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author | Upstream <upstream-import@none> | 1970-01-12 13:46:40 +0000 |
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committer | Upstream <upstream-import@none> | 1970-01-12 13:46:40 +0000 |
commit | d8543bb6618c17b12da906afa77d216f58cf4058 (patch) | |
tree | c58dc05ed86825bd0ef8d305d58c8205106b540f /JavaScriptCore/wtf/HashFunctions.h | |
download | external_webkit-d8543bb6618c17b12da906afa77d216f58cf4058.zip external_webkit-d8543bb6618c17b12da906afa77d216f58cf4058.tar.gz external_webkit-d8543bb6618c17b12da906afa77d216f58cf4058.tar.bz2 |
external/webkit r30707
Diffstat (limited to 'JavaScriptCore/wtf/HashFunctions.h')
-rw-r--r-- | JavaScriptCore/wtf/HashFunctions.h | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/JavaScriptCore/wtf/HashFunctions.h b/JavaScriptCore/wtf/HashFunctions.h new file mode 100644 index 0000000..bf85dc0 --- /dev/null +++ b/JavaScriptCore/wtf/HashFunctions.h @@ -0,0 +1,127 @@ +// -*- mode: c++; c-basic-offset: 4 -*- +/* + * This file is part of the KDE libraries + * Copyright (C) 2005, 2006 Apple Computer, Inc. + * + * 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(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) { return intHash(*reinterpret_cast<typename IntTypes<sizeof(T)>::UnsignedType*>(&key)); } + 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> > { + static unsigned hash(const RefPtr<P>& key) { return PtrHash<P*>::hash(key.get()); } + static bool equal(const RefPtr<P>& a, const RefPtr<P>& b) { return a == b; } + static const bool safeToCompareToEmptyOrDeleted = true; + }; + + // default hash function for each type + + template<typename T> struct DefaultHash; + + // make IntHash the default hash function for many integer types + + 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; }; + + 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; }; + +} // namespace WTF + +using WTF::DefaultHash; +using WTF::IntHash; +using WTF::PtrHash; + +#endif // WTF_HashFunctions_h |