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/*!
@file
Defines `boost::hana::members`.
@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_MEMBERS_HPP
#define BOOST_HANA_MEMBERS_HPP
#include <boost/hana/fwd/members.hpp>
#include <boost/hana/accessors.hpp>
#include <boost/hana/concept/struct.hpp>
#include <boost/hana/config.hpp>
#include <boost/hana/core/dispatch.hpp>
#include <boost/hana/second.hpp>
#include <boost/hana/transform.hpp>
BOOST_HANA_NAMESPACE_BEGIN
//! @cond
template <typename Object>
constexpr auto members_t::operator()(Object&& object) const {
using S = typename hana::tag_of<Object>::type;
using Members = BOOST_HANA_DISPATCH_IF(members_impl<S>,
hana::Struct<S>::value
);
#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
static_assert(hana::Struct<S>::value,
"hana::members(object) requires 'object' to be a Struct");
#endif
return Members::apply(static_cast<Object&&>(object));
}
//! @endcond
namespace struct_detail {
template <typename Holder, typename Forward>
struct members_helper {
Holder object;
template <typename Accessor>
constexpr decltype(auto) operator()(Accessor&& accessor) const {
return hana::second(static_cast<Accessor&&>(accessor))(
static_cast<Forward>(object)
);
}
};
}
template <typename S, bool condition>
struct members_impl<S, when<condition>> : default_ {
template <typename Object>
static constexpr auto apply(Object&& object) {
return hana::transform(hana::accessors<S>(),
struct_detail::members_helper<Object&, Object&&>{object}
);
}
};
BOOST_HANA_NAMESPACE_END
#endif // !BOOST_HANA_MEMBERS_HPP
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