringImpl;
     98 };
     99 
    100 } // namespace blink
    101 
    102 #endif // V8ValueCache_h
    103