1/*
2 * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Library General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
8 *
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Library General Public License for more details.
13 *
14 * You should have received a copy of the GNU Library General Public License
15 * along with this library; see the file COPYING.LIB. If not, write to
16 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
17 * Boston, MA 02110-1301, USA.
18 *
19 */
20
21#ifndef PropertyMapHashTable_h
22#define PropertyMapHashTable_h
23
24#include "UString.h"
25#include <wtf/Vector.h>
26
27namespace JSC {
28
29 struct PropertyMapEntry {
30 UString::Rep* key;
31 unsigned offset;
32 unsigned attributes;
33 JSCell* specificValue;
34 unsigned index;
35
36 PropertyMapEntry(UString::Rep* key, unsigned attributes, JSCell* specificValue)
37 : key(key)
38 , offset(0)
39 , attributes(attributes)
40 , specificValue(specificValue)
41 , index(0)
42 {
43 }
44
45 PropertyMapEntry(UString::Rep* key, unsigned offset, unsigned attributes, JSCell* specificValue, unsigned index)
46 : key(key)
47 , offset(offset)
48 , attributes(attributes)
49 , specificValue(specificValue)
50 , index(index)
51 {
52 }
53 };
54
55 // lastIndexUsed is an ever-increasing index used to identify the order items
56 // were inserted into the property map. It's required that getEnumerablePropertyNames
57 // return the properties in the order they were added for compatibility with other
58 // browsers' JavaScript implementations.
59 struct PropertyMapHashTable {
60 unsigned sizeMask;
61 unsigned size;
62 unsigned keyCount;
63 unsigned deletedSentinelCount;
64 unsigned anonymousSlotCount;
65 unsigned lastIndexUsed;
66 Vector<unsigned>* deletedOffsets;
67 unsigned entryIndices[1];
68
69 PropertyMapEntry* entries()
70 {
71 // The entries vector comes after the indices vector.
72 // The 0th item in the entries vector is not really used; it has to
73 // have a 0 in its key to allow the hash table lookup to handle deleted
74 // sentinels without any special-case code, but the other fields are unused.
75 return reinterpret_cast<PropertyMapEntry*>(&entryIndices[size]);
76 }
77
78 static size_t allocationSize(unsigned size)
79 {
80 // We never let a hash table get more than half full,
81 // So the number of indices we need is the size of the hash table.
82 // But the number of entries is half that (plus one for the deleted sentinel).
83 return sizeof(PropertyMapHashTable)
84 + (size - 1) * sizeof(unsigned)
85 + (1 + size / 2) * sizeof(PropertyMapEntry);
86 }
87 };
88
89} // namespace JSC
90
91#endif // PropertyMapHashTable_h
92

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