ceph/src/boost/boost/outcome/trait.hpp

   1 /* Traits for Outcome
   2 (C) 2018-2020 Niall Douglas <http://www.nedproductions.biz/> (8 commits)
   3 File Created: March 2018
   4
   5
   6 Boost Software License - Version 1.0 - August 17th, 2003
   7
   8 Permission is hereby granted, free of charge, to any person or organization
   9 obtaining a copy of the software and accompanying documentation covered by
  10 this license (the "Software") to use, reproduce, display, distribute,
  11 execute, and transmit the Software, and to prepare derivative works of the
  12 Software, and to permit third-parties to whom the Software is furnished to
  13 do so, all subject to the following:
  14
  15 The copyright notices in the Software and this entire statement, including
  16 the above license grant, this restriction and the following disclaimer,
  17 must be included in all copies of the Software, in whole or in part, and
  18 all derivative works of the Software, unless such copies or derivative
  19 works are solely in the form of machine-executable object code generated by
  20 a source language processor.
  21
  22 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  23 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  24 FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
  25 SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
  26 FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
  27 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  28 DEALINGS IN THE SOFTWARE.
  29 */
  30
  31 #ifndef BOOST_OUTCOME_TRAIT_HPP
  32 #define BOOST_OUTCOME_TRAIT_HPP
  33
  34 #include "config.hpp"
  35
  36 BOOST_OUTCOME_V2_NAMESPACE_BEGIN
  37
  38 namespace trait
  39 {
  40   /*! AWAITING HUGO JSON CONVERSION TOOL
  41 SIGNATURE NOT RECOGNISED
  42 */
  43   template <class R>                                                             //
  44   static constexpr bool type_can_be_used_in_basic_result =                       //
  45   (!std::is_reference<R>::value                                                  //
  46    && !BOOST_OUTCOME_V2_NAMESPACE::detail::is_in_place_type_t<std::decay_t<R>>::value  //
  47    && !is_success_type<R>                                                        //
  48    && !is_failure_type<R>                                                        //
  49    && !std::is_array<R>::value                                                   //
  50    && (std::is_void<R>::value || (std::is_object<R>::value                       //
  51                                   && std::is_destructible<R>::value))            //
  52   );
  53
  54   /*! AWAITING HUGO JSON CONVERSION TOOL
  55 type definition  is_error_type. Potential doc page: NOT FOUND
  56 */
  57   template <class E> struct is_error_type
  58   {
  59     static constexpr bool value = false;
  60   };
  61
  62   /*! AWAITING HUGO JSON CONVERSION TOOL
  63 type definition  is_error_type_enum. Potential doc page: NOT FOUND
  64 */
  65   template <class E, class Enum> struct is_error_type_enum
  66   {
  67     static constexpr bool value = false;
  68   };
  69
  70   namespace detail
  71   {
  72     template <class T> using devoid = BOOST_OUTCOME_V2_NAMESPACE::detail::devoid<T>;
  73     template <class T> std::add_rvalue_reference_t<devoid<T>> declval() noexcept;
  74
  75     // From http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4436.pdf
  76     namespace detector_impl
  77     {
  78       template <class...> using void_t = void;
  79       template <class Default, class, template <class...> class Op, class... Args> struct detector
  80       {
  81         static constexpr bool value = false;
  82         using type = Default;
  83       };
  84       template <class Default, template <class...> class Op, class... Args> struct detector<Default, void_t<Op<Args...>>, Op, Args...>
  85       {
  86         static constexpr bool value = true;
  87         using type = Op<Args...>;
  88       };
  89     }  // namespace detector_impl
  90     template <template <class...> class Op, class... Args> using is_detected = detector_impl::detector<void, void, Op, Args...>;
  91
  92     template <class Arg> using result_of_make_error_code = decltype(make_error_code(declval<Arg>()));
  93     template <class Arg> using introspect_make_error_code = is_detected<result_of_make_error_code, Arg>;
  94
  95     template <class Arg> using result_of_make_exception_ptr = decltype(make_exception_ptr(declval<Arg>()));
  96     template <class Arg> using introspect_make_exception_ptr = is_detected<result_of_make_exception_ptr, Arg>;
  97
  98     template <class T> struct _is_error_code_available
  99     {
 100       static constexpr bool value = detail::introspect_make_error_code<T>::value;
 101       using type = typename detail::introspect_make_error_code<T>::type;
 102     };
 103     template <class T> struct _is_exception_ptr_available
 104     {
 105       static constexpr bool value = detail::introspect_make_exception_ptr<T>::value;
 106       using type = typename detail::introspect_make_exception_ptr<T>::type;
 107     };
 108   }  // namespace detail
 109
 110   /*! AWAITING HUGO JSON CONVERSION TOOL
 111 type definition  is_error_code_available. Potential doc page: NOT FOUND
 112 */
 113   template <class T> struct is_error_code_available
 114   {
 115     static constexpr bool value = detail::_is_error_code_available<std::decay_t<T>>::value;
 116     using type = typename detail::_is_error_code_available<std::decay_t<T>>::type;
 117   };
 118   template <class T> constexpr bool is_error_code_available_v = detail::_is_error_code_available<std::decay_t<T>>::value;
 119
 120   /*! AWAITING HUGO JSON CONVERSION TOOL
 121 type definition  is_exception_ptr_available. Potential doc page: NOT FOUND
 122 */
 123   template <class T> struct is_exception_ptr_available
 124   {
 125     static constexpr bool value = detail::_is_exception_ptr_available<std::decay_t<T>>::value;
 126     using type = typename detail::_is_exception_ptr_available<std::decay_t<T>>::type;
 127   };
 128   template <class T> constexpr bool is_exception_ptr_available_v = detail::_is_exception_ptr_available<std::decay_t<T>>::value;
 129
 130
 131 }  // namespace trait
 132
 133 BOOST_OUTCOME_V2_NAMESPACE_END
 134
 135 #endif