2 * Copyright (C) 2005, 2006, 2008 Apple Inc. All rights reserved.
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.
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.
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.
21 #ifndef WTF_HashFunctions_h
22 #define WTF_HashFunctions_h
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
; };
35 // integer hash function
37 // Thomas Wang's 32 Bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm
38 inline unsigned intHash(uint8_t key8
)
50 // Thomas Wang's 32 Bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm
51 inline unsigned intHash(uint16_t key16
)
63 // Thomas Wang's 32 Bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm
64 inline unsigned intHash(uint32_t key
)
75 // Thomas Wang's 64 bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm
76 inline unsigned intHash(uint64_t key
)
86 return static_cast<unsigned>(key
);
89 template<typename T
> struct IntHash
{
90 static unsigned hash(T key
) { return intHash(static_cast<typename IntTypes
<sizeof(T
)>::UnsignedType
>(key
)); }
91 static bool equal(T a
, T b
) { return a
== b
; }
92 static const bool safeToCompareToEmptyOrDeleted
= true;
95 template<typename T
> struct FloatHash
{
96 static unsigned hash(T key
)
100 typename IntTypes
<sizeof(T
)>::UnsignedType bits
;
103 return intHash(u
.bits
);
105 static bool equal(T a
, T b
) { return a
== b
; }
106 static const bool safeToCompareToEmptyOrDeleted
= true;
109 // pointer identity hash function
111 template<typename T
> struct PtrHash
{
112 static unsigned hash(T key
)
115 #pragma warning(push)
116 #pragma warning(disable: 4244) // work around what seems to be a bug in MSVC's conversion warnings
118 return IntHash
<uintptr_t>::hash(reinterpret_cast<uintptr_t>(key
));
123 static bool equal(T a
, T b
) { return a
== b
; }
124 static const bool safeToCompareToEmptyOrDeleted
= true;
126 template<typename P
> struct PtrHash
<RefPtr
<P
> > : PtrHash
<P
*> {
127 using PtrHash
<P
*>::hash
;
128 static unsigned hash(const RefPtr
<P
>& key
) { return hash(key
.get()); }
129 using PtrHash
<P
*>::equal
;
130 static bool equal(const RefPtr
<P
>& a
, const RefPtr
<P
>& b
) { return a
== b
; }
131 static bool equal(P
* a
, const RefPtr
<P
>& b
) { return a
== b
; }
132 static bool equal(const RefPtr
<P
>& a
, P
* b
) { return a
== b
; }
135 // default hash function for each type
137 template<typename T
> struct DefaultHash
;
139 template<typename T
, typename U
> struct PairHash
{
140 static unsigned hash(const std::pair
<T
, U
>& p
)
142 return intHash((static_cast<uint64_t>(DefaultHash
<T
>::Hash::hash(p
.first
)) << 32 | DefaultHash
<U
>::Hash::hash(p
.second
)));
144 static bool equal(const std::pair
<T
, U
>& a
, const std::pair
<T
, U
>& b
)
146 return DefaultHash
<T
>::Hash::equal(a
.first
, b
.first
) && DefaultHash
<U
>::Hash::equal(a
.second
, b
.second
);
148 static const bool safeToCompareToEmptyOrDeleted
= DefaultHash
<T
>::Hash::safeToCompareToEmptyOrDeleted
149 && DefaultHash
<U
>::Hash::safeToCompareToEmptyOrDeleted
;
152 // make IntHash the default hash function for many integer types
154 template<> struct DefaultHash
<short> { typedef IntHash
<unsigned> Hash
; };
155 template<> struct DefaultHash
<unsigned short> { typedef IntHash
<unsigned> Hash
; };
156 template<> struct DefaultHash
<int> { typedef IntHash
<unsigned> Hash
; };
157 template<> struct DefaultHash
<unsigned> { typedef IntHash
<unsigned> Hash
; };
158 template<> struct DefaultHash
<long> { typedef IntHash
<unsigned long> Hash
; };
159 template<> struct DefaultHash
<unsigned long> { typedef IntHash
<unsigned long> Hash
; };
160 template<> struct DefaultHash
<long long> { typedef IntHash
<unsigned long long> Hash
; };
161 template<> struct DefaultHash
<unsigned long long> { typedef IntHash
<unsigned long long> Hash
; };
163 #if !COMPILER(MSVC) || defined(_NATIVE_WCHAR_T_DEFINED)
164 template<> struct DefaultHash
<wchar_t> { typedef IntHash
<wchar_t> Hash
; };
167 template<> struct DefaultHash
<float> { typedef FloatHash
<float> Hash
; };
168 template<> struct DefaultHash
<double> { typedef FloatHash
<double> Hash
; };
170 // make PtrHash the default hash function for pointer types that don't specialize
172 template<typename P
> struct DefaultHash
<P
*> { typedef PtrHash
<P
*> Hash
; };
173 template<typename P
> struct DefaultHash
<RefPtr
<P
> > { typedef PtrHash
<RefPtr
<P
> > Hash
; };
175 template<typename T
, typename U
> struct DefaultHash
<std::pair
<T
, U
> > { typedef PairHash
<T
, U
> Hash
; };
179 using WTF::DefaultHash
;
183 #endif // WTF_HashFunctions_h