libstdc++: hash_fun.h Source File

libstdc++

hash_fun.h
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1// 'struct hash' from SGI -*- C++ -*-
2
3// Copyright (C) 2001-2026 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
61namespace __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
c++config.h
__gnu_cxx
GNU extensions for public use.