/*!
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@file
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Adapts `boost::fusion::deque` for use with Hana.
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@copyright Louis Dionne 2013-2017
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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_EXT_BOOST_FUSION_DEQUE_HPP
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#define BOOST_HANA_EXT_BOOST_FUSION_DEQUE_HPP
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#include <boost/hana/at.hpp>
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#include <boost/hana/core/when.hpp>
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#include <boost/hana/config.hpp>
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#include <boost/hana/ext/boost/fusion/detail/common.hpp>
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#include <boost/hana/fwd/core/make.hpp>
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#include <boost/hana/fwd/core/tag_of.hpp>
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#include <boost/hana/fwd/drop_front.hpp>
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#include <boost/hana/length.hpp>
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#include <boost/fusion/container/deque.hpp>
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#include <boost/fusion/container/generation/make_deque.hpp>
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#include <boost/fusion/support/tag_of.hpp>
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#include <cstddef>
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#include <type_traits>
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#include <utility>
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#ifdef BOOST_HANA_DOXYGEN_INVOKED
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namespace boost { namespace fusion {
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//! @ingroup group-ext-fusion
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//! Adapter for Boost.Fusion deques.
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//!
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//!
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//! Modeled concepts
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//! ----------------
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//! A Fusion deque is a model of the `Sequence` concept, and all the
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//! concepts it refines. That makes it essentially the same as a Hana
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//! tuple, although the complexity of some operations might differ from
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//! that of a tuple.
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//!
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//! @include example/ext/boost/fusion/deque.cpp
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template <typename ...T>
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struct deque { };
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}}
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#endif
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BOOST_HANA_NAMESPACE_BEGIN
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namespace ext { namespace boost { namespace fusion {
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struct deque_tag;
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}}}
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template <typename T>
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struct tag_of<T, when<
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std::is_same<
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typename ::boost::fusion::traits::tag_of<T>::type,
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::boost::fusion::traits::tag_of<
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::boost::fusion::deque<>
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>::type
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>::value
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>> {
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using type = ext::boost::fusion::deque_tag;
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};
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namespace detail {
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template <>
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struct is_fusion_sequence<ext::boost::fusion::deque_tag> {
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static constexpr bool value = true;
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};
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}
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//////////////////////////////////////////////////////////////////////////
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// Iterable (the rest is in detail/common.hpp)
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//////////////////////////////////////////////////////////////////////////
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template <>
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struct drop_front_impl<ext::boost::fusion::deque_tag> {
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template <std::size_t n, typename Xs, std::size_t ...i>
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static constexpr auto drop_front_helper(Xs&& xs, std::index_sequence<i...>) {
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return hana::make<ext::boost::fusion::deque_tag>(
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hana::at_c<n + i>(static_cast<Xs&&>(xs))...
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);
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}
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template <typename Xs, typename N>
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static constexpr auto apply(Xs&& xs, N const&) {
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constexpr std::size_t n = N::value;
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constexpr std::size_t len = decltype(hana::length(xs))::value;
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return drop_front_helper<n>(static_cast<Xs&&>(xs),
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std::make_index_sequence<(n < len ? len - n : 0)>{});
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}
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};
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//////////////////////////////////////////////////////////////////////////
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// Sequence
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//////////////////////////////////////////////////////////////////////////
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template <>
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struct make_impl<ext::boost::fusion::deque_tag> {
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template <typename ...Xs>
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static constexpr auto apply(Xs&& ...xs) {
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return ::boost::fusion::make_deque(static_cast<Xs&&>(xs)...);
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}
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};
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_EXT_BOOST_FUSION_DEQUE_HPP
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