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/*!
@file
Defines `boost::hana::detail::variadic::drop_into`.
@copyright Louis Dionne 2013-2016
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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