1/* Storage for a very simple basic_result type
2(C) 2017-2024 Niall Douglas <http://www.nedproductions.biz/> (6 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_RESULT_STORAGE_HPP
32#define BOOST_OUTCOME_BASIC_RESULT_STORAGE_HPP
33
34#include "../success_failure.hpp"
35#include "../trait.hpp"
36#include "value_storage.hpp"
37
38BOOST_OUTCOME_V2_NAMESPACE_EXPORT_BEGIN
39
40namespace detail
41{
42 template <class R, class EC, class NoValuePolicy> class basic_result_storage;
43} // namespace detail
44
45namespace hooks
46{
47 template <class R, class S, class NoValuePolicy> constexpr inline uint16_t spare_storage(const detail::basic_result_storage<R, S, NoValuePolicy> *r) noexcept;
48 template <class R, class S, class NoValuePolicy>
49 constexpr inline void set_spare_storage(detail::basic_result_storage<R, S, NoValuePolicy> *r, uint16_t v) noexcept;
50} // namespace hooks
51
52namespace policy
53{
54 struct base;
55} // namespace policy
56
57namespace detail
58{
59 template <class R, class EC, class NoValuePolicy> //
60 class basic_result_storage
61 {
62 static_assert(trait::type_can_be_used_in_basic_result<R>, "The type R cannot be used in a basic_result");
63 static_assert(trait::type_can_be_used_in_basic_result<EC>, "The type S cannot be used in a basic_result");
64
65 friend struct policy::base;
66 template <class T, class U, class V> //
67 friend class basic_result_storage;
68 template <class T, class U, class V> friend class basic_result_final;
69 template <class T, class U, class V>
70 friend constexpr inline uint16_t hooks::spare_storage(const detail::basic_result_storage<T, U, V> *r) noexcept; // NOLINT
71 template <class T, class U, class V>
72 friend constexpr inline void hooks::set_spare_storage(detail::basic_result_storage<T, U, V> *r, uint16_t v) noexcept; // NOLINT
73
74 struct disable_in_place_value_type
75 {
76 };
77 struct disable_in_place_error_type
78 {
79 };
80
81 protected:
82 using _value_type = std::conditional_t<std::is_same<R, EC>::value, disable_in_place_value_type, R>;
83 using _error_type = std::conditional_t<std::is_same<R, EC>::value, disable_in_place_error_type, EC>;
84
85 using _state_type = value_storage_select_impl<_value_type, _error_type>;
86
87#ifdef BOOST_OUTCOME_STANDARDESE_IS_IN_THE_HOUSE
88 value_storage_trivial<_value_type, _error_type> _state;
89#else
90 _state_type _state;
91#endif
92
93 public:
94 // Used by iostream support to access state
95 _state_type &_iostreams_state() { return _state; }
96 const _state_type &_iostreams_state() const { return _state; }
97
98 protected:
99 basic_result_storage() = default;
100 basic_result_storage(const basic_result_storage &) = default; // NOLINT
101 basic_result_storage(basic_result_storage &&) = default; // NOLINT
102 basic_result_storage &operator=(const basic_result_storage &) = default; // NOLINT
103 basic_result_storage &operator=(basic_result_storage &&) = default; // NOLINT
104 ~basic_result_storage() = default;
105
106 template <class... Args>
107 constexpr explicit basic_result_storage(in_place_type_t<_value_type> _,
108 Args &&... args) noexcept(detail::is_nothrow_constructible<_value_type, Args...>)
109 : _state{_, static_cast<Args &&>(args)...}
110 {
111 }
112 template <class U, class... Args>
113 constexpr basic_result_storage(in_place_type_t<_value_type> _, std::initializer_list<U> il,
114 Args &&... args) noexcept(detail::is_nothrow_constructible<_value_type, std::initializer_list<U>, Args...>)
115 : _state{_, il, static_cast<Args &&>(args)...}
116 {
117 }
118 template <class... Args>
119 constexpr explicit basic_result_storage(in_place_type_t<_error_type> _,
120 Args &&... args) noexcept(detail::is_nothrow_constructible<_error_type, Args...>)
121 : _state{_, static_cast<Args &&>(args)...}
122 {
123 }
124 template <class U, class... Args>
125 constexpr basic_result_storage(in_place_type_t<_error_type> _, std::initializer_list<U> il,
126 Args &&... args) noexcept(detail::is_nothrow_constructible<_error_type, std::initializer_list<U>, Args...>)
127 : _state{_, il, static_cast<Args &&>(args)...}
128 {
129 }
130
131 struct compatible_conversion_tag
132 {
133 };
134 template <class T, class U, class V>
135 constexpr basic_result_storage(compatible_conversion_tag /*unused*/, const basic_result_storage<T, U, V> &o) noexcept(
136 detail::is_nothrow_constructible<_value_type, T> &&detail::is_nothrow_constructible<_error_type, U>)
137 : _state(o._state)
138 {
139 }
140 template <class T, class U, class V>
141 constexpr basic_result_storage(compatible_conversion_tag /*unused*/, basic_result_storage<T, U, V> &&o) noexcept(
142 detail::is_nothrow_constructible<_value_type, T> &&detail::is_nothrow_constructible<_error_type, U>)
143 : _state(static_cast<decltype(o._state) &&>(o._state))
144 {
145 }
146
147 struct make_error_code_compatible_conversion_tag
148 {
149 };
150 template <class T, class U, class V>
151 constexpr basic_result_storage(make_error_code_compatible_conversion_tag /*unused*/, const basic_result_storage<T, U, V> &o) noexcept(
152 detail::is_nothrow_constructible<_value_type, T> &&noexcept(make_error_code(std::declval<U>())))
153 : _state(o._state._status.have_value() ? _state_type(in_place_type<_value_type>, o._state._value) :
154 _state_type(in_place_type<_error_type>, make_error_code(o._state._error)))
155 {
156 }
157 template <class T, class U, class V>
158 constexpr basic_result_storage(make_error_code_compatible_conversion_tag /*unused*/, basic_result_storage<T, U, V> &&o) noexcept(
159 detail::is_nothrow_constructible<_value_type, T> &&noexcept(make_error_code(std::declval<U>())))
160 : _state(o._state._status.have_value() ? _state_type(in_place_type<_value_type>, static_cast<T &&>(o._state._value)) :
161 _state_type(in_place_type<_error_type>, make_error_code(static_cast<U &&>(o._state._error))))
162 {
163 }
164
165 struct make_exception_ptr_compatible_conversion_tag
166 {
167 };
168 template <class T, class U, class V>
169 constexpr basic_result_storage(make_exception_ptr_compatible_conversion_tag /*unused*/, const basic_result_storage<T, U, V> &o) noexcept(
170 detail::is_nothrow_constructible<_value_type, T> &&noexcept(make_exception_ptr(std::declval<U>())))
171 : _state(o._state._status.have_value() ? _state_type(in_place_type<_value_type>, o._state._value) :
172 _state_type(in_place_type<_error_type>, make_exception_ptr(o._state._error)))
173 {
174 }
175 template <class T, class U, class V>
176 constexpr basic_result_storage(make_exception_ptr_compatible_conversion_tag /*unused*/, basic_result_storage<T, U, V> &&o) noexcept(
177 detail::is_nothrow_constructible<_value_type, T> &&noexcept(make_exception_ptr(std::declval<U>())))
178 : _state(o._state._status.have_value() ? _state_type(in_place_type<_value_type>, static_cast<T &&>(o._state._value)) :
179 _state_type(in_place_type<_error_type>, make_exception_ptr(static_cast<U &&>(o._state._error))))
180 {
181 }
182 };
183
184} // namespace detail
185BOOST_OUTCOME_V2_NAMESPACE_END
186
187#endif
188

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