StructureTransitionTable.h 4.49 KB
Newer Older
1
/*
2
 * Copyright (C) 2008, 2009 Apple Inc. All rights reserved.
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
 *
 * 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 COMPUTER, INC. ``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 COMPUTER, INC. OR
 * 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. 
 */

darin@apple.com's avatar
darin@apple.com committed
26
27
#ifndef StructureTransitionTable_h
#define StructureTransitionTable_h
28

29
#include "UString.h"
30
#include "WeakGCMap.h"
31
#include <wtf/HashFunctions.h>
32
#include <wtf/OwnPtr.h>
33
34
35
36
#include <wtf/RefPtr.h>

namespace JSC {

37
class JSCell;
38
class Structure;
39

40
41
42
43
class StructureTransitionTable {
    static const intptr_t UsingSingleSlotFlag = 1;

    struct Hash {
44
        typedef std::pair<RefPtr<StringImpl>, unsigned> Key;
45
46
        static unsigned hash(const Key& p)
        {
47
            return p.first->existingHash();
48
49
50
51
52
53
54
55
56
57
        }

        static bool equal(const Key& a, const Key& b)
        {
            return a == b;
        }

        static const bool safeToCompareToEmptyOrDeleted = true;
    };

58
59
60
61
62
63
64
65
66
67
68
69
    struct WeakGCMapFinalizerCallback {
        static void* finalizerContextFor(Hash::Key)
        {
            return 0;
        }

        static inline Hash::Key keyForFinalizer(void* context, Structure* structure)
        {
            return keyForWeakGCMapFinalizer(context, structure);
        }
    };

70
    typedef WeakGCMap<Hash::Key, Structure, WeakGCMapFinalizerCallback, Hash> TransitionMap;
71
72

    static Hash::Key keyForWeakGCMapFinalizer(void* context, Structure*);
73

74
75
76
77
78
79
80
81
public:
    StructureTransitionTable()
        : m_data(UsingSingleSlotFlag)
    {
    }

    ~StructureTransitionTable()
    {
82
        if (!isUsingSingleSlot()) {
83
            delete map();
84
85
86
            return;
        }

87
88
        WeakImpl* impl = this->weakImpl();
        if (!impl)
89
            return;
90
        WeakHeap::deallocate(impl);
91
92
    }

93
    inline void add(JSGlobalData&, Structure*);
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
    inline bool contains(StringImpl* rep, unsigned attributes) const;
    inline Structure* get(StringImpl* rep, unsigned attributes) const;

private:
    bool isUsingSingleSlot() const
    {
        return m_data & UsingSingleSlotFlag;
    }

    TransitionMap* map() const
    {
        ASSERT(!isUsingSingleSlot());
        return reinterpret_cast<TransitionMap*>(m_data);
    }

109
    WeakImpl* weakImpl() const
110
111
    {
        ASSERT(isUsingSingleSlot());
112
        return reinterpret_cast<WeakImpl*>(m_data & ~UsingSingleSlotFlag);
113
114
    }

115
116
117
    void setMap(TransitionMap* map)
    {
        ASSERT(isUsingSingleSlot());
118
        
119
120
        if (WeakImpl* impl = this->weakImpl())
            WeakHeap::deallocate(impl);
121
122
123
124
125
126
127
128
129
130

        // This implicitly clears the flag that indicates we're using a single transition
        m_data = reinterpret_cast<intptr_t>(map);

        ASSERT(!isUsingSingleSlot());
    }

    Structure* singleTransition() const
    {
        ASSERT(isUsingSingleSlot());
131
132
133
        if (WeakImpl* impl = this->weakImpl()) {
            if (impl->state() == WeakImpl::Live)
                return reinterpret_cast<Structure*>(impl->jsValue().asCell());
134
135
        }
        return 0;
136
    }
137
138
139
140
    
    void setSingleTransition(JSGlobalData& globalData, Structure* structure)
    {
        ASSERT(isUsingSingleSlot());
141
142
143
144
        if (WeakImpl* impl = this->weakImpl())
            WeakHeap::deallocate(impl);
        WeakImpl* impl = globalData.heap.weakHeap()->allocate(reinterpret_cast<JSCell*>(structure));
        m_data = reinterpret_cast<intptr_t>(impl) | UsingSingleSlotFlag;
145
146
147
148
149
    }

    intptr_t m_data;
};

150
151
} // namespace JSC

darin@apple.com's avatar
darin@apple.com committed
152
#endif // StructureTransitionTable_h