ceph/src/boost/boost/outcome/experimental/status_result.hpp

   1 /* A very simple result type
   2 (C) 2018-2019 Niall Douglas <http://www.nedproductions.biz/> (11 commits)
   3 File Created: Apr 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_EXPERIMENTAL_STATUS_RESULT_HPP
  32 #define BOOST_OUTCOME_EXPERIMENTAL_STATUS_RESULT_HPP
  33
  34 #include "../basic_result.hpp"
  35 #include "../policy/fail_to_compile_observers.hpp"
  36
  37 #include "status-code/system_error2.hpp"
  38
  39 BOOST_OUTCOME_V2_NAMESPACE_EXPORT_BEGIN
  40
  41 namespace trait
  42 {
  43   namespace detail
  44   {
  45     // Shortcut this for lower build impact. Used to tell outcome's converting constructors
  46     // that they can do E => EC or E => EP as necessary.
  47     template <class DomainType> struct _is_error_code_available<BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code<DomainType>>
  48     {
  49       static constexpr bool value = true;
  50       using type = BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code<DomainType>;
  51     };
  52     template <class DomainType> struct _is_error_code_available<BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::errored_status_code<DomainType>>
  53     {
  54       static constexpr bool value = true;
  55       using type = BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::errored_status_code<DomainType>;
  56     };
  57   }  // namespace detail
  58 #if 0  // Do NOT enable weakened implicit construction for these types
  59   template <class DomainType> struct is_error_type<BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code<DomainType>>
  60   {
  61     static constexpr bool value = true;
  62   };
  63   template <> struct is_error_type<BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::errc>
  64   {
  65     static constexpr bool value = true;
  66   };
  67   template <class DomainType, class Enum> struct is_error_type_enum<BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code<DomainType>, Enum>
  68   {
  69     static constexpr bool value = boost::system::is_error_condition_enum<Enum>::value;
  70   };
  71 #endif
  72 }  // namespace trait
  73
  74 namespace detail
  75 {
  76   // Customise _set_error_is_errno
  77   template <class State> constexpr inline void _set_error_is_errno(State &state, const BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::generic_code & /*unused*/) { state._status |= status_error_is_errno; }
  78   template <class State> constexpr inline void _set_error_is_errno(State &state, const BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::posix_code & /*unused*/) { state._status |= status_error_is_errno; }
  79   template <class State> constexpr inline void _set_error_is_errno(State &state, const BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::errc & /*unused*/) { state._status |= status_error_is_errno; }
  80
  81 }  // namespace detail
  82
  83 namespace experimental
  84 {
  85   using namespace BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE;
  86   using BOOST_OUTCOME_V2_NAMESPACE::success;
  87   using BOOST_OUTCOME_V2_NAMESPACE::failure;
  88
  89   namespace policy
  90   {
  91     using namespace BOOST_OUTCOME_V2_NAMESPACE::policy;
  92     template <class T, class EC, class E> struct status_code_throw
  93     {
  94       static_assert(!std::is_same<T, T>::value, "policy::status_code_throw not specialised for these types, did you use status_result<T, status_code<DomainType>, E>?");
  95     };
  96     template <class T, class DomainType> struct status_code_throw<T, status_code<DomainType>, void> : base
  97     {
  98       using _base = base;
  99       template <class Impl> static constexpr void wide_value_check(Impl &&self)
 100       {
 101         if(!base::_has_value(static_cast<Impl &&>(self)))
 102         {
 103           if(base::_has_error(static_cast<Impl &&>(self)))
 104           {
 105 #ifndef BOOST_NO_EXCEPTIONS
 106             base::_error(static_cast<Impl &&>(self)).throw_exception();
 107 #else
 108             BOOST_OUTCOME_THROW_EXCEPTION("wide value check failed");
 109 #endif
 110           }
 111         }
 112       }
 113       template <class Impl> static constexpr void wide_error_check(Impl &&self) { _base::narrow_error_check(static_cast<Impl &&>(self)); }
 114     };
 115     template <class T, class DomainType> struct status_code_throw<T, errored_status_code<DomainType>, void> : status_code_throw<T, status_code<DomainType>, void>
 116     {
 117       status_code_throw() = default;
 118       using status_code_throw<T, status_code<DomainType>, void>::status_code_throw;
 119     };
 120
 121     template <class T, class EC>
 122     using default_status_result_policy = std::conditional_t<                            //
 123     std::is_void<EC>::value,                                                            //
 124     BOOST_OUTCOME_V2_NAMESPACE::policy::terminate,                                            //
 125     std::conditional_t<is_status_code<EC>::value || is_errored_status_code<EC>::value,  //
 126                        status_code_throw<T, EC, void>,                                  //
 127                        BOOST_OUTCOME_V2_NAMESPACE::policy::fail_to_compile_observers          //
 128                        >>;
 129   }  // namespace policy
 130
 131   /*! AWAITING HUGO JSON CONVERSION TOOL
 132 SIGNATURE NOT RECOGNISED
 133 */
 134   template <class R, class S = system_code, class NoValuePolicy = policy::default_status_result_policy<R, S>>  //
 135   using status_result = basic_result<R, S, NoValuePolicy>;
 136
 137 }  // namespace experimental
 138
 139 BOOST_OUTCOME_V2_NAMESPACE_END
 140
 141 #endif