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 | |
27 | namespace 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 | |