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/*!
@file
Defines common methods for all Boost.Fusion sequences.
Copyright Louis Dionne 2013-2022
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_EXT_BOOST_FUSION_DETAIL_COMMON_HPP
#define BOOST_HANA_EXT_BOOST_FUSION_DETAIL_COMMON_HPP
#include <boost/hana/bool.hpp>
#include <boost/hana/config.hpp>
#include <boost/hana/core/when.hpp>
#include <boost/hana/fwd/at.hpp>
#include <boost/hana/fwd/concept/sequence.hpp>
#include <boost/hana/fwd/is_empty.hpp>
#include <boost/hana/fwd/length.hpp>
#include <boost/hana/integral_constant.hpp>
#include <boost/fusion/sequence/intrinsic/at.hpp>
#include <boost/fusion/sequence/intrinsic/empty.hpp>
#include <boost/fusion/sequence/intrinsic/size.hpp>
#include <cstddef>
namespace boost { namespace hana {
namespace detail {
template <typename T>
struct is_fusion_sequence {
static constexpr bool value = false;
};
}
//////////////////////////////////////////////////////////////////////////
// Iterable
//////////////////////////////////////////////////////////////////////////
template <typename S>
struct at_impl<S, when<detail::is_fusion_sequence<S>::value>> {
template <typename Xs, typename N>
static constexpr decltype(auto) apply(Xs&& xs, N const&) {
constexpr std::size_t n = N::value;
return boost::fusion::at_c<n>(static_cast<Xs&&>(xs));
}
};
template <typename S>
struct is_empty_impl<S, when<detail::is_fusion_sequence<S>::value>> {
template <typename Xs>
static constexpr auto apply(Xs&& xs) {
using Empty = decltype(boost::fusion::empty(xs));
return hana::bool_c<Empty::value>;
}
};
//////////////////////////////////////////////////////////////////////////
// Foldable
//////////////////////////////////////////////////////////////////////////
template <typename S>
struct length_impl<S, when<detail::is_fusion_sequence<S>::value>> {
template <typename Xs>
static constexpr auto apply(Xs const&) {
using Size = typename boost::fusion::result_of::size<Xs>::type;
return hana::size_c<Size::value>;
}
};
//////////////////////////////////////////////////////////////////////////
// Sequence
//////////////////////////////////////////////////////////////////////////
template <typename S>
struct Sequence<S, when<detail::is_fusion_sequence<S>::value>> {
static constexpr bool value = true;
};
}} // end namespace boost::hana
#endif // !BOOST_HANA_EXT_BOOST_FUSION_DETAIL_COMMON_HPP
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