Boost C++ Libraries of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards


//  Copyright 2021 Matt Borland. Distributed under the Boost
//  Software License, Version 1.0. (See accompanying file
//  LICENSE_1_0.txt or copy at


#include <cstddef>
#include <functional>
#include <boost/multiprecision/detail/standalone_config.hpp>

namespace boost { namespace multiprecision { namespace detail {

template <typename T>
inline std::size_t hash_value(const T& v)
    std::hash<T> hasher;
    return hasher(v);

#if defined(BOOST_HAS_INT128)

std::size_t hash_value(const uint128_type& val);

inline std::size_t hash_value(const int128_type& val)
   return hash_value(static_cast<uint128_type>(val));


inline void hash_combine(std::size_t&) {}

template <typename T, typename... Args>
inline void hash_combine(std::size_t& seed, const T& v, Args... args) 
    constexpr std::size_t adder = 0x9e3779b9;
    seed = seed ^ (hash_value(v) + adder + (seed<<6) + (seed>>2));
    hash_combine(seed, args...);

#if defined(BOOST_HAS_INT128)

inline std::size_t hash_value(const uint128_type& val)
   std::size_t result = static_cast<std::size_t>(val);
   hash_combine(result, static_cast<std::size_t>(val >> 64));
   return result;


}}} // Namespaces