Torne (Richard Coles) | 5c87bf8 | 2012-11-14 11:46:17 +0000 | [diff] [blame] | 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 | |
| 27 | namespace 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 | #if COMPILER(MSVC) |
| 126 | #pragma warning(push) |
| 127 | #pragma warning(disable: 4244) // work around what seems to be a bug in MSVC's conversion warnings |
| 128 | #endif |
| 129 | return IntHash<uintptr_t>::hash(reinterpret_cast<uintptr_t>(key)); |
| 130 | #if COMPILER(MSVC) |
| 131 | #pragma warning(pop) |
| 132 | #endif |
| 133 | } |
| 134 | static bool equal(T a, T b) { return a == b; } |
| 135 | static const bool safeToCompareToEmptyOrDeleted = true; |
| 136 | }; |
| 137 | template<typename P> struct PtrHash<RefPtr<P> > : PtrHash<P*> { |
| 138 | using PtrHash<P*>::hash; |
| 139 | static unsigned hash(const RefPtr<P>& key) { return hash(key.get()); } |
| 140 | using PtrHash<P*>::equal; |
| 141 | static bool equal(const RefPtr<P>& a, const RefPtr<P>& b) { return a == b; } |
| 142 | static bool equal(P* a, const RefPtr<P>& b) { return a == b; } |
| 143 | static bool equal(const RefPtr<P>& a, P* b) { return a == b; } |
| 144 | }; |
| 145 | |
| 146 | // default hash function for each type |
| 147 | |
| 148 | template<typename T> struct DefaultHash; |
| 149 | |
| 150 | template<typename T, typename U> struct PairHash { |
| 151 | static unsigned hash(const std::pair<T, U>& p) |
| 152 | { |
| 153 | return pairIntHash(DefaultHash<T>::Hash::hash(p.first), DefaultHash<U>::Hash::hash(p.second)); |
| 154 | } |
| 155 | static bool equal(const std::pair<T, U>& a, const std::pair<T, U>& b) |
| 156 | { |
| 157 | return DefaultHash<T>::Hash::equal(a.first, b.first) && DefaultHash<U>::Hash::equal(a.second, b.second); |
| 158 | } |
| 159 | static const bool safeToCompareToEmptyOrDeleted = DefaultHash<T>::Hash::safeToCompareToEmptyOrDeleted |
| 160 | && DefaultHash<U>::Hash::safeToCompareToEmptyOrDeleted; |
| 161 | }; |
| 162 | |
| 163 | template<typename T, typename U> struct IntPairHash { |
| 164 | static unsigned hash(const std::pair<T, U>& p) { return pairIntHash(p.first, p.second); } |
| 165 | static bool equal(const std::pair<T, U>& a, const std::pair<T, U>& b) { return PairHash<T, T>::equal(a, b); } |
| 166 | static const bool safeToCompareToEmptyOrDeleted = PairHash<T, U>::safeToCompareToEmptyOrDeleted; |
| 167 | }; |
| 168 | |
| 169 | // make IntHash the default hash function for many integer types |
| 170 | |
| 171 | template<> struct DefaultHash<short> { typedef IntHash<unsigned> Hash; }; |
| 172 | template<> struct DefaultHash<unsigned short> { typedef IntHash<unsigned> Hash; }; |
| 173 | template<> struct DefaultHash<int> { typedef IntHash<unsigned> Hash; }; |
| 174 | template<> struct DefaultHash<unsigned> { typedef IntHash<unsigned> Hash; }; |
| 175 | template<> struct DefaultHash<long> { typedef IntHash<unsigned long> Hash; }; |
| 176 | template<> struct DefaultHash<unsigned long> { typedef IntHash<unsigned long> Hash; }; |
| 177 | template<> struct DefaultHash<long long> { typedef IntHash<unsigned long long> Hash; }; |
| 178 | template<> struct DefaultHash<unsigned long long> { typedef IntHash<unsigned long long> Hash; }; |
| 179 | |
| 180 | #if !COMPILER(MSVC) || defined(_NATIVE_WCHAR_T_DEFINED) |
| 181 | template<> struct DefaultHash<wchar_t> { typedef IntHash<wchar_t> Hash; }; |
| 182 | #endif |
| 183 | |
| 184 | template<> struct DefaultHash<float> { typedef FloatHash<float> Hash; }; |
| 185 | template<> struct DefaultHash<double> { typedef FloatHash<double> Hash; }; |
| 186 | |
| 187 | // make PtrHash the default hash function for pointer types that don't specialize |
| 188 | |
| 189 | template<typename P> struct DefaultHash<P*> { typedef PtrHash<P*> Hash; }; |
| 190 | template<typename P> struct DefaultHash<RefPtr<P> > { typedef PtrHash<RefPtr<P> > Hash; }; |
| 191 | |
| 192 | // make IntPairHash the default hash function for pairs of (at most) 32-bit integers. |
| 193 | |
| 194 | template<> struct DefaultHash<std::pair<short, short> > { typedef IntPairHash<short, short> Hash; }; |
| 195 | template<> struct DefaultHash<std::pair<short, unsigned short> > { typedef IntPairHash<short, unsigned short> Hash; }; |
| 196 | template<> struct DefaultHash<std::pair<short, int> > { typedef IntPairHash<short, int> Hash; }; |
| 197 | template<> struct DefaultHash<std::pair<short, unsigned> > { typedef IntPairHash<short, unsigned> Hash; }; |
| 198 | template<> struct DefaultHash<std::pair<unsigned short, short> > { typedef IntPairHash<unsigned short, short> Hash; }; |
| 199 | template<> struct DefaultHash<std::pair<unsigned short, unsigned short> > { typedef IntPairHash<unsigned short, unsigned short> Hash; }; |
| 200 | template<> struct DefaultHash<std::pair<unsigned short, int> > { typedef IntPairHash<unsigned short, int> Hash; }; |
| 201 | template<> struct DefaultHash<std::pair<unsigned short, unsigned> > { typedef IntPairHash<unsigned short, unsigned> Hash; }; |
| 202 | template<> struct DefaultHash<std::pair<int, short> > { typedef IntPairHash<int, short> Hash; }; |
| 203 | template<> struct DefaultHash<std::pair<int, unsigned short> > { typedef IntPairHash<int, unsigned short> Hash; }; |
| 204 | template<> struct DefaultHash<std::pair<int, int> > { typedef IntPairHash<int, int> Hash; }; |
| 205 | template<> struct DefaultHash<std::pair<int, unsigned> > { typedef IntPairHash<unsigned, unsigned> Hash; }; |
| 206 | template<> struct DefaultHash<std::pair<unsigned, short> > { typedef IntPairHash<unsigned, short> Hash; }; |
| 207 | template<> struct DefaultHash<std::pair<unsigned, unsigned short> > { typedef IntPairHash<unsigned, unsigned short> Hash; }; |
| 208 | template<> struct DefaultHash<std::pair<unsigned, int> > { typedef IntPairHash<unsigned, int> Hash; }; |
| 209 | template<> struct DefaultHash<std::pair<unsigned, unsigned> > { typedef IntPairHash<unsigned, unsigned> Hash; }; |
| 210 | |
| 211 | // make PairHash the default hash function for pairs of arbitrary values. |
| 212 | |
| 213 | template<typename T, typename U> struct DefaultHash<std::pair<T, U> > { typedef PairHash<T, U> Hash; }; |
| 214 | |
| 215 | } // namespace WTF |
| 216 | |
| 217 | using WTF::DefaultHash; |
| 218 | using WTF::IntHash; |
| 219 | using WTF::PtrHash; |
| 220 | |
| 221 | #endif // WTF_HashFunctions_h |