1/* Failure observers for outcome type
2(C) 2017-2024 Niall Douglas <http://www.nedproductions.biz/> (7 commits)
3File Created: Oct 2017
4
5
6Boost Software License - Version 1.0 - August 17th, 2003
7
8Permission is hereby granted, free of charge, to any person or organization
9obtaining a copy of the software and accompanying documentation covered by
10this license (the "Software") to use, reproduce, display, distribute,
11execute, and transmit the Software, and to prepare derivative works of the
12Software, and to permit third-parties to whom the Software is furnished to
13do so, all subject to the following:
14
15The copyright notices in the Software and this entire statement, including
16the above license grant, this restriction and the following disclaimer,
17must be included in all copies of the Software, in whole or in part, and
18all derivative works of the Software, unless such copies or derivative
19works are solely in the form of machine-executable object code generated by
20a source language processor.
21
22THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
23IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
24FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
25SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
26FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
27ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
28DEALINGS IN THE SOFTWARE.
29*/
30
31#ifndef BOOST_OUTCOME_BASIC_OUTCOME_FAILURE_OBSERVERS_HPP
32#define BOOST_OUTCOME_BASIC_OUTCOME_FAILURE_OBSERVERS_HPP
33
34#include "basic_result_storage.hpp"
35
36#include <exception>
37
38BOOST_OUTCOME_V2_NAMESPACE_EXPORT_BEGIN
39
40namespace detail
41{
42 namespace adl
43 {
44 struct search_detail_adl
45 {
46 };
47 // Do NOT use template requirements here!
48 template <class S, typename = decltype(basic_outcome_failure_exception_from_error(std::declval<S>()))>
49 inline auto _delayed_lookup_basic_outcome_failure_exception_from_error(const S &ec, search_detail_adl /*unused*/)
50 {
51 // ADL discovered
52 return basic_outcome_failure_exception_from_error(ec);
53 }
54 } // namespace adl
55#if defined(_MSC_VER) && _MSC_VER <= 1923 // VS2019
56 // VS2017 and VS2019 with /permissive- chokes on the correct form due to over eager early instantiation.
57 template <class S, class P> inline void _delayed_lookup_basic_outcome_failure_exception_from_error(...) { static_assert(sizeof(S) == 0, "No specialisation for these error and exception types available!"); }
58#else
59 template <class S, class P> inline void _delayed_lookup_basic_outcome_failure_exception_from_error(...) = delete; // NOLINT No specialisation for these error and exception types available!
60#endif
61
62 template <class exception_type> inline exception_type current_exception_or_fatal(std::exception_ptr e) { std::rethrow_exception(e); }
63 template <> inline std::exception_ptr current_exception_or_fatal<std::exception_ptr>(std::exception_ptr e) { return e; }
64
65 template <class Base, class R, class S, class P, class NoValuePolicy> class basic_outcome_failure_observers : public Base
66 {
67 public:
68 using exception_type = P;
69 using Base::Base;
70
71 exception_type failure() const noexcept
72 {
73#ifndef BOOST_NO_EXCEPTIONS
74 try
75#endif
76 {
77 if(this->_state._status.have_exception())
78 {
79 return this->assume_exception();
80 }
81 if(this->_state._status.have_error())
82 {
83 return _delayed_lookup_basic_outcome_failure_exception_from_error(this->assume_error(), adl::search_detail_adl());
84 }
85 return exception_type();
86 }
87#ifndef BOOST_NO_EXCEPTIONS
88 catch(...)
89 {
90 // Return the failure if exception_type is std::exception_ptr,
91 // otherwise terminate same as throwing an exception inside noexcept
92 return current_exception_or_fatal<exception_type>(std::current_exception());
93 }
94#endif
95 }
96 };
97
98} // namespace detail
99
100BOOST_OUTCOME_V2_NAMESPACE_END
101
102#endif
103

source code of boost/libs/outcome/include/boost/outcome/detail/basic_outcome_failure_observers.hpp