pair_hash.hpp

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#ifndef SPLA_PAIR_HASH_HPP
#define SPLA_PAIR_HASH_HPP
 
#include <utility>
 
namespace spla {
 
    template<class T>
    inline void hash_combine(std::size_t& seed, const T& v) {
        std::hash<T> hasher;
        seed ^= hasher(v) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
    }
 
    struct pair_hash {
    public:
        template<typename T, typename U>
        std::size_t operator()(const std::pair<T, U>& x) const {
            std::size_t seed = 0;
            hash_combine(seed, x.first);
            hash_combine(seed, x.second);
            return seed;
        }
    };
 
}// namespace spla
 
#endif//SPLA_PAIR_HASH_HPP