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
36namespace 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

source code of qtscript/src/3rdparty/javascriptcore/JavaScriptCore/runtime/SymbolTable.h