1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #ifndef _LIBCPP___TUPLE_SFINAE_HELPERS_H
10 #define _LIBCPP___TUPLE_SFINAE_HELPERS_H
11 
12 #include <__config>
13 #include <__fwd/tuple.h>
14 #include <__tuple/make_tuple_types.h>
15 #include <__tuple/tuple_element.h>
16 #include <__tuple/tuple_like_ext.h>
17 #include <__tuple/tuple_size.h>
18 #include <__tuple/tuple_types.h>
19 #include <__type_traits/enable_if.h>
20 #include <__type_traits/integral_constant.h>
21 #include <__type_traits/is_assignable.h>
22 #include <__type_traits/is_constructible.h>
23 #include <__type_traits/is_convertible.h>
24 #include <__type_traits/is_same.h>
25 #include <__type_traits/remove_cvref.h>
26 #include <__type_traits/remove_reference.h>
27 #include <cstddef>
28 
29 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
30 #  pragma GCC system_header
31 #endif
32 
33 _LIBCPP_BEGIN_NAMESPACE_STD
34 
35 #ifndef _LIBCPP_CXX03_LANG
36 
37 template <bool... _Preds>
38 struct __all_dummy;
39 
40 template <bool... _Pred>
41 struct __all : _IsSame<__all_dummy<_Pred...>, __all_dummy<((void)_Pred, true)...>> {};
42 
43 struct __tuple_sfinae_base {
44   template <template <class, class...> class _Trait, class... _LArgs, class... _RArgs>
45   static auto __do_test(__tuple_types<_LArgs...>, __tuple_types<_RArgs...>)
46       -> __all<__enable_if_t<_Trait<_LArgs, _RArgs>::value, bool>{true}...>;
47   template <template <class...> class>
48   static auto __do_test(...) -> false_type;
49 
50   template <class _FromArgs, class _ToArgs>
51   using __constructible = decltype(__do_test<is_constructible>(_ToArgs{}, _FromArgs{}));
52   template <class _FromArgs, class _ToArgs>
53   using __convertible = decltype(__do_test<is_convertible>(_FromArgs{}, _ToArgs{}));
54   template <class _FromArgs, class _ToArgs>
55   using __assignable = decltype(__do_test<is_assignable>(_ToArgs{}, _FromArgs{}));
56 };
57 
58 // __tuple_convertible
59 
60 template <class _Tp,
61           class _Up,
62           bool = __tuple_like_ext<__libcpp_remove_reference_t<_Tp> >::value,
63           bool = __tuple_like_ext<_Up>::value>
64 struct __tuple_convertible : public false_type {};
65 
66 template <class _Tp, class _Up>
67 struct __tuple_convertible<_Tp, _Up, true, true>
68     : public __tuple_sfinae_base::__convertible< typename __make_tuple_types<_Tp>::type,
69                                                  typename __make_tuple_types<_Up>::type > {};
70 
71 // __tuple_constructible
72 
73 template <class _Tp,
74           class _Up,
75           bool = __tuple_like_ext<__libcpp_remove_reference_t<_Tp> >::value,
76           bool = __tuple_like_ext<_Up>::value>
77 struct __tuple_constructible : public false_type {};
78 
79 template <class _Tp, class _Up>
80 struct __tuple_constructible<_Tp, _Up, true, true>
81     : public __tuple_sfinae_base::__constructible< typename __make_tuple_types<_Tp>::type,
82                                                    typename __make_tuple_types<_Up>::type > {};
83 
84 // __tuple_assignable
85 
86 template <class _Tp,
87           class _Up,
88           bool = __tuple_like_ext<__libcpp_remove_reference_t<_Tp> >::value,
89           bool = __tuple_like_ext<_Up>::value>
90 struct __tuple_assignable : public false_type {};
91 
92 template <class _Tp, class _Up>
93 struct __tuple_assignable<_Tp, _Up, true, true>
94     : public __tuple_sfinae_base::__assignable< typename __make_tuple_types<_Tp>::type,
95                                                 typename __make_tuple_types<_Up&>::type > {};
96 
97 template <size_t _Ip, class... _Tp>
98 struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, tuple<_Tp...> > {
99   typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, __tuple_types<_Tp...> >::type type;
100 };
101 
102 struct _LIBCPP_EXPORTED_FROM_ABI __check_tuple_constructor_fail {
103   static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_explicit_default() { return false; }
104   static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_implicit_default() { return false; }
105   template <class...>
106   static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_explicit() {
107     return false;
108   }
109   template <class...>
110   static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_implicit() {
111     return false;
112   }
113   template <class...>
114   static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_assign() {
115     return false;
116   }
117 };
118 #endif // !defined(_LIBCPP_CXX03_LANG)
119 
120 #if _LIBCPP_STD_VER >= 17
121 
122 template <bool _CanCopy, bool _CanMove>
123 struct __sfinae_ctor_base {};
124 template <>
125 struct __sfinae_ctor_base<false, false> {
126   __sfinae_ctor_base()                                     = default;
127   __sfinae_ctor_base(__sfinae_ctor_base const&)            = delete;
128   __sfinae_ctor_base(__sfinae_ctor_base&&)                 = delete;
129   __sfinae_ctor_base& operator=(__sfinae_ctor_base const&) = default;
130   __sfinae_ctor_base& operator=(__sfinae_ctor_base&&)      = default;
131 };
132 template <>
133 struct __sfinae_ctor_base<true, false> {
134   __sfinae_ctor_base()                                     = default;
135   __sfinae_ctor_base(__sfinae_ctor_base const&)            = default;
136   __sfinae_ctor_base(__sfinae_ctor_base&&)                 = delete;
137   __sfinae_ctor_base& operator=(__sfinae_ctor_base const&) = default;
138   __sfinae_ctor_base& operator=(__sfinae_ctor_base&&)      = default;
139 };
140 template <>
141 struct __sfinae_ctor_base<false, true> {
142   __sfinae_ctor_base()                                     = default;
143   __sfinae_ctor_base(__sfinae_ctor_base const&)            = delete;
144   __sfinae_ctor_base(__sfinae_ctor_base&&)                 = default;
145   __sfinae_ctor_base& operator=(__sfinae_ctor_base const&) = default;
146   __sfinae_ctor_base& operator=(__sfinae_ctor_base&&)      = default;
147 };
148 
149 template <bool _CanCopy, bool _CanMove>
150 struct __sfinae_assign_base {};
151 template <>
152 struct __sfinae_assign_base<false, false> {
153   __sfinae_assign_base()                                       = default;
154   __sfinae_assign_base(__sfinae_assign_base const&)            = default;
155   __sfinae_assign_base(__sfinae_assign_base&&)                 = default;
156   __sfinae_assign_base& operator=(__sfinae_assign_base const&) = delete;
157   __sfinae_assign_base& operator=(__sfinae_assign_base&&)      = delete;
158 };
159 template <>
160 struct __sfinae_assign_base<true, false> {
161   __sfinae_assign_base()                                       = default;
162   __sfinae_assign_base(__sfinae_assign_base const&)            = default;
163   __sfinae_assign_base(__sfinae_assign_base&&)                 = default;
164   __sfinae_assign_base& operator=(__sfinae_assign_base const&) = default;
165   __sfinae_assign_base& operator=(__sfinae_assign_base&&)      = delete;
166 };
167 template <>
168 struct __sfinae_assign_base<false, true> {
169   __sfinae_assign_base()                                       = default;
170   __sfinae_assign_base(__sfinae_assign_base const&)            = default;
171   __sfinae_assign_base(__sfinae_assign_base&&)                 = default;
172   __sfinae_assign_base& operator=(__sfinae_assign_base const&) = delete;
173   __sfinae_assign_base& operator=(__sfinae_assign_base&&)      = default;
174 };
175 #endif // _LIBCPP_STD_VER >= 17
176 
177 _LIBCPP_END_NAMESPACE_STD
178 
179 #endif // _LIBCPP___TUPLE_SFINAE_HELPERS_H
180