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1 : // TR1 functional -*- C++ -*-
2 :
3 : // Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc.
4 : //
5 : // This file is part of the GNU ISO C++ Library. This library is free
6 : // software; you can redistribute it and/or modify it under the
7 : // terms of the GNU General Public License as published by the
8 : // Free Software Foundation; either version 3, or (at your option)
9 : // any later version.
10 :
11 : // This library is distributed in the hope that it will be useful,
12 : // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 : // GNU General Public License for more details.
15 :
16 : // Under Section 7 of GPL version 3, you are granted additional
17 : // permissions described in the GCC Runtime Library Exception, version
18 : // 3.1, as published by the Free Software Foundation.
19 :
20 : // You should have received a copy of the GNU General Public License and
21 : // a copy of the GCC Runtime Library Exception along with this program;
22 : // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 : // <http://www.gnu.org/licenses/>.
24 :
25 : /** @file tr1_impl/functional_hash.h
26 : * This is an internal header file, included by other library headers.
27 : * You should not attempt to use it directly.
28 : */
29 :
30 : namespace std
31 : {
32 : _GLIBCXX_BEGIN_NAMESPACE_TR1
33 :
34 : /// Class template hash.
35 : // Declaration of default hash functor std::tr1::hash. The types for
36 : // which std::tr1::hash<T> is well-defined is in clause 6.3.3. of the PDTR.
37 : template<typename _Tp>
38 : struct hash : public std::unary_function<_Tp, size_t>
39 : {
40 : size_t
41 : operator()(_Tp __val) const;
42 : };
43 :
44 : /// Partial specializations for pointer types.
45 : template<typename _Tp>
46 : struct hash<_Tp*> : public std::unary_function<_Tp*, size_t>
47 : {
48 : size_t
49 11220 : operator()(_Tp* __p) const
50 11220 : { return reinterpret_cast<size_t>(__p); }
51 : };
52 :
53 : /// Explicit specializations for integer types.
54 : #define _TR1_hashtable_define_trivial_hash(_Tp) \
55 : template<> \
56 : inline size_t \
57 : hash<_Tp>::operator()(_Tp __val) const \
58 : { return static_cast<size_t>(__val); }
59 :
60 : _TR1_hashtable_define_trivial_hash(bool);
61 : _TR1_hashtable_define_trivial_hash(char);
62 : _TR1_hashtable_define_trivial_hash(signed char);
63 : _TR1_hashtable_define_trivial_hash(unsigned char);
64 : _TR1_hashtable_define_trivial_hash(wchar_t);
65 : #ifdef _GLIBCXX_INCLUDE_AS_CXX0X
66 : _TR1_hashtable_define_trivial_hash(char16_t);
67 : _TR1_hashtable_define_trivial_hash(char32_t);
68 : #endif
69 : _TR1_hashtable_define_trivial_hash(short);
70 0 : _TR1_hashtable_define_trivial_hash(int);
71 0 : _TR1_hashtable_define_trivial_hash(long);
72 : _TR1_hashtable_define_trivial_hash(long long);
73 : _TR1_hashtable_define_trivial_hash(unsigned short);
74 : _TR1_hashtable_define_trivial_hash(unsigned int);
75 : _TR1_hashtable_define_trivial_hash(unsigned long);
76 : _TR1_hashtable_define_trivial_hash(unsigned long long);
77 :
78 : #undef _TR1_hashtable_define_trivial_hash
79 :
80 : // Fowler / Noll / Vo (FNV) Hash (type FNV-1a)
81 : // (Used by the next specializations of std::tr1::hash.)
82 :
83 : /// Dummy generic implementation (for sizeof(size_t) != 4, 8).
84 : template<size_t = sizeof(size_t)>
85 : struct _Fnv_hash
86 : {
87 : static size_t
88 : hash(const char* __first, size_t __length)
89 : {
90 : size_t __result = 0;
91 : for (; __length > 0; --__length)
92 : __result = (__result * 131) + *__first++;
93 : return __result;
94 : }
95 : };
96 :
97 : template<>
98 : struct _Fnv_hash<4>
99 : {
100 : static size_t
101 : hash(const char* __first, size_t __length)
102 : {
103 : size_t __result = static_cast<size_t>(2166136261UL);
104 : for (; __length > 0; --__length)
105 : {
106 : __result ^= static_cast<size_t>(*__first++);
107 : __result *= static_cast<size_t>(16777619UL);
108 : }
109 : return __result;
110 : }
111 : };
112 :
113 : template<>
114 : struct _Fnv_hash<8>
115 : {
116 : static size_t
117 0 : hash(const char* __first, size_t __length)
118 : {
119 : size_t __result =
120 0 : static_cast<size_t>(14695981039346656037ULL);
121 0 : for (; __length > 0; --__length)
122 : {
123 0 : __result ^= static_cast<size_t>(*__first++);
124 0 : __result *= static_cast<size_t>(1099511628211ULL);
125 : }
126 0 : return __result;
127 : }
128 : };
129 :
130 : /// Explicit specializations for float.
131 : template<>
132 : inline size_t
133 0 : hash<float>::operator()(float __val) const
134 : {
135 0 : size_t __result = 0;
136 :
137 : // 0 and -0 both hash to zero.
138 0 : if (__val != 0.0f)
139 : __result = _Fnv_hash<>::hash(reinterpret_cast<const char*>(&__val),
140 0 : sizeof(__val));
141 0 : return __result;
142 : };
143 :
144 : /// Explicit specializations for double.
145 : template<>
146 : inline size_t
147 0 : hash<double>::operator()(double __val) const
148 : {
149 0 : size_t __result = 0;
150 :
151 : // 0 and -0 both hash to zero.
152 0 : if (__val != 0.0)
153 : __result = _Fnv_hash<>::hash(reinterpret_cast<const char*>(&__val),
154 0 : sizeof(__val));
155 0 : return __result;
156 : };
157 :
158 : /// Explicit specializations for long double.
159 : template<>
160 : size_t
161 : hash<long double>::operator()(long double __val) const;
162 :
163 : /// Explicit specialization of member operator for non-builtin types.
164 : template<>
165 : size_t
166 : hash<string>::operator()(string) const;
167 :
168 : template<>
169 : size_t
170 : hash<const string&>::operator()(const string&) const;
171 :
172 : #ifdef _GLIBCXX_USE_WCHAR_T
173 : template<>
174 : size_t
175 : hash<wstring>::operator()(wstring) const;
176 :
177 : template<>
178 : size_t
179 : hash<const wstring&>::operator()(const wstring&) const;
180 : #endif
181 :
182 : _GLIBCXX_END_NAMESPACE_TR1
183 : }
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