1/*!
2@file
3Defines `boost::hana::members`.
4
5Copyright Louis Dionne 2013-2022
6Distributed under the Boost Software License, Version 1.0.
7(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
8 */
9
10#ifndef BOOST_HANA_MEMBERS_HPP
11#define BOOST_HANA_MEMBERS_HPP
12
13#include <boost/hana/fwd/members.hpp>
14
15#include <boost/hana/accessors.hpp>
16#include <boost/hana/concept/struct.hpp>
17#include <boost/hana/config.hpp>
18#include <boost/hana/core/dispatch.hpp>
19#include <boost/hana/second.hpp>
20#include <boost/hana/transform.hpp>
21
22
23namespace boost { namespace hana {
24 //! @cond
25 template <typename Object>
26 constexpr auto members_t::operator()(Object&& object) const {
27 using S = typename hana::tag_of<Object>::type;
28 using Members = BOOST_HANA_DISPATCH_IF(members_impl<S>,
29 hana::Struct<S>::value
30 );
31
32 #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
33 static_assert(hana::Struct<S>::value,
34 "hana::members(object) requires 'object' to be a Struct");
35 #endif
36
37 return Members::apply(static_cast<Object&&>(object));
38 }
39 //! @endcond
40
41 namespace struct_detail {
42 template <typename Holder, typename Forward>
43 struct members_helper {
44 Holder object;
45 template <typename Accessor>
46 constexpr decltype(auto) operator()(Accessor&& accessor) const {
47 return hana::second(static_cast<Accessor&&>(accessor))(
48 static_cast<Forward>(object)
49 );
50 }
51 };
52 }
53
54 template <typename S, bool condition>
55 struct members_impl<S, when<condition>> : default_ {
56 template <typename Object>
57 static constexpr auto apply(Object&& object) {
58 return hana::transform(hana::accessors<S>(),
59 struct_detail::members_helper<Object&, Object&&>{object}
60 );
61 }
62 };
63}} // end namespace boost::hana
64
65#endif // !BOOST_HANA_MEMBERS_HPP
66

source code of boost/libs/hana/include/boost/hana/members.hpp