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1 : // TR1 functional_hash.h header -*- C++ -*-
2 :
3 : // Copyright (C) 2007-2013 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/functional_hash.h
26 : * This is an internal header file, included by other library headers.
27 : * Do not attempt to use it directly. @headername{tr1/functional}
28 : */
29 :
30 : #ifndef _GLIBCXX_TR1_FUNCTIONAL_HASH_H
31 : #define _GLIBCXX_TR1_FUNCTIONAL_HASH_H 1
32 :
33 : #pragma GCC system_header
34 :
35 : namespace std _GLIBCXX_VISIBILITY(default)
36 : {
37 : namespace tr1
38 : {
39 : _GLIBCXX_BEGIN_NAMESPACE_VERSION
40 :
41 : /// Class template hash.
42 : // Declaration of default hash functor std::tr1::hash. The types for
43 : // which std::tr1::hash<T> is well-defined is in clause 6.3.3. of the PDTR.
44 : template<typename _Tp>
45 : struct hash : public std::unary_function<_Tp, size_t>
46 : {
47 : size_t
48 : operator()(_Tp __val) const;
49 : };
50 :
51 : /// Partial specializations for pointer types.
52 : template<typename _Tp>
53 : struct hash<_Tp*> : public std::unary_function<_Tp*, size_t>
54 : {
55 : size_t
56 : operator()(_Tp* __p) const
57 : { return reinterpret_cast<size_t>(__p); }
58 : };
59 :
60 : /// Explicit specializations for integer types.
61 : #define _TR1_hashtable_define_trivial_hash(_Tp) \
62 : template<> \
63 : inline size_t \
64 : hash<_Tp>::operator()(_Tp __val) const \
65 : { return static_cast<size_t>(__val); }
66 :
67 : _TR1_hashtable_define_trivial_hash(bool);
68 : _TR1_hashtable_define_trivial_hash(char);
69 : _TR1_hashtable_define_trivial_hash(signed char);
70 : _TR1_hashtable_define_trivial_hash(unsigned char);
71 : _TR1_hashtable_define_trivial_hash(wchar_t);
72 : _TR1_hashtable_define_trivial_hash(short);
73 3976 : _TR1_hashtable_define_trivial_hash(int);
74 : _TR1_hashtable_define_trivial_hash(long);
75 0 : _TR1_hashtable_define_trivial_hash(long long);
76 : _TR1_hashtable_define_trivial_hash(unsigned short);
77 0 : _TR1_hashtable_define_trivial_hash(unsigned int);
78 : _TR1_hashtable_define_trivial_hash(unsigned long);
79 : _TR1_hashtable_define_trivial_hash(unsigned long long);
80 :
81 : #undef _TR1_hashtable_define_trivial_hash
82 :
83 : // Fowler / Noll / Vo (FNV) Hash (type FNV-1a)
84 : // (Used by the next specializations of std::tr1::hash.)
85 :
86 : /// Dummy generic implementation (for sizeof(size_t) != 4, 8).
87 : template<size_t>
88 : struct _Fnv_hash_base
89 : {
90 : template<typename _Tp>
91 : static size_t
92 : hash(const _Tp* __ptr, size_t __clength)
93 : {
94 : size_t __result = 0;
95 : const char* __cptr = reinterpret_cast<const char*>(__ptr);
96 : for (; __clength; --__clength)
97 : __result = (__result * 131) + *__cptr++;
98 : return __result;
99 : }
100 : };
101 :
102 : template<>
103 : struct _Fnv_hash_base<4>
104 : {
105 : template<typename _Tp>
106 : static size_t
107 : hash(const _Tp* __ptr, size_t __clength)
108 : {
109 : size_t __result = static_cast<size_t>(2166136261UL);
110 : const char* __cptr = reinterpret_cast<const char*>(__ptr);
111 : for (; __clength; --__clength)
112 : {
113 : __result ^= static_cast<size_t>(*__cptr++);
114 : __result *= static_cast<size_t>(16777619UL);
115 : }
116 : return __result;
117 : }
118 : };
119 :
120 : template<>
121 : struct _Fnv_hash_base<8>
122 : {
123 : template<typename _Tp>
124 : static size_t
125 : hash(const _Tp* __ptr, size_t __clength)
126 : {
127 : size_t __result
128 : = static_cast<size_t>(14695981039346656037ULL);
129 : const char* __cptr = reinterpret_cast<const char*>(__ptr);
130 : for (; __clength; --__clength)
131 : {
132 : __result ^= static_cast<size_t>(*__cptr++);
133 : __result *= static_cast<size_t>(1099511628211ULL);
134 : }
135 : return __result;
136 : }
137 : };
138 :
139 : struct _Fnv_hash
140 : : public _Fnv_hash_base<sizeof(size_t)>
141 : {
142 : using _Fnv_hash_base<sizeof(size_t)>::hash;
143 :
144 : template<typename _Tp>
145 : static size_t
146 : hash(const _Tp& __val)
147 : { return hash(&__val, sizeof(__val)); }
148 : };
149 :
150 : /// Explicit specializations for float.
151 : template<>
152 : inline size_t
153 : hash<float>::operator()(float __val) const
154 : {
155 : // 0 and -0 both hash to zero.
156 : return __val != 0.0f ? std::tr1::_Fnv_hash::hash(__val) : 0;
157 : }
158 :
159 : /// Explicit specializations for double.
160 : template<>
161 : inline size_t
162 : hash<double>::operator()(double __val) const
163 : {
164 : // 0 and -0 both hash to zero.
165 : return __val != 0.0 ? std::tr1::_Fnv_hash::hash(__val) : 0;
166 : }
167 :
168 : /// Explicit specializations for long double.
169 : template<>
170 : _GLIBCXX_PURE size_t
171 : hash<long double>::operator()(long double __val) const;
172 :
173 : /// Explicit specialization of member operator for non-builtin types.
174 : template<>
175 : _GLIBCXX_PURE size_t
176 : hash<string>::operator()(string) const;
177 :
178 : template<>
179 : _GLIBCXX_PURE size_t
180 : hash<const string&>::operator()(const string&) const;
181 :
182 : #ifdef _GLIBCXX_USE_WCHAR_T
183 : template<>
184 : _GLIBCXX_PURE size_t
185 : hash<wstring>::operator()(wstring) const;
186 :
187 : template<>
188 : _GLIBCXX_PURE size_t
189 : hash<const wstring&>::operator()(const wstring&) const;
190 : #endif
191 :
192 : _GLIBCXX_END_NAMESPACE_VERSION
193 : }
194 : }
195 :
196 : #endif // _GLIBCXX_TR1_FUNCTIONAL_HASH_H
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