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 PropertyMapEntryPropertyMapEntry36 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 PropertyMapEntryPropertyMapEntry45 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 lastIndexUsed; 65 Vector<unsigned>* deletedOffsets; 66 unsigned entryIndices[1]; 67 entriesPropertyMapHashTable68 PropertyMapEntry* entries() 69 { 70 // The entries vector comes after the indices vector. 71 // The 0th item in the entries vector is not really used; it has to 72 // have a 0 in its key to allow the hash table lookup to handle deleted 73 // sentinels without any special-case code, but the other fields are unused. 74 return reinterpret_cast<PropertyMapEntry*>(&entryIndices[size]); 75 } 76 allocationSizePropertyMapHashTable77 static size_t allocationSize(unsigned size) 78 { 79 // We never let a hash table get more than half full, 80 // So the number of indices we need is the size of the hash table. 81 // But the number of entries is half that (plus one for the deleted sentinel). 82 return sizeof(PropertyMapHashTable) 83 + (size - 1) * sizeof(unsigned) 84 + (1 + size / 2) * sizeof(PropertyMapEntry); 85 } 86 }; 87 88 } // namespace JSC 89 90 #endif // PropertyMapHashTable_h 91