mirror of
https://github.com/bolero-MURAKAMI/Sprout.git
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44 lines
1.6 KiB
C++
44 lines
1.6 KiB
C++
/*=============================================================================
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Copyright (c) 2011-2017 Bolero MURAKAMI
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https://github.com/bolero-MURAKAMI/Sprout
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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=============================================================================*/
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#ifndef SPROUT_FUNCTIONAL_HASH_HASH_COMBINE_HPP
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#define SPROUT_FUNCTIONAL_HASH_HASH_COMBINE_HPP
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#include <sprout/config.hpp>
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#include <sprout/workaround/std/cstddef.hpp>
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#include <sprout/functional/hash/hash_fwd.hpp>
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#include <sprout/functional/hash/to_hash.hpp>
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namespace sprout {
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namespace detail {
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template<typename T>
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inline SPROUT_CONSTEXPR std::size_t
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hash_combine_impl(std::size_t seed) {
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return seed;
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}
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template<typename T>
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inline SPROUT_CONSTEXPR std::size_t
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hash_combine_impl(std::size_t seed, T const& v) {
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return seed ^ (sprout::to_hash(v) + 0x9e3779b9 + (seed << 6) + (seed >> 2));
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}
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template<typename Head, typename... Tail>
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inline SPROUT_CONSTEXPR std::size_t
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hash_combine_impl(std::size_t seed, Head const& head, Tail const&... tail) {
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return sprout::detail::hash_combine_impl(sprout::detail::hash_combine_impl(seed, head), tail...);
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}
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} // namespace detail
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//
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// hash_combine
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//
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template<typename... Args>
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inline SPROUT_CONSTEXPR std::size_t
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hash_combine(std::size_t seed, Args const&... args) {
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return sprout::detail::hash_combine_impl(seed, args...);
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}
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} // namespace sprout
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#endif // #ifndef SPROUT_FUNCTIONAL_HASH_HASH_COMBINE_HPP
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