libstdc++
hash_fun.h
Go to the documentation of this file.
1 // 'struct hash' from SGI -*- C++ -*-
2 
3 // Copyright (C) 2001-2017 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 /*
26  * Copyright (c) 1996-1998
27  * Silicon Graphics Computer Systems, Inc.
28  *
29  * Permission to use, copy, modify, distribute and sell this software
30  * and its documentation for any purpose is hereby granted without fee,
31  * provided that the above copyright notice appear in all copies and
32  * that both that copyright notice and this permission notice appear
33  * in supporting documentation. Silicon Graphics makes no
34  * representations about the suitability of this software for any
35  * purpose. It is provided "as is" without express or implied warranty.
36  *
37  *
38  * Copyright (c) 1994
39  * Hewlett-Packard Company
40  *
41  * Permission to use, copy, modify, distribute and sell this software
42  * and its documentation for any purpose is hereby granted without fee,
43  * provided that the above copyright notice appear in all copies and
44  * that both that copyright notice and this permission notice appear
45  * in supporting documentation. Hewlett-Packard Company makes no
46  * representations about the suitability of this software for any
47  * purpose. It is provided "as is" without express or implied warranty.
48  *
49  */
50 
51 /** @file backward/hash_fun.h
52  * This file is a GNU extension to the Standard C++ Library (possibly
53  * containing extensions from the HP/SGI STL subset).
54  */
55 
56 #ifndef _BACKWARD_HASH_FUN_H
57 #define _BACKWARD_HASH_FUN_H 1
58 
59 #include <bits/c++config.h>
60 
61 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
62 {
63 _GLIBCXX_BEGIN_NAMESPACE_VERSION
64 
65  using std::size_t;
66 
67  template<class _Key>
68  struct hash { };
69 
70  inline size_t
71  __stl_hash_string(const char* __s)
72  {
73  unsigned long __h = 0;
74  for ( ; *__s; ++__s)
75  __h = 5 * __h + *__s;
76  return size_t(__h);
77  }
78 
79  template<>
80  struct hash<char*>
81  {
82  size_t
83  operator()(const char* __s) const
84  { return __stl_hash_string(__s); }
85  };
86 
87  template<>
88  struct hash<const char*>
89  {
90  size_t
91  operator()(const char* __s) const
92  { return __stl_hash_string(__s); }
93  };
94 
95  template<>
96  struct hash<char>
97  {
98  size_t
99  operator()(char __x) const
100  { return __x; }
101  };
102 
103  template<>
104  struct hash<unsigned char>
105  {
106  size_t
107  operator()(unsigned char __x) const
108  { return __x; }
109  };
110 
111  template<>
112  struct hash<signed char>
113  {
114  size_t
115  operator()(unsigned char __x) const
116  { return __x; }
117  };
118 
119  template<>
120  struct hash<short>
121  {
122  size_t
123  operator()(short __x) const
124  { return __x; }
125  };
126 
127  template<>
128  struct hash<unsigned short>
129  {
130  size_t
131  operator()(unsigned short __x) const
132  { return __x; }
133  };
134 
135  template<>
136  struct hash<int>
137  {
138  size_t
139  operator()(int __x) const
140  { return __x; }
141  };
142 
143  template<>
144  struct hash<unsigned int>
145  {
146  size_t
147  operator()(unsigned int __x) const
148  { return __x; }
149  };
150 
151  template<>
152  struct hash<long>
153  {
154  size_t
155  operator()(long __x) const
156  { return __x; }
157  };
158 
159  template<>
160  struct hash<unsigned long>
161  {
162  size_t
163  operator()(unsigned long __x) const
164  { return __x; }
165  };
166 
167 _GLIBCXX_END_NAMESPACE_VERSION
168 } // namespace
169 
170 #endif
__gnu_cxx
GNU extensions for public use.