1/* 2 * Copyright (C) 2005, 2006, 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 WTF_HashFunctions_h 22#define WTF_HashFunctions_h 23 24#include <wtf/RefPtr.h> 25#include <stdint.h> 26 27namespace WTF { 28 29 template<size_t size> struct IntTypes; 30 template<> struct IntTypes<1> { typedef int8_t SignedType; typedef uint8_t UnsignedType; }; 31 template<> struct IntTypes<2> { typedef int16_t SignedType; typedef uint16_t UnsignedType; }; 32 template<> struct IntTypes<4> { typedef int32_t SignedType; typedef uint32_t UnsignedType; }; 33 template<> struct IntTypes<8> { typedef int64_t SignedType; typedef uint64_t UnsignedType; }; 34 35 // integer hash function 36 37 // Thomas Wang's 32 Bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm 38 inline unsigned intHash(uint8_t key8) 39 { 40 unsigned key = key8; 41 key += ~(key << 15); 42 key ^= (key >> 10); 43 key += (key << 3); 44 key ^= (key >> 6); 45 key += ~(key << 11); 46 key ^= (key >> 16); 47 return key; 48 } 49 50 // Thomas Wang's 32 Bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm 51 inline unsigned intHash(uint16_t key16) 52 { 53 unsigned key = key16; 54 key += ~(key << 15); 55 key ^= (key >> 10); 56 key += (key << 3); 57 key ^= (key >> 6); 58 key += ~(key << 11); 59 key ^= (key >> 16); 60 return key; 61 } 62 63 // Thomas Wang's 32 Bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm 64 inline unsigned intHash(uint32_t key) 65 { 66 key += ~(key << 15); 67 key ^= (key >> 10); 68 key += (key << 3); 69 key ^= (key >> 6); 70 key += ~(key << 11); 71 key ^= (key >> 16); 72 return key; 73 } 74 75 // Thomas Wang's 64 bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm 76 inline unsigned intHash(uint64_t key) 77 { 78 key += ~(key << 32); 79 key ^= (key >> 22); 80 key += ~(key << 13); 81 key ^= (key >> 8); 82 key += (key << 3); 83 key ^= (key >> 15); 84 key += ~(key << 27); 85 key ^= (key >> 31); 86 return static_cast<unsigned>(key); 87 } 88 89 // Compound integer hash method: http://opendatastructures.org/versions/edition-0.1d/ods-java/node33.html#SECTION00832000000000000000 90 inline unsigned pairIntHash(unsigned key1, unsigned key2) 91 { 92 unsigned shortRandom1 = 277951225; // A random 32-bit value. 93 unsigned shortRandom2 = 95187966; // A random 32-bit value. 94 uint64_t longRandom = 19248658165952622LL; // A random 64-bit value. 95 96 uint64_t product = longRandom * (shortRandom1 * key1 + shortRandom2 * key2); 97 unsigned highBits = static_cast<unsigned>(product >> (sizeof(uint64_t) - sizeof(unsigned))); 98 return highBits; 99 } 100 101 template<typename T> struct IntHash { 102 static unsigned hash(T key) { return intHash(static_cast<typename IntTypes<sizeof(T)>::UnsignedType>(key)); } 103 static bool equal(T a, T b) { return a == b; } 104 static const bool safeToCompareToEmptyOrDeleted = true; 105 }; 106 107 template<typename T> struct FloatHash { 108 typedef typename IntTypes<sizeof(T)>::UnsignedType Bits; 109 static unsigned hash(T key) 110 { 111 return intHash(bitwise_cast<Bits>(key)); 112 } 113 static bool equal(T a, T b) 114 { 115 return bitwise_cast<Bits>(a) == bitwise_cast<Bits>(b); 116 } 117 static const bool safeToCompareToEmptyOrDeleted = true; 118 }; 119 120 // pointer identity hash function 121 122 template<typename T> struct PtrHash { 123 static unsigned hash(T key) 124 { 125 return IntHash<uintptr_t>::hash(reinterpret_cast<uintptr_t>(key)); 126 } 127 static bool equal(T a, T b) { return a == b; } 128 static const bool safeToCompareToEmptyOrDeleted = true; 129 }; 130 template<typename P> struct PtrHash<RefPtr<P>> : PtrHash<P*> { 131 using PtrHash<P*>::hash; 132 static unsigned hash(const RefPtr<P>& key) { return hash(key.get()); } 133 using PtrHash<P*>::equal; 134 static bool equal(const RefPtr<P>& a, const RefPtr<P>& b) { return a == b; } 135 static bool equal(P* a, const RefPtr<P>& b) { return a == b; } 136 static bool equal(const RefPtr<P>& a, P* b) { return a == b; } 137 }; 138 139 // default hash function for each type 140 141 template<typename T> struct DefaultHash; 142 143 template<typename T, typename U> struct PairHash { 144 static unsigned hash(const std::pair<T, U>& p) 145 { 146 return pairIntHash(DefaultHash<T>::Hash::hash(p.first), DefaultHash<U>::Hash::hash(p.second)); 147 } 148 static bool equal(const std::pair<T, U>& a, const std::pair<T, U>& b) 149 { 150 return DefaultHash<T>::Hash::equal(a.first, b.first) && DefaultHash<U>::Hash::equal(a.second, b.second); 151 } 152 static const bool safeToCompareToEmptyOrDeleted = DefaultHash<T>::Hash::safeToCompareToEmptyOrDeleted 153 && DefaultHash<U>::Hash::safeToCompareToEmptyOrDeleted; 154 }; 155 156 template<typename T, typename U> struct IntPairHash { 157 static unsigned hash(const std::pair<T, U>& p) { return pairIntHash(p.first, p.second); } 158 static bool equal(const std::pair<T, U>& a, const std::pair<T, U>& b) { return PairHash<T, T>::equal(a, b); } 159 static const bool safeToCompareToEmptyOrDeleted = PairHash<T, U>::safeToCompareToEmptyOrDeleted; 160 }; 161 162 // make IntHash the default hash function for many integer types 163 164 template<> struct DefaultHash<short> { typedef IntHash<unsigned> Hash; }; 165 template<> struct DefaultHash<unsigned short> { typedef IntHash<unsigned> Hash; }; 166 template<> struct DefaultHash<int> { typedef IntHash<unsigned> Hash; }; 167 template<> struct DefaultHash<unsigned> { typedef IntHash<unsigned> Hash; }; 168 template<> struct DefaultHash<long> { typedef IntHash<unsigned long> Hash; }; 169 template<> struct DefaultHash<unsigned long> { typedef IntHash<unsigned long> Hash; }; 170 template<> struct DefaultHash<long long> { typedef IntHash<unsigned long long> Hash; }; 171 template<> struct DefaultHash<unsigned long long> { typedef IntHash<unsigned long long> Hash; }; 172 173#if defined(_NATIVE_WCHAR_T_DEFINED) 174 template<> struct DefaultHash<wchar_t> { typedef IntHash<wchar_t> Hash; }; 175#endif 176 177 template<> struct DefaultHash<float> { typedef FloatHash<float> Hash; }; 178 template<> struct DefaultHash<double> { typedef FloatHash<double> Hash; }; 179 180 // make PtrHash the default hash function for pointer types that don't specialize 181 182 template<typename P> struct DefaultHash<P*> { typedef PtrHash<P*> Hash; }; 183 template<typename P> struct DefaultHash<RefPtr<P>> { typedef PtrHash<RefPtr<P>> Hash; }; 184 185 // make IntPairHash the default hash function for pairs of (at most) 32-bit integers. 186 187 template<> struct DefaultHash<std::pair<short, short>> { typedef IntPairHash<short, short> Hash; }; 188 template<> struct DefaultHash<std::pair<short, unsigned short>> { typedef IntPairHash<short, unsigned short> Hash; }; 189 template<> struct DefaultHash<std::pair<short, int>> { typedef IntPairHash<short, int> Hash; }; 190 template<> struct DefaultHash<std::pair<short, unsigned>> { typedef IntPairHash<short, unsigned> Hash; }; 191 template<> struct DefaultHash<std::pair<unsigned short, short>> { typedef IntPairHash<unsigned short, short> Hash; }; 192 template<> struct DefaultHash<std::pair<unsigned short, unsigned short>> { typedef IntPairHash<unsigned short, unsigned short> Hash; }; 193 template<> struct DefaultHash<std::pair<unsigned short, int>> { typedef IntPairHash<unsigned short, int> Hash; }; 194 template<> struct DefaultHash<std::pair<unsigned short, unsigned>> { typedef IntPairHash<unsigned short, unsigned> Hash; }; 195 template<> struct DefaultHash<std::pair<int, short>> { typedef IntPairHash<int, short> Hash; }; 196 template<> struct DefaultHash<std::pair<int, unsigned short>> { typedef IntPairHash<int, unsigned short> Hash; }; 197 template<> struct DefaultHash<std::pair<int, int>> { typedef IntPairHash<int, int> Hash; }; 198 template<> struct DefaultHash<std::pair<int, unsigned>> { typedef IntPairHash<unsigned, unsigned> Hash; }; 199 template<> struct DefaultHash<std::pair<unsigned, short>> { typedef IntPairHash<unsigned, short> Hash; }; 200 template<> struct DefaultHash<std::pair<unsigned, unsigned short>> { typedef IntPairHash<unsigned, unsigned short> Hash; }; 201 template<> struct DefaultHash<std::pair<unsigned, int>> { typedef IntPairHash<unsigned, int> Hash; }; 202 template<> struct DefaultHash<std::pair<unsigned, unsigned>> { typedef IntPairHash<unsigned, unsigned> Hash; }; 203 204 // make PairHash the default hash function for pairs of arbitrary values. 205 206 template<typename T, typename U> struct DefaultHash<std::pair<T, U>> { typedef PairHash<T, U> Hash; }; 207 208} // namespace WTF 209 210using WTF::DefaultHash; 211using WTF::IntHash; 212using WTF::PtrHash; 213 214#endif // WTF_HashFunctions_h 215