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 <__cstddef/size_t.h>
  14 #include <__fwd/tuple.h>
  15 #include <__tuple/make_tuple_types.h>
  16 #include <__tuple/tuple_element.h>
  17 #include <__tuple/tuple_like_ext.h>
  18 #include <__tuple/tuple_size.h>
  19 #include <__tuple/tuple_types.h>
  20 #include <__type_traits/conjunction.h>
  21 #include <__type_traits/enable_if.h>
  22 #include <__type_traits/integral_constant.h>
  23 #include <__type_traits/is_constructible.h>
  24 #include <__type_traits/is_same.h>
  25 #include <__type_traits/remove_cvref.h>
  26 #include <__type_traits/remove_reference.h>
  27
  28 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  29 #  pragma GCC system_header
  30 #endif
  31
  32 _LIBCPP_BEGIN_NAMESPACE_STD
  33
  34 #ifndef _LIBCPP_CXX03_LANG
  35
  36 struct __tuple_sfinae_base {
  37   template <template <class, class...> class _Trait, class... _LArgs, class... _RArgs>
  38   static auto __do_test(__tuple_types<_LArgs...>,
  39                         __tuple_types<_RArgs...>) -> __all<__enable_if_t<_Trait<_LArgs, _RArgs>::value, bool>{true}...>;
  40   template <template <class...> class>
  41   static auto __do_test(...) -> false_type;
  42
  43   template <class _FromArgs, class _ToArgs>
  44   using __constructible = decltype(__do_test<is_constructible>(_ToArgs{}, _FromArgs{}));
  45 };
  46
  47 // __tuple_constructible
  48
  49 template <class _Tp,
  50           class _Up,
  51           bool = __tuple_like_ext<__libcpp_remove_reference_t<_Tp> >::value,
  52           bool = __tuple_like_ext<_Up>::value>
  53 struct __tuple_constructible : public false_type {};
  54
  55 template <class _Tp, class _Up>
  56 struct __tuple_constructible<_Tp, _Up, true, true>
  57     : public __tuple_sfinae_base::__constructible< typename __make_tuple_types<_Tp>::type,
  58                                                    typename __make_tuple_types<_Up>::type > {};
  59
  60 template <size_t _Ip, class... _Tp>
  61 struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, tuple<_Tp...> > {
  62   using type _LIBCPP_NODEBUG = typename tuple_element<_Ip, __tuple_types<_Tp...> >::type;
  63 };
  64
  65 struct _LIBCPP_EXPORTED_FROM_ABI __check_tuple_constructor_fail {
  66   static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_explicit_default() { return false; }
  67   static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_implicit_default() { return false; }
  68   template <class...>
  69   static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_explicit() {
  70     return false;
  71   }
  72   template <class...>
  73   static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_implicit() {
  74     return false;
  75   }
  76   template <class...>
  77   static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_assign() {
  78     return false;
  79   }
  80 };
  81 #endif // !defined(_LIBCPP_CXX03_LANG)
  82
  83 #if _LIBCPP_STD_VER >= 17
  84
  85 template <bool _CanCopy, bool _CanMove>
  86 struct __sfinae_ctor_base {};
  87 template <>
  88 struct __sfinae_ctor_base<false, false> {
  89   __sfinae_ctor_base()                                     = default;
  90   __sfinae_ctor_base(__sfinae_ctor_base const&)            = delete;
  91   __sfinae_ctor_base(__sfinae_ctor_base&&)                 = delete;
  92   __sfinae_ctor_base& operator=(__sfinae_ctor_base const&) = default;
  93   __sfinae_ctor_base& operator=(__sfinae_ctor_base&&)      = default;
  94 };
  95 template <>
  96 struct __sfinae_ctor_base<true, false> {
  97   __sfinae_ctor_base()                                     = default;
  98   __sfinae_ctor_base(__sfinae_ctor_base const&)            = default;
  99   __sfinae_ctor_base(__sfinae_ctor_base&&)                 = delete;
 100   __sfinae_ctor_base& operator=(__sfinae_ctor_base const&) = default;
 101   __sfinae_ctor_base& operator=(__sfinae_ctor_base&&)      = default;
 102 };
 103 template <>
 104 struct __sfinae_ctor_base<false, true> {
 105   __sfinae_ctor_base()                                     = default;
 106   __sfinae_ctor_base(__sfinae_ctor_base const&)            = delete;
 107   __sfinae_ctor_base(__sfinae_ctor_base&&)                 = default;
 108   __sfinae_ctor_base& operator=(__sfinae_ctor_base const&) = default;
 109   __sfinae_ctor_base& operator=(__sfinae_ctor_base&&)      = default;
 110 };
 111
 112 template <bool _CanCopy, bool _CanMove>
 113 struct __sfinae_assign_base {};
 114 template <>
 115 struct __sfinae_assign_base<false, false> {
 116   __sfinae_assign_base()                                       = default;
 117   __sfinae_assign_base(__sfinae_assign_base const&)            = default;
 118   __sfinae_assign_base(__sfinae_assign_base&&)                 = default;
 119   __sfinae_assign_base& operator=(__sfinae_assign_base const&) = delete;
 120   __sfinae_assign_base& operator=(__sfinae_assign_base&&)      = delete;
 121 };
 122 template <>
 123 struct __sfinae_assign_base<true, false> {
 124   __sfinae_assign_base()                                       = default;
 125   __sfinae_assign_base(__sfinae_assign_base const&)            = default;
 126   __sfinae_assign_base(__sfinae_assign_base&&)                 = default;
 127   __sfinae_assign_base& operator=(__sfinae_assign_base const&) = default;
 128   __sfinae_assign_base& operator=(__sfinae_assign_base&&)      = delete;
 129 };
 130 template <>
 131 struct __sfinae_assign_base<false, true> {
 132   __sfinae_assign_base()                                       = default;
 133   __sfinae_assign_base(__sfinae_assign_base const&)            = default;
 134   __sfinae_assign_base(__sfinae_assign_base&&)                 = default;
 135   __sfinae_assign_base& operator=(__sfinae_assign_base const&) = delete;
 136   __sfinae_assign_base& operator=(__sfinae_assign_base&&)      = default;
 137 };
 138 #endif // _LIBCPP_STD_VER >= 17
 139
 140 _LIBCPP_END_NAMESPACE_STD
 141
 142 #endif // _LIBCPP___TUPLE_SFINAE_HELPERS_H