1 | // <optional> -*- C++ -*- |
2 | |
3 | // Copyright (C) 2013-2023 Free Software Foundation, Inc. |
4 | // Copyright The GNU Toolchain Authors. |
5 | // |
6 | // This file is part of the GNU ISO C++ Library. This library is free |
7 | // software; you can redistribute it and/or modify it under the |
8 | // terms of the GNU General Public License as published by the |
9 | // Free Software Foundation; either version 3, or (at your option) |
10 | // any later version. |
11 | |
12 | // This library is distributed in the hope that it will be useful, |
13 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
14 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
15 | // GNU General Public License for more details. |
16 | |
17 | // Under Section 7 of GPL version 3, you are granted additional |
18 | // permissions described in the GCC Runtime Library Exception, version |
19 | // 3.1, as published by the Free Software Foundation. |
20 | |
21 | // You should have received a copy of the GNU General Public License and |
22 | // a copy of the GCC Runtime Library Exception along with this program; |
23 | // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
24 | // <http://www.gnu.org/licenses/>. |
25 | |
26 | /** @file include/optional |
27 | * This is a Standard C++ Library header. |
28 | */ |
29 | |
30 | #ifndef _GLIBCXX_OPTIONAL |
31 | #define _GLIBCXX_OPTIONAL 1 |
32 | |
33 | #pragma GCC system_header |
34 | |
35 | #if __cplusplus >= 201703L |
36 | |
37 | #include <type_traits> |
38 | #include <exception> |
39 | #include <new> |
40 | #include <initializer_list> |
41 | #include <bits/enable_special_members.h> |
42 | #include <bits/exception_defines.h> |
43 | #include <bits/functional_hash.h> |
44 | #include <bits/stl_construct.h> // _Construct |
45 | #include <bits/utility.h> // in_place_t |
46 | #if __cplusplus > 201703L |
47 | # include <compare> |
48 | # include <bits/invoke.h> // std::__invoke |
49 | #endif |
50 | #if __cplusplus > 202002L |
51 | # include <concepts> |
52 | #endif |
53 | |
54 | namespace std _GLIBCXX_VISIBILITY(default) |
55 | { |
56 | _GLIBCXX_BEGIN_NAMESPACE_VERSION |
57 | |
58 | /** |
59 | * @addtogroup utilities |
60 | * @{ |
61 | */ |
62 | |
63 | #if __cplusplus > 202002L && __cpp_lib_concepts |
64 | # define __cpp_lib_optional 202110L |
65 | #elif __cplusplus >= 202002L |
66 | # define __cpp_lib_optional 202106L |
67 | #else |
68 | # define __cpp_lib_optional 201606L |
69 | #endif |
70 | |
71 | template<typename _Tp> |
72 | class optional; |
73 | |
74 | /// Tag type to disengage optional objects. |
75 | struct nullopt_t |
76 | { |
77 | // Do not user-declare default constructor at all for |
78 | // optional_value = {} syntax to work. |
79 | // nullopt_t() = delete; |
80 | |
81 | // Used for constructing nullopt. |
82 | enum class _Construct { _Token }; |
83 | |
84 | // Must be constexpr for nullopt_t to be literal. |
85 | explicit constexpr nullopt_t(_Construct) noexcept { } |
86 | }; |
87 | |
88 | /// Tag to disengage optional objects. |
89 | inline constexpr nullopt_t nullopt { nullopt_t::_Construct::_Token }; |
90 | |
91 | template<typename _Fn> struct _Optional_func { _Fn& _M_f; }; |
92 | |
93 | /** |
94 | * @brief Exception class thrown when a disengaged optional object is |
95 | * dereferenced. |
96 | * @ingroup exceptions |
97 | */ |
98 | class bad_optional_access : public exception |
99 | { |
100 | public: |
101 | bad_optional_access() = default; |
102 | virtual ~bad_optional_access() = default; |
103 | |
104 | const char* what() const noexcept override |
105 | { return "bad optional access" ; } |
106 | }; |
107 | |
108 | // XXX Does not belong here. |
109 | [[__noreturn__]] inline void |
110 | __throw_bad_optional_access() |
111 | { _GLIBCXX_THROW_OR_ABORT(bad_optional_access()); } |
112 | |
113 | // This class template manages construction/destruction of |
114 | // the contained value for a std::optional. |
115 | template <typename _Tp> |
116 | struct _Optional_payload_base |
117 | { |
118 | using _Stored_type = remove_const_t<_Tp>; |
119 | |
120 | _Optional_payload_base() = default; |
121 | ~_Optional_payload_base() = default; |
122 | |
123 | template<typename... _Args> |
124 | constexpr |
125 | _Optional_payload_base(in_place_t __tag, _Args&&... __args) |
126 | : _M_payload(__tag, std::forward<_Args>(__args)...), |
127 | _M_engaged(true) |
128 | { } |
129 | |
130 | template<typename _Up, typename... _Args> |
131 | constexpr |
132 | _Optional_payload_base(std::initializer_list<_Up> __il, |
133 | _Args&&... __args) |
134 | : _M_payload(__il, std::forward<_Args>(__args)...), |
135 | _M_engaged(true) |
136 | { } |
137 | |
138 | // Constructor used by _Optional_base copy constructor when the |
139 | // contained value is not trivially copy constructible. |
140 | constexpr |
141 | _Optional_payload_base(bool /* __engaged */, |
142 | const _Optional_payload_base& __other) |
143 | { |
144 | if (__other._M_engaged) |
145 | this->_M_construct(__other._M_get()); |
146 | } |
147 | |
148 | // Constructor used by _Optional_base move constructor when the |
149 | // contained value is not trivially move constructible. |
150 | constexpr |
151 | _Optional_payload_base(bool /* __engaged */, |
152 | _Optional_payload_base&& __other) |
153 | { |
154 | if (__other._M_engaged) |
155 | this->_M_construct(std::move(__other._M_get())); |
156 | } |
157 | |
158 | // Copy constructor is only used to when the contained value is |
159 | // trivially copy constructible. |
160 | _Optional_payload_base(const _Optional_payload_base&) = default; |
161 | |
162 | // Move constructor is only used to when the contained value is |
163 | // trivially copy constructible. |
164 | _Optional_payload_base(_Optional_payload_base&&) = default; |
165 | |
166 | _Optional_payload_base& |
167 | operator=(const _Optional_payload_base&) = default; |
168 | |
169 | _Optional_payload_base& |
170 | operator=(_Optional_payload_base&&) = default; |
171 | |
172 | // used to perform non-trivial copy assignment. |
173 | constexpr void |
174 | _M_copy_assign(const _Optional_payload_base& __other) |
175 | { |
176 | if (this->_M_engaged && __other._M_engaged) |
177 | this->_M_get() = __other._M_get(); |
178 | else |
179 | { |
180 | if (__other._M_engaged) |
181 | this->_M_construct(__other._M_get()); |
182 | else |
183 | this->_M_reset(); |
184 | } |
185 | } |
186 | |
187 | // used to perform non-trivial move assignment. |
188 | constexpr void |
189 | _M_move_assign(_Optional_payload_base&& __other) |
190 | noexcept(__and_v<is_nothrow_move_constructible<_Tp>, |
191 | is_nothrow_move_assignable<_Tp>>) |
192 | { |
193 | if (this->_M_engaged && __other._M_engaged) |
194 | this->_M_get() = std::move(__other._M_get()); |
195 | else |
196 | { |
197 | if (__other._M_engaged) |
198 | this->_M_construct(std::move(__other._M_get())); |
199 | else |
200 | this->_M_reset(); |
201 | } |
202 | } |
203 | |
204 | struct _Empty_byte { }; |
205 | |
206 | template<typename _Up, bool = is_trivially_destructible_v<_Up>> |
207 | union _Storage |
208 | { |
209 | constexpr _Storage() noexcept : _M_empty() { } |
210 | |
211 | template<typename... _Args> |
212 | constexpr |
213 | _Storage(in_place_t, _Args&&... __args) |
214 | : _M_value(std::forward<_Args>(__args)...) |
215 | { } |
216 | |
217 | template<typename _Vp, typename... _Args> |
218 | constexpr |
219 | _Storage(std::initializer_list<_Vp> __il, _Args&&... __args) |
220 | : _M_value(__il, std::forward<_Args>(__args)...) |
221 | { } |
222 | |
223 | #if __cplusplus >= 202002L |
224 | template<typename _Fn, typename _Arg> |
225 | constexpr |
226 | _Storage(_Optional_func<_Fn> __f, _Arg&& __arg) |
227 | : _M_value(std::__invoke(std::forward<_Fn>(__f._M_f), |
228 | std::forward<_Arg>(__arg))) |
229 | { } |
230 | #endif |
231 | |
232 | _Empty_byte _M_empty; |
233 | _Up _M_value; |
234 | }; |
235 | |
236 | template<typename _Up> |
237 | union _Storage<_Up, false> |
238 | { |
239 | constexpr _Storage() noexcept : _M_empty() { } |
240 | |
241 | template<typename... _Args> |
242 | constexpr |
243 | _Storage(in_place_t, _Args&&... __args) |
244 | : _M_value(std::forward<_Args>(__args)...) |
245 | { } |
246 | |
247 | template<typename _Vp, typename... _Args> |
248 | constexpr |
249 | _Storage(std::initializer_list<_Vp> __il, _Args&&... __args) |
250 | : _M_value(__il, std::forward<_Args>(__args)...) |
251 | { } |
252 | |
253 | #if __cplusplus >= 202002L |
254 | template<typename _Fn, typename _Arg> |
255 | constexpr |
256 | _Storage(_Optional_func<_Fn> __f, _Arg&& __arg) |
257 | : _M_value(std::__invoke(std::forward<_Fn>(__f._M_f), |
258 | std::forward<_Arg>(__arg))) |
259 | { } |
260 | #endif |
261 | |
262 | // User-provided destructor is needed when _Up has non-trivial dtor. |
263 | _GLIBCXX20_CONSTEXPR ~_Storage() { } |
264 | |
265 | _Empty_byte _M_empty; |
266 | _Up _M_value; |
267 | }; |
268 | |
269 | _Storage<_Stored_type> _M_payload; |
270 | |
271 | bool _M_engaged = false; |
272 | |
273 | template<typename... _Args> |
274 | constexpr void |
275 | _M_construct(_Args&&... __args) |
276 | noexcept(is_nothrow_constructible_v<_Stored_type, _Args...>) |
277 | { |
278 | std::_Construct(std::__addressof(this->_M_payload._M_value), |
279 | std::forward<_Args>(__args)...); |
280 | this->_M_engaged = true; |
281 | } |
282 | |
283 | constexpr void |
284 | _M_destroy() noexcept |
285 | { |
286 | _M_engaged = false; |
287 | _M_payload._M_value.~_Stored_type(); |
288 | } |
289 | |
290 | #if __cplusplus >= 202002L |
291 | template<typename _Fn, typename _Up> |
292 | constexpr void |
293 | _M_apply(_Optional_func<_Fn> __f, _Up&& __x) |
294 | { |
295 | std::construct_at(std::__addressof(this->_M_payload), |
296 | __f, std::forward<_Up>(__x)); |
297 | _M_engaged = true; |
298 | } |
299 | #endif |
300 | |
301 | // The _M_get() operations have _M_engaged as a precondition. |
302 | // They exist to access the contained value with the appropriate |
303 | // const-qualification, because _M_payload has had the const removed. |
304 | |
305 | constexpr _Tp& |
306 | _M_get() noexcept |
307 | { return this->_M_payload._M_value; } |
308 | |
309 | constexpr const _Tp& |
310 | _M_get() const noexcept |
311 | { return this->_M_payload._M_value; } |
312 | |
313 | // _M_reset is a 'safe' operation with no precondition. |
314 | constexpr void |
315 | _M_reset() noexcept |
316 | { |
317 | if (this->_M_engaged) |
318 | _M_destroy(); |
319 | else // This seems redundant but improves codegen, see PR 112480. |
320 | this->_M_engaged = false; |
321 | } |
322 | }; |
323 | |
324 | // Class template that manages the payload for optionals. |
325 | template <typename _Tp, |
326 | bool /*_HasTrivialDestructor*/ = |
327 | is_trivially_destructible_v<_Tp>, |
328 | bool /*_HasTrivialCopy */ = |
329 | is_trivially_copy_assignable_v<_Tp> |
330 | && is_trivially_copy_constructible_v<_Tp>, |
331 | bool /*_HasTrivialMove */ = |
332 | is_trivially_move_assignable_v<_Tp> |
333 | && is_trivially_move_constructible_v<_Tp>> |
334 | struct _Optional_payload; |
335 | |
336 | // Payload for potentially-constexpr optionals (trivial copy/move/destroy). |
337 | template <typename _Tp> |
338 | struct _Optional_payload<_Tp, true, true, true> |
339 | : _Optional_payload_base<_Tp> |
340 | { |
341 | using _Optional_payload_base<_Tp>::_Optional_payload_base; |
342 | |
343 | _Optional_payload() = default; |
344 | }; |
345 | |
346 | // Payload for optionals with non-trivial copy construction/assignment. |
347 | template <typename _Tp> |
348 | struct _Optional_payload<_Tp, true, false, true> |
349 | : _Optional_payload_base<_Tp> |
350 | { |
351 | using _Optional_payload_base<_Tp>::_Optional_payload_base; |
352 | |
353 | _Optional_payload() = default; |
354 | ~_Optional_payload() = default; |
355 | _Optional_payload(const _Optional_payload&) = default; |
356 | _Optional_payload(_Optional_payload&&) = default; |
357 | _Optional_payload& operator=(_Optional_payload&&) = default; |
358 | |
359 | // Non-trivial copy assignment. |
360 | constexpr |
361 | _Optional_payload& |
362 | operator=(const _Optional_payload& __other) |
363 | { |
364 | this->_M_copy_assign(__other); |
365 | return *this; |
366 | } |
367 | }; |
368 | |
369 | // Payload for optionals with non-trivial move construction/assignment. |
370 | template <typename _Tp> |
371 | struct _Optional_payload<_Tp, true, true, false> |
372 | : _Optional_payload_base<_Tp> |
373 | { |
374 | using _Optional_payload_base<_Tp>::_Optional_payload_base; |
375 | |
376 | _Optional_payload() = default; |
377 | ~_Optional_payload() = default; |
378 | _Optional_payload(const _Optional_payload&) = default; |
379 | _Optional_payload(_Optional_payload&&) = default; |
380 | _Optional_payload& operator=(const _Optional_payload&) = default; |
381 | |
382 | // Non-trivial move assignment. |
383 | constexpr |
384 | _Optional_payload& |
385 | operator=(_Optional_payload&& __other) |
386 | noexcept(__and_v<is_nothrow_move_constructible<_Tp>, |
387 | is_nothrow_move_assignable<_Tp>>) |
388 | { |
389 | this->_M_move_assign(std::move(__other)); |
390 | return *this; |
391 | } |
392 | }; |
393 | |
394 | // Payload for optionals with non-trivial copy and move assignment. |
395 | template <typename _Tp> |
396 | struct _Optional_payload<_Tp, true, false, false> |
397 | : _Optional_payload_base<_Tp> |
398 | { |
399 | using _Optional_payload_base<_Tp>::_Optional_payload_base; |
400 | |
401 | _Optional_payload() = default; |
402 | ~_Optional_payload() = default; |
403 | _Optional_payload(const _Optional_payload&) = default; |
404 | _Optional_payload(_Optional_payload&&) = default; |
405 | |
406 | // Non-trivial copy assignment. |
407 | constexpr |
408 | _Optional_payload& |
409 | operator=(const _Optional_payload& __other) |
410 | { |
411 | this->_M_copy_assign(__other); |
412 | return *this; |
413 | } |
414 | |
415 | // Non-trivial move assignment. |
416 | constexpr |
417 | _Optional_payload& |
418 | operator=(_Optional_payload&& __other) |
419 | noexcept(__and_v<is_nothrow_move_constructible<_Tp>, |
420 | is_nothrow_move_assignable<_Tp>>) |
421 | { |
422 | this->_M_move_assign(std::move(__other)); |
423 | return *this; |
424 | } |
425 | }; |
426 | |
427 | // Payload for optionals with non-trivial destructors. |
428 | template <typename _Tp, bool _Copy, bool _Move> |
429 | struct _Optional_payload<_Tp, false, _Copy, _Move> |
430 | : _Optional_payload<_Tp, true, false, false> |
431 | { |
432 | // Base class implements all the constructors and assignment operators: |
433 | using _Optional_payload<_Tp, true, false, false>::_Optional_payload; |
434 | _Optional_payload() = default; |
435 | _Optional_payload(const _Optional_payload&) = default; |
436 | _Optional_payload(_Optional_payload&&) = default; |
437 | _Optional_payload& operator=(const _Optional_payload&) = default; |
438 | _Optional_payload& operator=(_Optional_payload&&) = default; |
439 | |
440 | // Destructor needs to destroy the contained value: |
441 | _GLIBCXX20_CONSTEXPR ~_Optional_payload() { this->_M_reset(); } |
442 | }; |
443 | |
444 | // Common base class for _Optional_base<T> to avoid repeating these |
445 | // member functions in each specialization. |
446 | template<typename _Tp, typename _Dp> |
447 | class _Optional_base_impl |
448 | { |
449 | protected: |
450 | using _Stored_type = remove_const_t<_Tp>; |
451 | |
452 | // The _M_construct operation has !_M_engaged as a precondition |
453 | // while _M_destruct has _M_engaged as a precondition. |
454 | template<typename... _Args> |
455 | constexpr void |
456 | _M_construct(_Args&&... __args) |
457 | noexcept(is_nothrow_constructible_v<_Stored_type, _Args...>) |
458 | { |
459 | static_cast<_Dp*>(this)->_M_payload._M_construct( |
460 | std::forward<_Args>(__args)...); |
461 | } |
462 | |
463 | constexpr void |
464 | _M_destruct() noexcept |
465 | { static_cast<_Dp*>(this)->_M_payload._M_destroy(); } |
466 | |
467 | // _M_reset is a 'safe' operation with no precondition. |
468 | constexpr void |
469 | _M_reset() noexcept |
470 | { static_cast<_Dp*>(this)->_M_payload._M_reset(); } |
471 | |
472 | constexpr bool _M_is_engaged() const noexcept |
473 | { return static_cast<const _Dp*>(this)->_M_payload._M_engaged; } |
474 | |
475 | // The _M_get operations have _M_engaged as a precondition. |
476 | constexpr _Tp& |
477 | _M_get() noexcept |
478 | { |
479 | __glibcxx_assert(this->_M_is_engaged()); |
480 | return static_cast<_Dp*>(this)->_M_payload._M_get(); |
481 | } |
482 | |
483 | constexpr const _Tp& |
484 | _M_get() const noexcept |
485 | { |
486 | __glibcxx_assert(this->_M_is_engaged()); |
487 | return static_cast<const _Dp*>(this)->_M_payload._M_get(); |
488 | } |
489 | }; |
490 | |
491 | /** |
492 | * @brief Class template that provides copy/move constructors of optional. |
493 | * |
494 | * Such a separate base class template is necessary in order to |
495 | * conditionally make copy/move constructors trivial. |
496 | * |
497 | * When the contained value is trivially copy/move constructible, |
498 | * the copy/move constructors of _Optional_base will invoke the |
499 | * trivial copy/move constructor of _Optional_payload. Otherwise, |
500 | * they will invoke _Optional_payload(bool, const _Optional_payload&) |
501 | * or _Optional_payload(bool, _Optional_payload&&) to initialize |
502 | * the contained value, if copying/moving an engaged optional. |
503 | * |
504 | * Whether the other special members are trivial is determined by the |
505 | * _Optional_payload<_Tp> specialization used for the _M_payload member. |
506 | * |
507 | * @see optional, _Enable_special_members |
508 | */ |
509 | template<typename _Tp, |
510 | bool = is_trivially_copy_constructible_v<_Tp>, |
511 | bool = is_trivially_move_constructible_v<_Tp>> |
512 | struct _Optional_base |
513 | : _Optional_base_impl<_Tp, _Optional_base<_Tp>> |
514 | { |
515 | // Constructors for disengaged optionals. |
516 | constexpr _Optional_base() = default; |
517 | |
518 | // Constructors for engaged optionals. |
519 | template<typename... _Args, |
520 | enable_if_t<is_constructible_v<_Tp, _Args...>, bool> = false> |
521 | constexpr explicit |
522 | _Optional_base(in_place_t, _Args&&... __args) |
523 | : _M_payload(in_place, std::forward<_Args>(__args)...) |
524 | { } |
525 | |
526 | template<typename _Up, typename... _Args, |
527 | enable_if_t<is_constructible_v<_Tp, |
528 | initializer_list<_Up>&, |
529 | _Args...>, bool> = false> |
530 | constexpr explicit |
531 | _Optional_base(in_place_t, |
532 | initializer_list<_Up> __il, |
533 | _Args&&... __args) |
534 | : _M_payload(in_place, __il, std::forward<_Args>(__args)...) |
535 | { } |
536 | |
537 | // Copy and move constructors. |
538 | constexpr |
539 | _Optional_base(const _Optional_base& __other) |
540 | : _M_payload(__other._M_payload._M_engaged, __other._M_payload) |
541 | { } |
542 | |
543 | constexpr |
544 | _Optional_base(_Optional_base&& __other) |
545 | noexcept(is_nothrow_move_constructible_v<_Tp>) |
546 | : _M_payload(__other._M_payload._M_engaged, |
547 | std::move(__other._M_payload)) |
548 | { } |
549 | |
550 | // Assignment operators. |
551 | _Optional_base& operator=(const _Optional_base&) = default; |
552 | _Optional_base& operator=(_Optional_base&&) = default; |
553 | |
554 | _Optional_payload<_Tp> _M_payload; |
555 | }; |
556 | |
557 | template<typename _Tp> |
558 | struct _Optional_base<_Tp, false, true> |
559 | : _Optional_base_impl<_Tp, _Optional_base<_Tp>> |
560 | { |
561 | // Constructors for disengaged optionals. |
562 | constexpr _Optional_base() = default; |
563 | |
564 | // Constructors for engaged optionals. |
565 | template<typename... _Args, |
566 | enable_if_t<is_constructible_v<_Tp, _Args...>, bool> = false> |
567 | constexpr explicit |
568 | _Optional_base(in_place_t, _Args&&... __args) |
569 | : _M_payload(in_place, std::forward<_Args>(__args)...) |
570 | { } |
571 | |
572 | template<typename _Up, typename... _Args, |
573 | enable_if_t<is_constructible_v<_Tp, |
574 | initializer_list<_Up>&, |
575 | _Args...>, bool> = false> |
576 | constexpr explicit |
577 | _Optional_base(in_place_t, |
578 | initializer_list<_Up> __il, |
579 | _Args... __args) |
580 | : _M_payload(in_place, __il, std::forward<_Args>(__args)...) |
581 | { } |
582 | |
583 | // Copy and move constructors. |
584 | constexpr _Optional_base(const _Optional_base& __other) |
585 | : _M_payload(__other._M_payload._M_engaged, __other._M_payload) |
586 | { } |
587 | |
588 | constexpr _Optional_base(_Optional_base&& __other) = default; |
589 | |
590 | // Assignment operators. |
591 | _Optional_base& operator=(const _Optional_base&) = default; |
592 | _Optional_base& operator=(_Optional_base&&) = default; |
593 | |
594 | _Optional_payload<_Tp> _M_payload; |
595 | }; |
596 | |
597 | template<typename _Tp> |
598 | struct _Optional_base<_Tp, true, false> |
599 | : _Optional_base_impl<_Tp, _Optional_base<_Tp>> |
600 | { |
601 | // Constructors for disengaged optionals. |
602 | constexpr _Optional_base() = default; |
603 | |
604 | // Constructors for engaged optionals. |
605 | template<typename... _Args, |
606 | enable_if_t<is_constructible_v<_Tp, _Args...>, bool> = false> |
607 | constexpr explicit |
608 | _Optional_base(in_place_t, _Args&&... __args) |
609 | : _M_payload(in_place, std::forward<_Args>(__args)...) |
610 | { } |
611 | |
612 | template<typename _Up, typename... _Args, |
613 | enable_if_t<is_constructible_v<_Tp, |
614 | initializer_list<_Up>&, |
615 | _Args...>, bool> = false> |
616 | constexpr explicit |
617 | _Optional_base(in_place_t, |
618 | initializer_list<_Up> __il, |
619 | _Args&&... __args) |
620 | : _M_payload(in_place, __il, std::forward<_Args>(__args)...) |
621 | { } |
622 | |
623 | // Copy and move constructors. |
624 | constexpr _Optional_base(const _Optional_base& __other) = default; |
625 | |
626 | constexpr |
627 | _Optional_base(_Optional_base&& __other) |
628 | noexcept(is_nothrow_move_constructible_v<_Tp>) |
629 | : _M_payload(__other._M_payload._M_engaged, |
630 | std::move(__other._M_payload)) |
631 | { } |
632 | |
633 | // Assignment operators. |
634 | _Optional_base& operator=(const _Optional_base&) = default; |
635 | _Optional_base& operator=(_Optional_base&&) = default; |
636 | |
637 | _Optional_payload<_Tp> _M_payload; |
638 | }; |
639 | |
640 | template<typename _Tp> |
641 | struct _Optional_base<_Tp, true, true> |
642 | : _Optional_base_impl<_Tp, _Optional_base<_Tp>> |
643 | { |
644 | // Constructors for disengaged optionals. |
645 | constexpr _Optional_base() = default; |
646 | |
647 | // Constructors for engaged optionals. |
648 | template<typename... _Args, |
649 | enable_if_t<is_constructible_v<_Tp, _Args...>, bool> = false> |
650 | constexpr explicit |
651 | _Optional_base(in_place_t, _Args&&... __args) |
652 | : _M_payload(in_place, std::forward<_Args>(__args)...) |
653 | { } |
654 | |
655 | template<typename _Up, typename... _Args, |
656 | enable_if_t<is_constructible_v<_Tp, |
657 | initializer_list<_Up>&, |
658 | _Args...>, bool> = false> |
659 | constexpr explicit |
660 | _Optional_base(in_place_t, |
661 | initializer_list<_Up> __il, |
662 | _Args&&... __args) |
663 | : _M_payload(in_place, __il, std::forward<_Args>(__args)...) |
664 | { } |
665 | |
666 | // Copy and move constructors. |
667 | constexpr _Optional_base(const _Optional_base& __other) = default; |
668 | constexpr _Optional_base(_Optional_base&& __other) = default; |
669 | |
670 | // Assignment operators. |
671 | _Optional_base& operator=(const _Optional_base&) = default; |
672 | _Optional_base& operator=(_Optional_base&&) = default; |
673 | |
674 | _Optional_payload<_Tp> _M_payload; |
675 | }; |
676 | |
677 | template<typename _Tp> |
678 | class optional; |
679 | |
680 | template<typename _Tp> |
681 | inline constexpr bool __is_optional_v = false; |
682 | template<typename _Tp> |
683 | inline constexpr bool __is_optional_v<optional<_Tp>> = true; |
684 | |
685 | template<typename _Tp, typename _Up> |
686 | using __converts_from_optional = |
687 | __or_<is_constructible<_Tp, const optional<_Up>&>, |
688 | is_constructible<_Tp, optional<_Up>&>, |
689 | is_constructible<_Tp, const optional<_Up>&&>, |
690 | is_constructible<_Tp, optional<_Up>&&>, |
691 | is_convertible<const optional<_Up>&, _Tp>, |
692 | is_convertible<optional<_Up>&, _Tp>, |
693 | is_convertible<const optional<_Up>&&, _Tp>, |
694 | is_convertible<optional<_Up>&&, _Tp>>; |
695 | |
696 | template<typename _Tp, typename _Up> |
697 | using __assigns_from_optional = |
698 | __or_<is_assignable<_Tp&, const optional<_Up>&>, |
699 | is_assignable<_Tp&, optional<_Up>&>, |
700 | is_assignable<_Tp&, const optional<_Up>&&>, |
701 | is_assignable<_Tp&, optional<_Up>&&>>; |
702 | |
703 | /** |
704 | * @brief Class template for optional values. |
705 | */ |
706 | template<typename _Tp> |
707 | class optional |
708 | : private _Optional_base<_Tp>, |
709 | private _Enable_copy_move< |
710 | // Copy constructor. |
711 | is_copy_constructible_v<_Tp>, |
712 | // Copy assignment. |
713 | __and_v<is_copy_constructible<_Tp>, is_copy_assignable<_Tp>>, |
714 | // Move constructor. |
715 | is_move_constructible_v<_Tp>, |
716 | // Move assignment. |
717 | __and_v<is_move_constructible<_Tp>, is_move_assignable<_Tp>>, |
718 | // Unique tag type. |
719 | optional<_Tp>> |
720 | { |
721 | static_assert(!is_same_v<remove_cv_t<_Tp>, nullopt_t>); |
722 | static_assert(!is_same_v<remove_cv_t<_Tp>, in_place_t>); |
723 | static_assert(is_object_v<_Tp> && !is_array_v<_Tp>); |
724 | |
725 | private: |
726 | using _Base = _Optional_base<_Tp>; |
727 | |
728 | // SFINAE helpers |
729 | template<typename _Up> |
730 | using __not_self = __not_<is_same<optional, __remove_cvref_t<_Up>>>; |
731 | template<typename _Up> |
732 | using __not_tag = __not_<is_same<in_place_t, __remove_cvref_t<_Up>>>; |
733 | template<typename... _Cond> |
734 | using _Requires = enable_if_t<__and_v<_Cond...>, bool>; |
735 | |
736 | public: |
737 | using value_type = _Tp; |
738 | |
739 | constexpr optional() noexcept { } |
740 | |
741 | constexpr optional(nullopt_t) noexcept { } |
742 | |
743 | // Converting constructors for engaged optionals. |
744 | template<typename _Up = _Tp, |
745 | _Requires<__not_self<_Up>, __not_tag<_Up>, |
746 | is_constructible<_Tp, _Up>, |
747 | is_convertible<_Up, _Tp>> = true> |
748 | constexpr |
749 | optional(_Up&& __t) |
750 | noexcept(is_nothrow_constructible_v<_Tp, _Up>) |
751 | : _Base(std::in_place, std::forward<_Up>(__t)) { } |
752 | |
753 | template<typename _Up = _Tp, |
754 | _Requires<__not_self<_Up>, __not_tag<_Up>, |
755 | is_constructible<_Tp, _Up>, |
756 | __not_<is_convertible<_Up, _Tp>>> = false> |
757 | explicit constexpr |
758 | optional(_Up&& __t) |
759 | noexcept(is_nothrow_constructible_v<_Tp, _Up>) |
760 | : _Base(std::in_place, std::forward<_Up>(__t)) { } |
761 | |
762 | template<typename _Up, |
763 | _Requires<__not_<is_same<_Tp, _Up>>, |
764 | is_constructible<_Tp, const _Up&>, |
765 | is_convertible<const _Up&, _Tp>, |
766 | __not_<__converts_from_optional<_Tp, _Up>>> = true> |
767 | constexpr |
768 | optional(const optional<_Up>& __t) |
769 | noexcept(is_nothrow_constructible_v<_Tp, const _Up&>) |
770 | { |
771 | if (__t) |
772 | emplace(*__t); |
773 | } |
774 | |
775 | template<typename _Up, |
776 | _Requires<__not_<is_same<_Tp, _Up>>, |
777 | is_constructible<_Tp, const _Up&>, |
778 | __not_<is_convertible<const _Up&, _Tp>>, |
779 | __not_<__converts_from_optional<_Tp, _Up>>> = false> |
780 | explicit constexpr |
781 | optional(const optional<_Up>& __t) |
782 | noexcept(is_nothrow_constructible_v<_Tp, const _Up&>) |
783 | { |
784 | if (__t) |
785 | emplace(*__t); |
786 | } |
787 | |
788 | template<typename _Up, |
789 | _Requires<__not_<is_same<_Tp, _Up>>, |
790 | is_constructible<_Tp, _Up>, |
791 | is_convertible<_Up, _Tp>, |
792 | __not_<__converts_from_optional<_Tp, _Up>>> = true> |
793 | constexpr |
794 | optional(optional<_Up>&& __t) |
795 | noexcept(is_nothrow_constructible_v<_Tp, _Up>) |
796 | { |
797 | if (__t) |
798 | emplace(std::move(*__t)); |
799 | } |
800 | |
801 | template<typename _Up, |
802 | _Requires<__not_<is_same<_Tp, _Up>>, |
803 | is_constructible<_Tp, _Up>, |
804 | __not_<is_convertible<_Up, _Tp>>, |
805 | __not_<__converts_from_optional<_Tp, _Up>>> = false> |
806 | explicit constexpr |
807 | optional(optional<_Up>&& __t) |
808 | noexcept(is_nothrow_constructible_v<_Tp, _Up>) |
809 | { |
810 | if (__t) |
811 | emplace(std::move(*__t)); |
812 | } |
813 | |
814 | template<typename... _Args, |
815 | _Requires<is_constructible<_Tp, _Args...>> = false> |
816 | explicit constexpr |
817 | optional(in_place_t, _Args&&... __args) |
818 | noexcept(is_nothrow_constructible_v<_Tp, _Args...>) |
819 | : _Base(std::in_place, std::forward<_Args>(__args)...) { } |
820 | |
821 | template<typename _Up, typename... _Args, |
822 | _Requires<is_constructible<_Tp, |
823 | initializer_list<_Up>&, |
824 | _Args...>> = false> |
825 | explicit constexpr |
826 | optional(in_place_t, initializer_list<_Up> __il, _Args&&... __args) |
827 | noexcept(is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, |
828 | _Args...>) |
829 | : _Base(std::in_place, __il, std::forward<_Args>(__args)...) { } |
830 | |
831 | |
832 | // Assignment operators. |
833 | _GLIBCXX20_CONSTEXPR optional& |
834 | operator=(nullopt_t) noexcept |
835 | { |
836 | this->_M_reset(); |
837 | return *this; |
838 | } |
839 | |
840 | template<typename _Up = _Tp> |
841 | _GLIBCXX20_CONSTEXPR |
842 | enable_if_t<__and_v<__not_self<_Up>, |
843 | __not_<__and_<is_scalar<_Tp>, |
844 | is_same<_Tp, decay_t<_Up>>>>, |
845 | is_constructible<_Tp, _Up>, |
846 | is_assignable<_Tp&, _Up>>, |
847 | optional&> |
848 | operator=(_Up&& __u) |
849 | noexcept(__and_v<is_nothrow_constructible<_Tp, _Up>, |
850 | is_nothrow_assignable<_Tp&, _Up>>) |
851 | { |
852 | if (this->_M_is_engaged()) |
853 | this->_M_get() = std::forward<_Up>(__u); |
854 | else |
855 | this->_M_construct(std::forward<_Up>(__u)); |
856 | |
857 | return *this; |
858 | } |
859 | |
860 | template<typename _Up> |
861 | _GLIBCXX20_CONSTEXPR |
862 | enable_if_t<__and_v<__not_<is_same<_Tp, _Up>>, |
863 | is_constructible<_Tp, const _Up&>, |
864 | is_assignable<_Tp&, const _Up&>, |
865 | __not_<__converts_from_optional<_Tp, _Up>>, |
866 | __not_<__assigns_from_optional<_Tp, _Up>>>, |
867 | optional&> |
868 | operator=(const optional<_Up>& __u) |
869 | noexcept(__and_v<is_nothrow_constructible<_Tp, const _Up&>, |
870 | is_nothrow_assignable<_Tp&, const _Up&>>) |
871 | { |
872 | if (__u) |
873 | { |
874 | if (this->_M_is_engaged()) |
875 | this->_M_get() = *__u; |
876 | else |
877 | this->_M_construct(*__u); |
878 | } |
879 | else |
880 | { |
881 | this->_M_reset(); |
882 | } |
883 | return *this; |
884 | } |
885 | |
886 | template<typename _Up> |
887 | _GLIBCXX20_CONSTEXPR |
888 | enable_if_t<__and_v<__not_<is_same<_Tp, _Up>>, |
889 | is_constructible<_Tp, _Up>, |
890 | is_assignable<_Tp&, _Up>, |
891 | __not_<__converts_from_optional<_Tp, _Up>>, |
892 | __not_<__assigns_from_optional<_Tp, _Up>>>, |
893 | optional&> |
894 | operator=(optional<_Up>&& __u) |
895 | noexcept(__and_v<is_nothrow_constructible<_Tp, _Up>, |
896 | is_nothrow_assignable<_Tp&, _Up>>) |
897 | { |
898 | if (__u) |
899 | { |
900 | if (this->_M_is_engaged()) |
901 | this->_M_get() = std::move(*__u); |
902 | else |
903 | this->_M_construct(std::move(*__u)); |
904 | } |
905 | else |
906 | { |
907 | this->_M_reset(); |
908 | } |
909 | |
910 | return *this; |
911 | } |
912 | |
913 | template<typename... _Args> |
914 | _GLIBCXX20_CONSTEXPR |
915 | enable_if_t<is_constructible_v<_Tp, _Args...>, _Tp&> |
916 | emplace(_Args&&... __args) |
917 | noexcept(is_nothrow_constructible_v<_Tp, _Args...>) |
918 | { |
919 | this->_M_reset(); |
920 | this->_M_construct(std::forward<_Args>(__args)...); |
921 | return this->_M_get(); |
922 | } |
923 | |
924 | template<typename _Up, typename... _Args> |
925 | _GLIBCXX20_CONSTEXPR |
926 | enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, |
927 | _Tp&> |
928 | emplace(initializer_list<_Up> __il, _Args&&... __args) |
929 | noexcept(is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, |
930 | _Args...>) |
931 | { |
932 | this->_M_reset(); |
933 | this->_M_construct(__il, std::forward<_Args>(__args)...); |
934 | return this->_M_get(); |
935 | } |
936 | |
937 | // Destructor is implicit, implemented in _Optional_base. |
938 | |
939 | // Swap. |
940 | _GLIBCXX20_CONSTEXPR void |
941 | swap(optional& __other) |
942 | noexcept(is_nothrow_move_constructible_v<_Tp> |
943 | && is_nothrow_swappable_v<_Tp>) |
944 | { |
945 | using std::swap; |
946 | |
947 | if (this->_M_is_engaged() && __other._M_is_engaged()) |
948 | swap(this->_M_get(), __other._M_get()); |
949 | else if (this->_M_is_engaged()) |
950 | { |
951 | __other._M_construct(std::move(this->_M_get())); |
952 | this->_M_destruct(); |
953 | } |
954 | else if (__other._M_is_engaged()) |
955 | { |
956 | this->_M_construct(std::move(__other._M_get())); |
957 | __other._M_destruct(); |
958 | } |
959 | } |
960 | |
961 | // Observers. |
962 | constexpr const _Tp* |
963 | operator->() const noexcept |
964 | { return std::__addressof(this->_M_get()); } |
965 | |
966 | constexpr _Tp* |
967 | operator->() noexcept |
968 | { return std::__addressof(this->_M_get()); } |
969 | |
970 | constexpr const _Tp& |
971 | operator*() const& noexcept |
972 | { return this->_M_get(); } |
973 | |
974 | constexpr _Tp& |
975 | operator*()& noexcept |
976 | { return this->_M_get(); } |
977 | |
978 | constexpr _Tp&& |
979 | operator*()&& noexcept |
980 | { return std::move(this->_M_get()); } |
981 | |
982 | constexpr const _Tp&& |
983 | operator*() const&& noexcept |
984 | { return std::move(this->_M_get()); } |
985 | |
986 | constexpr explicit operator bool() const noexcept |
987 | { return this->_M_is_engaged(); } |
988 | |
989 | constexpr bool has_value() const noexcept |
990 | { return this->_M_is_engaged(); } |
991 | |
992 | constexpr const _Tp& |
993 | value() const& |
994 | { |
995 | if (this->_M_is_engaged()) |
996 | return this->_M_get(); |
997 | __throw_bad_optional_access(); |
998 | } |
999 | |
1000 | constexpr _Tp& |
1001 | value()& |
1002 | { |
1003 | if (this->_M_is_engaged()) |
1004 | return this->_M_get(); |
1005 | __throw_bad_optional_access(); |
1006 | } |
1007 | |
1008 | constexpr _Tp&& |
1009 | value()&& |
1010 | { |
1011 | if (this->_M_is_engaged()) |
1012 | return std::move(this->_M_get()); |
1013 | __throw_bad_optional_access(); |
1014 | } |
1015 | |
1016 | constexpr const _Tp&& |
1017 | value() const&& |
1018 | { |
1019 | if (this->_M_is_engaged()) |
1020 | return std::move(this->_M_get()); |
1021 | __throw_bad_optional_access(); |
1022 | } |
1023 | |
1024 | template<typename _Up> |
1025 | constexpr _Tp |
1026 | value_or(_Up&& __u) const& |
1027 | { |
1028 | static_assert(is_copy_constructible_v<_Tp>); |
1029 | static_assert(is_convertible_v<_Up&&, _Tp>); |
1030 | |
1031 | if (this->_M_is_engaged()) |
1032 | return this->_M_get(); |
1033 | else |
1034 | return static_cast<_Tp>(std::forward<_Up>(__u)); |
1035 | } |
1036 | |
1037 | template<typename _Up> |
1038 | constexpr _Tp |
1039 | value_or(_Up&& __u) && |
1040 | { |
1041 | static_assert(is_move_constructible_v<_Tp>); |
1042 | static_assert(is_convertible_v<_Up&&, _Tp>); |
1043 | |
1044 | if (this->_M_is_engaged()) |
1045 | return std::move(this->_M_get()); |
1046 | else |
1047 | return static_cast<_Tp>(std::forward<_Up>(__u)); |
1048 | } |
1049 | |
1050 | #if __cpp_lib_optional >= 202110L |
1051 | // [optional.monadic] |
1052 | |
1053 | template<typename _Fn> |
1054 | constexpr auto |
1055 | and_then(_Fn&& __f) & |
1056 | { |
1057 | using _Up = remove_cvref_t<invoke_result_t<_Fn, _Tp&>>; |
1058 | static_assert(__is_optional_v<remove_cvref_t<_Up>>, |
1059 | "the function passed to std::optional<T>::and_then " |
1060 | "must return a std::optional" ); |
1061 | if (has_value()) |
1062 | return std::__invoke(std::forward<_Fn>(__f), **this); |
1063 | else |
1064 | return _Up(); |
1065 | } |
1066 | |
1067 | template<typename _Fn> |
1068 | constexpr auto |
1069 | and_then(_Fn&& __f) const & |
1070 | { |
1071 | using _Up = remove_cvref_t<invoke_result_t<_Fn, const _Tp&>>; |
1072 | static_assert(__is_optional_v<_Up>, |
1073 | "the function passed to std::optional<T>::and_then " |
1074 | "must return a std::optional" ); |
1075 | if (has_value()) |
1076 | return std::__invoke(std::forward<_Fn>(__f), **this); |
1077 | else |
1078 | return _Up(); |
1079 | } |
1080 | |
1081 | template<typename _Fn> |
1082 | constexpr auto |
1083 | and_then(_Fn&& __f) && |
1084 | { |
1085 | using _Up = remove_cvref_t<invoke_result_t<_Fn, _Tp>>; |
1086 | static_assert(__is_optional_v<remove_cvref_t<_Up>>, |
1087 | "the function passed to std::optional<T>::and_then " |
1088 | "must return a std::optional" ); |
1089 | if (has_value()) |
1090 | return std::__invoke(std::forward<_Fn>(__f), std::move(**this)); |
1091 | else |
1092 | return _Up(); |
1093 | } |
1094 | |
1095 | template<typename _Fn> |
1096 | constexpr auto |
1097 | and_then(_Fn&& __f) const && |
1098 | { |
1099 | using _Up = remove_cvref_t<invoke_result_t<_Fn, const _Tp>>; |
1100 | static_assert(__is_optional_v<remove_cvref_t<_Up>>, |
1101 | "the function passed to std::optional<T>::and_then " |
1102 | "must return a std::optional" ); |
1103 | if (has_value()) |
1104 | return std::__invoke(std::forward<_Fn>(__f), std::move(**this)); |
1105 | else |
1106 | return _Up(); |
1107 | } |
1108 | |
1109 | template<typename _Fn> |
1110 | constexpr auto |
1111 | transform(_Fn&& __f) & |
1112 | { |
1113 | using _Up = remove_cv_t<invoke_result_t<_Fn, _Tp&>>; |
1114 | if (has_value()) |
1115 | return optional<_Up>(_Optional_func<_Fn>{__f}, **this); |
1116 | else |
1117 | return optional<_Up>(); |
1118 | } |
1119 | |
1120 | template<typename _Fn> |
1121 | constexpr auto |
1122 | transform(_Fn&& __f) const & |
1123 | { |
1124 | using _Up = remove_cv_t<invoke_result_t<_Fn, const _Tp&>>; |
1125 | if (has_value()) |
1126 | return optional<_Up>(_Optional_func<_Fn>{__f}, **this); |
1127 | else |
1128 | return optional<_Up>(); |
1129 | } |
1130 | |
1131 | template<typename _Fn> |
1132 | constexpr auto |
1133 | transform(_Fn&& __f) && |
1134 | { |
1135 | using _Up = remove_cv_t<invoke_result_t<_Fn, _Tp>>; |
1136 | if (has_value()) |
1137 | return optional<_Up>(_Optional_func<_Fn>{__f}, std::move(**this)); |
1138 | else |
1139 | return optional<_Up>(); |
1140 | } |
1141 | |
1142 | template<typename _Fn> |
1143 | constexpr auto |
1144 | transform(_Fn&& __f) const && |
1145 | { |
1146 | using _Up = remove_cv_t<invoke_result_t<_Fn, const _Tp>>; |
1147 | if (has_value()) |
1148 | return optional<_Up>(_Optional_func<_Fn>{__f}, std::move(**this)); |
1149 | else |
1150 | return optional<_Up>(); |
1151 | } |
1152 | |
1153 | template<typename _Fn> requires invocable<_Fn> && copy_constructible<_Tp> |
1154 | constexpr optional |
1155 | or_else(_Fn&& __f) const& |
1156 | { |
1157 | using _Up = invoke_result_t<_Fn>; |
1158 | static_assert(is_same_v<remove_cvref_t<_Up>, optional>, |
1159 | "the function passed to std::optional<T>::or_else " |
1160 | "must return a std::optional<T>" ); |
1161 | |
1162 | if (has_value()) |
1163 | return *this; |
1164 | else |
1165 | return std::forward<_Fn>(__f)(); |
1166 | } |
1167 | |
1168 | template<typename _Fn> requires invocable<_Fn> && move_constructible<_Tp> |
1169 | constexpr optional |
1170 | or_else(_Fn&& __f) && |
1171 | { |
1172 | using _Up = invoke_result_t<_Fn>; |
1173 | static_assert(is_same_v<remove_cvref_t<_Up>, optional>, |
1174 | "the function passed to std::optional<T>::or_else " |
1175 | "must return a std::optional<T>" ); |
1176 | |
1177 | if (has_value()) |
1178 | return std::move(*this); |
1179 | else |
1180 | return std::forward<_Fn>(__f)(); |
1181 | } |
1182 | #endif |
1183 | |
1184 | _GLIBCXX20_CONSTEXPR void reset() noexcept { this->_M_reset(); } |
1185 | |
1186 | private: |
1187 | #if __cplusplus >= 202002L |
1188 | template<typename _Up> friend class optional; |
1189 | |
1190 | template<typename _Fn, typename _Value> |
1191 | explicit constexpr |
1192 | optional(_Optional_func<_Fn> __f, _Value&& __v) |
1193 | { |
1194 | this->_M_payload._M_apply(__f, std::forward<_Value>(__v)); |
1195 | } |
1196 | #endif |
1197 | }; |
1198 | |
1199 | template<typename _Tp> |
1200 | using __optional_relop_t = |
1201 | enable_if_t<is_convertible<_Tp, bool>::value, bool>; |
1202 | |
1203 | template<typename _Tp, typename _Up> |
1204 | using __optional_eq_t = __optional_relop_t< |
1205 | decltype(std::declval<const _Tp&>() == std::declval<const _Up&>()) |
1206 | >; |
1207 | |
1208 | template<typename _Tp, typename _Up> |
1209 | using __optional_ne_t = __optional_relop_t< |
1210 | decltype(std::declval<const _Tp&>() != std::declval<const _Up&>()) |
1211 | >; |
1212 | |
1213 | template<typename _Tp, typename _Up> |
1214 | using __optional_lt_t = __optional_relop_t< |
1215 | decltype(std::declval<const _Tp&>() < std::declval<const _Up&>()) |
1216 | >; |
1217 | |
1218 | template<typename _Tp, typename _Up> |
1219 | using __optional_gt_t = __optional_relop_t< |
1220 | decltype(std::declval<const _Tp&>() > std::declval<const _Up&>()) |
1221 | >; |
1222 | |
1223 | template<typename _Tp, typename _Up> |
1224 | using __optional_le_t = __optional_relop_t< |
1225 | decltype(std::declval<const _Tp&>() <= std::declval<const _Up&>()) |
1226 | >; |
1227 | |
1228 | template<typename _Tp, typename _Up> |
1229 | using __optional_ge_t = __optional_relop_t< |
1230 | decltype(std::declval<const _Tp&>() >= std::declval<const _Up&>()) |
1231 | >; |
1232 | |
1233 | // Comparisons between optional values. |
1234 | template<typename _Tp, typename _Up> |
1235 | constexpr auto |
1236 | operator==(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
1237 | -> __optional_eq_t<_Tp, _Up> |
1238 | { |
1239 | return static_cast<bool>(__lhs) == static_cast<bool>(__rhs) |
1240 | && (!__lhs || *__lhs == *__rhs); |
1241 | } |
1242 | |
1243 | template<typename _Tp, typename _Up> |
1244 | constexpr auto |
1245 | operator!=(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
1246 | -> __optional_ne_t<_Tp, _Up> |
1247 | { |
1248 | return static_cast<bool>(__lhs) != static_cast<bool>(__rhs) |
1249 | || (static_cast<bool>(__lhs) && *__lhs != *__rhs); |
1250 | } |
1251 | |
1252 | template<typename _Tp, typename _Up> |
1253 | constexpr auto |
1254 | operator<(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
1255 | -> __optional_lt_t<_Tp, _Up> |
1256 | { |
1257 | return static_cast<bool>(__rhs) && (!__lhs || *__lhs < *__rhs); |
1258 | } |
1259 | |
1260 | template<typename _Tp, typename _Up> |
1261 | constexpr auto |
1262 | operator>(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
1263 | -> __optional_gt_t<_Tp, _Up> |
1264 | { |
1265 | return static_cast<bool>(__lhs) && (!__rhs || *__lhs > *__rhs); |
1266 | } |
1267 | |
1268 | template<typename _Tp, typename _Up> |
1269 | constexpr auto |
1270 | operator<=(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
1271 | -> __optional_le_t<_Tp, _Up> |
1272 | { |
1273 | return !__lhs || (static_cast<bool>(__rhs) && *__lhs <= *__rhs); |
1274 | } |
1275 | |
1276 | template<typename _Tp, typename _Up> |
1277 | constexpr auto |
1278 | operator>=(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
1279 | -> __optional_ge_t<_Tp, _Up> |
1280 | { |
1281 | return !__rhs || (static_cast<bool>(__lhs) && *__lhs >= *__rhs); |
1282 | } |
1283 | |
1284 | #ifdef __cpp_lib_three_way_comparison |
1285 | template<typename _Tp, three_way_comparable_with<_Tp> _Up> |
1286 | constexpr compare_three_way_result_t<_Tp, _Up> |
1287 | operator<=>(const optional<_Tp>& __x, const optional<_Up>& __y) |
1288 | { |
1289 | return __x && __y ? *__x <=> *__y : bool(__x) <=> bool(__y); |
1290 | } |
1291 | #endif |
1292 | |
1293 | // Comparisons with nullopt. |
1294 | template<typename _Tp> |
1295 | constexpr bool |
1296 | operator==(const optional<_Tp>& __lhs, nullopt_t) noexcept |
1297 | { return !__lhs; } |
1298 | |
1299 | #ifdef __cpp_lib_three_way_comparison |
1300 | template<typename _Tp> |
1301 | constexpr strong_ordering |
1302 | operator<=>(const optional<_Tp>& __x, nullopt_t) noexcept |
1303 | { return bool(__x) <=> false; } |
1304 | #else |
1305 | template<typename _Tp> |
1306 | constexpr bool |
1307 | operator==(nullopt_t, const optional<_Tp>& __rhs) noexcept |
1308 | { return !__rhs; } |
1309 | |
1310 | template<typename _Tp> |
1311 | constexpr bool |
1312 | operator!=(const optional<_Tp>& __lhs, nullopt_t) noexcept |
1313 | { return static_cast<bool>(__lhs); } |
1314 | |
1315 | template<typename _Tp> |
1316 | constexpr bool |
1317 | operator!=(nullopt_t, const optional<_Tp>& __rhs) noexcept |
1318 | { return static_cast<bool>(__rhs); } |
1319 | |
1320 | template<typename _Tp> |
1321 | constexpr bool |
1322 | operator<(const optional<_Tp>& /* __lhs */, nullopt_t) noexcept |
1323 | { return false; } |
1324 | |
1325 | template<typename _Tp> |
1326 | constexpr bool |
1327 | operator<(nullopt_t, const optional<_Tp>& __rhs) noexcept |
1328 | { return static_cast<bool>(__rhs); } |
1329 | |
1330 | template<typename _Tp> |
1331 | constexpr bool |
1332 | operator>(const optional<_Tp>& __lhs, nullopt_t) noexcept |
1333 | { return static_cast<bool>(__lhs); } |
1334 | |
1335 | template<typename _Tp> |
1336 | constexpr bool |
1337 | operator>(nullopt_t, const optional<_Tp>& /* __rhs */) noexcept |
1338 | { return false; } |
1339 | |
1340 | template<typename _Tp> |
1341 | constexpr bool |
1342 | operator<=(const optional<_Tp>& __lhs, nullopt_t) noexcept |
1343 | { return !__lhs; } |
1344 | |
1345 | template<typename _Tp> |
1346 | constexpr bool |
1347 | operator<=(nullopt_t, const optional<_Tp>& /* __rhs */) noexcept |
1348 | { return true; } |
1349 | |
1350 | template<typename _Tp> |
1351 | constexpr bool |
1352 | operator>=(const optional<_Tp>& /* __lhs */, nullopt_t) noexcept |
1353 | { return true; } |
1354 | |
1355 | template<typename _Tp> |
1356 | constexpr bool |
1357 | operator>=(nullopt_t, const optional<_Tp>& __rhs) noexcept |
1358 | { return !__rhs; } |
1359 | #endif // three-way-comparison |
1360 | |
1361 | // Comparisons with value type. |
1362 | template<typename _Tp, typename _Up> |
1363 | constexpr auto |
1364 | operator==(const optional<_Tp>& __lhs, const _Up& __rhs) |
1365 | -> __optional_eq_t<_Tp, _Up> |
1366 | { return __lhs && *__lhs == __rhs; } |
1367 | |
1368 | template<typename _Tp, typename _Up> |
1369 | constexpr auto |
1370 | operator==(const _Up& __lhs, const optional<_Tp>& __rhs) |
1371 | -> __optional_eq_t<_Up, _Tp> |
1372 | { return __rhs && __lhs == *__rhs; } |
1373 | |
1374 | template<typename _Tp, typename _Up> |
1375 | constexpr auto |
1376 | operator!=(const optional<_Tp>& __lhs, const _Up& __rhs) |
1377 | -> __optional_ne_t<_Tp, _Up> |
1378 | { return !__lhs || *__lhs != __rhs; } |
1379 | |
1380 | template<typename _Tp, typename _Up> |
1381 | constexpr auto |
1382 | operator!=(const _Up& __lhs, const optional<_Tp>& __rhs) |
1383 | -> __optional_ne_t<_Up, _Tp> |
1384 | { return !__rhs || __lhs != *__rhs; } |
1385 | |
1386 | template<typename _Tp, typename _Up> |
1387 | constexpr auto |
1388 | operator<(const optional<_Tp>& __lhs, const _Up& __rhs) |
1389 | -> __optional_lt_t<_Tp, _Up> |
1390 | { return !__lhs || *__lhs < __rhs; } |
1391 | |
1392 | template<typename _Tp, typename _Up> |
1393 | constexpr auto |
1394 | operator<(const _Up& __lhs, const optional<_Tp>& __rhs) |
1395 | -> __optional_lt_t<_Up, _Tp> |
1396 | { return __rhs && __lhs < *__rhs; } |
1397 | |
1398 | template<typename _Tp, typename _Up> |
1399 | constexpr auto |
1400 | operator>(const optional<_Tp>& __lhs, const _Up& __rhs) |
1401 | -> __optional_gt_t<_Tp, _Up> |
1402 | { return __lhs && *__lhs > __rhs; } |
1403 | |
1404 | template<typename _Tp, typename _Up> |
1405 | constexpr auto |
1406 | operator>(const _Up& __lhs, const optional<_Tp>& __rhs) |
1407 | -> __optional_gt_t<_Up, _Tp> |
1408 | { return !__rhs || __lhs > *__rhs; } |
1409 | |
1410 | template<typename _Tp, typename _Up> |
1411 | constexpr auto |
1412 | operator<=(const optional<_Tp>& __lhs, const _Up& __rhs) |
1413 | -> __optional_le_t<_Tp, _Up> |
1414 | { return !__lhs || *__lhs <= __rhs; } |
1415 | |
1416 | template<typename _Tp, typename _Up> |
1417 | constexpr auto |
1418 | operator<=(const _Up& __lhs, const optional<_Tp>& __rhs) |
1419 | -> __optional_le_t<_Up, _Tp> |
1420 | { return __rhs && __lhs <= *__rhs; } |
1421 | |
1422 | template<typename _Tp, typename _Up> |
1423 | constexpr auto |
1424 | operator>=(const optional<_Tp>& __lhs, const _Up& __rhs) |
1425 | -> __optional_ge_t<_Tp, _Up> |
1426 | { return __lhs && *__lhs >= __rhs; } |
1427 | |
1428 | template<typename _Tp, typename _Up> |
1429 | constexpr auto |
1430 | operator>=(const _Up& __lhs, const optional<_Tp>& __rhs) |
1431 | -> __optional_ge_t<_Up, _Tp> |
1432 | { return !__rhs || __lhs >= *__rhs; } |
1433 | |
1434 | #ifdef __cpp_lib_three_way_comparison |
1435 | template<typename _Tp, typename _Up> |
1436 | requires (!__is_optional_v<_Up>) |
1437 | && three_way_comparable_with<_Tp, _Up> |
1438 | constexpr compare_three_way_result_t<_Tp, _Up> |
1439 | operator<=>(const optional<_Tp>& __x, const _Up& __v) |
1440 | { return bool(__x) ? *__x <=> __v : strong_ordering::less; } |
1441 | #endif |
1442 | |
1443 | // Swap and creation functions. |
1444 | |
1445 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
1446 | // 2748. swappable traits for optionals |
1447 | template<typename _Tp> |
1448 | _GLIBCXX20_CONSTEXPR |
1449 | inline enable_if_t<is_move_constructible_v<_Tp> && is_swappable_v<_Tp>> |
1450 | swap(optional<_Tp>& __lhs, optional<_Tp>& __rhs) |
1451 | noexcept(noexcept(__lhs.swap(__rhs))) |
1452 | { __lhs.swap(__rhs); } |
1453 | |
1454 | template<typename _Tp> |
1455 | enable_if_t<!(is_move_constructible_v<_Tp> && is_swappable_v<_Tp>)> |
1456 | swap(optional<_Tp>&, optional<_Tp>&) = delete; |
1457 | |
1458 | template<typename _Tp> |
1459 | constexpr |
1460 | enable_if_t<is_constructible_v<decay_t<_Tp>, _Tp>, |
1461 | optional<decay_t<_Tp>>> |
1462 | make_optional(_Tp&& __t) |
1463 | noexcept(is_nothrow_constructible_v<optional<decay_t<_Tp>>, _Tp>) |
1464 | { return optional<decay_t<_Tp>>{ std::forward<_Tp>(__t) }; } |
1465 | |
1466 | template<typename _Tp, typename... _Args> |
1467 | constexpr |
1468 | enable_if_t<is_constructible_v<_Tp, _Args...>, |
1469 | optional<_Tp>> |
1470 | make_optional(_Args&&... __args) |
1471 | noexcept(is_nothrow_constructible_v<_Tp, _Args...>) |
1472 | { return optional<_Tp>{ in_place, std::forward<_Args>(__args)... }; } |
1473 | |
1474 | template<typename _Tp, typename _Up, typename... _Args> |
1475 | constexpr |
1476 | enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, |
1477 | optional<_Tp>> |
1478 | make_optional(initializer_list<_Up> __il, _Args&&... __args) |
1479 | noexcept(is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, _Args...>) |
1480 | { return optional<_Tp>{ in_place, __il, std::forward<_Args>(__args)... }; } |
1481 | |
1482 | // Hash. |
1483 | |
1484 | template<typename _Tp, typename _Up = remove_const_t<_Tp>, |
1485 | bool = __poison_hash<_Up>::__enable_hash_call> |
1486 | struct __optional_hash_call_base |
1487 | { |
1488 | size_t |
1489 | operator()(const optional<_Tp>& __t) const |
1490 | noexcept(noexcept(hash<_Up>{}(*__t))) |
1491 | { |
1492 | // We pick an arbitrary hash for disengaged optionals which hopefully |
1493 | // usual values of _Tp won't typically hash to. |
1494 | constexpr size_t __magic_disengaged_hash = static_cast<size_t>(-3333); |
1495 | return __t ? hash<_Up>{}(*__t) : __magic_disengaged_hash; |
1496 | } |
1497 | }; |
1498 | |
1499 | template<typename _Tp, typename _Up> |
1500 | struct __optional_hash_call_base<_Tp, _Up, false> {}; |
1501 | |
1502 | template<typename _Tp> |
1503 | struct hash<optional<_Tp>> |
1504 | : private __poison_hash<remove_const_t<_Tp>>, |
1505 | public __optional_hash_call_base<_Tp> |
1506 | { |
1507 | using result_type [[__deprecated__]] = size_t; |
1508 | using argument_type [[__deprecated__]] = optional<_Tp>; |
1509 | }; |
1510 | |
1511 | template<typename _Tp> |
1512 | struct __is_fast_hash<hash<optional<_Tp>>> : __is_fast_hash<hash<_Tp>> |
1513 | { }; |
1514 | |
1515 | /// @} |
1516 | |
1517 | #if __cpp_deduction_guides >= 201606 |
1518 | template <typename _Tp> optional(_Tp) -> optional<_Tp>; |
1519 | #endif |
1520 | |
1521 | _GLIBCXX_END_NAMESPACE_VERSION |
1522 | } // namespace std |
1523 | |
1524 | #endif // C++17 |
1525 | |
1526 | #endif // _GLIBCXX_OPTIONAL |
1527 | |