The C and C++ Include Header Files

/usr/include/c++/11/backward/hash_fun.h


$ cat -n /usr/include/c++/11/backward/hash_fun.h

     1	// 'struct hash' from SGI -*- C++ -*-
     2	
     3	// Copyright (C) 2001-2021 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	
    61	namespace __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