1 | // <optional> -*- C++ -*- |
2 | |
3 | // Copyright (C) 2013-2024 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 | #define __glibcxx_want_freestanding_optional |
36 | #define __glibcxx_want_optional |
37 | #include <bits/version.h> |
38 | |
39 | #ifdef __cpp_lib_optional // C++ >= 17 |
40 | |
41 | #include <type_traits> |
42 | #include <exception> |
43 | #include <new> |
44 | #include <initializer_list> |
45 | #include <bits/enable_special_members.h> |
46 | #include <bits/exception_defines.h> |
47 | #include <bits/functional_hash.h> |
48 | #include <bits/stl_construct.h> // _Construct |
49 | #include <bits/utility.h> // in_place_t |
50 | #if __cplusplus > 201703L |
51 | # include <compare> |
52 | # include <bits/invoke.h> // std::__invoke |
53 | #endif |
54 | #if __cplusplus > 202002L |
55 | # include <concepts> |
56 | #endif |
57 | |
58 | namespace std _GLIBCXX_VISIBILITY(default) |
59 | { |
60 | _GLIBCXX_BEGIN_NAMESPACE_VERSION |
61 | |
62 | /** |
63 | * @addtogroup utilities |
64 | * @{ |
65 | */ |
66 | |
67 | template<typename _Tp> |
68 | class optional; |
69 | |
70 | /// Tag type to disengage optional objects. |
71 | struct nullopt_t |
72 | { |
73 | // Do not user-declare default constructor at all for |
74 | // optional_value = {} syntax to work. |
75 | // nullopt_t() = delete; |
76 | |
77 | // Used for constructing nullopt. |
78 | enum class _Construct { _Token }; |
79 | |
80 | // Must be constexpr for nullopt_t to be literal. |
81 | explicit constexpr nullopt_t(_Construct) noexcept { } |
82 | }; |
83 | |
84 | /// Tag to disengage optional objects. |
85 | inline constexpr nullopt_t nullopt { nullopt_t::_Construct::_Token }; |
86 | |
87 | template<typename _Fn> struct _Optional_func { _Fn& _M_f; }; |
88 | |
89 | /** |
90 | * @brief Exception class thrown when a disengaged optional object is |
91 | * dereferenced. |
92 | * @ingroup exceptions |
93 | */ |
94 | class bad_optional_access : public exception |
95 | { |
96 | public: |
97 | bad_optional_access() = default; |
98 | virtual ~bad_optional_access() = default; |
99 | |
100 | const char* what() const noexcept override |
101 | { return "bad optional access" ; } |
102 | }; |
103 | |
104 | // XXX Does not belong here. |
105 | [[__noreturn__]] inline void |
106 | __throw_bad_optional_access() |
107 | { _GLIBCXX_THROW_OR_ABORT(bad_optional_access()); } |
108 | |
109 | // This class template manages construction/destruction of |
110 | // the contained value for a std::optional. |
111 | template <typename _Tp> |
112 | struct _Optional_payload_base |
113 | { |
114 | using _Stored_type = remove_const_t<_Tp>; |
115 | |
116 | _Optional_payload_base() = default; |
117 | ~_Optional_payload_base() = default; |
118 | |
119 | template<typename... _Args> |
120 | constexpr |
121 | _Optional_payload_base(in_place_t __tag, _Args&&... __args) |
122 | : _M_payload(__tag, std::forward<_Args>(__args)...), |
123 | _M_engaged(true) |
124 | { } |
125 | |
126 | template<typename _Up, typename... _Args> |
127 | constexpr |
128 | _Optional_payload_base(std::initializer_list<_Up> __il, |
129 | _Args&&... __args) |
130 | : _M_payload(__il, std::forward<_Args>(__args)...), |
131 | _M_engaged(true) |
132 | { } |
133 | |
134 | // Constructor used by _Optional_base copy constructor when the |
135 | // contained value is not trivially copy constructible. |
136 | constexpr |
137 | _Optional_payload_base(bool /* __engaged */, |
138 | const _Optional_payload_base& __other) |
139 | { |
140 | if (__other._M_engaged) |
141 | this->_M_construct(__other._M_get()); |
142 | } |
143 | |
144 | // Constructor used by _Optional_base move constructor when the |
145 | // contained value is not trivially move constructible. |
146 | constexpr |
147 | _Optional_payload_base(bool /* __engaged */, |
148 | _Optional_payload_base&& __other) |
149 | { |
150 | if (__other._M_engaged) |
151 | this->_M_construct(std::move(__other._M_get())); |
152 | } |
153 | |
154 | // Copy constructor is only used to when the contained value is |
155 | // trivially copy constructible. |
156 | _Optional_payload_base(const _Optional_payload_base&) = default; |
157 | |
158 | // Move constructor is only used to when the contained value is |
159 | // trivially copy constructible. |
160 | _Optional_payload_base(_Optional_payload_base&&) = default; |
161 | |
162 | _Optional_payload_base& |
163 | operator=(const _Optional_payload_base&) = default; |
164 | |
165 | _Optional_payload_base& |
166 | operator=(_Optional_payload_base&&) = default; |
167 | |
168 | // used to perform non-trivial copy assignment. |
169 | constexpr void |
170 | _M_copy_assign(const _Optional_payload_base& __other) |
171 | { |
172 | if (this->_M_engaged && __other._M_engaged) |
173 | this->_M_get() = __other._M_get(); |
174 | else |
175 | { |
176 | if (__other._M_engaged) |
177 | this->_M_construct(__other._M_get()); |
178 | else |
179 | this->_M_reset(); |
180 | } |
181 | } |
182 | |
183 | // used to perform non-trivial move assignment. |
184 | constexpr void |
185 | _M_move_assign(_Optional_payload_base&& __other) |
186 | noexcept(__and_v<is_nothrow_move_constructible<_Tp>, |
187 | is_nothrow_move_assignable<_Tp>>) |
188 | { |
189 | if (this->_M_engaged && __other._M_engaged) |
190 | this->_M_get() = std::move(__other._M_get()); |
191 | else |
192 | { |
193 | if (__other._M_engaged) |
194 | this->_M_construct(std::move(__other._M_get())); |
195 | else |
196 | this->_M_reset(); |
197 | } |
198 | } |
199 | |
200 | struct _Empty_byte { }; |
201 | |
202 | template<typename _Up, bool = is_trivially_destructible_v<_Up>> |
203 | union _Storage |
204 | { |
205 | constexpr _Storage() noexcept : _M_empty() { } |
206 | |
207 | template<typename... _Args> |
208 | constexpr |
209 | _Storage(in_place_t, _Args&&... __args) |
210 | : _M_value(std::forward<_Args>(__args)...) |
211 | { } |
212 | |
213 | template<typename _Vp, typename... _Args> |
214 | constexpr |
215 | _Storage(std::initializer_list<_Vp> __il, _Args&&... __args) |
216 | : _M_value(__il, std::forward<_Args>(__args)...) |
217 | { } |
218 | |
219 | #if __cplusplus >= 202002L |
220 | template<typename _Fn, typename _Arg> |
221 | constexpr |
222 | _Storage(_Optional_func<_Fn> __f, _Arg&& __arg) |
223 | : _M_value(std::__invoke(std::forward<_Fn>(__f._M_f), |
224 | std::forward<_Arg>(__arg))) |
225 | { } |
226 | #endif |
227 | |
228 | _Empty_byte _M_empty; |
229 | _Up _M_value; |
230 | }; |
231 | |
232 | template<typename _Up> |
233 | union _Storage<_Up, false> |
234 | { |
235 | constexpr _Storage() noexcept : _M_empty() { } |
236 | |
237 | template<typename... _Args> |
238 | constexpr |
239 | _Storage(in_place_t, _Args&&... __args) |
240 | : _M_value(std::forward<_Args>(__args)...) |
241 | { } |
242 | |
243 | template<typename _Vp, typename... _Args> |
244 | constexpr |
245 | _Storage(std::initializer_list<_Vp> __il, _Args&&... __args) |
246 | : _M_value(__il, std::forward<_Args>(__args)...) |
247 | { } |
248 | |
249 | #if __cplusplus >= 202002L |
250 | template<typename _Fn, typename _Arg> |
251 | constexpr |
252 | _Storage(_Optional_func<_Fn> __f, _Arg&& __arg) |
253 | : _M_value(std::__invoke(std::forward<_Fn>(__f._M_f), |
254 | std::forward<_Arg>(__arg))) |
255 | { } |
256 | #endif |
257 | |
258 | // User-provided destructor is needed when _Up has non-trivial dtor. |
259 | _GLIBCXX20_CONSTEXPR ~_Storage() { } |
260 | |
261 | _Empty_byte _M_empty; |
262 | _Up _M_value; |
263 | }; |
264 | |
265 | _Storage<_Stored_type> _M_payload; |
266 | |
267 | bool _M_engaged = false; |
268 | |
269 | template<typename... _Args> |
270 | constexpr void |
271 | _M_construct(_Args&&... __args) |
272 | noexcept(is_nothrow_constructible_v<_Stored_type, _Args...>) |
273 | { |
274 | std::_Construct(std::__addressof(this->_M_payload._M_value), |
275 | std::forward<_Args>(__args)...); |
276 | this->_M_engaged = true; |
277 | } |
278 | |
279 | constexpr void |
280 | _M_destroy() noexcept |
281 | { |
282 | _M_engaged = false; |
283 | _M_payload._M_value.~_Stored_type(); |
284 | } |
285 | |
286 | #if __cplusplus >= 202002L |
287 | template<typename _Fn, typename _Up> |
288 | constexpr void |
289 | _M_apply(_Optional_func<_Fn> __f, _Up&& __x) |
290 | { |
291 | std::construct_at(std::__addressof(this->_M_payload), |
292 | __f, std::forward<_Up>(__x)); |
293 | _M_engaged = true; |
294 | } |
295 | #endif |
296 | |
297 | // The _M_get() operations have _M_engaged as a precondition. |
298 | // They exist to access the contained value with the appropriate |
299 | // const-qualification, because _M_payload has had the const removed. |
300 | |
301 | constexpr _Tp& |
302 | _M_get() noexcept |
303 | { return this->_M_payload._M_value; } |
304 | |
305 | constexpr const _Tp& |
306 | _M_get() const noexcept |
307 | { return this->_M_payload._M_value; } |
308 | |
309 | // _M_reset is a 'safe' operation with no precondition. |
310 | constexpr void |
311 | _M_reset() noexcept |
312 | { |
313 | if (this->_M_engaged) |
314 | _M_destroy(); |
315 | else // This seems redundant but improves codegen, see PR 112480. |
316 | this->_M_engaged = false; |
317 | } |
318 | }; |
319 | |
320 | // Class template that manages the payload for optionals. |
321 | template <typename _Tp, |
322 | bool /*_HasTrivialDestructor*/ = |
323 | is_trivially_destructible_v<_Tp>, |
324 | bool /*_HasTrivialCopy */ = |
325 | is_trivially_copy_assignable_v<_Tp> |
326 | && is_trivially_copy_constructible_v<_Tp>, |
327 | bool /*_HasTrivialMove */ = |
328 | is_trivially_move_assignable_v<_Tp> |
329 | && is_trivially_move_constructible_v<_Tp>> |
330 | struct _Optional_payload; |
331 | |
332 | // Payload for potentially-constexpr optionals (trivial copy/move/destroy). |
333 | template <typename _Tp> |
334 | struct _Optional_payload<_Tp, true, true, true> |
335 | : _Optional_payload_base<_Tp> |
336 | { |
337 | using _Optional_payload_base<_Tp>::_Optional_payload_base; |
338 | |
339 | _Optional_payload() = default; |
340 | }; |
341 | |
342 | // Payload for optionals with non-trivial copy construction/assignment. |
343 | template <typename _Tp> |
344 | struct _Optional_payload<_Tp, true, false, true> |
345 | : _Optional_payload_base<_Tp> |
346 | { |
347 | using _Optional_payload_base<_Tp>::_Optional_payload_base; |
348 | |
349 | _Optional_payload() = default; |
350 | ~_Optional_payload() = default; |
351 | _Optional_payload(const _Optional_payload&) = default; |
352 | _Optional_payload(_Optional_payload&&) = default; |
353 | _Optional_payload& operator=(_Optional_payload&&) = default; |
354 | |
355 | // Non-trivial copy assignment. |
356 | constexpr |
357 | _Optional_payload& |
358 | operator=(const _Optional_payload& __other) |
359 | { |
360 | this->_M_copy_assign(__other); |
361 | return *this; |
362 | } |
363 | }; |
364 | |
365 | // Payload for optionals with non-trivial move construction/assignment. |
366 | template <typename _Tp> |
367 | struct _Optional_payload<_Tp, true, true, false> |
368 | : _Optional_payload_base<_Tp> |
369 | { |
370 | using _Optional_payload_base<_Tp>::_Optional_payload_base; |
371 | |
372 | _Optional_payload() = default; |
373 | ~_Optional_payload() = default; |
374 | _Optional_payload(const _Optional_payload&) = default; |
375 | _Optional_payload(_Optional_payload&&) = default; |
376 | _Optional_payload& operator=(const _Optional_payload&) = default; |
377 | |
378 | // Non-trivial move assignment. |
379 | constexpr |
380 | _Optional_payload& |
381 | operator=(_Optional_payload&& __other) |
382 | noexcept(__and_v<is_nothrow_move_constructible<_Tp>, |
383 | is_nothrow_move_assignable<_Tp>>) |
384 | { |
385 | this->_M_move_assign(std::move(__other)); |
386 | return *this; |
387 | } |
388 | }; |
389 | |
390 | // Payload for optionals with non-trivial copy and move assignment. |
391 | template <typename _Tp> |
392 | struct _Optional_payload<_Tp, true, false, false> |
393 | : _Optional_payload_base<_Tp> |
394 | { |
395 | using _Optional_payload_base<_Tp>::_Optional_payload_base; |
396 | |
397 | _Optional_payload() = default; |
398 | ~_Optional_payload() = default; |
399 | _Optional_payload(const _Optional_payload&) = default; |
400 | _Optional_payload(_Optional_payload&&) = default; |
401 | |
402 | // Non-trivial copy assignment. |
403 | constexpr |
404 | _Optional_payload& |
405 | operator=(const _Optional_payload& __other) |
406 | { |
407 | this->_M_copy_assign(__other); |
408 | return *this; |
409 | } |
410 | |
411 | // Non-trivial move assignment. |
412 | constexpr |
413 | _Optional_payload& |
414 | operator=(_Optional_payload&& __other) |
415 | noexcept(__and_v<is_nothrow_move_constructible<_Tp>, |
416 | is_nothrow_move_assignable<_Tp>>) |
417 | { |
418 | this->_M_move_assign(std::move(__other)); |
419 | return *this; |
420 | } |
421 | }; |
422 | |
423 | // Payload for optionals with non-trivial destructors. |
424 | template <typename _Tp, bool _Copy, bool _Move> |
425 | struct _Optional_payload<_Tp, false, _Copy, _Move> |
426 | : _Optional_payload<_Tp, true, false, false> |
427 | { |
428 | // Base class implements all the constructors and assignment operators: |
429 | using _Optional_payload<_Tp, true, false, false>::_Optional_payload; |
430 | _Optional_payload() = default; |
431 | _Optional_payload(const _Optional_payload&) = default; |
432 | _Optional_payload(_Optional_payload&&) = default; |
433 | _Optional_payload& operator=(const _Optional_payload&) = default; |
434 | _Optional_payload& operator=(_Optional_payload&&) = default; |
435 | |
436 | // Destructor needs to destroy the contained value: |
437 | _GLIBCXX20_CONSTEXPR ~_Optional_payload() { this->_M_reset(); } |
438 | }; |
439 | |
440 | // Common base class for _Optional_base<T> to avoid repeating these |
441 | // member functions in each specialization. |
442 | template<typename _Tp, typename _Dp> |
443 | class _Optional_base_impl |
444 | { |
445 | protected: |
446 | using _Stored_type = remove_const_t<_Tp>; |
447 | |
448 | // The _M_construct operation has !_M_engaged as a precondition |
449 | // while _M_destruct has _M_engaged as a precondition. |
450 | template<typename... _Args> |
451 | constexpr void |
452 | _M_construct(_Args&&... __args) |
453 | noexcept(is_nothrow_constructible_v<_Stored_type, _Args...>) |
454 | { |
455 | static_cast<_Dp*>(this)->_M_payload._M_construct( |
456 | std::forward<_Args>(__args)...); |
457 | } |
458 | |
459 | constexpr void |
460 | _M_destruct() noexcept |
461 | { static_cast<_Dp*>(this)->_M_payload._M_destroy(); } |
462 | |
463 | // _M_reset is a 'safe' operation with no precondition. |
464 | constexpr void |
465 | _M_reset() noexcept |
466 | { static_cast<_Dp*>(this)->_M_payload._M_reset(); } |
467 | |
468 | constexpr bool _M_is_engaged() const noexcept |
469 | { return static_cast<const _Dp*>(this)->_M_payload._M_engaged; } |
470 | |
471 | // The _M_get operations have _M_engaged as a precondition. |
472 | constexpr _Tp& |
473 | _M_get() noexcept |
474 | { |
475 | __glibcxx_assert(this->_M_is_engaged()); |
476 | return static_cast<_Dp*>(this)->_M_payload._M_get(); |
477 | } |
478 | |
479 | constexpr const _Tp& |
480 | _M_get() const noexcept |
481 | { |
482 | __glibcxx_assert(this->_M_is_engaged()); |
483 | return static_cast<const _Dp*>(this)->_M_payload._M_get(); |
484 | } |
485 | }; |
486 | |
487 | /** |
488 | * @brief Class template that provides copy/move constructors of optional. |
489 | * |
490 | * Such a separate base class template is necessary in order to |
491 | * conditionally make copy/move constructors trivial. |
492 | * |
493 | * When the contained value is trivially copy/move constructible, |
494 | * the copy/move constructors of _Optional_base will invoke the |
495 | * trivial copy/move constructor of _Optional_payload. Otherwise, |
496 | * they will invoke _Optional_payload(bool, const _Optional_payload&) |
497 | * or _Optional_payload(bool, _Optional_payload&&) to initialize |
498 | * the contained value, if copying/moving an engaged optional. |
499 | * |
500 | * Whether the other special members are trivial is determined by the |
501 | * _Optional_payload<_Tp> specialization used for the _M_payload member. |
502 | * |
503 | * @see optional, _Enable_special_members |
504 | */ |
505 | template<typename _Tp, |
506 | bool = is_trivially_copy_constructible_v<_Tp>, |
507 | bool = is_trivially_move_constructible_v<_Tp>> |
508 | struct _Optional_base |
509 | : _Optional_base_impl<_Tp, _Optional_base<_Tp>> |
510 | { |
511 | // Constructors for disengaged optionals. |
512 | constexpr _Optional_base() = default; |
513 | |
514 | // Constructors for engaged optionals. |
515 | template<typename... _Args, |
516 | enable_if_t<is_constructible_v<_Tp, _Args...>, bool> = false> |
517 | constexpr explicit |
518 | _Optional_base(in_place_t, _Args&&... __args) |
519 | : _M_payload(in_place, std::forward<_Args>(__args)...) |
520 | { } |
521 | |
522 | template<typename _Up, typename... _Args, |
523 | enable_if_t<is_constructible_v<_Tp, |
524 | initializer_list<_Up>&, |
525 | _Args...>, bool> = false> |
526 | constexpr explicit |
527 | _Optional_base(in_place_t, |
528 | initializer_list<_Up> __il, |
529 | _Args&&... __args) |
530 | : _M_payload(in_place, __il, std::forward<_Args>(__args)...) |
531 | { } |
532 | |
533 | // Copy and move constructors. |
534 | constexpr |
535 | _Optional_base(const _Optional_base& __other) |
536 | : _M_payload(__other._M_payload._M_engaged, __other._M_payload) |
537 | { } |
538 | |
539 | constexpr |
540 | _Optional_base(_Optional_base&& __other) |
541 | noexcept(is_nothrow_move_constructible_v<_Tp>) |
542 | : _M_payload(__other._M_payload._M_engaged, |
543 | std::move(__other._M_payload)) |
544 | { } |
545 | |
546 | // Assignment operators. |
547 | _Optional_base& operator=(const _Optional_base&) = default; |
548 | _Optional_base& operator=(_Optional_base&&) = default; |
549 | |
550 | _Optional_payload<_Tp> _M_payload; |
551 | }; |
552 | |
553 | template<typename _Tp> |
554 | struct _Optional_base<_Tp, false, true> |
555 | : _Optional_base_impl<_Tp, _Optional_base<_Tp>> |
556 | { |
557 | // Constructors for disengaged optionals. |
558 | constexpr _Optional_base() = default; |
559 | |
560 | // Constructors for engaged optionals. |
561 | template<typename... _Args, |
562 | enable_if_t<is_constructible_v<_Tp, _Args...>, bool> = false> |
563 | constexpr explicit |
564 | _Optional_base(in_place_t, _Args&&... __args) |
565 | : _M_payload(in_place, std::forward<_Args>(__args)...) |
566 | { } |
567 | |
568 | template<typename _Up, typename... _Args, |
569 | enable_if_t<is_constructible_v<_Tp, |
570 | initializer_list<_Up>&, |
571 | _Args...>, bool> = false> |
572 | constexpr explicit |
573 | _Optional_base(in_place_t, |
574 | initializer_list<_Up> __il, |
575 | _Args... __args) |
576 | : _M_payload(in_place, __il, std::forward<_Args>(__args)...) |
577 | { } |
578 | |
579 | // Copy and move constructors. |
580 | constexpr _Optional_base(const _Optional_base& __other) |
581 | : _M_payload(__other._M_payload._M_engaged, __other._M_payload) |
582 | { } |
583 | |
584 | constexpr _Optional_base(_Optional_base&& __other) = default; |
585 | |
586 | // Assignment operators. |
587 | _Optional_base& operator=(const _Optional_base&) = default; |
588 | _Optional_base& operator=(_Optional_base&&) = default; |
589 | |
590 | _Optional_payload<_Tp> _M_payload; |
591 | }; |
592 | |
593 | template<typename _Tp> |
594 | struct _Optional_base<_Tp, true, false> |
595 | : _Optional_base_impl<_Tp, _Optional_base<_Tp>> |
596 | { |
597 | // Constructors for disengaged optionals. |
598 | constexpr _Optional_base() = default; |
599 | |
600 | // Constructors for engaged optionals. |
601 | template<typename... _Args, |
602 | enable_if_t<is_constructible_v<_Tp, _Args...>, bool> = false> |
603 | constexpr explicit |
604 | _Optional_base(in_place_t, _Args&&... __args) |
605 | : _M_payload(in_place, std::forward<_Args>(__args)...) |
606 | { } |
607 | |
608 | template<typename _Up, typename... _Args, |
609 | enable_if_t<is_constructible_v<_Tp, |
610 | initializer_list<_Up>&, |
611 | _Args...>, bool> = false> |
612 | constexpr explicit |
613 | _Optional_base(in_place_t, |
614 | initializer_list<_Up> __il, |
615 | _Args&&... __args) |
616 | : _M_payload(in_place, __il, std::forward<_Args>(__args)...) |
617 | { } |
618 | |
619 | // Copy and move constructors. |
620 | constexpr _Optional_base(const _Optional_base& __other) = default; |
621 | |
622 | constexpr |
623 | _Optional_base(_Optional_base&& __other) |
624 | noexcept(is_nothrow_move_constructible_v<_Tp>) |
625 | : _M_payload(__other._M_payload._M_engaged, |
626 | std::move(__other._M_payload)) |
627 | { } |
628 | |
629 | // Assignment operators. |
630 | _Optional_base& operator=(const _Optional_base&) = default; |
631 | _Optional_base& operator=(_Optional_base&&) = default; |
632 | |
633 | _Optional_payload<_Tp> _M_payload; |
634 | }; |
635 | |
636 | template<typename _Tp> |
637 | struct _Optional_base<_Tp, true, true> |
638 | : _Optional_base_impl<_Tp, _Optional_base<_Tp>> |
639 | { |
640 | // Constructors for disengaged optionals. |
641 | constexpr _Optional_base() = default; |
642 | |
643 | // Constructors for engaged optionals. |
644 | template<typename... _Args, |
645 | enable_if_t<is_constructible_v<_Tp, _Args...>, bool> = false> |
646 | constexpr explicit |
647 | _Optional_base(in_place_t, _Args&&... __args) |
648 | : _M_payload(in_place, std::forward<_Args>(__args)...) |
649 | { } |
650 | |
651 | template<typename _Up, typename... _Args, |
652 | enable_if_t<is_constructible_v<_Tp, |
653 | initializer_list<_Up>&, |
654 | _Args...>, bool> = false> |
655 | constexpr explicit |
656 | _Optional_base(in_place_t, |
657 | initializer_list<_Up> __il, |
658 | _Args&&... __args) |
659 | : _M_payload(in_place, __il, std::forward<_Args>(__args)...) |
660 | { } |
661 | |
662 | // Copy and move constructors. |
663 | constexpr _Optional_base(const _Optional_base& __other) = default; |
664 | constexpr _Optional_base(_Optional_base&& __other) = default; |
665 | |
666 | // Assignment operators. |
667 | _Optional_base& operator=(const _Optional_base&) = default; |
668 | _Optional_base& operator=(_Optional_base&&) = default; |
669 | |
670 | _Optional_payload<_Tp> _M_payload; |
671 | }; |
672 | |
673 | template<typename _Tp> |
674 | class optional; |
675 | |
676 | template<typename _Tp> |
677 | inline constexpr bool __is_optional_v = false; |
678 | template<typename _Tp> |
679 | inline constexpr bool __is_optional_v<optional<_Tp>> = true; |
680 | |
681 | template<typename _Tp, typename _Up> |
682 | using __converts_from_optional = |
683 | __or_<is_constructible<_Tp, const optional<_Up>&>, |
684 | is_constructible<_Tp, optional<_Up>&>, |
685 | is_constructible<_Tp, const optional<_Up>&&>, |
686 | is_constructible<_Tp, optional<_Up>&&>, |
687 | is_convertible<const optional<_Up>&, _Tp>, |
688 | is_convertible<optional<_Up>&, _Tp>, |
689 | is_convertible<const optional<_Up>&&, _Tp>, |
690 | is_convertible<optional<_Up>&&, _Tp>>; |
691 | |
692 | template<typename _Tp, typename _Up> |
693 | using __assigns_from_optional = |
694 | __or_<is_assignable<_Tp&, const optional<_Up>&>, |
695 | is_assignable<_Tp&, optional<_Up>&>, |
696 | is_assignable<_Tp&, const optional<_Up>&&>, |
697 | is_assignable<_Tp&, optional<_Up>&&>>; |
698 | |
699 | /** |
700 | * @brief Class template for optional values. |
701 | */ |
702 | template<typename _Tp> |
703 | class optional |
704 | : private _Optional_base<_Tp>, |
705 | private _Enable_copy_move< |
706 | // Copy constructor. |
707 | is_copy_constructible_v<_Tp>, |
708 | // Copy assignment. |
709 | __and_v<is_copy_constructible<_Tp>, is_copy_assignable<_Tp>>, |
710 | // Move constructor. |
711 | is_move_constructible_v<_Tp>, |
712 | // Move assignment. |
713 | __and_v<is_move_constructible<_Tp>, is_move_assignable<_Tp>>, |
714 | // Unique tag type. |
715 | optional<_Tp>> |
716 | { |
717 | static_assert(!is_same_v<remove_cv_t<_Tp>, nullopt_t>); |
718 | static_assert(!is_same_v<remove_cv_t<_Tp>, in_place_t>); |
719 | static_assert(is_object_v<_Tp> && !is_array_v<_Tp>); |
720 | |
721 | private: |
722 | using _Base = _Optional_base<_Tp>; |
723 | |
724 | // SFINAE helpers |
725 | template<typename _Up> |
726 | using __not_self = __not_<is_same<optional, __remove_cvref_t<_Up>>>; |
727 | template<typename _Up> |
728 | using __not_tag = __not_<is_same<in_place_t, __remove_cvref_t<_Up>>>; |
729 | template<typename... _Cond> |
730 | using _Requires = enable_if_t<__and_v<_Cond...>, bool>; |
731 | |
732 | public: |
733 | using value_type = _Tp; |
734 | |
735 | constexpr optional() noexcept { } |
736 | |
737 | constexpr optional(nullopt_t) noexcept { } |
738 | |
739 | // Converting constructors for engaged optionals. |
740 | template<typename _Up = _Tp, |
741 | _Requires<__not_self<_Up>, __not_tag<_Up>, |
742 | is_constructible<_Tp, _Up>, |
743 | is_convertible<_Up, _Tp>> = true> |
744 | constexpr |
745 | optional(_Up&& __t) |
746 | noexcept(is_nothrow_constructible_v<_Tp, _Up>) |
747 | : _Base(std::in_place, std::forward<_Up>(__t)) { } |
748 | |
749 | template<typename _Up = _Tp, |
750 | _Requires<__not_self<_Up>, __not_tag<_Up>, |
751 | is_constructible<_Tp, _Up>, |
752 | __not_<is_convertible<_Up, _Tp>>> = false> |
753 | explicit constexpr |
754 | optional(_Up&& __t) |
755 | noexcept(is_nothrow_constructible_v<_Tp, _Up>) |
756 | : _Base(std::in_place, std::forward<_Up>(__t)) { } |
757 | |
758 | template<typename _Up, |
759 | _Requires<__not_<is_same<_Tp, _Up>>, |
760 | is_constructible<_Tp, const _Up&>, |
761 | is_convertible<const _Up&, _Tp>, |
762 | __not_<__converts_from_optional<_Tp, _Up>>> = true> |
763 | constexpr |
764 | optional(const optional<_Up>& __t) |
765 | noexcept(is_nothrow_constructible_v<_Tp, const _Up&>) |
766 | { |
767 | if (__t) |
768 | emplace(*__t); |
769 | } |
770 | |
771 | template<typename _Up, |
772 | _Requires<__not_<is_same<_Tp, _Up>>, |
773 | is_constructible<_Tp, const _Up&>, |
774 | __not_<is_convertible<const _Up&, _Tp>>, |
775 | __not_<__converts_from_optional<_Tp, _Up>>> = false> |
776 | explicit constexpr |
777 | optional(const optional<_Up>& __t) |
778 | noexcept(is_nothrow_constructible_v<_Tp, const _Up&>) |
779 | { |
780 | if (__t) |
781 | emplace(*__t); |
782 | } |
783 | |
784 | template<typename _Up, |
785 | _Requires<__not_<is_same<_Tp, _Up>>, |
786 | is_constructible<_Tp, _Up>, |
787 | is_convertible<_Up, _Tp>, |
788 | __not_<__converts_from_optional<_Tp, _Up>>> = true> |
789 | constexpr |
790 | optional(optional<_Up>&& __t) |
791 | noexcept(is_nothrow_constructible_v<_Tp, _Up>) |
792 | { |
793 | if (__t) |
794 | emplace(std::move(*__t)); |
795 | } |
796 | |
797 | template<typename _Up, |
798 | _Requires<__not_<is_same<_Tp, _Up>>, |
799 | is_constructible<_Tp, _Up>, |
800 | __not_<is_convertible<_Up, _Tp>>, |
801 | __not_<__converts_from_optional<_Tp, _Up>>> = false> |
802 | explicit constexpr |
803 | optional(optional<_Up>&& __t) |
804 | noexcept(is_nothrow_constructible_v<_Tp, _Up>) |
805 | { |
806 | if (__t) |
807 | emplace(std::move(*__t)); |
808 | } |
809 | |
810 | template<typename... _Args, |
811 | _Requires<is_constructible<_Tp, _Args...>> = false> |
812 | explicit constexpr |
813 | optional(in_place_t, _Args&&... __args) |
814 | noexcept(is_nothrow_constructible_v<_Tp, _Args...>) |
815 | : _Base(std::in_place, std::forward<_Args>(__args)...) { } |
816 | |
817 | template<typename _Up, typename... _Args, |
818 | _Requires<is_constructible<_Tp, |
819 | initializer_list<_Up>&, |
820 | _Args...>> = false> |
821 | explicit constexpr |
822 | optional(in_place_t, initializer_list<_Up> __il, _Args&&... __args) |
823 | noexcept(is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, |
824 | _Args...>) |
825 | : _Base(std::in_place, __il, std::forward<_Args>(__args)...) { } |
826 | |
827 | |
828 | // Assignment operators. |
829 | _GLIBCXX20_CONSTEXPR optional& |
830 | operator=(nullopt_t) noexcept |
831 | { |
832 | this->_M_reset(); |
833 | return *this; |
834 | } |
835 | |
836 | template<typename _Up = _Tp> |
837 | _GLIBCXX20_CONSTEXPR |
838 | enable_if_t<__and_v<__not_self<_Up>, |
839 | __not_<__and_<is_scalar<_Tp>, |
840 | is_same<_Tp, decay_t<_Up>>>>, |
841 | is_constructible<_Tp, _Up>, |
842 | is_assignable<_Tp&, _Up>>, |
843 | optional&> |
844 | operator=(_Up&& __u) |
845 | noexcept(__and_v<is_nothrow_constructible<_Tp, _Up>, |
846 | is_nothrow_assignable<_Tp&, _Up>>) |
847 | { |
848 | if (this->_M_is_engaged()) |
849 | this->_M_get() = std::forward<_Up>(__u); |
850 | else |
851 | this->_M_construct(std::forward<_Up>(__u)); |
852 | |
853 | return *this; |
854 | } |
855 | |
856 | template<typename _Up> |
857 | _GLIBCXX20_CONSTEXPR |
858 | enable_if_t<__and_v<__not_<is_same<_Tp, _Up>>, |
859 | is_constructible<_Tp, const _Up&>, |
860 | is_assignable<_Tp&, const _Up&>, |
861 | __not_<__converts_from_optional<_Tp, _Up>>, |
862 | __not_<__assigns_from_optional<_Tp, _Up>>>, |
863 | optional&> |
864 | operator=(const optional<_Up>& __u) |
865 | noexcept(__and_v<is_nothrow_constructible<_Tp, const _Up&>, |
866 | is_nothrow_assignable<_Tp&, const _Up&>>) |
867 | { |
868 | if (__u) |
869 | { |
870 | if (this->_M_is_engaged()) |
871 | this->_M_get() = *__u; |
872 | else |
873 | this->_M_construct(*__u); |
874 | } |
875 | else |
876 | { |
877 | this->_M_reset(); |
878 | } |
879 | return *this; |
880 | } |
881 | |
882 | template<typename _Up> |
883 | _GLIBCXX20_CONSTEXPR |
884 | enable_if_t<__and_v<__not_<is_same<_Tp, _Up>>, |
885 | is_constructible<_Tp, _Up>, |
886 | is_assignable<_Tp&, _Up>, |
887 | __not_<__converts_from_optional<_Tp, _Up>>, |
888 | __not_<__assigns_from_optional<_Tp, _Up>>>, |
889 | optional&> |
890 | operator=(optional<_Up>&& __u) |
891 | noexcept(__and_v<is_nothrow_constructible<_Tp, _Up>, |
892 | is_nothrow_assignable<_Tp&, _Up>>) |
893 | { |
894 | if (__u) |
895 | { |
896 | if (this->_M_is_engaged()) |
897 | this->_M_get() = std::move(*__u); |
898 | else |
899 | this->_M_construct(std::move(*__u)); |
900 | } |
901 | else |
902 | { |
903 | this->_M_reset(); |
904 | } |
905 | |
906 | return *this; |
907 | } |
908 | |
909 | template<typename... _Args> |
910 | _GLIBCXX20_CONSTEXPR |
911 | enable_if_t<is_constructible_v<_Tp, _Args...>, _Tp&> |
912 | emplace(_Args&&... __args) |
913 | noexcept(is_nothrow_constructible_v<_Tp, _Args...>) |
914 | { |
915 | this->_M_reset(); |
916 | this->_M_construct(std::forward<_Args>(__args)...); |
917 | return this->_M_get(); |
918 | } |
919 | |
920 | template<typename _Up, typename... _Args> |
921 | _GLIBCXX20_CONSTEXPR |
922 | enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, |
923 | _Tp&> |
924 | emplace(initializer_list<_Up> __il, _Args&&... __args) |
925 | noexcept(is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, |
926 | _Args...>) |
927 | { |
928 | this->_M_reset(); |
929 | this->_M_construct(__il, std::forward<_Args>(__args)...); |
930 | return this->_M_get(); |
931 | } |
932 | |
933 | // Destructor is implicit, implemented in _Optional_base. |
934 | |
935 | // Swap. |
936 | _GLIBCXX20_CONSTEXPR void |
937 | swap(optional& __other) |
938 | noexcept(is_nothrow_move_constructible_v<_Tp> |
939 | && is_nothrow_swappable_v<_Tp>) |
940 | { |
941 | using std::swap; |
942 | |
943 | if (this->_M_is_engaged() && __other._M_is_engaged()) |
944 | swap(this->_M_get(), __other._M_get()); |
945 | else if (this->_M_is_engaged()) |
946 | { |
947 | __other._M_construct(std::move(this->_M_get())); |
948 | this->_M_destruct(); |
949 | } |
950 | else if (__other._M_is_engaged()) |
951 | { |
952 | this->_M_construct(std::move(__other._M_get())); |
953 | __other._M_destruct(); |
954 | } |
955 | } |
956 | |
957 | // Observers. |
958 | constexpr const _Tp* |
959 | operator->() const noexcept |
960 | { return std::__addressof(this->_M_get()); } |
961 | |
962 | constexpr _Tp* |
963 | operator->() noexcept |
964 | { return std::__addressof(this->_M_get()); } |
965 | |
966 | constexpr const _Tp& |
967 | operator*() const& noexcept |
968 | { return this->_M_get(); } |
969 | |
970 | constexpr _Tp& |
971 | operator*()& noexcept |
972 | { return this->_M_get(); } |
973 | |
974 | constexpr _Tp&& |
975 | operator*()&& noexcept |
976 | { return std::move(this->_M_get()); } |
977 | |
978 | constexpr const _Tp&& |
979 | operator*() const&& noexcept |
980 | { return std::move(this->_M_get()); } |
981 | |
982 | constexpr explicit operator bool() const noexcept |
983 | { return this->_M_is_engaged(); } |
984 | |
985 | constexpr bool has_value() const noexcept |
986 | { return this->_M_is_engaged(); } |
987 | |
988 | constexpr const _Tp& |
989 | value() const& |
990 | { |
991 | if (this->_M_is_engaged()) |
992 | return this->_M_get(); |
993 | __throw_bad_optional_access(); |
994 | } |
995 | |
996 | constexpr _Tp& |
997 | value()& |
998 | { |
999 | if (this->_M_is_engaged()) |
1000 | return this->_M_get(); |
1001 | __throw_bad_optional_access(); |
1002 | } |
1003 | |
1004 | constexpr _Tp&& |
1005 | value()&& |
1006 | { |
1007 | if (this->_M_is_engaged()) |
1008 | return std::move(this->_M_get()); |
1009 | __throw_bad_optional_access(); |
1010 | } |
1011 | |
1012 | constexpr const _Tp&& |
1013 | value() const&& |
1014 | { |
1015 | if (this->_M_is_engaged()) |
1016 | return std::move(this->_M_get()); |
1017 | __throw_bad_optional_access(); |
1018 | } |
1019 | |
1020 | template<typename _Up> |
1021 | constexpr _Tp |
1022 | value_or(_Up&& __u) const& |
1023 | { |
1024 | static_assert(is_copy_constructible_v<_Tp>); |
1025 | static_assert(is_convertible_v<_Up&&, _Tp>); |
1026 | |
1027 | if (this->_M_is_engaged()) |
1028 | return this->_M_get(); |
1029 | else |
1030 | return static_cast<_Tp>(std::forward<_Up>(__u)); |
1031 | } |
1032 | |
1033 | template<typename _Up> |
1034 | constexpr _Tp |
1035 | value_or(_Up&& __u) && |
1036 | { |
1037 | static_assert(is_move_constructible_v<_Tp>); |
1038 | static_assert(is_convertible_v<_Up&&, _Tp>); |
1039 | |
1040 | if (this->_M_is_engaged()) |
1041 | return std::move(this->_M_get()); |
1042 | else |
1043 | return static_cast<_Tp>(std::forward<_Up>(__u)); |
1044 | } |
1045 | |
1046 | #if __cpp_lib_optional >= 202110L |
1047 | // [optional.monadic] |
1048 | |
1049 | template<typename _Fn> |
1050 | constexpr auto |
1051 | and_then(_Fn&& __f) & |
1052 | { |
1053 | using _Up = remove_cvref_t<invoke_result_t<_Fn, _Tp&>>; |
1054 | static_assert(__is_optional_v<remove_cvref_t<_Up>>, |
1055 | "the function passed to std::optional<T>::and_then " |
1056 | "must return a std::optional" ); |
1057 | if (has_value()) |
1058 | return std::__invoke(std::forward<_Fn>(__f), **this); |
1059 | else |
1060 | return _Up(); |
1061 | } |
1062 | |
1063 | template<typename _Fn> |
1064 | constexpr auto |
1065 | and_then(_Fn&& __f) const & |
1066 | { |
1067 | using _Up = remove_cvref_t<invoke_result_t<_Fn, const _Tp&>>; |
1068 | static_assert(__is_optional_v<_Up>, |
1069 | "the function passed to std::optional<T>::and_then " |
1070 | "must return a std::optional" ); |
1071 | if (has_value()) |
1072 | return std::__invoke(std::forward<_Fn>(__f), **this); |
1073 | else |
1074 | return _Up(); |
1075 | } |
1076 | |
1077 | template<typename _Fn> |
1078 | constexpr auto |
1079 | and_then(_Fn&& __f) && |
1080 | { |
1081 | using _Up = remove_cvref_t<invoke_result_t<_Fn, _Tp>>; |
1082 | static_assert(__is_optional_v<remove_cvref_t<_Up>>, |
1083 | "the function passed to std::optional<T>::and_then " |
1084 | "must return a std::optional" ); |
1085 | if (has_value()) |
1086 | return std::__invoke(std::forward<_Fn>(__f), std::move(**this)); |
1087 | else |
1088 | return _Up(); |
1089 | } |
1090 | |
1091 | template<typename _Fn> |
1092 | constexpr auto |
1093 | and_then(_Fn&& __f) const && |
1094 | { |
1095 | using _Up = remove_cvref_t<invoke_result_t<_Fn, const _Tp>>; |
1096 | static_assert(__is_optional_v<remove_cvref_t<_Up>>, |
1097 | "the function passed to std::optional<T>::and_then " |
1098 | "must return a std::optional" ); |
1099 | if (has_value()) |
1100 | return std::__invoke(std::forward<_Fn>(__f), std::move(**this)); |
1101 | else |
1102 | return _Up(); |
1103 | } |
1104 | |
1105 | template<typename _Fn> |
1106 | constexpr auto |
1107 | transform(_Fn&& __f) & |
1108 | { |
1109 | using _Up = remove_cv_t<invoke_result_t<_Fn, _Tp&>>; |
1110 | if (has_value()) |
1111 | return optional<_Up>(_Optional_func<_Fn>{__f}, **this); |
1112 | else |
1113 | return optional<_Up>(); |
1114 | } |
1115 | |
1116 | template<typename _Fn> |
1117 | constexpr auto |
1118 | transform(_Fn&& __f) const & |
1119 | { |
1120 | using _Up = remove_cv_t<invoke_result_t<_Fn, const _Tp&>>; |
1121 | if (has_value()) |
1122 | return optional<_Up>(_Optional_func<_Fn>{__f}, **this); |
1123 | else |
1124 | return optional<_Up>(); |
1125 | } |
1126 | |
1127 | template<typename _Fn> |
1128 | constexpr auto |
1129 | transform(_Fn&& __f) && |
1130 | { |
1131 | using _Up = remove_cv_t<invoke_result_t<_Fn, _Tp>>; |
1132 | if (has_value()) |
1133 | return optional<_Up>(_Optional_func<_Fn>{__f}, std::move(**this)); |
1134 | else |
1135 | return optional<_Up>(); |
1136 | } |
1137 | |
1138 | template<typename _Fn> |
1139 | constexpr auto |
1140 | transform(_Fn&& __f) const && |
1141 | { |
1142 | using _Up = remove_cv_t<invoke_result_t<_Fn, const _Tp>>; |
1143 | if (has_value()) |
1144 | return optional<_Up>(_Optional_func<_Fn>{__f}, std::move(**this)); |
1145 | else |
1146 | return optional<_Up>(); |
1147 | } |
1148 | |
1149 | template<typename _Fn> requires invocable<_Fn> && copy_constructible<_Tp> |
1150 | constexpr optional |
1151 | or_else(_Fn&& __f) const& |
1152 | { |
1153 | using _Up = invoke_result_t<_Fn>; |
1154 | static_assert(is_same_v<remove_cvref_t<_Up>, optional>, |
1155 | "the function passed to std::optional<T>::or_else " |
1156 | "must return a std::optional<T>" ); |
1157 | |
1158 | if (has_value()) |
1159 | return *this; |
1160 | else |
1161 | return std::forward<_Fn>(__f)(); |
1162 | } |
1163 | |
1164 | template<typename _Fn> requires invocable<_Fn> && move_constructible<_Tp> |
1165 | constexpr optional |
1166 | or_else(_Fn&& __f) && |
1167 | { |
1168 | using _Up = invoke_result_t<_Fn>; |
1169 | static_assert(is_same_v<remove_cvref_t<_Up>, optional>, |
1170 | "the function passed to std::optional<T>::or_else " |
1171 | "must return a std::optional<T>" ); |
1172 | |
1173 | if (has_value()) |
1174 | return std::move(*this); |
1175 | else |
1176 | return std::forward<_Fn>(__f)(); |
1177 | } |
1178 | #endif |
1179 | |
1180 | _GLIBCXX20_CONSTEXPR void reset() noexcept { this->_M_reset(); } |
1181 | |
1182 | private: |
1183 | #if __cplusplus >= 202002L |
1184 | template<typename _Up> friend class optional; |
1185 | |
1186 | template<typename _Fn, typename _Value> |
1187 | explicit constexpr |
1188 | optional(_Optional_func<_Fn> __f, _Value&& __v) |
1189 | { |
1190 | this->_M_payload._M_apply(__f, std::forward<_Value>(__v)); |
1191 | } |
1192 | #endif |
1193 | }; |
1194 | |
1195 | template<typename _Tp> |
1196 | using __optional_relop_t = |
1197 | enable_if_t<is_convertible<_Tp, bool>::value, bool>; |
1198 | |
1199 | template<typename _Tp, typename _Up> |
1200 | using __optional_eq_t = __optional_relop_t< |
1201 | decltype(std::declval<const _Tp&>() == std::declval<const _Up&>()) |
1202 | >; |
1203 | |
1204 | template<typename _Tp, typename _Up> |
1205 | using __optional_ne_t = __optional_relop_t< |
1206 | decltype(std::declval<const _Tp&>() != std::declval<const _Up&>()) |
1207 | >; |
1208 | |
1209 | template<typename _Tp, typename _Up> |
1210 | using __optional_lt_t = __optional_relop_t< |
1211 | decltype(std::declval<const _Tp&>() < std::declval<const _Up&>()) |
1212 | >; |
1213 | |
1214 | template<typename _Tp, typename _Up> |
1215 | using __optional_gt_t = __optional_relop_t< |
1216 | decltype(std::declval<const _Tp&>() > std::declval<const _Up&>()) |
1217 | >; |
1218 | |
1219 | template<typename _Tp, typename _Up> |
1220 | using __optional_le_t = __optional_relop_t< |
1221 | decltype(std::declval<const _Tp&>() <= std::declval<const _Up&>()) |
1222 | >; |
1223 | |
1224 | template<typename _Tp, typename _Up> |
1225 | using __optional_ge_t = __optional_relop_t< |
1226 | decltype(std::declval<const _Tp&>() >= std::declval<const _Up&>()) |
1227 | >; |
1228 | |
1229 | // Comparisons between optional values. |
1230 | template<typename _Tp, typename _Up> |
1231 | constexpr auto |
1232 | operator==(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
1233 | -> __optional_eq_t<_Tp, _Up> |
1234 | { |
1235 | return static_cast<bool>(__lhs) == static_cast<bool>(__rhs) |
1236 | && (!__lhs || *__lhs == *__rhs); |
1237 | } |
1238 | |
1239 | template<typename _Tp, typename _Up> |
1240 | constexpr auto |
1241 | operator!=(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
1242 | -> __optional_ne_t<_Tp, _Up> |
1243 | { |
1244 | return static_cast<bool>(__lhs) != static_cast<bool>(__rhs) |
1245 | || (static_cast<bool>(__lhs) && *__lhs != *__rhs); |
1246 | } |
1247 | |
1248 | template<typename _Tp, typename _Up> |
1249 | constexpr auto |
1250 | operator<(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
1251 | -> __optional_lt_t<_Tp, _Up> |
1252 | { |
1253 | return static_cast<bool>(__rhs) && (!__lhs || *__lhs < *__rhs); |
1254 | } |
1255 | |
1256 | template<typename _Tp, typename _Up> |
1257 | constexpr auto |
1258 | operator>(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
1259 | -> __optional_gt_t<_Tp, _Up> |
1260 | { |
1261 | return static_cast<bool>(__lhs) && (!__rhs || *__lhs > *__rhs); |
1262 | } |
1263 | |
1264 | template<typename _Tp, typename _Up> |
1265 | constexpr auto |
1266 | operator<=(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
1267 | -> __optional_le_t<_Tp, _Up> |
1268 | { |
1269 | return !__lhs || (static_cast<bool>(__rhs) && *__lhs <= *__rhs); |
1270 | } |
1271 | |
1272 | template<typename _Tp, typename _Up> |
1273 | constexpr auto |
1274 | operator>=(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
1275 | -> __optional_ge_t<_Tp, _Up> |
1276 | { |
1277 | return !__rhs || (static_cast<bool>(__lhs) && *__lhs >= *__rhs); |
1278 | } |
1279 | |
1280 | #ifdef __cpp_lib_three_way_comparison |
1281 | template<typename _Tp, three_way_comparable_with<_Tp> _Up> |
1282 | constexpr compare_three_way_result_t<_Tp, _Up> |
1283 | operator<=>(const optional<_Tp>& __x, const optional<_Up>& __y) |
1284 | { |
1285 | return __x && __y ? *__x <=> *__y : bool(__x) <=> bool(__y); |
1286 | } |
1287 | #endif |
1288 | |
1289 | // Comparisons with nullopt. |
1290 | template<typename _Tp> |
1291 | constexpr bool |
1292 | operator==(const optional<_Tp>& __lhs, nullopt_t) noexcept |
1293 | { return !__lhs; } |
1294 | |
1295 | #ifdef __cpp_lib_three_way_comparison |
1296 | template<typename _Tp> |
1297 | constexpr strong_ordering |
1298 | operator<=>(const optional<_Tp>& __x, nullopt_t) noexcept |
1299 | { return bool(__x) <=> false; } |
1300 | #else |
1301 | template<typename _Tp> |
1302 | constexpr bool |
1303 | operator==(nullopt_t, const optional<_Tp>& __rhs) noexcept |
1304 | { return !__rhs; } |
1305 | |
1306 | template<typename _Tp> |
1307 | constexpr bool |
1308 | operator!=(const optional<_Tp>& __lhs, nullopt_t) noexcept |
1309 | { return static_cast<bool>(__lhs); } |
1310 | |
1311 | template<typename _Tp> |
1312 | constexpr bool |
1313 | operator!=(nullopt_t, const optional<_Tp>& __rhs) noexcept |
1314 | { return static_cast<bool>(__rhs); } |
1315 | |
1316 | template<typename _Tp> |
1317 | constexpr bool |
1318 | operator<(const optional<_Tp>& /* __lhs */, nullopt_t) noexcept |
1319 | { return false; } |
1320 | |
1321 | template<typename _Tp> |
1322 | constexpr bool |
1323 | operator<(nullopt_t, const optional<_Tp>& __rhs) noexcept |
1324 | { return static_cast<bool>(__rhs); } |
1325 | |
1326 | template<typename _Tp> |
1327 | constexpr bool |
1328 | operator>(const optional<_Tp>& __lhs, nullopt_t) noexcept |
1329 | { return static_cast<bool>(__lhs); } |
1330 | |
1331 | template<typename _Tp> |
1332 | constexpr bool |
1333 | operator>(nullopt_t, const optional<_Tp>& /* __rhs */) noexcept |
1334 | { return false; } |
1335 | |
1336 | template<typename _Tp> |
1337 | constexpr bool |
1338 | operator<=(const optional<_Tp>& __lhs, nullopt_t) noexcept |
1339 | { return !__lhs; } |
1340 | |
1341 | template<typename _Tp> |
1342 | constexpr bool |
1343 | operator<=(nullopt_t, const optional<_Tp>& /* __rhs */) noexcept |
1344 | { return true; } |
1345 | |
1346 | template<typename _Tp> |
1347 | constexpr bool |
1348 | operator>=(const optional<_Tp>& /* __lhs */, nullopt_t) noexcept |
1349 | { return true; } |
1350 | |
1351 | template<typename _Tp> |
1352 | constexpr bool |
1353 | operator>=(nullopt_t, const optional<_Tp>& __rhs) noexcept |
1354 | { return !__rhs; } |
1355 | #endif // three-way-comparison |
1356 | |
1357 | // Comparisons with value type. |
1358 | template<typename _Tp, typename _Up> |
1359 | constexpr auto |
1360 | operator==(const optional<_Tp>& __lhs, const _Up& __rhs) |
1361 | -> __optional_eq_t<_Tp, _Up> |
1362 | { return __lhs && *__lhs == __rhs; } |
1363 | |
1364 | template<typename _Tp, typename _Up> |
1365 | constexpr auto |
1366 | operator==(const _Up& __lhs, const optional<_Tp>& __rhs) |
1367 | -> __optional_eq_t<_Up, _Tp> |
1368 | { return __rhs && __lhs == *__rhs; } |
1369 | |
1370 | template<typename _Tp, typename _Up> |
1371 | constexpr auto |
1372 | operator!=(const optional<_Tp>& __lhs, const _Up& __rhs) |
1373 | -> __optional_ne_t<_Tp, _Up> |
1374 | { return !__lhs || *__lhs != __rhs; } |
1375 | |
1376 | template<typename _Tp, typename _Up> |
1377 | constexpr auto |
1378 | operator!=(const _Up& __lhs, const optional<_Tp>& __rhs) |
1379 | -> __optional_ne_t<_Up, _Tp> |
1380 | { return !__rhs || __lhs != *__rhs; } |
1381 | |
1382 | template<typename _Tp, typename _Up> |
1383 | constexpr auto |
1384 | operator<(const optional<_Tp>& __lhs, const _Up& __rhs) |
1385 | -> __optional_lt_t<_Tp, _Up> |
1386 | { return !__lhs || *__lhs < __rhs; } |
1387 | |
1388 | template<typename _Tp, typename _Up> |
1389 | constexpr auto |
1390 | operator<(const _Up& __lhs, const optional<_Tp>& __rhs) |
1391 | -> __optional_lt_t<_Up, _Tp> |
1392 | { return __rhs && __lhs < *__rhs; } |
1393 | |
1394 | template<typename _Tp, typename _Up> |
1395 | constexpr auto |
1396 | operator>(const optional<_Tp>& __lhs, const _Up& __rhs) |
1397 | -> __optional_gt_t<_Tp, _Up> |
1398 | { return __lhs && *__lhs > __rhs; } |
1399 | |
1400 | template<typename _Tp, typename _Up> |
1401 | constexpr auto |
1402 | operator>(const _Up& __lhs, const optional<_Tp>& __rhs) |
1403 | -> __optional_gt_t<_Up, _Tp> |
1404 | { return !__rhs || __lhs > *__rhs; } |
1405 | |
1406 | template<typename _Tp, typename _Up> |
1407 | constexpr auto |
1408 | operator<=(const optional<_Tp>& __lhs, const _Up& __rhs) |
1409 | -> __optional_le_t<_Tp, _Up> |
1410 | { return !__lhs || *__lhs <= __rhs; } |
1411 | |
1412 | template<typename _Tp, typename _Up> |
1413 | constexpr auto |
1414 | operator<=(const _Up& __lhs, const optional<_Tp>& __rhs) |
1415 | -> __optional_le_t<_Up, _Tp> |
1416 | { return __rhs && __lhs <= *__rhs; } |
1417 | |
1418 | template<typename _Tp, typename _Up> |
1419 | constexpr auto |
1420 | operator>=(const optional<_Tp>& __lhs, const _Up& __rhs) |
1421 | -> __optional_ge_t<_Tp, _Up> |
1422 | { return __lhs && *__lhs >= __rhs; } |
1423 | |
1424 | template<typename _Tp, typename _Up> |
1425 | constexpr auto |
1426 | operator>=(const _Up& __lhs, const optional<_Tp>& __rhs) |
1427 | -> __optional_ge_t<_Up, _Tp> |
1428 | { return !__rhs || __lhs >= *__rhs; } |
1429 | |
1430 | #ifdef __cpp_lib_three_way_comparison |
1431 | template<typename _Tp, typename _Up> |
1432 | requires (!__is_optional_v<_Up>) |
1433 | && three_way_comparable_with<_Up, _Tp> |
1434 | constexpr compare_three_way_result_t<_Tp, _Up> |
1435 | operator<=>(const optional<_Tp>& __x, const _Up& __v) |
1436 | { return bool(__x) ? *__x <=> __v : strong_ordering::less; } |
1437 | #endif |
1438 | |
1439 | // Swap and creation functions. |
1440 | |
1441 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
1442 | // 2748. swappable traits for optionals |
1443 | template<typename _Tp> |
1444 | _GLIBCXX20_CONSTEXPR |
1445 | inline enable_if_t<is_move_constructible_v<_Tp> && is_swappable_v<_Tp>> |
1446 | swap(optional<_Tp>& __lhs, optional<_Tp>& __rhs) |
1447 | noexcept(noexcept(__lhs.swap(__rhs))) |
1448 | { __lhs.swap(__rhs); } |
1449 | |
1450 | template<typename _Tp> |
1451 | enable_if_t<!(is_move_constructible_v<_Tp> && is_swappable_v<_Tp>)> |
1452 | swap(optional<_Tp>&, optional<_Tp>&) = delete; |
1453 | |
1454 | template<typename _Tp> |
1455 | constexpr |
1456 | enable_if_t<is_constructible_v<decay_t<_Tp>, _Tp>, |
1457 | optional<decay_t<_Tp>>> |
1458 | make_optional(_Tp&& __t) |
1459 | noexcept(is_nothrow_constructible_v<optional<decay_t<_Tp>>, _Tp>) |
1460 | { return optional<decay_t<_Tp>>{ std::forward<_Tp>(__t) }; } |
1461 | |
1462 | template<typename _Tp, typename... _Args> |
1463 | constexpr |
1464 | enable_if_t<is_constructible_v<_Tp, _Args...>, |
1465 | optional<_Tp>> |
1466 | make_optional(_Args&&... __args) |
1467 | noexcept(is_nothrow_constructible_v<_Tp, _Args...>) |
1468 | { return optional<_Tp>{ in_place, std::forward<_Args>(__args)... }; } |
1469 | |
1470 | template<typename _Tp, typename _Up, typename... _Args> |
1471 | constexpr |
1472 | enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, |
1473 | optional<_Tp>> |
1474 | make_optional(initializer_list<_Up> __il, _Args&&... __args) |
1475 | noexcept(is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, _Args...>) |
1476 | { return optional<_Tp>{ in_place, __il, std::forward<_Args>(__args)... }; } |
1477 | |
1478 | // Hash. |
1479 | |
1480 | template<typename _Tp, typename _Up = remove_const_t<_Tp>, |
1481 | bool = __poison_hash<_Up>::__enable_hash_call> |
1482 | struct __optional_hash_call_base |
1483 | { |
1484 | size_t |
1485 | operator()(const optional<_Tp>& __t) const |
1486 | noexcept(noexcept(hash<_Up>{}(*__t))) |
1487 | { |
1488 | // We pick an arbitrary hash for disengaged optionals which hopefully |
1489 | // usual values of _Tp won't typically hash to. |
1490 | constexpr size_t __magic_disengaged_hash = static_cast<size_t>(-3333); |
1491 | return __t ? hash<_Up>{}(*__t) : __magic_disengaged_hash; |
1492 | } |
1493 | }; |
1494 | |
1495 | template<typename _Tp, typename _Up> |
1496 | struct __optional_hash_call_base<_Tp, _Up, false> {}; |
1497 | |
1498 | template<typename _Tp> |
1499 | struct hash<optional<_Tp>> |
1500 | : private __poison_hash<remove_const_t<_Tp>>, |
1501 | public __optional_hash_call_base<_Tp> |
1502 | { |
1503 | using result_type [[__deprecated__]] = size_t; |
1504 | using argument_type [[__deprecated__]] = optional<_Tp>; |
1505 | }; |
1506 | |
1507 | template<typename _Tp> |
1508 | struct __is_fast_hash<hash<optional<_Tp>>> : __is_fast_hash<hash<_Tp>> |
1509 | { }; |
1510 | |
1511 | /// @} |
1512 | |
1513 | #if __cpp_deduction_guides >= 201606 |
1514 | template <typename _Tp> optional(_Tp) -> optional<_Tp>; |
1515 | #endif |
1516 | |
1517 | _GLIBCXX_END_NAMESPACE_VERSION |
1518 | } // namespace std |
1519 | |
1520 | #endif // __cpp_lib_optional |
1521 | |
1522 | #endif // _GLIBCXX_OPTIONAL |
1523 | |