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HashTraits.h
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1// -*- mode: c++; c-basic-offset: 4 -*-
2/*
3 * Copyright (C) 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Library General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Library General Public License for more details.
14 *
15 * You should have received a copy of the GNU Library General Public License
16 * along with this library; see the file COPYING.LIB. If not, write to
17 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
18 * Boston, MA 02110-1301, USA.
19 *
20 */
21
22#ifndef WTF_HashTraits_h
23#define WTF_HashTraits_h
24
25#include "Assertions.h"
26#include "HashFunctions.h"
27#include <utility>
28#include <limits>
29
30namespace WTF {
31
32 using std::pair;
33 using std::make_pair;
34
35 template<typename T> struct IsInteger { static const bool value = false; };
36 template<> struct IsInteger<bool> { static const bool value = true; };
37 template<> struct IsInteger<char> { static const bool value = true; };
38 template<> struct IsInteger<signed char> { static const bool value = true; };
39 template<> struct IsInteger<unsigned char> { static const bool value = true; };
40 template<> struct IsInteger<short> { static const bool value = true; };
41 template<> struct IsInteger<unsigned short> { static const bool value = true; };
42 template<> struct IsInteger<int> { static const bool value = true; };
43 template<> struct IsInteger<unsigned int> { static const bool value = true; };
44 template<> struct IsInteger<long> { static const bool value = true; };
45 template<> struct IsInteger<unsigned long> { static const bool value = true; };
46 template<> struct IsInteger<long long> { static const bool value = true; };
47 template<> struct IsInteger<unsigned long long> { static const bool value = true; };
48
49#if !COMPILER(MSVC) || defined(_NATIVE_WCHAR_T_DEFINED)
50 template<> struct IsInteger<wchar_t> { static const bool value = true; };
51#endif
52
53 COMPILE_ASSERT(IsInteger<bool>::value, WTF_IsInteger_bool_true)
54 COMPILE_ASSERT(IsInteger<char>::value, WTF_IsInteger_char_true)
55 COMPILE_ASSERT(IsInteger<signed char>::value, WTF_IsInteger_signed_char_true)
56 COMPILE_ASSERT(IsInteger<unsigned char>::value, WTF_IsInteger_unsigned_char_true)
57 COMPILE_ASSERT(IsInteger<short>::value, WTF_IsInteger_short_true)
58 COMPILE_ASSERT(IsInteger<unsigned short>::value, WTF_IsInteger_unsigned_short_true)
59 COMPILE_ASSERT(IsInteger<int>::value, WTF_IsInteger_int_true)
60 COMPILE_ASSERT(IsInteger<unsigned int>::value, WTF_IsInteger_unsigned_int_true)
61 COMPILE_ASSERT(IsInteger<long>::value, WTF_IsInteger_long_true)
62 COMPILE_ASSERT(IsInteger<unsigned long>::value, WTF_IsInteger_unsigned_long_true)
63 COMPILE_ASSERT(IsInteger<long long>::value, WTF_IsInteger_long_long_true)
64 COMPILE_ASSERT(IsInteger<unsigned long long>::value, WTF_IsInteger_unsigned_long_long_true)
65
66#if !COMPILER(MSVC) || defined(_NATIVE_WCHAR_T_DEFINED)
67 COMPILE_ASSERT(IsInteger<wchar_t>::value, WTF_IsInteger_wchar_t_true)
68#endif
69
70 COMPILE_ASSERT(!IsInteger<char*>::value, WTF_IsInteger_char_pointer_false)
71 COMPILE_ASSERT(!IsInteger<const char* >::value, WTF_IsInteger_const_char_pointer_false)
72 COMPILE_ASSERT(!IsInteger<volatile char* >::value, WTF_IsInteger_volatile_char_pointer__false)
73 COMPILE_ASSERT(!IsInteger<double>::value, WTF_IsInteger_double_false)
74 COMPILE_ASSERT(!IsInteger<float>::value, WTF_IsInteger_float_false)
75
76 template<typename T> struct HashTraits;
77
78 template<bool isInteger, typename T> struct GenericHashTraitsBase;
79
80 template<typename T> struct GenericHashTraitsBase<false, T> {
81 static const bool emptyValueIsZero = false;
82 static const bool needsDestruction = true;
83 };
84
85 // default integer traits disallow both 0 and -1 as keys (max value instead of -1 for unsigned)
86 template<typename T> struct GenericHashTraitsBase<true, T> {
87 static const bool emptyValueIsZero = true;
88 static const bool needsDestruction = false;
89 static void constructDeletedValue(T* slot) { *slot = static_cast<T>(-1); }
90 static bool isDeletedValue(T value) { return value == static_cast<T>(-1); }
91 };
92
93 template<typename T> struct GenericHashTraits : GenericHashTraitsBase<IsInteger<T>::value, T> {
94 typedef T TraitType;
95 static T emptyValue() { return T(); }
96 };
97
98 template<typename T> struct HashTraits : GenericHashTraits<T> { };
99
100 template<typename T> struct FloatHashTraits : GenericHashTraits<T> {
101 static const bool needsDestruction = false;
102 static T emptyValue() { return std::numeric_limits<T>::infinity(); }
103 static void constructDeletedValue(T* slot) { *slot = -std::numeric_limits<T>::infinity(); }
104 static bool isDeletedValue(T value) { return value == -std::numeric_limits<T>::infinity(); }
105 };
106
107 template<> struct HashTraits<float> : FloatHashTraits<float> { };
108 template<> struct HashTraits<double> : FloatHashTraits<double> { };
109
110 template<typename P> struct HashTraits<P*> : GenericHashTraits<P*> {
111 static const bool emptyValueIsZero = true;
112 static const bool needsDestruction = false;
113 static void constructDeletedValue(P** slot) { *slot = reinterpret_cast<P*>(-1); }
114 static bool isDeletedValue(P* value) { return value == reinterpret_cast<P*>(-1); }
115 };
116
117 template<typename P> struct HashTraits<RefPtr<P> > : GenericHashTraits<RefPtr<P> > {
118 static const bool emptyValueIsZero = true;
119 static void constructDeletedValue(RefPtr<P>* slot) { new (slot) RefPtr<P>(HashTableDeletedValue); }
120 static bool isDeletedValue(const RefPtr<P>& value) { return value.isHashTableDeletedValue(); }
121 };
122
123 // special traits for pairs, helpful for their use in HashMap implementation
124
125 template<typename FirstTraitsArg, typename SecondTraitsArg>
126 struct PairHashTraits : GenericHashTraits<pair<typename FirstTraitsArg::TraitType, typename SecondTraitsArg::TraitType> > {
127 typedef FirstTraitsArg FirstTraits;
128 typedef SecondTraitsArg SecondTraits;
129 typedef pair<typename FirstTraits::TraitType, typename SecondTraits::TraitType> TraitType;
130
131 static const bool emptyValueIsZero = FirstTraits::emptyValueIsZero && SecondTraits::emptyValueIsZero;
132 static TraitType emptyValue() { return make_pair(FirstTraits::emptyValue(), SecondTraits::emptyValue()); }
133
134 static const bool needsDestruction = FirstTraits::needsDestruction || SecondTraits::needsDestruction;
135
136 static void constructDeletedValue(TraitType* slot) { FirstTraits::constructDeletedValue(&slot->first); }
137 static bool isDeletedValue(const TraitType& value) { return FirstTraits::isDeletedValue(value.first); }
138 };
139
140 template<typename First, typename Second>
141 struct HashTraits<pair<First, Second> > : public PairHashTraits<HashTraits<First>, HashTraits<Second> > { };
142
143} // namespace WTF
144
145using WTF::HashTraits;
146using WTF::PairHashTraits;
147
148#endif // WTF_HashTraits_h
Assertions.h
COMPILE_ASSERT
#define COMPILE_ASSERT(exp, name)
Definition: Assertions.h:38
HashFunctions.h
WTF::RefPtr
Definition: RefPtr.h:37
WTF::RefPtr::isHashTableDeletedValue
bool isHashTableDeletedValue() const
Definition: RefPtr.h:50
int
WTF
Definition: ASCIICType.h:45
WTF::HashTableDeletedValue
@ HashTableDeletedValue
Definition: RefPtr.h:35
WTF::FloatHashTraits
Definition: HashTraits.h:100
WTF::FloatHashTraits::isDeletedValue
static bool isDeletedValue(T value)
Definition: HashTraits.h:104
WTF::FloatHashTraits::constructDeletedValue
static void constructDeletedValue(T *slot)
Definition: HashTraits.h:103
WTF::FloatHashTraits::emptyValue
static T emptyValue()
Definition: HashTraits.h:102
WTF::FloatHashTraits::needsDestruction
static const bool needsDestruction
Definition: HashTraits.h:101
WTF::GenericHashTraitsBase< true, T >::isDeletedValue
static bool isDeletedValue(T value)
Definition: HashTraits.h:90
WTF::GenericHashTraitsBase< true, T >::constructDeletedValue
static void constructDeletedValue(T *slot)
Definition: HashTraits.h:89
WTF::GenericHashTraitsBase
Definition: HashTraits.h:78
WTF::GenericHashTraits
Definition: HashTraits.h:93
WTF::GenericHashTraits::TraitType
T TraitType
Definition: HashTraits.h:94
WTF::GenericHashTraits::emptyValue
static T emptyValue()
Definition: HashTraits.h:95
WTF::HashTraits< P * >::constructDeletedValue
static void constructDeletedValue(P **slot)
Definition: HashTraits.h:113
WTF::HashTraits< P * >::isDeletedValue
static bool isDeletedValue(P *value)
Definition: HashTraits.h:114
WTF::HashTraits< RefPtr< P > >::isDeletedValue
static bool isDeletedValue(const RefPtr< P > &value)
Definition: HashTraits.h:120
WTF::HashTraits< RefPtr< P > >::constructDeletedValue
static void constructDeletedValue(RefPtr< P > *slot)
Definition: HashTraits.h:119
WTF::HashTraits
Definition: HashTraits.h:98
WTF::IsInteger
Definition: HashTraits.h:35
WTF::IsInteger::value
static const bool value
Definition: HashTraits.h:35
WTF::PairHashTraits
Definition: HashTraits.h:126
WTF::PairHashTraits::emptyValueIsZero
static const bool emptyValueIsZero
Definition: HashTraits.h:131
WTF::PairHashTraits::SecondTraits
SecondTraitsArg SecondTraits
Definition: HashTraits.h:128
WTF::PairHashTraits::needsDestruction
static const bool needsDestruction
Definition: HashTraits.h:134
WTF::PairHashTraits::constructDeletedValue
static void constructDeletedValue(TraitType *slot)
Definition: HashTraits.h:136
WTF::PairHashTraits::TraitType
pair< typename FirstTraits::TraitType, typename SecondTraits::TraitType > TraitType
Definition: HashTraits.h:129
WTF::PairHashTraits::emptyValue
static TraitType emptyValue()
Definition: HashTraits.h:132
WTF::PairHashTraits::isDeletedValue
static bool isDeletedValue(const TraitType &value)
Definition: HashTraits.h:137
WTF::PairHashTraits::FirstTraits
FirstTraitsArg FirstTraits
Definition: HashTraits.h:127
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