Hash.h

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/* Author: Mark Moll */

#ifndef OMPL_UTIL_HASH_
#define OMPL_UTIL_HASH_

#include <functional>
#include <type_traits>
#include <utility>

namespace ompl
{
    // copied from <boost/functional/hash.hpp>
    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);
    }
}

namespace std
{
    template <class U, class V>
    struct hash<std::pair<U, V>>
    {
        using argument_type = std::pair<U, V>;
        using result_type = std::size_t;
        result_type operator()(argument_type const &p) const
        {
            result_type h = std::hash<typename std::remove_cv<U>::type>()(p.first);
            ompl::hash_combine(h, p.second);
            return h;
        }
    };
}

#endif