type_traits revision 360784 
1// -*- C++ -*-
2//===-------------------------- type_traits -------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP_EXPERIMENTAL_TYPE_TRAITS
11#define _LIBCPP_EXPERIMENTAL_TYPE_TRAITS
12
13/**
14    experimental/type_traits synopsis
15
16// C++1y
17#include <type_traits>
18
19namespace std {
20namespace experimental {
21inline namespace fundamentals_v1 {
22
23  // 3.3.2, Other type transformations
24  template <class> class invocation_type; // not defined
25  template <class F, class... ArgTypes> class invocation_type<F(ArgTypes...)>;
26  template <class> class raw_invocation_type; // not defined
27  template <class F, class... ArgTypes> class raw_invocation_type<F(ArgTypes...)>;
28
29  template <class T>
30    using invocation_type_t = typename invocation_type<T>::type;
31  template <class T>
32    using raw_invocation_type_t = typename raw_invocation_type<T>::type;
33
34  // 3.3.4, Detection idiom
35  template <class...> using void_t = void;
36
37  struct nonesuch {
38    nonesuch() = delete;
39    ~nonesuch() = delete;
40    nonesuch(nonesuch const&) = delete;
41    void operator=(nonesuch const&) = delete;
42  };
43
44  template <template<class...> class Op, class... Args>
45    using is_detected = see below;
46  template <template<class...> class Op, class... Args>
47    constexpr bool is_detected_v = is_detected<Op, Args...>::value;
48  template <template<class...> class Op, class... Args>
49    using detected_t = see below;
50  template <class Default, template<class...> class Op, class... Args>
51    using detected_or = see below;
52  template <class Default, template<class...> class Op, class... Args>
53    using detected_or_t = typename detected_or<Default, Op, Args...>::type;
54  template <class Expected, template<class...> class Op, class... Args>
55    using is_detected_exact = is_same<Expected, detected_t<Op, Args...>>;
56  template <class Expected, template<class...> class Op, class... Args>
57    constexpr bool is_detected_exact_v
58      = is_detected_exact<Expected, Op, Args...>::value;
59  template <class To, template<class...> class Op, class... Args>
60     using is_detected_convertible = is_convertible<detected_t<Op, Args...>, To>;
61  template <class To, template<class...> class Op, class... Args>
62     constexpr bool is_detected_convertible_v
63       = is_detected_convertible<To, Op, Args...>::value;
64
65} // namespace fundamentals_v1
66} // namespace experimental
67} // namespace std
68
69 */
70
71#include <experimental/__config>
72
73#if _LIBCPP_STD_VER > 11
74
75#include <initializer_list>
76#include <type_traits>
77
78#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
79#pragma GCC system_header
80#endif
81
82_LIBCPP_BEGIN_NAMESPACE_LFTS
83
84// 3.3.2, Other type transformations
85/*
86template <class>
87class _LIBCPP_TEMPLATE_VIS raw_invocation_type;
88
89template <class _Fn, class ..._Args>
90class _LIBCPP_TEMPLATE_VIS raw_invocation_type<_Fn(_Args...)>;
91
92template <class>
93class _LIBCPP_TEMPLATE_VIS invokation_type;
94
95template <class _Fn, class ..._Args>
96class _LIBCPP_TEMPLATE_VIS invokation_type<_Fn(_Args...)>;
97
98template <class _Tp>
99using invokation_type_t = typename invokation_type<_Tp>::type;
100
101template <class _Tp>
102using raw_invocation_type_t = typename raw_invocation_type<_Tp>::type;
103*/
104
105// 3.3.4, Detection idiom
106template <class...> using void_t = void;
107
108struct nonesuch : private _VSTD::__nat { // make nonesuch "not an aggregate"
109  ~nonesuch() = delete;
110  nonesuch      (nonesuch const&) = delete;
111  void operator=(nonesuch const&) = delete;
112  };
113
114template <class _Default, class _AlwaysVoid, template <class...> class _Op, class... _Args>
115struct _DETECTOR {
116   using value_t = false_type;
117   using type = _Default;
118   };
119
120template <class _Default, template <class...> class _Op, class... _Args>
121struct _DETECTOR<_Default, void_t<_Op<_Args...>>, _Op, _Args...> {
122   using value_t = true_type;
123   using type = _Op<_Args...>;
124   };
125
126
127template <template<class...> class _Op, class... _Args>
128  using is_detected = typename _DETECTOR<nonesuch, void, _Op, _Args...>::value_t;
129template <template<class...> class _Op, class... _Args>
130  using detected_t = typename _DETECTOR<nonesuch, void, _Op, _Args...>::type;
131template <template<class...> class _Op, class... _Args>
132  _LIBCPP_CONSTEXPR bool is_detected_v = is_detected<_Op, _Args...>::value;
133
134template <class Default, template<class...> class _Op, class... _Args>
135  using detected_or = _DETECTOR<Default, void, _Op, _Args...>;
136template <class Default, template<class...> class _Op, class... _Args>
137  using detected_or_t = typename detected_or<Default, _Op, _Args...>::type;
138
139template <class Expected, template<class...> class _Op, class... _Args>
140  using is_detected_exact = is_same<Expected, detected_t<_Op, _Args...>>;
141template <class Expected, template<class...> class _Op, class... _Args>
142  _LIBCPP_CONSTEXPR bool is_detected_exact_v = is_detected_exact<Expected, _Op, _Args...>::value;
143
144template <class To, template<class...> class _Op, class... _Args>
145  using is_detected_convertible = is_convertible<detected_t<_Op, _Args...>, To>;
146template <class To, template<class...> class _Op, class... _Args>
147  _LIBCPP_CONSTEXPR bool is_detected_convertible_v = is_detected_convertible<To, _Op, _Args...>::value;
148
149
150_LIBCPP_END_NAMESPACE_LFTS
151
152#endif /* _LIBCPP_STD_VER > 11 */
153
154#endif /* _LIBCPP_EXPERIMENTAL_TYPE_TRAITS */
155