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 "wtf/StdLibExtras.h" 26 #include <stdint.h> 27 28 namespace WTF { 29 30 template<size_t size> struct IntTypes; 31 template<> struct IntTypes<1> { typedef int8_t SignedType; typedef uint8_t UnsignedType; }; 32 template<> struct IntTypes<2> { typedef int16_t SignedType; typedef uint16_t UnsignedType; }; 33 template<> struct IntTypes<4> { typedef int32_t SignedType; typedef uint32_t UnsignedType; }; 34 template<> struct IntTypes<8> { typedef int64_t SignedType; typedef uint64_t UnsignedType; }; 35 36 // integer hash function 37 38 // Thomas Wang's 32 Bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm 39 inline unsigned intHash(uint8_t key8) 40 { 41 unsigned key = key8; 42 key += ~(key << 15); 43 key ^= (key >> 10); 44 key += (key << 3); 45 key ^= (key >> 6); 46 key += ~(key << 11); 47 key ^= (key >> 16); 48 return key; 49 } 50 51 // Thomas Wang's 32 Bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm 52 inline unsigned intHash(uint16_t key16) 53 { 54 unsigned key = key16; 55 key += ~(key << 15); 56 key ^= (key >> 10); 57 key += (key << 3); 58 key ^= (key >> 6); 59 key += ~(key << 11); 60 key ^= (key >> 16); 61 return key; 62 } 63 64 // Thomas Wang's 32 Bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm 65 inline unsigned intHash(uint32_t key) 66 { 67 key += ~(key << 15); 68 key ^= (key >> 10); 69 key += (key << 3); 70 key ^= (key >> 6); 71 key += ~(key << 11); 72 key ^= (key >> 16); 73 return key; 74 } 75 76 // Thomas Wang's 64 bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm 77 inline unsigned intHash(uint64_t key) 78 { 79 key += ~(key << 32); 80 key ^= (key >> 22); 81 key += ~(key << 13); 82 key ^= (key >> 8); 83 key += (key << 3); 84 key ^= (key >> 15); 85 key += ~(key << 27); 86 key ^= (key >> 31); 87 return static_cast<unsigned>(key); 88 } 89 90 // Compound integer hash method: http://opendatastructures.org/versions/edition-0.1d/ods-java/node33.html#SECTION00832000000000000000 91 inline unsigned pairIntHash(unsigned key1, unsigned key2) 92 { 93 unsigned shortRandom1 = 277951225; // A random 32-bit value. 94 unsigned shortRandom2 = 95187966; // A random 32-bit value. 95 uint64_t longRandom = 19248658165952622LL; // A random 64-bit value. 96 97 uint64_t product = longRandom * (shortRandom1 * key1 + shortRandom2 * key2); 98 unsigned highBits = static_cast<unsigned>(product >> (sizeof(uint64_t) - sizeof(unsigned))); 99 return highBits; 100 } 101 102 template<typename T> struct IntHash { 103 static unsigned hash(T key) { return intHash(static_cast<typename IntTypes<sizeof(T)>::UnsignedType>(key)); } 104 static bool equal(T a, T b) { return a == b; } 105 static const bool safeToCompareToEmptyOrDeleted = true; 106 }; 107 108 template<typename T> struct FloatHash { 109 typedef typename IntTypes<sizeof(T)>::UnsignedType Bits; 110 static unsigned hash(T key) 111 { 112 return intHash(bitwise_cast<Bits>(key)); 113 } 114 static bool equal(T a, T b) 115 { 116 return bitwise_cast<Bits>(a) == bitwise_cast<Bits>(b); 117 } 118 static const bool safeToCompareToEmptyOrDeleted = true; 119 }; 120 121 // pointer identity hash function 122 123 template<typename T> struct PtrHash { 124 static unsigned hash(T key) 125 { 126 #if COMPILER(MSVC) 127 #pragma warning(push) 128 #pragma warning(disable: 4244) // work around what seems to be a bug in MSVC's conversion warnings 129 #endif 130 return IntHash<uintptr_t>::hash(reinterpret_cast<uintptr_t>(key)); 131 #if COMPILER(MSVC) 132 #pragma warning(pop) 133 #endif 134 } 135 static bool equal(T a, T b) { return a == b; } 136 static const bool safeToCompareToEmptyOrDeleted = true; 137 }; 138 template<typename P> struct PtrHash<RefPtr<P> > : PtrHash<P*> { 139 using PtrHash<P*>::hash; 140 static unsigned hash(const RefPtr<P>& key) { return hash(key.get()); } 141 using PtrHash<P*>::equal; 142 static bool equal(const RefPtr<P>& a, const RefPtr<P>& b) { return a == b; } 143 static bool equal(P* a, const RefPtr<P>& b) { return a == b; } 144 static bool equal(const RefPtr<P>& a, P* b) { return a == b; } 145 }; 146 147 // default hash function for each type 148 149 template<typename T> struct DefaultHash; 150 151 template<typename T, typename U> struct PairHash { 152 static unsigned hash(const std::pair<T, U>& p) 153 { 154 return pairIntHash(DefaultHash<T>::Hash::hash(p.first), DefaultHash<U>::Hash::hash(p.second)); 155 } 156 static bool equal(const std::pair<T, U>& a, const std::pair<T, U>& b) 157 { 158 return DefaultHash<T>::Hash::equal(a.first, b.first) && DefaultHash<U>::Hash::equal(a.second, b.second); 159 } 160 static const bool safeToCompareToEmptyOrDeleted = DefaultHash<T>::Hash::safeToCompareToEmptyOrDeleted 161 && DefaultHash<U>::Hash::safeToCompareToEmptyOrDeleted; 162 }; 163 164 template<typename T, typename U> struct IntPairHash { 165 static unsigned hash(const std::pair<T, U>& p) { return pairIntHash(p.first, p.second); } 166 static bool equal(const std::pair<T, U>& a, const std::pair<T, U>& b) { return PairHash<T, T>::equal(a, b); } 167 static const bool safeToCompareToEmptyOrDeleted = PairHash<T, U>::safeToCompareToEmptyOrDeleted; 168 }; 169 170 // make IntHash the default hash function for many integer types 171 172 template<> struct DefaultHash<short> { typedef IntHash<unsigned> Hash; }; 173 template<> struct DefaultHash<unsigned short> { typedef IntHash<unsigned> Hash; }; 174 template<> struct DefaultHash<int> { typedef IntHash<unsigned> Hash; }; 175 template<> struct DefaultHash<unsigned> { typedef IntHash<unsigned> Hash; }; 176 template<> struct DefaultHash<long> { typedef IntHash<unsigned long> Hash; }; 177 template<> struct DefaultHash<unsigned long> { typedef IntHash<unsigned long> Hash; }; 178 template<> struct DefaultHash<long long> { typedef IntHash<unsigned long long> Hash; }; 179 template<> struct DefaultHash<unsigned long long> { typedef IntHash<unsigned long long> Hash; }; 180 181 #if !COMPILER(MSVC) || defined(_NATIVE_WCHAR_T_DEFINED) 182 template<> struct DefaultHash<wchar_t> { typedef IntHash<wchar_t> Hash; }; 183 #endif 184 185 template<> struct DefaultHash<float> { typedef FloatHash<float> Hash; }; 186 template<> struct DefaultHash<double> { typedef FloatHash<double> Hash; }; 187 188 // make PtrHash the default hash function for pointer types that don't specialize 189 190 template<typename P> struct DefaultHash<P*> { typedef PtrHash<P*> Hash; }; 191 template<typename P> struct DefaultHash<RefPtr<P> > { typedef PtrHash<RefPtr<P> > Hash; }; 192 193 // make IntPairHash the default hash function for pairs of (at most) 32-bit integers. 194 195 template<> struct DefaultHash<std::pair<short, short> > { typedef IntPairHash<short, short> Hash; }; 196 template<> struct DefaultHash<std::pair<short, unsigned short> > { typedef IntPairHash<short, unsigned short> Hash; }; 197 template<> struct DefaultHash<std::pair<short, int> > { typedef IntPairHash<short, int> Hash; }; 198 template<> struct DefaultHash<std::pair<short, unsigned> > { typedef IntPairHash<short, unsigned> Hash; }; 199 template<> struct DefaultHash<std::pair<unsigned short, short> > { typedef IntPairHash<unsigned short, short> Hash; }; 200 template<> struct DefaultHash<std::pair<unsigned short, unsigned short> > { typedef IntPairHash<unsigned short, unsigned short> Hash; }; 201 template<> struct DefaultHash<std::pair<unsigned short, int> > { typedef IntPairHash<unsigned short, int> Hash; }; 202 template<> struct DefaultHash<std::pair<unsigned short, unsigned> > { typedef IntPairHash<unsigned short, unsigned> Hash; }; 203 template<> struct DefaultHash<std::pair<int, short> > { typedef IntPairHash<int, short> Hash; }; 204 template<> struct DefaultHash<std::pair<int, unsigned short> > { typedef IntPairHash<int, unsigned short> Hash; }; 205 template<> struct DefaultHash<std::pair<int, int> > { typedef IntPairHash<int, int> Hash; }; 206 template<> struct DefaultHash<std::pair<int, unsigned> > { typedef IntPairHash<unsigned, unsigned> Hash; }; 207 template<> struct DefaultHash<std::pair<unsigned, short> > { typedef IntPairHash<unsigned, short> Hash; }; 208 template<> struct DefaultHash<std::pair<unsigned, unsigned short> > { typedef IntPairHash<unsigned, unsigned short> Hash; }; 209 template<> struct DefaultHash<std::pair<unsigned, int> > { typedef IntPairHash<unsigned, int> Hash; }; 210 template<> struct DefaultHash<std::pair<unsigned, unsigned> > { typedef IntPairHash<unsigned, unsigned> Hash; }; 211 212 // make PairHash the default hash function for pairs of arbitrary values. 213 214 template<typename T, typename U> struct DefaultHash<std::pair<T, U> > { typedef PairHash<T, U> Hash; }; 215 216 } // namespace WTF 217 218 using WTF::DefaultHash; 219 using WTF::IntHash; 220 using WTF::PtrHash; 221 222 #endif // WTF_HashFunctions_h 223