/*! @file Defines `boost::hana::detail::variadic::split_at`. @copyright Louis Dionne 2013-2017 Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt) */ #ifndef BOOST_HANA_DETAIL_VARIADIC_SPLIT_AT_HPP #define BOOST_HANA_DETAIL_VARIADIC_SPLIT_AT_HPP #include <boost/hana/config.hpp> #include <boost/hana/functional/partial.hpp> #include <boost/hana/functional/reverse_partial.hpp> #include <cstddef> BOOST_HANA_NAMESPACE_BEGIN namespace detail { namespace variadic { template <std::size_t n> struct split_at_t { template <typename F, typename X1, typename X2, typename X3, typename X4, typename X5, typename X6, typename X7, typename X8, typename ...Xs> constexpr decltype(auto) operator()(F&& f, X1&& x1, X2&& x2, X3&& x3, X4&& x4, X5&& x5, X6&& x6, X7&& x7, X8&& x8, Xs&& ...xs) const { return split_at_t<n - 8>{}( hana::partial(static_cast<F&&>(f), static_cast<X1&&>(x1), static_cast<X2&&>(x2), static_cast<X3&&>(x3), static_cast<X4&&>(x4), static_cast<X5&&>(x5), static_cast<X6&&>(x6), static_cast<X7&&>(x7), static_cast<X8&&>(x8) ), static_cast<Xs&&>(xs)... ); } }; template <> struct split_at_t<0> { template <typename F, typename ...Xs> constexpr decltype(auto) operator()(F&& f, Xs&& ...xs) const { return static_cast<F&&>(f)()(static_cast<Xs&&>(xs)...); } }; template <> struct split_at_t<1> { template <typename F, typename X1, typename ...Xs> constexpr decltype(auto) operator()(F&& f, X1&& x1, Xs&& ...xs) const { return static_cast<F&&>(f)( static_cast<X1&&>(x1) )(static_cast<Xs&&>(xs)...); } }; template <> struct split_at_t<2> { template <typename F, typename X1, typename X2, typename ...Xs> constexpr decltype(auto) operator()(F&& f, X1&& x1, X2&& x2, Xs&& ...xs) const { return static_cast<F&&>(f)( static_cast<X1&&>(x1), static_cast<X2&&>(x2) )(static_cast<Xs&&>(xs)...); } }; template <> struct split_at_t<3> { template <typename F, typename X1, typename X2, typename X3, typename ...Xs> constexpr decltype(auto) operator()(F&& f, X1&& x1, X2&& x2, X3&& x3, Xs&& ...xs) const { return static_cast<F&&>(f)( static_cast<X1&&>(x1), static_cast<X2&&>(x2), static_cast<X3&&>(x3) )(static_cast<Xs&&>(xs)...); } }; template <> struct split_at_t<4> { template <typename F, typename X1, typename X2, typename X3, typename X4, typename ...Xs> constexpr decltype(auto) operator()(F&& f, X1&& x1, X2&& x2, X3&& x3, X4&& x4, Xs&& ...xs) const { return static_cast<F&&>(f)( static_cast<X1&&>(x1), static_cast<X2&&>(x2), static_cast<X3&&>(x3), static_cast<X4&&>(x4) )(static_cast<Xs&&>(xs)...); } }; template <> struct split_at_t<5> { template <typename F, typename X1, typename X2, typename X3, typename X4, typename X5, typename ...Xs> constexpr decltype(auto) operator()(F&& f, X1&& x1, X2&& x2, X3&& x3, X4&& x4, X5&& x5, Xs&& ...xs) const { return static_cast<F&&>(f)( static_cast<X1&&>(x1), static_cast<X2&&>(x2), static_cast<X3&&>(x3), static_cast<X4&&>(x4), static_cast<X5&&>(x5) )(static_cast<Xs&&>(xs)...); } }; template <> struct split_at_t<6> { template <typename F, typename X1, typename X2, typename X3, typename X4, typename X5, typename X6, typename ...Xs> constexpr decltype(auto) operator()(F&& f, X1&& x1, X2&& x2, X3&& x3, X4&& x4, X5&& x5, X6&& x6, Xs&& ...xs) const { return static_cast<F&&>(f)( static_cast<X1&&>(x1), static_cast<X2&&>(x2), static_cast<X3&&>(x3), static_cast<X4&&>(x4), static_cast<X5&&>(x5), static_cast<X6&&>(x6) )(static_cast<Xs&&>(xs)...); } }; template <> struct split_at_t<7> { template <typename F, typename X1, typename X2, typename X3, typename X4, typename X5, typename X6, typename X7, typename ...Xs> constexpr decltype(auto) operator()(F&& f, X1&& x1, X2&& x2, X3&& x3, X4&& x4, X5&& x5, X6&& x6, X7&& x7, Xs&& ...xs) const { return static_cast<F&&>(f)( static_cast<X1&&>(x1), static_cast<X2&&>(x2), static_cast<X3&&>(x3), static_cast<X4&&>(x4), static_cast<X5&&>(x5), static_cast<X6&&>(x6), static_cast<X7&&>(x7) )(static_cast<Xs&&>(xs)...); } }; template <std::size_t n> struct _makesplit_at_t { template <typename ...Xs> constexpr decltype(auto) operator()(Xs&& ...xs) const { return hana::reverse_partial(split_at_t<n>{}, static_cast<Xs&&>(xs)...); } }; template <std::size_t n> constexpr _makesplit_at_t<n> split_at{}; }} BOOST_HANA_NAMESPACE_END #endif // !BOOST_HANA_DETAIL_VARIADIC_SPLIT_AT_HPP