hash_fun.h
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// 'struct hash' from SGI -*- C++ -*-
// Copyright (C) 2001-2025 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
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/*
* 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 <bits/c++config.h>
namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
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_VERSION
} // namespace
#endif
c++config.h
__gnu_cxx
GNU extensions for public use.