libcxx/include/__tuple/sfinae_helpers.h

   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,
  45             class ..._LArgs, class ..._RArgs>
  46   static auto __do_test(__tuple_types<_LArgs...>, __tuple_types<_RArgs...>)
  47     -> __all<__enable_if_t<_Trait<_LArgs, _RArgs>::value, bool>{true}...>;
  48   template <template <class...> class>
  49   static auto __do_test(...) -> false_type;
  50
  51   template <class _FromArgs, class _ToArgs>
  52   using __constructible = decltype(__do_test<is_constructible>(_ToArgs{}, _FromArgs{}));
  53   template <class _FromArgs, class _ToArgs>
  54   using __convertible = decltype(__do_test<is_convertible>(_FromArgs{}, _ToArgs{}));
  55   template <class _FromArgs, class _ToArgs>
  56   using __assignable = decltype(__do_test<is_assignable>(_ToArgs{}, _FromArgs{}));
  57 };
  58
  59 // __tuple_convertible
  60
  61 template <class _Tp, class _Up, bool = __tuple_like_ext<__libcpp_remove_reference_t<_Tp> >::value,
  62                                 bool = __tuple_like_ext<_Up>::value>
  63 struct __tuple_convertible
  64     : public false_type {};
  65
  66 template <class _Tp, class _Up>
  67 struct __tuple_convertible<_Tp, _Up, true, true>
  68     : public __tuple_sfinae_base::__convertible<
  69       typename __make_tuple_types<_Tp>::type
  70     , typename __make_tuple_types<_Up>::type
  71     >
  72 {};
  73
  74 // __tuple_constructible
  75
  76 template <class _Tp, class _Up, bool = __tuple_like_ext<__libcpp_remove_reference_t<_Tp> >::value,
  77                                 bool = __tuple_like_ext<_Up>::value>
  78 struct __tuple_constructible
  79     : public false_type {};
  80
  81 template <class _Tp, class _Up>
  82 struct __tuple_constructible<_Tp, _Up, true, true>
  83     : public __tuple_sfinae_base::__constructible<
  84       typename __make_tuple_types<_Tp>::type
  85     , typename __make_tuple_types<_Up>::type
  86     >
  87 {};
  88
  89 // __tuple_assignable
  90
  91 template <class _Tp, class _Up, bool = __tuple_like_ext<__libcpp_remove_reference_t<_Tp> >::value,
  92                                 bool = __tuple_like_ext<_Up>::value>
  93 struct __tuple_assignable
  94     : public false_type {};
  95
  96 template <class _Tp, class _Up>
  97 struct __tuple_assignable<_Tp, _Up, true, true>
  98     : public __tuple_sfinae_base::__assignable<
  99       typename __make_tuple_types<_Tp>::type
 100     , typename __make_tuple_types<_Up&>::type
 101     >
 102 {};
 103
 104
 105 template <size_t _Ip, class ..._Tp>
 106 struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, tuple<_Tp...> >
 107 {
 108     typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, __tuple_types<_Tp...> >::type type;
 109 };
 110
 111 struct _LIBCPP_EXPORTED_FROM_ABI __check_tuple_constructor_fail {
 112
 113     static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_explicit_default() { return false; }
 114     static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_implicit_default() { return false; }
 115     template <class ...>
 116     static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_explicit() { return false; }
 117     template <class ...>
 118     static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_implicit() { return false; }
 119     template <class ...>
 120     static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_assign() { return false; }
 121 };
 122 #endif // !defined(_LIBCPP_CXX03_LANG)
 123
 124 #if _LIBCPP_STD_VER >= 17
 125
 126 template <bool _CanCopy, bool _CanMove>
 127 struct __sfinae_ctor_base {};
 128 template <>
 129 struct __sfinae_ctor_base<false, false> {
 130   __sfinae_ctor_base() = default;
 131   __sfinae_ctor_base(__sfinae_ctor_base const&) = delete;
 132   __sfinae_ctor_base(__sfinae_ctor_base &&) = delete;
 133   __sfinae_ctor_base& operator=(__sfinae_ctor_base const&) = default;
 134   __sfinae_ctor_base& operator=(__sfinae_ctor_base&&) = default;
 135 };
 136 template <>
 137 struct __sfinae_ctor_base<true, false> {
 138   __sfinae_ctor_base() = default;
 139   __sfinae_ctor_base(__sfinae_ctor_base const&) = default;
 140   __sfinae_ctor_base(__sfinae_ctor_base &&) = delete;
 141   __sfinae_ctor_base& operator=(__sfinae_ctor_base const&) = default;
 142   __sfinae_ctor_base& operator=(__sfinae_ctor_base&&) = default;
 143 };
 144 template <>
 145 struct __sfinae_ctor_base<false, true> {
 146   __sfinae_ctor_base() = default;
 147   __sfinae_ctor_base(__sfinae_ctor_base const&) = delete;
 148   __sfinae_ctor_base(__sfinae_ctor_base &&) = default;
 149   __sfinae_ctor_base& operator=(__sfinae_ctor_base const&) = default;
 150   __sfinae_ctor_base& operator=(__sfinae_ctor_base&&) = default;
 151 };
 152
 153 template <bool _CanCopy, bool _CanMove>
 154 struct __sfinae_assign_base {};
 155 template <>
 156 struct __sfinae_assign_base<false, false> {
 157   __sfinae_assign_base() = default;
 158   __sfinae_assign_base(__sfinae_assign_base const&) = default;
 159   __sfinae_assign_base(__sfinae_assign_base &&) = default;
 160   __sfinae_assign_base& operator=(__sfinae_assign_base const&) = delete;
 161   __sfinae_assign_base& operator=(__sfinae_assign_base&&) = delete;
 162 };
 163 template <>
 164 struct __sfinae_assign_base<true, false> {
 165   __sfinae_assign_base() = default;
 166   __sfinae_assign_base(__sfinae_assign_base const&) = default;
 167   __sfinae_assign_base(__sfinae_assign_base &&) = default;
 168   __sfinae_assign_base& operator=(__sfinae_assign_base const&) = default;
 169   __sfinae_assign_base& operator=(__sfinae_assign_base&&) = delete;
 170 };
 171 template <>
 172 struct __sfinae_assign_base<false, true> {
 173   __sfinae_assign_base() = default;
 174   __sfinae_assign_base(__sfinae_assign_base const&) = default;
 175   __sfinae_assign_base(__sfinae_assign_base &&) = default;
 176   __sfinae_assign_base& operator=(__sfinae_assign_base const&) = delete;
 177   __sfinae_assign_base& operator=(__sfinae_assign_base&&) = default;
 178 };
 179 #endif // _LIBCPP_STD_VER >= 17
 180
 181 _LIBCPP_END_NAMESPACE_STD
 182
 183 #endif // _LIBCPP___TUPLE_SFINAE_HELPERS_H