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/*!
@file
Defines `boost::hana::insert`.
@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_INSERT_HPP
#define BOOST_HANA_INSERT_HPP
#include <boost/hana/fwd/insert.hpp>
#include <boost/hana/append.hpp>
#include <boost/hana/concat.hpp>
#include <boost/hana/concept/sequence.hpp>
#include <boost/hana/config.hpp>
#include <boost/hana/core/dispatch.hpp>
#include <boost/hana/drop_front.hpp>
#include <boost/hana/take_front.hpp>
BOOST_HANA_NAMESPACE_BEGIN
//! @cond
template <typename Set, typename ...Args>
constexpr decltype(auto) insert_t::operator()(Set&& set, Args&& ...args) const {
return insert_impl<typename hana::tag_of<Set>::type>::apply(
static_cast<Set&&>(set),
static_cast<Args&&>(args)...
);
}
//! @endcond
template <typename T, bool condition>
struct insert_impl<T, when<condition>> : default_ {
template <typename ...Args>
static constexpr auto apply(Args&& ...) = delete;
};
template <typename S>
struct insert_impl<S, when<Sequence<S>::value>> {
template <typename Xs, typename N, typename Element>
static constexpr auto apply(Xs&& xs, N const& n, Element&& e) {
return hana::concat(hana::append(hana::take_front(xs, n),
static_cast<Element&&>(e)),
hana::drop_front(xs, n));
}
};
BOOST_HANA_NAMESPACE_END
#endif // !BOOST_HANA_INSERT_HPP
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