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1 | /*! | |
2 | @file | |
3 | Defines `boost::hana::pair`. | |
4 | ||
5 | @copyright Louis Dionne 2013-2017 | |
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_PAIR_HPP | |
11 | #define BOOST_HANA_PAIR_HPP | |
12 | ||
13 | #include <boost/hana/fwd/pair.hpp> | |
14 | ||
15 | #include <boost/hana/config.hpp> | |
16 | #include <boost/hana/detail/decay.hpp> | |
17 | #include <boost/hana/detail/ebo.hpp> | |
18 | #include <boost/hana/detail/intrinsics.hpp> | |
19 | #include <boost/hana/detail/operators/adl.hpp> | |
20 | #include <boost/hana/detail/operators/comparable.hpp> | |
21 | #include <boost/hana/detail/operators/orderable.hpp> | |
22 | #include <boost/hana/fwd/core/make.hpp> | |
23 | #include <boost/hana/fwd/first.hpp> | |
24 | #include <boost/hana/fwd/second.hpp> | |
25 | ||
26 | #include <type_traits> | |
27 | #include <utility> | |
28 | ||
29 | ||
30 | namespace boost { namespace hana { | |
31 | namespace detail { | |
32 | template <int> struct pix; // pair index | |
33 | } | |
34 | ||
35 | ////////////////////////////////////////////////////////////////////////// | |
36 | // pair | |
37 | ////////////////////////////////////////////////////////////////////////// | |
38 | //! @cond | |
39 | template <typename First, typename Second> | |
40 | #ifdef BOOST_HANA_WORKAROUND_MSVC_EMPTYBASE | |
41 | struct __declspec(empty_bases) pair : detail::operators::adl<pair<First, Second>> | |
42 | #else | |
43 | struct pair : detail::operators::adl<pair<First, Second>> | |
44 | #endif | |
45 | , private detail::ebo<detail::pix<0>, First> | |
46 | , private detail::ebo<detail::pix<1>, Second> | |
47 | { | |
48 | // Default constructor | |
49 | template <typename ...dummy, typename = typename std::enable_if< | |
50 | BOOST_HANA_TT_IS_CONSTRUCTIBLE(First, dummy...) && | |
51 | BOOST_HANA_TT_IS_CONSTRUCTIBLE(Second, dummy...) | |
52 | >::type> | |
53 | constexpr pair() | |
54 | : detail::ebo<detail::pix<0>, First>() | |
55 | , detail::ebo<detail::pix<1>, Second>() | |
56 | { } | |
57 | ||
58 | // Variadic constructors | |
59 | template <typename ...dummy, typename = typename std::enable_if< | |
60 | BOOST_HANA_TT_IS_CONSTRUCTIBLE(First, First const&, dummy...) && | |
61 | BOOST_HANA_TT_IS_CONSTRUCTIBLE(Second, Second const&, dummy...) | |
62 | >::type> | |
63 | constexpr pair(First const& fst, Second const& snd) | |
64 | : detail::ebo<detail::pix<0>, First>(fst) | |
65 | , detail::ebo<detail::pix<1>, Second>(snd) | |
66 | { } | |
67 | ||
68 | template <typename T, typename U, typename = typename std::enable_if< | |
69 | BOOST_HANA_TT_IS_CONVERTIBLE(T&&, First) && | |
70 | BOOST_HANA_TT_IS_CONVERTIBLE(U&&, Second) | |
71 | >::type> | |
72 | constexpr pair(T&& t, U&& u) | |
73 | : detail::ebo<detail::pix<0>, First>(static_cast<T&&>(t)) | |
74 | , detail::ebo<detail::pix<1>, Second>(static_cast<U&&>(u)) | |
75 | { } | |
76 | ||
77 | ||
78 | // Possibly converting copy and move constructors | |
79 | template <typename T, typename U, typename = typename std::enable_if< | |
80 | BOOST_HANA_TT_IS_CONSTRUCTIBLE(First, T const&) && | |
81 | BOOST_HANA_TT_IS_CONSTRUCTIBLE(Second, U const&) && | |
82 | BOOST_HANA_TT_IS_CONVERTIBLE(T const&, First) && | |
83 | BOOST_HANA_TT_IS_CONVERTIBLE(U const&, Second) | |
84 | >::type> | |
85 | constexpr pair(pair<T, U> const& other) | |
86 | : detail::ebo<detail::pix<0>, First>(hana::first(other)) | |
87 | , detail::ebo<detail::pix<1>, Second>(hana::second(other)) | |
88 | { } | |
89 | ||
90 | template <typename T, typename U, typename = typename std::enable_if< | |
91 | BOOST_HANA_TT_IS_CONSTRUCTIBLE(First, T&&) && | |
92 | BOOST_HANA_TT_IS_CONSTRUCTIBLE(Second, U&&) && | |
93 | BOOST_HANA_TT_IS_CONVERTIBLE(T&&, First) && | |
94 | BOOST_HANA_TT_IS_CONVERTIBLE(U&&, Second) | |
95 | >::type> | |
96 | constexpr pair(pair<T, U>&& other) | |
97 | : detail::ebo<detail::pix<0>, First>(hana::first(static_cast<pair<T, U>&&>(other))) | |
98 | , detail::ebo<detail::pix<1>, Second>(hana::second(static_cast<pair<T, U>&&>(other))) | |
99 | { } | |
100 | ||
101 | ||
102 | // Copy and move assignment | |
103 | template <typename T, typename U, typename = typename std::enable_if< | |
104 | BOOST_HANA_TT_IS_ASSIGNABLE(First&, T const&) && | |
105 | BOOST_HANA_TT_IS_ASSIGNABLE(Second&, U const&) | |
106 | >::type> | |
107 | constexpr pair& operator=(pair<T, U> const& other) { | |
108 | hana::first(*this) = hana::first(other); | |
109 | hana::second(*this) = hana::second(other); | |
110 | return *this; | |
111 | } | |
112 | ||
113 | template <typename T, typename U, typename = typename std::enable_if< | |
114 | BOOST_HANA_TT_IS_ASSIGNABLE(First&, T&&) && | |
115 | BOOST_HANA_TT_IS_ASSIGNABLE(Second&, U&&) | |
116 | >::type> | |
117 | constexpr pair& operator=(pair<T, U>&& other) { | |
118 | hana::first(*this) = hana::first(static_cast<pair<T, U>&&>(other)); | |
119 | hana::second(*this) = hana::second(static_cast<pair<T, U>&&>(other)); | |
120 | return *this; | |
121 | } | |
122 | ||
123 | // Prevent the compiler from defining the default copy and move | |
124 | // constructors, which interfere with the SFINAE above. | |
125 | ~pair() = default; | |
126 | ||
127 | friend struct first_impl<pair_tag>; | |
128 | friend struct second_impl<pair_tag>; | |
129 | template <typename F, typename S> friend struct pair; | |
130 | }; | |
131 | //! @endcond | |
132 | ||
133 | template <typename First, typename Second> | |
134 | struct tag_of<pair<First, Second>> { | |
135 | using type = pair_tag; | |
136 | }; | |
137 | ||
138 | ////////////////////////////////////////////////////////////////////////// | |
139 | // Operators | |
140 | ////////////////////////////////////////////////////////////////////////// | |
141 | namespace detail { | |
142 | template <> | |
143 | struct comparable_operators<pair_tag> { | |
144 | static constexpr bool value = true; | |
145 | }; | |
146 | template <> | |
147 | struct orderable_operators<pair_tag> { | |
148 | static constexpr bool value = true; | |
149 | }; | |
150 | } | |
151 | ||
152 | ////////////////////////////////////////////////////////////////////////// | |
153 | // Product | |
154 | ////////////////////////////////////////////////////////////////////////// | |
155 | template <> | |
156 | struct make_impl<pair_tag> { | |
157 | template <typename F, typename S> | |
158 | static constexpr pair< | |
159 | typename detail::decay<F>::type, | |
160 | typename detail::decay<S>::type | |
161 | > apply(F&& f, S&& s) { | |
162 | return {static_cast<F&&>(f), static_cast<S&&>(s)}; | |
163 | } | |
164 | }; | |
165 | ||
166 | template <> | |
167 | struct first_impl<pair_tag> { | |
168 | template <typename First, typename Second> | |
169 | static constexpr decltype(auto) apply(hana::pair<First, Second>& p) { | |
170 | return detail::ebo_get<detail::pix<0>>( | |
171 | static_cast<detail::ebo<detail::pix<0>, First>&>(p) | |
172 | ); | |
173 | } | |
174 | template <typename First, typename Second> | |
175 | static constexpr decltype(auto) apply(hana::pair<First, Second> const& p) { | |
176 | return detail::ebo_get<detail::pix<0>>( | |
177 | static_cast<detail::ebo<detail::pix<0>, First> const&>(p) | |
178 | ); | |
179 | } | |
180 | template <typename First, typename Second> | |
181 | static constexpr decltype(auto) apply(hana::pair<First, Second>&& p) { | |
182 | return detail::ebo_get<detail::pix<0>>( | |
183 | static_cast<detail::ebo<detail::pix<0>, First>&&>(p) | |
184 | ); | |
185 | } | |
186 | }; | |
187 | ||
188 | template <> | |
189 | struct second_impl<pair_tag> { | |
190 | template <typename First, typename Second> | |
191 | static constexpr decltype(auto) apply(hana::pair<First, Second>& p) { | |
192 | return detail::ebo_get<detail::pix<1>>( | |
193 | static_cast<detail::ebo<detail::pix<1>, Second>&>(p) | |
194 | ); | |
195 | } | |
196 | template <typename First, typename Second> | |
197 | static constexpr decltype(auto) apply(hana::pair<First, Second> const& p) { | |
198 | return detail::ebo_get<detail::pix<1>>( | |
199 | static_cast<detail::ebo<detail::pix<1>, Second> const&>(p) | |
200 | ); | |
201 | } | |
202 | template <typename First, typename Second> | |
203 | static constexpr decltype(auto) apply(hana::pair<First, Second>&& p) { | |
204 | return detail::ebo_get<detail::pix<1>>( | |
205 | static_cast<detail::ebo<detail::pix<1>, Second>&&>(p) | |
206 | ); | |
207 | } | |
208 | }; | |
209 | }} // end namespace boost::hana | |
210 | ||
211 | #endif // !BOOST_HANA_PAIR_HPP |