kicad/libs/kimath/include/hash.h

59 lines
2.0 KiB
C++

/*
* This program source code file is part of KiCad, a free EDA CAD application.
*
* Copyright (C) 2022 KiCad Developers, see CHANGELOG.TXT for contributors.
*
* This program 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
* of the License, or (at your option) any later version.
*
* This program 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, you may find one here:
* http://www.gnu.org/licenses/gpl-3.0.html
* or you may search the http://www.gnu.org website for the version 3 license,
* or you may write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
*/
#pragma once
#ifndef LIBS_KIMATH_INCLUDE_HASH_H_
#define LIBS_KIMATH_INCLUDE_HASH_H_
#include <functional>
/**
* This is a dummy function to take the final case of hash_combine below
* @param seed
*/
static inline void hash_combine( std::size_t &seed ) {}
/**
* Combine multiple hashes utilizing previous hash result.
*
* @tparam T A hashable type
* @param seed A seed value input and output for the result.
* @param val A hashable object of type T
*/
template< typename T, typename ... Types >
static inline void hash_combine( std::size_t &seed, const T &val, const Types &... args )
{
seed ^= std::hash<T>()( val ) + 0x9e3779b9 + ( seed << 6 ) + ( seed >> 2 );
hash_combine( seed, args... );
}
template <typename... Types>
static inline std::size_t hash_val( const Types &... args )
{
std::size_t seed = 0xa82de1c0;
hash_combine( seed, args... );
return seed;
}
#endif /* LIBS_KIMATH_INCLUDE_HASH_H_ */