xlnt/include/xlnt/utils/hash_combine.hpp
2016-10-25 20:22:22 -04:00

49 lines
2.0 KiB
C++

// Copyright 2005-2014 Daniel James.
// Boost Software License - Version 1.0 - August 17th, 2003
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
//
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//
// Based on Peter Dimov's proposal
// http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2005/n1756.pdf
// issue 6.18.
#pragma once
#include <functional>
#include <xlnt/xlnt_config.hpp>
namespace xlnt {
// TODO: Can this be in source->detail, or must it be in a header?
/// <summary>
/// Return a value by combining the hashed value of v (using std::hash) with seed.
/// </summary>
template <class T>
inline void XLNT_API hash_combine(std::size_t &seed, const T &v)
{
std::hash<T> hasher;
seed ^= hasher(v) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
}
} // namespace xlnt