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/OwnPtr.h" 25 #include "wtf/RefPtr.h" 26 #include "wtf/StdLibExtras.h" 27 #include <stdint.h> 28 29 namespace WTF { 30 31 template<size_t size> struct IntTypes; 32 template<> struct IntTypes<1> { typedef int8_t SignedType; typedef uint8_t UnsignedType; }; 33 template<> struct IntTypes<2> { typedef int16_t SignedType; typedef uint16_t UnsignedType; }; 34 template<> struct IntTypes<4> { typedef int32_t SignedType; typedef uint32_t UnsignedType; }; 35 template<> struct IntTypes<8> { typedef int64_t SignedType; typedef uint64_t UnsignedType; }; 36 37 // integer hash function 38 39 // Thomas Wang's 32 Bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm 40 inline unsigned intHash(uint8_t key8) 41 { 42 unsigned key = key8; 43 key += ~(key << 15); 44 key ^= (key >> 10); 45 key += (key << 3); 46 key ^= (key >> 6); 47 key += ~(key << 11); 48 key ^= (key >> 16); 49 return key; 50 } 51 52 // Thomas Wang's 32 Bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm 53 inline unsigned intHash(uint16_t key16) 54 { 55 unsigned key = key16; 56 key += ~(key << 15); 57 key ^= (key >> 10); 58 key += (key << 3); 59 key ^= (key >> 6); 60 key += ~(key << 11); 61 key ^= (key >> 16); 62 return key; 63 } 64 65 // Thomas Wang's 32 Bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm 66 inline unsigned intHash(uint32_t key) 67 { 68 key += ~(key << 15); 69 key ^= (key >> 10); 70 key += (key << 3); 71 key ^= (key >> 6); 72 key += ~(key << 11); 73 key ^= (key >> 16); 74 return key; 75 } 76 77 // Thomas Wang's 64 bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm 78 inline unsigned intHash(uint64_t key) 79 { 80 key += ~(key << 32); 81 key ^= (key >> 22); 82 key += ~(key << 13); 83 key ^= (key >> 8); 84 key += (key << 3); 85 key ^= (key >> 15); 86 key += ~(key << 27); 87 key ^= (key >> 31); 88 return static_cast<unsigned>(key); 89 } 90 91 // Compound integer hash method: http://opendatastructures.org/versions/edition-0.1d/ods-java/node33.html#SECTION00832000000000000000 92 inline unsigned pairIntHash(unsigned key1, unsigned key2) 93 { 94 unsigned shortRandom1 = 277951225; // A random 32-bit value. 95 unsigned shortRandom2 = 95187966; // A random 32-bit value. 96 uint64_t longRandom = 19248658165952622LL; // A random 64-bit value. 97 98 uint64_t product = longRandom * (shortRandom1 * key1 + shortRandom2 * key2); 99 unsigned highBits = static_cast<unsigned>(product >> (sizeof(uint64_t) - sizeof(unsigned))); 100 return highBits; 101 } 102 103 template<typename T> struct IntHash { 104 static unsigned hash(T key) { return intHash(static_cast<typename IntTypes<sizeof(T)>::UnsignedType>(key)); } 105 static bool equal(T a, T b) { return a == b; } 106 static const bool safeToCompareToEmptyOrDeleted = true; 107 }; 108 109 template<typename T> struct FloatHash { 110 typedef typename IntTypes<sizeof(T)>::UnsignedType Bits; 111 static unsigned hash(T key) 112 { 113 return intHash(bitwise_cast<Bits>(key)); 114 } 115 static bool equal(T a, T b) 116 { 117 return bitwise_cast<Bits>(a) == bitwise_cast<Bits>(b); 118 } 119 static const bool safeToCompareToEmptyOrDeleted = true; 120 }; 121 122 // pointer identity hash function 123 124 template<typename T> struct PtrHash { 125 static unsigned hash(T key) 126 { 127 #if COMPILER(MSVC) 128 #pragma warning(push) 129 #pragma warning(disable: 4244) // work around what seems to be a bug in MSVC's conversion warnings 130 #endif 131 return IntHash<uintptr_t>::hash(reinterpret_cast<uintptr_t>(key)); 132 #if COMPILER(MSVC) 133 #pragma warning(pop) 134 #endif 135 } 136 static bool equal(T a, T b) { return a == b; } 137 static bool equal(std::nullptr_t, T b) { return b == 0; } 138 static bool equal(T a, std::nullptr_t) { return a == 0; } 139 static const bool safeToCompareToEmptyOrDeleted = true; 140 }; 141 template<typename P> struct PtrHash<RefPtr<P> > : PtrHash<P*> { 142 using PtrHash<P*>::hash; 143 static unsigned hash(const RefPtr<P>& key) { return hash(key.get()); } 144 static unsigned hash(const PassRefPtr<P>& key) { return hash(key.get()); } 145 using PtrHash<P*>::equal; 146 static bool equal(const RefPtr<P>& a, const RefPtr<P>& b) { return a == b; } 147 static bool equal(P* a, const RefPtr<P>& b) { return a == b; } 148 static bool equal(const RefPtr<P>& a, P* b) { return a == b; } 149 static bool equal(const RefPtr<P>& a, const PassRefPtr<P>& b) { return a == b; } 150 }; 151 template<typename P> struct PtrHash<RawPtr<P> > : PtrHash<P*> { 152 using PtrHash<P*>::hash; 153 static unsigned hash(const RawPtr<P>& key) { return hash(key.get()); } 154 using PtrHash<P*>::equal; 155 static bool equal(const RawPtr<P>& a, const RawPtr<P>& b) { return a == b; } 156 static bool equal(P* a, const RawPtr<P>& b) { return a == b; } 157 static bool equal(const RawPtr<P>& a, P* b) { return a == b; } 158 }; 159 template<typename P> struct PtrHash<OwnPtr<P> > : PtrHash<P*> { 160 using PtrHash<P*>::hash; 161 static unsigned hash(const OwnPtr<P>& key) { return hash(key.get()); } 162 static unsigned hash(const PassOwnPtr<P>& key) { return hash(key.get()); } 163 164 static bool equal(const OwnPtr<P>& a, const OwnPtr<P>& b) 165 { 166 return a.get() == b.get(); 167 } 168 static bool equal(const OwnPtr<P>& a, P* b) { return a == b; } 169 static bool equal(const OwnPtr<P>& a, const PassOwnPtr<P>& b) 170 { 171 return a.get() == b.get(); 172 } 173 }; 174 175 // default hash function for each type 176 177 template<typename T> struct DefaultHash; 178 179 template<typename T, typename U> struct PairHash { 180 static unsigned hash(const std::pair<T, U>& p) 181 { 182 return pairIntHash(DefaultHash<T>::Hash::hash(p.first), DefaultHash<U>::Hash::hash(p.second)); 183 } 184 static bool equal(const std::pair<T, U>& a, const std::pair<T, U>& b) 185 { 186 return DefaultHash<T>::Hash::equal(a.first, b.first) && DefaultHash<U>::Hash::equal(a.second, b.second); 187 } 188 static const bool safeToCompareToEmptyOrDeleted = DefaultHash<T>::Hash::safeToCompareToEmptyOrDeleted 189 && DefaultHash<U>::Hash::safeToCompareToEmptyOrDeleted; 190 }; 191 192 template<typename T, typename U> struct IntPairHash { 193 static unsigned hash(const std::pair<T, U>& p) { return pairIntHash(p.first, p.second); } 194 static bool equal(const std::pair<T, U>& a, const std::pair<T, U>& b) { return PairHash<T, T>::equal(a, b); } 195 static const bool safeToCompareToEmptyOrDeleted = PairHash<T, U>::safeToCompareToEmptyOrDeleted; 196 }; 197 198 // make IntHash the default hash function for many integer types 199 200 template<> struct DefaultHash<short> { typedef IntHash<unsigned> Hash; }; 201 template<> struct DefaultHash<unsigned short> { typedef IntHash<unsigned> Hash; }; 202 template<> struct DefaultHash<int> { typedef IntHash<unsigned> Hash; }; 203 template<> struct DefaultHash<unsigned> { typedef IntHash<unsigned> Hash; }; 204 template<> struct DefaultHash<long> { typedef IntHash<unsigned long> Hash; }; 205 template<> struct DefaultHash<unsigned long> { typedef IntHash<unsigned long> Hash; }; 206 template<> struct DefaultHash<long long> { typedef IntHash<unsigned long long> Hash; }; 207 template<> struct DefaultHash<unsigned long long> { typedef IntHash<unsigned long long> Hash; }; 208 209 #if !COMPILER(MSVC) || defined(_NATIVE_WCHAR_T_DEFINED) 210 template<> struct DefaultHash<wchar_t> { typedef IntHash<wchar_t> Hash; }; 211 #endif 212 213 template<> struct DefaultHash<float> { typedef FloatHash<float> Hash; }; 214 template<> struct DefaultHash<double> { typedef FloatHash<double> Hash; }; 215 216 // make PtrHash the default hash function for pointer types that don't specialize 217 218 template<typename P> struct DefaultHash<P*> { typedef PtrHash<P*> Hash; }; 219 template<typename P> struct DefaultHash<RefPtr<P> > { typedef PtrHash<RefPtr<P> > Hash; }; 220 template<typename P> struct DefaultHash<RawPtr<P> > { typedef PtrHash<RawPtr<P> > Hash; }; 221 template<typename P> struct DefaultHash<OwnPtr<P> > { typedef PtrHash<OwnPtr<P> > Hash; }; 222 223 // make IntPairHash the default hash function for pairs of (at most) 32-bit integers. 224 225 template<> struct DefaultHash<std::pair<short, short> > { typedef IntPairHash<short, short> Hash; }; 226 template<> struct DefaultHash<std::pair<short, unsigned short> > { typedef IntPairHash<short, unsigned short> Hash; }; 227 template<> struct DefaultHash<std::pair<short, int> > { typedef IntPairHash<short, int> Hash; }; 228 template<> struct DefaultHash<std::pair<short, unsigned> > { typedef IntPairHash<short, unsigned> Hash; }; 229 template<> struct DefaultHash<std::pair<unsigned short, short> > { typedef IntPairHash<unsigned short, short> Hash; }; 230 template<> struct DefaultHash<std::pair<unsigned short, unsigned short> > { typedef IntPairHash<unsigned short, unsigned short> Hash; }; 231 template<> struct DefaultHash<std::pair<unsigned short, int> > { typedef IntPairHash<unsigned short, int> Hash; }; 232 template<> struct DefaultHash<std::pair<unsigned short, unsigned> > { typedef IntPairHash<unsigned short, unsigned> Hash; }; 233 template<> struct DefaultHash<std::pair<int, short> > { typedef IntPairHash<int, short> Hash; }; 234 template<> struct DefaultHash<std::pair<int, unsigned short> > { typedef IntPairHash<int, unsigned short> Hash; }; 235 template<> struct DefaultHash<std::pair<int, int> > { typedef IntPairHash<int, int> Hash; }; 236 template<> struct DefaultHash<std::pair<int, unsigned> > { typedef IntPairHash<unsigned, unsigned> Hash; }; 237 template<> struct DefaultHash<std::pair<unsigned, short> > { typedef IntPairHash<unsigned, short> Hash; }; 238 template<> struct DefaultHash<std::pair<unsigned, unsigned short> > { typedef IntPairHash<unsigned, unsigned short> Hash; }; 239 template<> struct DefaultHash<std::pair<unsigned, int> > { typedef IntPairHash<unsigned, int> Hash; }; 240 template<> struct DefaultHash<std::pair<unsigned, unsigned> > { typedef IntPairHash<unsigned, unsigned> Hash; }; 241 242 // make PairHash the default hash function for pairs of arbitrary values. 243 244 template<typename T, typename U> struct DefaultHash<std::pair<T, U> > { typedef PairHash<T, U> Hash; }; 245 246 } // namespace WTF 247 248 using WTF::DefaultHash; 249 using WTF::IntHash; 250 using WTF::PtrHash; 251 252 #endif // WTF_HashFunctions_h 253