libstdc++
hash_fun.h
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1 // 'struct hash' from SGI -*- C++ -*-
2 
3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2009, 2010
4 // Free Software Foundation, Inc.
5 //
6 // This file is part of the GNU ISO C++ Library. This library is free
7 // software; you can redistribute it and/or modify it under the
8 // terms of the GNU General Public License as published by the
9 // Free Software Foundation; either version 3, or (at your option)
10 // any later version.
11 
12 // This library is distributed in the hope that it will be useful,
13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 // GNU General Public License for more details.
16 
17 // Under Section 7 of GPL version 3, you are granted additional
18 // permissions described in the GCC Runtime Library Exception, version
19 // 3.1, as published by the Free Software Foundation.
20 
21 // You should have received a copy of the GNU General Public License and
22 // a copy of the GCC Runtime Library Exception along with this program;
23 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24 // <http://www.gnu.org/licenses/>.
25 
26 /*
27  * Copyright (c) 1996-1998
28  * Silicon Graphics Computer Systems, Inc.
29  *
30  * Permission to use, copy, modify, distribute and sell this software
31  * and its documentation for any purpose is hereby granted without fee,
32  * provided that the above copyright notice appear in all copies and
33  * that both that copyright notice and this permission notice appear
34  * in supporting documentation. Silicon Graphics makes no
35  * representations about the suitability of this software for any
36  * purpose. It is provided "as is" without express or implied warranty.
37  *
38  *
39  * Copyright (c) 1994
40  * Hewlett-Packard Company
41  *
42  * Permission to use, copy, modify, distribute and sell this software
43  * and its documentation for any purpose is hereby granted without fee,
44  * provided that the above copyright notice appear in all copies and
45  * that both that copyright notice and this permission notice appear
46  * in supporting documentation. Hewlett-Packard Company makes no
47  * representations about the suitability of this software for any
48  * purpose. It is provided "as is" without express or implied warranty.
49  *
50  */
51 
52 /** @file backward/hash_fun.h
53  * This file is a GNU extension to the Standard C++ Library (possibly
54  * containing extensions from the HP/SGI STL subset).
55  */
56 
57 #ifndef _BACKWARD_HASH_FUN_H
58 #define _BACKWARD_HASH_FUN_H 1
59 
60 #include <cstddef>
61 
62 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
63 
64  using std::size_t;
65 
66  template<class _Key>
67  struct hash { };
68 
69  inline size_t
70  __stl_hash_string(const char* __s)
71  {
72  unsigned long __h = 0;
73  for ( ; *__s; ++__s)
74  __h = 5 * __h + *__s;
75  return size_t(__h);
76  }
77 
78  template<>
79  struct hash<char*>
80  {
81  size_t
82  operator()(const char* __s) const
83  { return __stl_hash_string(__s); }
84  };
85 
86  template<>
87  struct hash<const char*>
88  {
89  size_t
90  operator()(const char* __s) const
91  { return __stl_hash_string(__s); }
92  };
93 
94  template<>
95  struct hash<char>
96  {
97  size_t
98  operator()(char __x) const
99  { return __x; }
100  };
101 
102  template<>
103  struct hash<unsigned char>
104  {
105  size_t
106  operator()(unsigned char __x) const
107  { return __x; }
108  };
109 
110  template<>
111  struct hash<signed char>
112  {
113  size_t
114  operator()(unsigned char __x) const
115  { return __x; }
116  };
117 
118  template<>
119  struct hash<short>
120  {
121  size_t
122  operator()(short __x) const
123  { return __x; }
124  };
125 
126  template<>
127  struct hash<unsigned short>
128  {
129  size_t
130  operator()(unsigned short __x) const
131  { return __x; }
132  };
133 
134  template<>
135  struct hash<int>
136  {
137  size_t
138  operator()(int __x) const
139  { return __x; }
140  };
141 
142  template<>
143  struct hash<unsigned int>
144  {
145  size_t
146  operator()(unsigned int __x) const
147  { return __x; }
148  };
149 
150  template<>
151  struct hash<long>
152  {
153  size_t
154  operator()(long __x) const
155  { return __x; }
156  };
157 
158  template<>
159  struct hash<unsigned long>
160  {
161  size_t
162  operator()(unsigned long __x) const
163  { return __x; }
164  };
165 
166 _GLIBCXX_END_NAMESPACE
167 
168 #endif