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- /*!
- @file
- Defines `boost::hana::detail::variadic::drop_into`.
- @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_DROP_INTO_HPP
- #define BOOST_HANA_DETAIL_VARIADIC_DROP_INTO_HPP
- #include <boost/hana/config.hpp>
- #include <cstddef>
- #include <utility>
- BOOST_HANA_NAMESPACE_BEGIN namespace detail { namespace variadic {
- template <std::size_t n, typename F, typename = std::make_index_sequence<n>>
- struct dropper;
- template <std::size_t n, typename F, std::size_t ...ignore>
- struct dropper<n, F, std::index_sequence<ignore...>> {
- F f;
- template <typename ...Rest>
- constexpr auto go(decltype(ignore, (void*)0)..., Rest ...rest) const
- { return f(*rest...); }
- template <typename ...Xs>
- constexpr auto operator()(Xs ...xs) const
- { return go(&xs...); }
- };
- template <std::size_t n>
- struct make_dropper {
- template <typename F>
- constexpr auto operator()(F f) const
- { return dropper<n, decltype(f)>{f}; }
- };
- template <std::size_t n>
- constexpr make_dropper<n> drop_into{};
- }} BOOST_HANA_NAMESPACE_END
- #endif // !BOOST_HANA_DETAIL_VARIADIC_DROP_INTO_HPP
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