3 Defines `boost::hana::detail::variadic::take`.
5 @copyright Louis Dionne 2013-2016
6 Distributed under the Boost Software License, Version 1.0.
7 (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
10 #ifndef BOOST_HANA_DETAIL_VARIADIC_TAKE_HPP
11 #define BOOST_HANA_DETAIL_VARIADIC_TAKE_HPP
13 #include <boost/hana/config.hpp>
14 #include <boost/hana/detail/variadic/split_at.hpp>
15 #include <boost/hana/functional/always.hpp>
16 #include <boost/hana/functional/reverse_partial.hpp>
21 BOOST_HANA_NAMESPACE_BEGIN namespace detail { namespace variadic {
23 template <typename F, typename ...Xs>
24 constexpr decltype(auto) operator()(F&& f, Xs&& ...xs) const {
25 return static_cast<F&&>(f)(static_cast<Xs&&>(xs)...);
30 template <typename ...Xs>
31 constexpr auto operator()(Xs&& ...xs) const {
33 reverse_partial(take_impl2{},
34 static_cast<Xs&&>(xs)...)
39 template <std::size_t n>
41 template <typename ...Xs>
42 constexpr decltype(auto) operator()(Xs&& ...xs) const {
43 return variadic::split_at<n>(static_cast<Xs&&>(xs)...)(take_impl1{});
47 template <std::size_t n>
48 constexpr take_t<n> take{};
49 }} BOOST_HANA_NAMESPACE_END
51 #endif // !BOOST_HANA_DETAIL_VARIADIC_TAKE_HPP