[std::function<R(Args...)>] → [std::function<R(std::tuple<Args...>)]

fuse_cast.hpp

#include<functional>
#include<tuple>

namespace tupleple
{
	namespace deteil{
		template<size_t ...R>
		struct size_t_List{};

		template<size_t N>
		class make_size_t_List
		{
			template<class T>struct Inc;
			template<size_t ...R>
			struct Inc<size_t_List<R...>>
			{
				using type = size_t_List<0, (R + 1)...>;
			};
		public:
			using type = typename Inc<typename make_size_t_List<N - 1>::type>::type;
		};
		template<>
		struct make_size_t_List<0>
		{
			using type = size_t_List<>;
		};

		template<class R, class ...Args, size_t ...N >
		std::function<R(std::tuple<Args...>&&)>  fuse_cast_impl(const std::function<R(Args...)>&func, size_t_List<N...>)
		{
			return  [=](std::tuple<Args...>&&tuple)
			{
				return func(std::get<N>(tuple)...);
			};
		}
	}
	template<class R, class ...Args>
	std::function<R(std::tuple<Args...>&&)> fuse_cast(const std::function<R(Args...)>&func)
	{
		using List = typename make_size_t_List<sizeof...(Args)>::type;
		return n_cast_impl(func, List());
	}
}