#ifndef BOOST_VARIANT_MATCH_HPP
#define BOOST_VARIANT_MATCH_HPP

#include <boost/variant/variant.hpp>
#include <boost/variant/get.hpp>

#include <type_traits>

namespace boost
{
	namespace detail
	{
		template<typename...>
		struct variant_matcher;

		template<typename A, typename... As>
		struct variant_matcher<A, boost::detail::variant::void_, As...>
		{
			template<typename V, typename F>
			static auto match(V && v, F && f) ->
				decltype(f(boost::get<A>(std::forward<V>(v))))
			{
				return f(boost::get<A>(std::forward<V>(v)));
			}
		};

		template<typename A, typename... As>
		struct variant_matcher<A, As...>
		{
			template<typename V, typename F, typename... Fs>
			static auto match(V && v, F f, Fs... fs) ->
				typename std::common_type<
					decltype(f(boost::get<A>(v))),
					decltype(variant_matcher<As...>::match(v, std::forward<Fs>(fs)...))
				>::type
			{
				if (auto * const p = boost::get<A>(&v)) // (if only we had N4127!)
					return f(*p);
				else
					return variant_matcher<As...>::match(v, std::forward<Fs>(fs)...);
			}
		};
	}

	template<typename... X, typename... F>
	auto match(variant<X...> & v, F && ... f)
		-> decltype(detail::variant_matcher<X...>::template match(v, std::forward<F>(f)...))
	{
		return detail::variant_matcher<X...>::template match(v, std::forward<F>(f)...);
	}

	template<typename... X, typename... F>
	auto match(variant<X...> const & v, F && ... f)
		-> decltype(detail::variant_matcher<X...>::template match(v, std::forward<F>(f)...))
	{
		return detail::variant_matcher<X...>::template match(v, std::forward<F>(f)...);
	}
}

#endif