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
36namespace blink {
37
38class StringCacheMapTraits : public V8PersistentValueMapTraits<StringImpl*, v8::String, true> {
39public:
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
61class StringCache {
62public:
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
85private:
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