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Diffstat (limited to 'src/3rdparty/webkit/JavaScriptCore/wtf/HashFunctions.h')
-rw-r--r-- | src/3rdparty/webkit/JavaScriptCore/wtf/HashFunctions.h | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/src/3rdparty/webkit/JavaScriptCore/wtf/HashFunctions.h b/src/3rdparty/webkit/JavaScriptCore/wtf/HashFunctions.h new file mode 100644 index 0000000..13afb72 --- /dev/null +++ b/src/3rdparty/webkit/JavaScriptCore/wtf/HashFunctions.h @@ -0,0 +1,186 @@ +/* + * 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 "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); + } + + 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 { + static unsigned hash(T key) + { + union { + T key; + typename IntTypes<sizeof(T)>::UnsignedType bits; + } u; + u.key = key; + return intHash(u.bits); + } + static bool equal(T a, T b) { return a == 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 intHash((static_cast<uint64_t>(DefaultHash<T>::Hash::hash(p.first)) << 32 | 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; + }; + + // 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; }; + + template<typename T, typename U> struct DefaultHash<std::pair<T, U> > { typedef PairHash<T, U> Hash; }; + + // Golden ratio - arbitrary start value to avoid mapping all 0's to all 0's + static const unsigned stringHashingStartValue = 0x9e3779b9U; + +} // namespace WTF + +using WTF::DefaultHash; +using WTF::IntHash; +using WTF::PtrHash; + +#endif // WTF_HashFunctions_h |