text: // 'struct hash' from SGI -*- C++ -*-
  
  // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2009, 2010
  // Free Software Foundation, Inc.
  //
  // This file is part of the GNU ISO C++ Library.  This library is free
  // software; you can redistribute it and/or modify it under the
  // terms of the GNU General Public License as published by the
  // Free Software Foundation; either version 3, or (at your option)
  // any later version.
  
  // This library is distributed in the hope that it will be useful,
  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  // GNU General Public License for more details.
  
  // Under Section 7 of GPL version 3, you are granted additional
  // permissions described in the GCC Runtime Library Exception, version
  // 3.1, as published by the Free Software Foundation.
  
  // You should have received a copy of the GNU General Public License and
  // a copy of the GCC Runtime Library Exception along with this program;
  // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  // <http://www.gnu.org/licenses/>.
  
  /*
   * Copyright (c) 1996-1998
   * Silicon Graphics Computer Systems, Inc.
   *
   * Permission to use, copy, modify, distribute and sell this software
   * and its documentation for any purpose is hereby granted without fee,
   * provided that the above copyright notice appear in all copies and
   * that both that copyright notice and this permission notice appear
   * in supporting documentation.  Silicon Graphics makes no
   * representations about the suitability of this software for any
   * purpose.  It is provided "as is" without express or implied warranty.
   *
   *
   * Copyright (c) 1994
   * Hewlett-Packard Company
   *
   * Permission to use, copy, modify, distribute and sell this software
   * and its documentation for any purpose is hereby granted without fee,
   * provided that the above copyright notice appear in all copies and
   * that both that copyright notice and this permission notice appear
   * in supporting documentation.  Hewlett-Packard Company makes no
   * representations about the suitability of this software for any
   * purpose.  It is provided "as is" without express or implied warranty.
   *
   */
  
  /** @file backward/hash_fun.h
   *  This file is a GNU extension to the Standard C++ Library (possibly
   *  containing extensions from the HP/SGI STL subset).
   */
  
  #ifndef _BACKWARD_HASH_FUN_H
  #define _BACKWARD_HASH_FUN_H 1
  
  #include <cstddef>
  
  _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
  
    using std::size_t;
  
    template<class _Key>
      struct hash { };
  
    inline size_t
    __stl_hash_string(const char* __s)
    {
      unsigned long __h = 0;
      for ( ; *__s; ++__s)
        __h = 5 * __h + *__s;
      return size_t(__h);
    }
  
    template<>
      struct hash<char*>
      {
        size_t
        operator()(const char* __s) const
        { return __stl_hash_string(__s); }
      };
  
    template<>
      struct hash<const char*>
      {
        size_t
        operator()(const char* __s) const
        { return __stl_hash_string(__s); }
      };
  
    template<>
      struct hash<char>
      { 
        size_t
        operator()(char __x) const
        { return __x; }
      };
  
    template<>
      struct hash<unsigned char>
      { 
        size_t
        operator()(unsigned char __x) const
        { return __x; }
      };
  
    template<>
      struct hash<signed char>
      {
        size_t
        operator()(unsigned char __x) const
        { return __x; }
      };
  
    template<>
      struct hash<short>
      {
        size_t
        operator()(short __x) const
        { return __x; }
      };
  
    template<>
      struct hash<unsigned short>
      {
        size_t
        operator()(unsigned short __x) const
        { return __x; }
      };
  
    template<>
      struct hash<int>
      { 
        size_t 
        operator()(int __x) const 
        { return __x; }
      };
  
    template<>
      struct hash<unsigned int>
      { 
        size_t
        operator()(unsigned int __x) const
        { return __x; }
      };
  
    template<>
      struct hash<long>
      {
        size_t
        operator()(long __x) const
        { return __x; }
      };
  
    template<>
      struct hash<unsigned long>
      {
        size_t
        operator()(unsigned long __x) const
        { return __x; }
      };
  
  _GLIBCXX_END_NAMESPACE
  
  #endif
  