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

   1 // 'struct hash' from SGI -*- C++ -*-
   2
   3 // Copyright (C) 2001, 2002, 2003, 2004 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, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  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).  You should only
  59  *  include this header if you are using GCC 3 or later.
  60  */
  61
  62 #ifndef _HASH_FUN_H
  63 #define _HASH_FUN_H 1
  64
  65 #include <cstddef>
  66
  67 namespace __gnu_cxx
  68 {
  69   using std::size_t;
  70
  71   template<class _Key>
  72     struct hash { };
  73
  74   inline size_t
  75   __stl_hash_string(const char* __s)
  76   {
  77     unsigned long __h = 0;
  78     for ( ; *__s; ++__s)
  79       __h = 5 * __h + *__s;
  80     return size_t(__h);
  81   }
  82
  83   template<>
  84     struct hash<char*>
  85     {
  86       size_t
  87       operator()(const char* __s) const
  88       { return __stl_hash_string(__s); }
  89     };
  90
  91   template<>
  92     struct hash<const char*>
  93     {
  94       size_t
  95       operator()(const char* __s) const
  96       { return __stl_hash_string(__s); }
  97     };
  98
  99   template<>
 100     struct hash<char>
 101     {
 102       size_t
 103       operator()(char __x) const
 104       { return __x; }
 105     };
 106
 107   template<>
 108     struct hash<unsigned char>
 109     {
 110       size_t
 111       operator()(unsigned char __x) const
 112       { return __x; }
 113     };
 114
 115   template<>
 116     struct hash<signed char>
 117     {
 118       size_t
 119       operator()(unsigned char __x) const
 120       { return __x; }
 121     };
 122
 123   template<>
 124     struct hash<short>
 125     {
 126       size_t
 127       operator()(short __x) const
 128       { return __x; }
 129     };
 130
 131   template<>
 132     struct hash<unsigned short>
 133     {
 134       size_t
 135       operator()(unsigned short __x) const
 136       { return __x; }
 137     };
 138
 139   template<>
 140     struct hash<int>
 141     {
 142       size_t
 143       operator()(int __x) const
 144       { return __x; }
 145     };
 146
 147   template<>
 148     struct hash<unsigned int>
 149     {
 150       size_t
 151       operator()(unsigned int __x) const
 152       { return __x; }
 153     };
 154
 155   template<>
 156     struct hash<long>
 157     {
 158       size_t
 159       operator()(long __x) const
 160       { return __x; }
 161     };
 162
 163   template<>
 164     struct hash<unsigned long>
 165     {
 166       size_t
 167       operator()(unsigned long __x) const
 168       { return __x; }
 169     };
 170 } // namespace __gnu_cxx
 171
 172 #endif