libstdc++-v3/include/ext/hash_fun.h

   1 // 'struct hash' from SGI -*- C++ -*-
   2
   3 // Copyright (C) 2001, 2002, 2003, 2004, 2005 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 2, 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 // You should have received a copy of the GNU General Public License along
  17 // with this library; see the file COPYING.  If not, write to the Free
  18 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  19 // USA.
  20
  21 // As a special exception, you may use this file as part of a free software
  22 // library without restriction.  Specifically, if other files instantiate
  23 // templates or use macros or inline functions from this file, or you compile
  24 // this file and link it with other files to produce an executable, this
  25 // file does not by itself cause the resulting executable to be covered by
  26 // the GNU General Public License.  This exception does not however
  27 // invalidate any other reasons why the executable file might be covered by
  28 // the GNU General Public License.
  29
  30 /*
  31  * Copyright (c) 1996-1998
  32  * Silicon Graphics Computer Systems, Inc.
  33  *
  34  * Permission to use, copy, modify, distribute and sell this software
  35  * and its documentation for any purpose is hereby granted without fee,
  36  * provided that the above copyright notice appear in all copies and
  37  * that both that copyright notice and this permission notice appear
  38  * in supporting documentation.  Silicon Graphics makes no
  39  * representations about the suitability of this software for any
  40  * purpose.  It is provided "as is" without express or implied warranty.
  41  *
  42  *
  43  * Copyright (c) 1994
  44  * Hewlett-Packard Company
  45  *
  46  * Permission to use, copy, modify, distribute and sell this software
  47  * and its documentation for any purpose is hereby granted without fee,
  48  * provided that the above copyright notice appear in all copies and
  49  * that both that copyright notice and this permission notice appear
  50  * in supporting documentation.  Hewlett-Packard Company makes no
  51  * representations about the suitability of this software for any
  52  * purpose.  It is provided "as is" without express or implied warranty.
  53  *
  54  */
  55
  56 /** @file ext/hash_fun.h
  57  *  This file is a GNU extension to the Standard C++ Library (possibly
  58  *  containing extensions from the HP/SGI STL subset).
  59  */
  60
  61 #ifndef _HASH_FUN_H
  62 #define _HASH_FUN_H 1
  63
  64 #include <cstddef>
  65
  66 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
  67
  68   using std::size_t;
  69
  70   template<class _Key>
  71     struct hash { };
  72
  73   inline size_t
  74   __stl_hash_string(const char* __s)
  75   {
  76     unsigned long __h = 0;
  77     for ( ; *__s; ++__s)
  78       __h = 5 * __h + *__s;
  79     return size_t(__h);
  80   }
  81
  82   template<>
  83     struct hash<char*>
  84     {
  85       size_t
  86       operator()(const char* __s) const
  87       { return __stl_hash_string(__s); }
  88     };
  89
  90   template<>
  91     struct hash<const char*>
  92     {
  93       size_t
  94       operator()(const char* __s) const
  95       { return __stl_hash_string(__s); }
  96     };
  97
  98   template<>
  99     struct hash<char>
 100     {
 101       size_t
 102       operator()(char __x) const
 103       { return __x; }
 104     };
 105
 106   template<>
 107     struct hash<unsigned char>
 108     {
 109       size_t
 110       operator()(unsigned char __x) const
 111       { return __x; }
 112     };
 113
 114   template<>
 115     struct hash<signed char>
 116     {
 117       size_t
 118       operator()(unsigned char __x) const
 119       { return __x; }
 120     };
 121
 122   template<>
 123     struct hash<short>
 124     {
 125       size_t
 126       operator()(short __x) const
 127       { return __x; }
 128     };
 129
 130   template<>
 131     struct hash<unsigned short>
 132     {
 133       size_t
 134       operator()(unsigned short __x) const
 135       { return __x; }
 136     };
 137
 138   template<>
 139     struct hash<int>
 140     {
 141       size_t
 142       operator()(int __x) const
 143       { return __x; }
 144     };
 145
 146   template<>
 147     struct hash<unsigned int>
 148     {
 149       size_t
 150       operator()(unsigned int __x) const
 151       { return __x; }
 152     };
 153
 154   template<>
 155     struct hash<long>
 156     {
 157       size_t
 158       operator()(long __x) const
 159       { return __x; }
 160     };
 161
 162   template<>
 163     struct hash<unsigned long>
 164     {
 165       size_t
 166       operator()(unsigned long __x) const
 167       { return __x; }
 168     };
 169
 170 _GLIBCXX_END_NAMESPACE
 171
 172 #endif