| /* |
| * Copyright (C) 2005, 2006, 2008 Apple Inc. All rights reserved. |
| * |
| * This library is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Library General Public |
| * License as published by the Free Software Foundation; either |
| * version 2 of the License, or (at your option) any later version. |
| * |
| * This library is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Library General Public License for more details. |
| * |
| * You should have received a copy of the GNU Library General Public License |
| * along with this library; see the file COPYING.LIB. If not, write to |
| * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, |
| * Boston, MA 02110-1301, USA. |
| * |
| */ |
| |
| #ifndef WTF_HashFunctions_h |
| #define WTF_HashFunctions_h |
| |
| #include <wtf/RefPtr.h> |
| #include <stdint.h> |
| |
| namespace WTF { |
| |
| template<size_t size> struct IntTypes; |
| template<> struct IntTypes<1> { typedef int8_t SignedType; typedef uint8_t UnsignedType; }; |
| template<> struct IntTypes<2> { typedef int16_t SignedType; typedef uint16_t UnsignedType; }; |
| template<> struct IntTypes<4> { typedef int32_t SignedType; typedef uint32_t UnsignedType; }; |
| template<> struct IntTypes<8> { typedef int64_t SignedType; typedef uint64_t UnsignedType; }; |
| |
| // integer hash function |
| |
| // Thomas Wang's 32 Bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm |
| inline unsigned intHash(uint8_t key8) |
| { |
| unsigned key = key8; |
| key += ~(key << 15); |
| key ^= (key >> 10); |
| key += (key << 3); |
| key ^= (key >> 6); |
| key += ~(key << 11); |
| key ^= (key >> 16); |
| return key; |
| } |
| |
| // Thomas Wang's 32 Bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm |
| inline unsigned intHash(uint16_t key16) |
| { |
| unsigned key = key16; |
| key += ~(key << 15); |
| key ^= (key >> 10); |
| key += (key << 3); |
| key ^= (key >> 6); |
| key += ~(key << 11); |
| key ^= (key >> 16); |
| return key; |
| } |
| |
| // Thomas Wang's 32 Bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm |
| inline unsigned intHash(uint32_t key) |
| { |
| key += ~(key << 15); |
| key ^= (key >> 10); |
| key += (key << 3); |
| key ^= (key >> 6); |
| key += ~(key << 11); |
| key ^= (key >> 16); |
| return key; |
| } |
| |
| // Thomas Wang's 64 bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm |
| inline unsigned intHash(uint64_t key) |
| { |
| key += ~(key << 32); |
| key ^= (key >> 22); |
| key += ~(key << 13); |
| key ^= (key >> 8); |
| key += (key << 3); |
| key ^= (key >> 15); |
| key += ~(key << 27); |
| key ^= (key >> 31); |
| return static_cast<unsigned>(key); |
| } |
| |
| // Compound integer hash method: http://opendatastructures.org/versions/edition-0.1d/ods-java/node33.html#SECTION00832000000000000000 |
| inline unsigned pairIntHash(unsigned key1, unsigned key2) |
| { |
| unsigned shortRandom1 = 277951225; // A random 32-bit value. |
| unsigned shortRandom2 = 95187966; // A random 32-bit value. |
| uint64_t longRandom = 19248658165952622LL; // A random 64-bit value. |
| |
| uint64_t product = longRandom * (shortRandom1 * key1 + shortRandom2 * key2); |
| unsigned highBits = static_cast<unsigned>(product >> (sizeof(uint64_t) - sizeof(unsigned))); |
| return highBits; |
| } |
| |
| template<typename T> struct IntHash { |
| static unsigned hash(T key) { return intHash(static_cast<typename IntTypes<sizeof(T)>::UnsignedType>(key)); } |
| static bool equal(T a, T b) { return a == b; } |
| static const bool safeToCompareToEmptyOrDeleted = true; |
| }; |
| |
| template<typename T> struct FloatHash { |
| typedef typename IntTypes<sizeof(T)>::UnsignedType Bits; |
| static unsigned hash(T key) |
| { |
| return intHash(bitwise_cast<Bits>(key)); |
| } |
| static bool equal(T a, T b) |
| { |
| return bitwise_cast<Bits>(a) == bitwise_cast<Bits>(b); |
| } |
| static const bool safeToCompareToEmptyOrDeleted = true; |
| }; |
| |
| // pointer identity hash function |
| |
| template<typename T> struct PtrHash { |
| static unsigned hash(T key) |
| { |
| #if COMPILER(MSVC) |
| #pragma warning(push) |
| #pragma warning(disable: 4244) // work around what seems to be a bug in MSVC's conversion warnings |
| #endif |
| return IntHash<uintptr_t>::hash(reinterpret_cast<uintptr_t>(key)); |
| #if COMPILER(MSVC) |
| #pragma warning(pop) |
| #endif |
| } |
| static bool equal(T a, T b) { return a == b; } |
| static const bool safeToCompareToEmptyOrDeleted = true; |
| }; |
| template<typename P> struct PtrHash<RefPtr<P> > : PtrHash<P*> { |
| using PtrHash<P*>::hash; |
| static unsigned hash(const RefPtr<P>& key) { return hash(key.get()); } |
| using PtrHash<P*>::equal; |
| static bool equal(const RefPtr<P>& a, const RefPtr<P>& b) { return a == b; } |
| static bool equal(P* a, const RefPtr<P>& b) { return a == b; } |
| static bool equal(const RefPtr<P>& a, P* b) { return a == b; } |
| }; |
| |
| // default hash function for each type |
| |
| template<typename T> struct DefaultHash; |
| |
| template<typename T, typename U> struct PairHash { |
| static unsigned hash(const std::pair<T, U>& p) |
| { |
| return pairIntHash(DefaultHash<T>::Hash::hash(p.first), DefaultHash<U>::Hash::hash(p.second)); |
| } |
| static bool equal(const std::pair<T, U>& a, const std::pair<T, U>& b) |
| { |
| return DefaultHash<T>::Hash::equal(a.first, b.first) && DefaultHash<U>::Hash::equal(a.second, b.second); |
| } |
| static const bool safeToCompareToEmptyOrDeleted = DefaultHash<T>::Hash::safeToCompareToEmptyOrDeleted |
| && DefaultHash<U>::Hash::safeToCompareToEmptyOrDeleted; |
| }; |
| |
| template<typename T, typename U> struct IntPairHash { |
| static unsigned hash(const std::pair<T, U>& p) { return pairIntHash(p.first, p.second); } |
| static bool equal(const std::pair<T, U>& a, const std::pair<T, U>& b) { return PairHash<T, T>::equal(a, b); } |
| static const bool safeToCompareToEmptyOrDeleted = PairHash<T, U>::safeToCompareToEmptyOrDeleted; |
| }; |
| |
| // make IntHash the default hash function for many integer types |
| |
| template<> struct DefaultHash<short> { typedef IntHash<unsigned> Hash; }; |
| template<> struct DefaultHash<unsigned short> { typedef IntHash<unsigned> Hash; }; |
| template<> struct DefaultHash<int> { typedef IntHash<unsigned> Hash; }; |
| template<> struct DefaultHash<unsigned> { typedef IntHash<unsigned> Hash; }; |
| template<> struct DefaultHash<long> { typedef IntHash<unsigned long> Hash; }; |
| template<> struct DefaultHash<unsigned long> { typedef IntHash<unsigned long> Hash; }; |
| template<> struct DefaultHash<long long> { typedef IntHash<unsigned long long> Hash; }; |
| template<> struct DefaultHash<unsigned long long> { typedef IntHash<unsigned long long> Hash; }; |
| |
| #if !COMPILER(MSVC) || defined(_NATIVE_WCHAR_T_DEFINED) |
| template<> struct DefaultHash<wchar_t> { typedef IntHash<wchar_t> Hash; }; |
| #endif |
| |
| template<> struct DefaultHash<float> { typedef FloatHash<float> Hash; }; |
| template<> struct DefaultHash<double> { typedef FloatHash<double> Hash; }; |
| |
| // make PtrHash the default hash function for pointer types that don't specialize |
| |
| template<typename P> struct DefaultHash<P*> { typedef PtrHash<P*> Hash; }; |
| template<typename P> struct DefaultHash<RefPtr<P> > { typedef PtrHash<RefPtr<P> > Hash; }; |
| |
| // make IntPairHash the default hash function for pairs of (at most) 32-bit integers. |
| |
| template<> struct DefaultHash<std::pair<short, short> > { typedef IntPairHash<short, short> Hash; }; |
| template<> struct DefaultHash<std::pair<short, unsigned short> > { typedef IntPairHash<short, unsigned short> Hash; }; |
| template<> struct DefaultHash<std::pair<short, int> > { typedef IntPairHash<short, int> Hash; }; |
| template<> struct DefaultHash<std::pair<short, unsigned> > { typedef IntPairHash<short, unsigned> Hash; }; |
| template<> struct DefaultHash<std::pair<unsigned short, short> > { typedef IntPairHash<unsigned short, short> Hash; }; |
| template<> struct DefaultHash<std::pair<unsigned short, unsigned short> > { typedef IntPairHash<unsigned short, unsigned short> Hash; }; |
| template<> struct DefaultHash<std::pair<unsigned short, int> > { typedef IntPairHash<unsigned short, int> Hash; }; |
| template<> struct DefaultHash<std::pair<unsigned short, unsigned> > { typedef IntPairHash<unsigned short, unsigned> Hash; }; |
| template<> struct DefaultHash<std::pair<int, short> > { typedef IntPairHash<int, short> Hash; }; |
| template<> struct DefaultHash<std::pair<int, unsigned short> > { typedef IntPairHash<int, unsigned short> Hash; }; |
| template<> struct DefaultHash<std::pair<int, int> > { typedef IntPairHash<int, int> Hash; }; |
| template<> struct DefaultHash<std::pair<int, unsigned> > { typedef IntPairHash<unsigned, unsigned> Hash; }; |
| template<> struct DefaultHash<std::pair<unsigned, short> > { typedef IntPairHash<unsigned, short> Hash; }; |
| template<> struct DefaultHash<std::pair<unsigned, unsigned short> > { typedef IntPairHash<unsigned, unsigned short> Hash; }; |
| template<> struct DefaultHash<std::pair<unsigned, int> > { typedef IntPairHash<unsigned, int> Hash; }; |
| template<> struct DefaultHash<std::pair<unsigned, unsigned> > { typedef IntPairHash<unsigned, unsigned> Hash; }; |
| |
| // make PairHash the default hash function for pairs of arbitrary values. |
| |
| template<typename T, typename U> struct DefaultHash<std::pair<T, U> > { typedef PairHash<T, U> Hash; }; |
| |
| } // namespace WTF |
| |
| using WTF::DefaultHash; |
| using WTF::IntHash; |
| using WTF::PtrHash; |
| |
| #endif // WTF_HashFunctions_h |