1 | /* |
2 | * Copyright (C) 2007, 2008 Apple 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 | * |
8 | * 1. Redistributions of source code must retain the above copyright |
9 | * notice, this list of conditions and the following disclaimer. |
10 | * 2. Redistributions in binary form must reproduce the above copyright |
11 | * notice, this list of conditions and the following disclaimer in the |
12 | * documentation and/or other materials provided with the distribution. |
13 | * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of |
14 | * its contributors may be used to endorse or promote products derived |
15 | * from this software without specific prior written permission. |
16 | * |
17 | * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY |
18 | * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
19 | * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
20 | * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY |
21 | * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
22 | * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
23 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
24 | * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
27 | */ |
28 | |
29 | #ifndef SymbolTable_h |
30 | #define SymbolTable_h |
31 | |
32 | #include "JSObject.h" |
33 | #include "UString.h" |
34 | #include <wtf/AlwaysInline.h> |
35 | |
36 | namespace JSC { |
37 | |
38 | static ALWAYS_INLINE int missingSymbolMarker() { return std::numeric_limits<int>::max(); } |
39 | |
40 | // The bit twiddling in this class assumes that every register index is a |
41 | // reasonably small positive or negative number, and therefore has its high |
42 | // four bits all set or all unset. |
43 | |
44 | struct SymbolTableEntry { |
45 | SymbolTableEntry() |
46 | : m_bits(0) |
47 | { |
48 | } |
49 | |
50 | SymbolTableEntry(int index) |
51 | { |
52 | ASSERT(isValidIndex(index)); |
53 | pack(index, readOnly: false, dontEnum: false); |
54 | } |
55 | |
56 | SymbolTableEntry(int index, unsigned attributes) |
57 | { |
58 | ASSERT(isValidIndex(index)); |
59 | pack(index, readOnly: attributes & ReadOnly, dontEnum: attributes & DontEnum); |
60 | } |
61 | |
62 | bool isNull() const |
63 | { |
64 | return !m_bits; |
65 | } |
66 | |
67 | int getIndex() const |
68 | { |
69 | return m_bits >> FlagBits; |
70 | } |
71 | |
72 | unsigned getAttributes() const |
73 | { |
74 | unsigned attributes = 0; |
75 | if (m_bits & ReadOnlyFlag) |
76 | attributes |= ReadOnly; |
77 | if (m_bits & DontEnumFlag) |
78 | attributes |= DontEnum; |
79 | return attributes; |
80 | } |
81 | |
82 | void setAttributes(unsigned attributes) |
83 | { |
84 | pack(index: getIndex(), readOnly: attributes & ReadOnly, dontEnum: attributes & DontEnum); |
85 | } |
86 | |
87 | bool isReadOnly() const |
88 | { |
89 | return m_bits & ReadOnlyFlag; |
90 | } |
91 | |
92 | private: |
93 | static const unsigned ReadOnlyFlag = 0x1; |
94 | static const unsigned DontEnumFlag = 0x2; |
95 | static const unsigned NotNullFlag = 0x4; |
96 | static const unsigned FlagBits = 3; |
97 | |
98 | void pack(int index, bool readOnly, bool dontEnum) |
99 | { |
100 | m_bits = (index << FlagBits) | NotNullFlag; |
101 | if (readOnly) |
102 | m_bits |= ReadOnlyFlag; |
103 | if (dontEnum) |
104 | m_bits |= DontEnumFlag; |
105 | } |
106 | |
107 | bool isValidIndex(int index) |
108 | { |
109 | return ((index << FlagBits) >> FlagBits) == index; |
110 | } |
111 | |
112 | int m_bits; |
113 | }; |
114 | |
115 | struct SymbolTableIndexHashTraits { |
116 | typedef SymbolTableEntry TraitType; |
117 | static SymbolTableEntry emptyValue() { return SymbolTableEntry(); } |
118 | static const bool emptyValueIsZero = true; |
119 | static const bool needsDestruction = false; |
120 | }; |
121 | |
122 | typedef HashMap<RefPtr<UString::Rep>, SymbolTableEntry, IdentifierRepHash, HashTraits<RefPtr<UString::Rep> >, SymbolTableIndexHashTraits> SymbolTable; |
123 | |
124 | class SharedSymbolTable : public SymbolTable, public RefCounted<SharedSymbolTable> |
125 | { |
126 | }; |
127 | |
128 | } // namespace JSC |
129 | |
130 | #endif // SymbolTable_h |
131 | |