1 //
2 // traits/set_error_member.hpp
3 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~
4 //
5 // Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
6 //
7 // Distributed under the Boost Software License, Version 1.0. (See accompanying
8 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
9 //
10 
11 #ifndef BOOST_ASIO_TRAITS_SET_ERROR_MEMBER_HPP
12 #define BOOST_ASIO_TRAITS_SET_ERROR_MEMBER_HPP
13 
14 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
15 # pragma once
16 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
17 
18 #include <boost/asio/detail/config.hpp>
19 #include <boost/asio/detail/type_traits.hpp>
20 
21 #if defined(BOOST_ASIO_HAS_DECLTYPE) \
22   && defined(BOOST_ASIO_HAS_NOEXCEPT) \
23   && defined(BOOST_ASIO_HAS_WORKING_EXPRESSION_SFINAE)
24 # define BOOST_ASIO_HAS_DEDUCED_SET_ERROR_MEMBER_TRAIT 1
25 #endif // defined(BOOST_ASIO_HAS_DECLTYPE)
26        //   && defined(BOOST_ASIO_HAS_NOEXCEPT)
27        //   && defined(BOOST_ASIO_HAS_WORKING_EXPRESSION_SFINAE)
28 
29 #include <boost/asio/detail/push_options.hpp>
30 
31 namespace boost {
32 namespace asio {
33 namespace traits {
34 
35 template <typename T, typename E, typename = void>
36 struct set_error_member_default;
37 
38 template <typename T, typename E, typename = void>
39 struct set_error_member;
40 
41 } // namespace traits
42 namespace detail {
43 
44 struct no_set_error_member
45 {
46   BOOST_ASIO_STATIC_CONSTEXPR(bool, is_valid = false);
47   BOOST_ASIO_STATIC_CONSTEXPR(bool, is_noexcept = false);
48 };
49 
50 #if defined(BOOST_ASIO_HAS_DEDUCED_SET_ERROR_MEMBER_TRAIT)
51 
52 template <typename T, typename E, typename = void>
53 struct set_error_member_trait : no_set_error_member
54 {
55 };
56 
57 template <typename T, typename E>
58 struct set_error_member_trait<T, E,
59   typename void_type<
60     decltype(declval<T>().set_error(declval<E>()))
61   >::type>
62 {
63   BOOST_ASIO_STATIC_CONSTEXPR(bool, is_valid = true);
64 
65   using result_type = decltype(
66     declval<T>().set_error(declval<E>()));
67 
68   BOOST_ASIO_STATIC_CONSTEXPR(bool, is_noexcept = noexcept(
69     declval<T>().set_error(declval<E>())));
70 };
71 
72 #else // defined(BOOST_ASIO_HAS_DEDUCED_SET_ERROR_MEMBER_TRAIT)
73 
74 template <typename T, typename E, typename = void>
75 struct set_error_member_trait :
76   conditional<
77     is_same<T, typename remove_reference<T>::type>::value
78       && is_same<E, typename decay<E>::type>::value,
79     typename conditional<
80       is_same<T, typename add_const<T>::type>::value,
81       no_set_error_member,
82       traits::set_error_member<typename add_const<T>::type, E>
83     >::type,
84     traits::set_error_member<
85       typename remove_reference<T>::type,
86       typename decay<E>::type>
87   >::type
88 {
89 };
90 
91 #endif // defined(BOOST_ASIO_HAS_DEDUCED_SET_ERROR_MEMBER_TRAIT)
92 
93 } // namespace detail
94 namespace traits {
95 
96 template <typename T, typename E, typename>
97 struct set_error_member_default :
98   detail::set_error_member_trait<T, E>
99 {
100 };
101 
102 template <typename T, typename E, typename>
103 struct set_error_member :
104   set_error_member_default<T, E>
105 {
106 };
107 
108 } // namespace traits
109 } // namespace asio
110 } // namespace boost
111 
112 #include <boost/asio/detail/pop_options.hpp>
113 
114 #endif // BOOST_ASIO_TRAITS_SET_ERROR_MEMBER_HPP
115