third_party/WebKit/Source/bindings/core/v8/V8ValueCache.h

/*
 * Copyright (C) 2009 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef V8ValueCache_h
#define V8ValueCache_h

#include "bindings/core/v8/V8GlobalValueMap.h"
#include "core/CoreExport.h"
#include "v8/include/v8.h"
#include "wtf/Allocator.h"
#include "wtf/HashMap.h"
#include "wtf/Noncopyable.h"
#include "wtf/RefPtr.h"
#include "wtf/text/AtomicString.h"
#include "wtf/text/WTFString.h"

namespace blink {

class StringCacheMapTraits
    : public V8GlobalValueMapTraits<StringImpl*,
                                    v8::String,
                                    v8::kWeakWithParameter> {
  STATIC_ONLY(StringCacheMapTraits);

 public:
  // Weak traits:
  typedef StringImpl WeakCallbackDataType;
  typedef v8::GlobalValueMap<StringImpl*, v8::String, StringCacheMapTraits>
      MapType;

  static WeakCallbackDataType* WeakCallbackParameter(
      MapType* map,
      StringImpl* key,
      v8::Local<v8::String>& value) {
    return key;
  }
  static void DisposeCallbackData(WeakCallbackDataType* callbackData) {}

  static MapType* MapFromWeakCallbackInfo(
      const v8::WeakCallbackInfo<WeakCallbackDataType>&);

  static StringImpl* KeyFromWeakCallbackInfo(
      const v8::WeakCallbackInfo<WeakCallbackDataType>& data) {
    return data.GetParameter();
  }

  static void OnWeakCallback(const v8::WeakCallbackInfo<WeakCallbackDataType>&);

  static void Dispose(v8::Isolate*,
                      v8::Global<v8::String> value,
                      StringImpl* key);
  static void DisposeWeak(const v8::WeakCallbackInfo<WeakCallbackDataType>&);
};

class CORE_EXPORT StringCache {
  USING_FAST_MALLOC(StringCache);
  WTF_MAKE_NONCOPYABLE(StringCache);

 public:
  explicit StringCache(v8::Isolate* isolate) : m_stringCache(isolate) {}

  v8::Local<v8::String> v8ExternalString(v8::Isolate* isolate,
                                         StringImpl* stringImpl) {
    ASSERT(stringImpl);
    if (m_lastStringImpl.get() == stringImpl)
      return m_lastV8String.NewLocal(isolate);
    return v8ExternalStringSlow(isolate, stringImpl);
  }

  void setReturnValueFromString(v8::ReturnValue<v8::Value> returnValue,
                                StringImpl* stringImpl) {
    ASSERT(stringImpl);
    if (m_lastStringImpl.get() == stringImpl)
      m_lastV8String.SetReturnValue(returnValue);
    else
      setReturnValueFromStringSlow(returnValue, stringImpl);
  }

  void dispose();

  friend class StringCacheMapTraits;

 private:
  v8::Local<v8::String> v8ExternalStringSlow(v8::Isolate*, StringImpl*);
  void setReturnValueFromStringSlow(v8::ReturnValue<v8::Value>, StringImpl*);
  v8::Local<v8::String> createStringAndInsertIntoCache(v8::Isolate*,
                                                       StringImpl*);
  void InvalidateLastString();

  StringCacheMapTraits::MapType m_stringCache;
  StringCacheMapTraits::MapType::PersistentValueReference m_lastV8String;

  // Note: RefPtr is a must as we cache by StringImpl* equality, not identity
  // hence lastStringImpl might be not a key of the cache (in sense of identity)
  // and hence it's not refed on addition.
  RefPtr<StringImpl> m_lastStringImpl;
};

}  // namespace blink

#endif  // V8ValueCache_h