53 lines
1.6 KiB
C++
53 lines
1.6 KiB
C++
/*!
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@file
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Defines `boost::hana::insert`.
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@copyright Louis Dionne 2013-2016
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
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*/
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#ifndef BOOST_HANA_INSERT_HPP
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#define BOOST_HANA_INSERT_HPP
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#include <boost/hana/fwd/insert.hpp>
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#include <boost/hana/append.hpp>
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#include <boost/hana/concat.hpp>
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#include <boost/hana/concept/sequence.hpp>
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#include <boost/hana/config.hpp>
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#include <boost/hana/core/dispatch.hpp>
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#include <boost/hana/drop_front.hpp>
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#include <boost/hana/take_front.hpp>
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BOOST_HANA_NAMESPACE_BEGIN
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//! @cond
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template <typename Set, typename ...Args>
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constexpr decltype(auto) insert_t::operator()(Set&& set, Args&& ...args) const {
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return insert_impl<typename hana::tag_of<Set>::type>::apply(
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static_cast<Set&&>(set),
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static_cast<Args&&>(args)...
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);
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}
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//! @endcond
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template <typename T, bool condition>
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struct insert_impl<T, when<condition>> : default_ {
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template <typename ...Args>
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static constexpr auto apply(Args&& ...) = delete;
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};
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template <typename S>
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struct insert_impl<S, when<Sequence<S>::value>> {
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template <typename Xs, typename N, typename Element>
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static constexpr auto apply(Xs&& xs, N const& n, Element&& e) {
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return hana::concat(hana::append(hana::take_front(xs, n),
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static_cast<Element&&>(e)),
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hana::drop_front(xs, n));
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}
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};
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_INSERT_HPP
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