40 lines
928 B
C
40 lines
928 B
C
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#pragma once
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#include <tuple>
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namespace std {
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namespace {
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template <typename T>
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void hash_combine(size_t& seed, const T& value) {
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seed ^= std::hash<T>()(value) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
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}
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// Recursive template code derived from Matthieu M.
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template <typename Tuple, size_t Index = tuple_size<Tuple>::value - 1>
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struct HashValueImpl {
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static void apply(size_t& seed, const Tuple& tuple) {
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HashValueImpl<Tuple, Index - 1>::apply(seed, tuple);
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hash_combine(seed, std::get<Index>(tuple));
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}
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};
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template <typename Tuple>
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struct HashValueImpl<Tuple, 0> {
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static void apply(size_t& seed, const Tuple& tuple) {
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hash_combine(seed, std::get<0>(tuple));
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}
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};
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}
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template <typename ... TT>
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struct hash<tuple<TT...>> {
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size_t operator()(const tuple<TT...>& tt) const {
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size_t seed = 0;
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HashValueImpl<tuple<TT...> >::apply(seed, tt);
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return seed;
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}
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};
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}
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