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1 | /*! |
2 | @file | |
3 | Defines `boost::hana::accessors`. | |
4 | ||
5 | @copyright Louis Dionne 2013-2016 | |
6 | Distributed 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_ACCESSORS_HPP | |
11 | #define BOOST_HANA_ACCESSORS_HPP | |
12 | ||
13 | #include <boost/hana/fwd/accessors.hpp> | |
14 | ||
15 | #include <boost/hana/concept/struct.hpp> | |
16 | #include <boost/hana/config.hpp> | |
17 | #include <boost/hana/core/dispatch.hpp> | |
18 | ||
19 | ||
20 | BOOST_HANA_NAMESPACE_BEGIN | |
21 | template <typename S> | |
22 | struct accessors_t { | |
23 | #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS | |
24 | static_assert(hana::Struct<S>::value, | |
25 | "hana::accessors<S> requires 'S' to be a Struct"); | |
26 | #endif | |
27 | ||
28 | constexpr decltype(auto) operator()() const { | |
29 | using Accessors = BOOST_HANA_DISPATCH_IF(accessors_impl<S>, | |
30 | hana::Struct<S>::value | |
31 | ); | |
32 | ||
33 | return Accessors::apply(); | |
34 | } | |
35 | }; | |
36 | ||
37 | template <typename S, bool condition> | |
38 | struct accessors_impl<S, when<condition>> : default_ { | |
39 | template <typename ...Args> | |
40 | static constexpr auto apply(Args&& ...) = delete; | |
41 | }; | |
42 | ||
43 | namespace struct_detail { | |
44 | template <typename ...> | |
45 | struct is_valid { static constexpr bool value = true; }; | |
46 | } | |
47 | ||
48 | template <typename S> | |
49 | struct accessors_impl<S, when< | |
50 | struct_detail::is_valid<typename S::hana_accessors_impl>::value | |
51 | >> | |
52 | : S::hana_accessors_impl | |
53 | { }; | |
54 | BOOST_HANA_NAMESPACE_END | |
55 | ||
56 | #endif // !BOOST_HANA_ACCESSORS_HPP |