/*!
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@file
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Defines common methods for all Boost.Fusion sequences.
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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_DETAIL_COMMON_HPP
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#define BOOST_HANA_EXT_BOOST_FUSION_DETAIL_COMMON_HPP
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#include <boost/hana/bool.hpp>
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#include <boost/hana/config.hpp>
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#include <boost/hana/core/when.hpp>
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#include <boost/hana/fwd/at.hpp>
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#include <boost/hana/fwd/concept/sequence.hpp>
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#include <boost/hana/fwd/is_empty.hpp>
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#include <boost/hana/fwd/length.hpp>
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#include <boost/hana/integral_constant.hpp>
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#include <boost/fusion/sequence/intrinsic/at.hpp>
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#include <boost/fusion/sequence/intrinsic/empty.hpp>
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#include <boost/fusion/sequence/intrinsic/size.hpp>
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#include <cstddef>
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BOOST_HANA_NAMESPACE_BEGIN
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namespace detail {
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template <typename T>
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struct is_fusion_sequence {
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static constexpr bool value = false;
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};
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}
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//////////////////////////////////////////////////////////////////////////
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// Iterable
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//////////////////////////////////////////////////////////////////////////
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template <typename S>
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struct at_impl<S, when<detail::is_fusion_sequence<S>::value>> {
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template <typename Xs, typename N>
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static constexpr decltype(auto) apply(Xs&& xs, N const&) {
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constexpr std::size_t n = N::value;
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return boost::fusion::at_c<n>(static_cast<Xs&&>(xs));
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}
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};
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template <typename S>
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struct is_empty_impl<S, when<detail::is_fusion_sequence<S>::value>> {
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template <typename Xs>
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static constexpr auto apply(Xs&& xs) {
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using Empty = decltype(boost::fusion::empty(xs));
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return hana::bool_c<Empty::value>;
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}
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};
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//////////////////////////////////////////////////////////////////////////
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// Foldable
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//////////////////////////////////////////////////////////////////////////
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template <typename S>
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struct length_impl<S, when<detail::is_fusion_sequence<S>::value>> {
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template <typename Xs>
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static constexpr auto apply(Xs const&) {
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using Size = typename boost::fusion::result_of::size<Xs>::type;
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return hana::size_c<Size::value>;
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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 <typename S>
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struct Sequence<S, when<detail::is_fusion_sequence<S>::value>> {
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static constexpr bool value = true;
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};
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_EXT_BOOST_FUSION_DETAIL_COMMON_HPP
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