1 | // <optional> -*- C++ -*- |
2 | |
3 | // Copyright (C) 2013-2021 Free Software Foundation, Inc. |
4 | // |
5 | // This file is part of the GNU ISO C++ Library. This library is free |
6 | // software; you can redistribute it and/or modify it under the |
7 | // terms of the GNU General Public License as published by the |
8 | // Free Software Foundation; either version 3, or (at your option) |
9 | // any later version. |
10 | |
11 | // This library is distributed in the hope that it will be useful, |
12 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
14 | // GNU General Public License for more details. |
15 | |
16 | // Under Section 7 of GPL version 3, you are granted additional |
17 | // permissions described in the GCC Runtime Library Exception, version |
18 | // 3.1, as published by the Free Software Foundation. |
19 | |
20 | // You should have received a copy of the GNU General Public License and |
21 | // a copy of the GCC Runtime Library Exception along with this program; |
22 | // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
23 | // <http://www.gnu.org/licenses/>. |
24 | |
25 | /** @file include/optional |
26 | * This is a Standard C++ Library header. |
27 | */ |
28 | |
29 | #ifndef _GLIBCXX_OPTIONAL |
30 | #define _GLIBCXX_OPTIONAL 1 |
31 | |
32 | #pragma GCC system_header |
33 | |
34 | #if __cplusplus >= 201703L |
35 | |
36 | #include <utility> |
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 | #if __cplusplus > 201703L |
46 | # include <compare> |
47 | #endif |
48 | |
49 | namespace std _GLIBCXX_VISIBILITY(default) |
50 | { |
51 | _GLIBCXX_BEGIN_NAMESPACE_VERSION |
52 | |
53 | /** |
54 | * @addtogroup utilities |
55 | * @{ |
56 | */ |
57 | |
58 | #if __cplusplus == 201703L |
59 | # define __cpp_lib_optional 201606L |
60 | #else |
61 | # define __cpp_lib_optional 202106L |
62 | #endif |
63 | |
64 | template<typename _Tp> |
65 | class optional; |
66 | |
67 | /// Tag type to disengage optional objects. |
68 | struct nullopt_t |
69 | { |
70 | // Do not user-declare default constructor at all for |
71 | // optional_value = {} syntax to work. |
72 | // nullopt_t() = delete; |
73 | |
74 | // Used for constructing nullopt. |
75 | enum class _Construct { _Token }; |
76 | |
77 | // Must be constexpr for nullopt_t to be literal. |
78 | explicit constexpr nullopt_t(_Construct) noexcept { } |
79 | }; |
80 | |
81 | /// Tag to disengage optional objects. |
82 | inline constexpr nullopt_t nullopt { nullopt_t::_Construct::_Token }; |
83 | |
84 | /** |
85 | * @brief Exception class thrown when a disengaged optional object is |
86 | * dereferenced. |
87 | * @ingroup exceptions |
88 | */ |
89 | class bad_optional_access : public exception |
90 | { |
91 | public: |
92 | bad_optional_access() = default; |
93 | virtual ~bad_optional_access() = default; |
94 | |
95 | const char* what() const noexcept override |
96 | { return "bad optional access" ; } |
97 | }; |
98 | |
99 | // XXX Does not belong here. |
100 | [[__noreturn__]] inline void |
101 | __throw_bad_optional_access() |
102 | { _GLIBCXX_THROW_OR_ABORT(bad_optional_access()); } |
103 | |
104 | // This class template manages construction/destruction of |
105 | // the contained value for a std::optional. |
106 | template <typename _Tp> |
107 | struct _Optional_payload_base |
108 | { |
109 | using _Stored_type = remove_const_t<_Tp>; |
110 | |
111 | _Optional_payload_base() = default; |
112 | ~_Optional_payload_base() = default; |
113 | |
114 | template<typename... _Args> |
115 | constexpr |
116 | _Optional_payload_base(in_place_t __tag, _Args&&... __args) |
117 | : _M_payload(__tag, std::forward<_Args>(__args)...), |
118 | _M_engaged(true) |
119 | { } |
120 | |
121 | template<typename _Up, typename... _Args> |
122 | constexpr |
123 | _Optional_payload_base(std::initializer_list<_Up> __il, |
124 | _Args&&... __args) |
125 | : _M_payload(__il, std::forward<_Args>(__args)...), |
126 | _M_engaged(true) |
127 | { } |
128 | |
129 | // Constructor used by _Optional_base copy constructor when the |
130 | // contained value is not trivially copy constructible. |
131 | constexpr |
132 | _Optional_payload_base(bool __engaged, |
133 | const _Optional_payload_base& __other) |
134 | { |
135 | if (__other._M_engaged) |
136 | this->_M_construct(__other._M_get()); |
137 | } |
138 | |
139 | // Constructor used by _Optional_base move constructor when the |
140 | // contained value is not trivially move constructible. |
141 | constexpr |
142 | _Optional_payload_base(bool __engaged, |
143 | _Optional_payload_base&& __other) |
144 | { |
145 | if (__other._M_engaged) |
146 | this->_M_construct(std::move(__other._M_get())); |
147 | } |
148 | |
149 | // Copy constructor is only used to when the contained value is |
150 | // trivially copy constructible. |
151 | _Optional_payload_base(const _Optional_payload_base&) = default; |
152 | |
153 | // Move constructor is only used to when the contained value is |
154 | // trivially copy constructible. |
155 | _Optional_payload_base(_Optional_payload_base&&) = default; |
156 | |
157 | _Optional_payload_base& |
158 | operator=(const _Optional_payload_base&) = default; |
159 | |
160 | _Optional_payload_base& |
161 | operator=(_Optional_payload_base&&) = default; |
162 | |
163 | // used to perform non-trivial copy assignment. |
164 | constexpr void |
165 | _M_copy_assign(const _Optional_payload_base& __other) |
166 | { |
167 | if (this->_M_engaged && __other._M_engaged) |
168 | this->_M_get() = __other._M_get(); |
169 | else |
170 | { |
171 | if (__other._M_engaged) |
172 | this->_M_construct(__other._M_get()); |
173 | else |
174 | this->_M_reset(); |
175 | } |
176 | } |
177 | |
178 | // used to perform non-trivial move assignment. |
179 | constexpr void |
180 | _M_move_assign(_Optional_payload_base&& __other) |
181 | noexcept(__and_v<is_nothrow_move_constructible<_Tp>, |
182 | is_nothrow_move_assignable<_Tp>>) |
183 | { |
184 | if (this->_M_engaged && __other._M_engaged) |
185 | this->_M_get() = std::move(__other._M_get()); |
186 | else |
187 | { |
188 | if (__other._M_engaged) |
189 | this->_M_construct(std::move(__other._M_get())); |
190 | else |
191 | this->_M_reset(); |
192 | } |
193 | } |
194 | |
195 | struct _Empty_byte { }; |
196 | |
197 | template<typename _Up, bool = is_trivially_destructible_v<_Up>> |
198 | union _Storage |
199 | { |
200 | constexpr _Storage() noexcept : _M_empty() { } |
201 | |
202 | template<typename... _Args> |
203 | constexpr |
204 | _Storage(in_place_t, _Args&&... __args) |
205 | : _M_value(std::forward<_Args>(__args)...) |
206 | { } |
207 | |
208 | template<typename _Vp, typename... _Args> |
209 | constexpr |
210 | _Storage(std::initializer_list<_Vp> __il, _Args&&... __args) |
211 | : _M_value(__il, std::forward<_Args>(__args)...) |
212 | { } |
213 | |
214 | _Empty_byte _M_empty; |
215 | _Up _M_value; |
216 | }; |
217 | |
218 | template<typename _Up> |
219 | union _Storage<_Up, false> |
220 | { |
221 | constexpr _Storage() noexcept : _M_empty() { } |
222 | |
223 | template<typename... _Args> |
224 | constexpr |
225 | _Storage(in_place_t, _Args&&... __args) |
226 | : _M_value(std::forward<_Args>(__args)...) |
227 | { } |
228 | |
229 | template<typename _Vp, typename... _Args> |
230 | constexpr |
231 | _Storage(std::initializer_list<_Vp> __il, _Args&&... __args) |
232 | : _M_value(__il, std::forward<_Args>(__args)...) |
233 | { } |
234 | |
235 | // User-provided destructor is needed when _Up has non-trivial dtor. |
236 | _GLIBCXX20_CONSTEXPR ~_Storage() { } |
237 | |
238 | _Empty_byte _M_empty; |
239 | _Up _M_value; |
240 | }; |
241 | |
242 | _Storage<_Stored_type> _M_payload; |
243 | |
244 | bool _M_engaged = false; |
245 | |
246 | template<typename... _Args> |
247 | constexpr void |
248 | _M_construct(_Args&&... __args) |
249 | noexcept(is_nothrow_constructible_v<_Stored_type, _Args...>) |
250 | { |
251 | std::_Construct(std::__addressof(this->_M_payload._M_value), |
252 | std::forward<_Args>(__args)...); |
253 | this->_M_engaged = true; |
254 | } |
255 | |
256 | constexpr void |
257 | _M_destroy() noexcept |
258 | { |
259 | _M_engaged = false; |
260 | _M_payload._M_value.~_Stored_type(); |
261 | } |
262 | |
263 | // The _M_get() operations have _M_engaged as a precondition. |
264 | // They exist to access the contained value with the appropriate |
265 | // const-qualification, because _M_payload has had the const removed. |
266 | |
267 | constexpr _Tp& |
268 | _M_get() noexcept |
269 | { return this->_M_payload._M_value; } |
270 | |
271 | constexpr const _Tp& |
272 | _M_get() const noexcept |
273 | { return this->_M_payload._M_value; } |
274 | |
275 | // _M_reset is a 'safe' operation with no precondition. |
276 | constexpr void |
277 | _M_reset() noexcept |
278 | { |
279 | if (this->_M_engaged) |
280 | _M_destroy(); |
281 | } |
282 | }; |
283 | |
284 | // Class template that manages the payload for optionals. |
285 | template <typename _Tp, |
286 | bool /*_HasTrivialDestructor*/ = |
287 | is_trivially_destructible_v<_Tp>, |
288 | bool /*_HasTrivialCopy */ = |
289 | is_trivially_copy_assignable_v<_Tp> |
290 | && is_trivially_copy_constructible_v<_Tp>, |
291 | bool /*_HasTrivialMove */ = |
292 | is_trivially_move_assignable_v<_Tp> |
293 | && is_trivially_move_constructible_v<_Tp>> |
294 | struct _Optional_payload; |
295 | |
296 | // Payload for potentially-constexpr optionals (trivial copy/move/destroy). |
297 | template <typename _Tp> |
298 | struct _Optional_payload<_Tp, true, true, true> |
299 | : _Optional_payload_base<_Tp> |
300 | { |
301 | using _Optional_payload_base<_Tp>::_Optional_payload_base; |
302 | |
303 | _Optional_payload() = default; |
304 | }; |
305 | |
306 | // Payload for optionals with non-trivial copy construction/assignment. |
307 | template <typename _Tp> |
308 | struct _Optional_payload<_Tp, true, false, true> |
309 | : _Optional_payload_base<_Tp> |
310 | { |
311 | using _Optional_payload_base<_Tp>::_Optional_payload_base; |
312 | |
313 | _Optional_payload() = default; |
314 | ~_Optional_payload() = default; |
315 | _Optional_payload(const _Optional_payload&) = default; |
316 | _Optional_payload(_Optional_payload&&) = default; |
317 | _Optional_payload& operator=(_Optional_payload&&) = default; |
318 | |
319 | // Non-trivial copy assignment. |
320 | constexpr |
321 | _Optional_payload& |
322 | operator=(const _Optional_payload& __other) |
323 | { |
324 | this->_M_copy_assign(__other); |
325 | return *this; |
326 | } |
327 | }; |
328 | |
329 | // Payload for optionals with non-trivial move construction/assignment. |
330 | template <typename _Tp> |
331 | struct _Optional_payload<_Tp, true, true, false> |
332 | : _Optional_payload_base<_Tp> |
333 | { |
334 | using _Optional_payload_base<_Tp>::_Optional_payload_base; |
335 | |
336 | _Optional_payload() = default; |
337 | ~_Optional_payload() = default; |
338 | _Optional_payload(const _Optional_payload&) = default; |
339 | _Optional_payload(_Optional_payload&&) = default; |
340 | _Optional_payload& operator=(const _Optional_payload&) = default; |
341 | |
342 | // Non-trivial move assignment. |
343 | constexpr |
344 | _Optional_payload& |
345 | operator=(_Optional_payload&& __other) |
346 | noexcept(__and_v<is_nothrow_move_constructible<_Tp>, |
347 | is_nothrow_move_assignable<_Tp>>) |
348 | { |
349 | this->_M_move_assign(std::move(__other)); |
350 | return *this; |
351 | } |
352 | }; |
353 | |
354 | // Payload for optionals with non-trivial copy and move assignment. |
355 | template <typename _Tp> |
356 | struct _Optional_payload<_Tp, true, false, false> |
357 | : _Optional_payload_base<_Tp> |
358 | { |
359 | using _Optional_payload_base<_Tp>::_Optional_payload_base; |
360 | |
361 | _Optional_payload() = default; |
362 | ~_Optional_payload() = default; |
363 | _Optional_payload(const _Optional_payload&) = default; |
364 | _Optional_payload(_Optional_payload&&) = default; |
365 | |
366 | // Non-trivial copy assignment. |
367 | constexpr |
368 | _Optional_payload& |
369 | operator=(const _Optional_payload& __other) |
370 | { |
371 | this->_M_copy_assign(__other); |
372 | return *this; |
373 | } |
374 | |
375 | // Non-trivial move assignment. |
376 | constexpr |
377 | _Optional_payload& |
378 | operator=(_Optional_payload&& __other) |
379 | noexcept(__and_v<is_nothrow_move_constructible<_Tp>, |
380 | is_nothrow_move_assignable<_Tp>>) |
381 | { |
382 | this->_M_move_assign(std::move(__other)); |
383 | return *this; |
384 | } |
385 | }; |
386 | |
387 | // Payload for optionals with non-trivial destructors. |
388 | template <typename _Tp, bool _Copy, bool _Move> |
389 | struct _Optional_payload<_Tp, false, _Copy, _Move> |
390 | : _Optional_payload<_Tp, true, false, false> |
391 | { |
392 | // Base class implements all the constructors and assignment operators: |
393 | using _Optional_payload<_Tp, true, false, false>::_Optional_payload; |
394 | _Optional_payload() = default; |
395 | _Optional_payload(const _Optional_payload&) = default; |
396 | _Optional_payload(_Optional_payload&&) = default; |
397 | _Optional_payload& operator=(const _Optional_payload&) = default; |
398 | _Optional_payload& operator=(_Optional_payload&&) = default; |
399 | |
400 | // Destructor needs to destroy the contained value: |
401 | _GLIBCXX20_CONSTEXPR ~_Optional_payload() { this->_M_reset(); } |
402 | }; |
403 | |
404 | // Common base class for _Optional_base<T> to avoid repeating these |
405 | // member functions in each specialization. |
406 | template<typename _Tp, typename _Dp> |
407 | class _Optional_base_impl |
408 | { |
409 | protected: |
410 | using _Stored_type = remove_const_t<_Tp>; |
411 | |
412 | // The _M_construct operation has !_M_engaged as a precondition |
413 | // while _M_destruct has _M_engaged as a precondition. |
414 | template<typename... _Args> |
415 | constexpr void |
416 | _M_construct(_Args&&... __args) |
417 | noexcept(is_nothrow_constructible_v<_Stored_type, _Args...>) |
418 | { |
419 | static_cast<_Dp*>(this)->_M_payload._M_construct( |
420 | std::forward<_Args>(__args)...); |
421 | } |
422 | |
423 | constexpr void |
424 | _M_destruct() noexcept |
425 | { static_cast<_Dp*>(this)->_M_payload._M_destroy(); } |
426 | |
427 | // _M_reset is a 'safe' operation with no precondition. |
428 | constexpr void |
429 | _M_reset() noexcept |
430 | { static_cast<_Dp*>(this)->_M_payload._M_reset(); } |
431 | |
432 | constexpr bool _M_is_engaged() const noexcept |
433 | { return static_cast<const _Dp*>(this)->_M_payload._M_engaged; } |
434 | |
435 | // The _M_get operations have _M_engaged as a precondition. |
436 | constexpr _Tp& |
437 | _M_get() noexcept |
438 | { |
439 | __glibcxx_assert(this->_M_is_engaged()); |
440 | return static_cast<_Dp*>(this)->_M_payload._M_get(); |
441 | } |
442 | |
443 | constexpr const _Tp& |
444 | _M_get() const noexcept |
445 | { |
446 | __glibcxx_assert(this->_M_is_engaged()); |
447 | return static_cast<const _Dp*>(this)->_M_payload._M_get(); |
448 | } |
449 | }; |
450 | |
451 | /** |
452 | * @brief Class template that provides copy/move constructors of optional. |
453 | * |
454 | * Such a separate base class template is necessary in order to |
455 | * conditionally make copy/move constructors trivial. |
456 | * |
457 | * When the contained value is trivially copy/move constructible, |
458 | * the copy/move constructors of _Optional_base will invoke the |
459 | * trivial copy/move constructor of _Optional_payload. Otherwise, |
460 | * they will invoke _Optional_payload(bool, const _Optional_payload&) |
461 | * or _Optional_payload(bool, _Optional_payload&&) to initialize |
462 | * the contained value, if copying/moving an engaged optional. |
463 | * |
464 | * Whether the other special members are trivial is determined by the |
465 | * _Optional_payload<_Tp> specialization used for the _M_payload member. |
466 | * |
467 | * @see optional, _Enable_special_members |
468 | */ |
469 | template<typename _Tp, |
470 | bool = is_trivially_copy_constructible_v<_Tp>, |
471 | bool = is_trivially_move_constructible_v<_Tp>> |
472 | struct _Optional_base |
473 | : _Optional_base_impl<_Tp, _Optional_base<_Tp>> |
474 | { |
475 | // Constructors for disengaged optionals. |
476 | constexpr _Optional_base() = default; |
477 | |
478 | // Constructors for engaged optionals. |
479 | template<typename... _Args, |
480 | enable_if_t<is_constructible_v<_Tp, _Args...>, bool> = false> |
481 | constexpr explicit |
482 | _Optional_base(in_place_t, _Args&&... __args) |
483 | : _M_payload(in_place, std::forward<_Args>(__args)...) |
484 | { } |
485 | |
486 | template<typename _Up, typename... _Args, |
487 | enable_if_t<is_constructible_v<_Tp, |
488 | initializer_list<_Up>&, |
489 | _Args...>, bool> = false> |
490 | constexpr explicit |
491 | _Optional_base(in_place_t, |
492 | initializer_list<_Up> __il, |
493 | _Args&&... __args) |
494 | : _M_payload(in_place, __il, std::forward<_Args>(__args)...) |
495 | { } |
496 | |
497 | // Copy and move constructors. |
498 | constexpr |
499 | _Optional_base(const _Optional_base& __other) |
500 | : _M_payload(__other._M_payload._M_engaged, __other._M_payload) |
501 | { } |
502 | |
503 | constexpr |
504 | _Optional_base(_Optional_base&& __other) |
505 | noexcept(is_nothrow_move_constructible_v<_Tp>) |
506 | : _M_payload(__other._M_payload._M_engaged, |
507 | std::move(__other._M_payload)) |
508 | { } |
509 | |
510 | // Assignment operators. |
511 | _Optional_base& operator=(const _Optional_base&) = default; |
512 | _Optional_base& operator=(_Optional_base&&) = default; |
513 | |
514 | _Optional_payload<_Tp> _M_payload; |
515 | }; |
516 | |
517 | template<typename _Tp> |
518 | struct _Optional_base<_Tp, false, true> |
519 | : _Optional_base_impl<_Tp, _Optional_base<_Tp>> |
520 | { |
521 | // Constructors for disengaged optionals. |
522 | constexpr _Optional_base() = default; |
523 | |
524 | // Constructors for engaged optionals. |
525 | template<typename... _Args, |
526 | enable_if_t<is_constructible_v<_Tp, _Args...>, bool> = false> |
527 | constexpr explicit |
528 | _Optional_base(in_place_t, _Args&&... __args) |
529 | : _M_payload(in_place, std::forward<_Args>(__args)...) |
530 | { } |
531 | |
532 | template<typename _Up, typename... _Args, |
533 | enable_if_t<is_constructible_v<_Tp, |
534 | initializer_list<_Up>&, |
535 | _Args...>, bool> = false> |
536 | constexpr explicit |
537 | _Optional_base(in_place_t, |
538 | initializer_list<_Up> __il, |
539 | _Args... __args) |
540 | : _M_payload(in_place, __il, std::forward<_Args>(__args)...) |
541 | { } |
542 | |
543 | // Copy and move constructors. |
544 | constexpr _Optional_base(const _Optional_base& __other) |
545 | : _M_payload(__other._M_payload._M_engaged, __other._M_payload) |
546 | { } |
547 | |
548 | constexpr _Optional_base(_Optional_base&& __other) = default; |
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, true, false> |
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) = default; |
585 | |
586 | constexpr |
587 | _Optional_base(_Optional_base&& __other) |
588 | noexcept(is_nothrow_move_constructible_v<_Tp>) |
589 | : _M_payload(__other._M_payload._M_engaged, |
590 | std::move(__other._M_payload)) |
591 | { } |
592 | |
593 | // Assignment operators. |
594 | _Optional_base& operator=(const _Optional_base&) = default; |
595 | _Optional_base& operator=(_Optional_base&&) = default; |
596 | |
597 | _Optional_payload<_Tp> _M_payload; |
598 | }; |
599 | |
600 | template<typename _Tp> |
601 | struct _Optional_base<_Tp, true, true> |
602 | : _Optional_base_impl<_Tp, _Optional_base<_Tp>> |
603 | { |
604 | // Constructors for disengaged optionals. |
605 | constexpr _Optional_base() = default; |
606 | |
607 | // Constructors for engaged optionals. |
608 | template<typename... _Args, |
609 | enable_if_t<is_constructible_v<_Tp, _Args...>, bool> = false> |
610 | constexpr explicit |
611 | _Optional_base(in_place_t, _Args&&... __args) |
612 | : _M_payload(in_place, std::forward<_Args>(__args)...) |
613 | { } |
614 | |
615 | template<typename _Up, typename... _Args, |
616 | enable_if_t<is_constructible_v<_Tp, |
617 | initializer_list<_Up>&, |
618 | _Args...>, bool> = false> |
619 | constexpr explicit |
620 | _Optional_base(in_place_t, |
621 | initializer_list<_Up> __il, |
622 | _Args&&... __args) |
623 | : _M_payload(in_place, __il, std::forward<_Args>(__args)...) |
624 | { } |
625 | |
626 | // Copy and move constructors. |
627 | constexpr _Optional_base(const _Optional_base& __other) = default; |
628 | constexpr _Optional_base(_Optional_base&& __other) = default; |
629 | |
630 | // Assignment operators. |
631 | _Optional_base& operator=(const _Optional_base&) = default; |
632 | _Optional_base& operator=(_Optional_base&&) = default; |
633 | |
634 | _Optional_payload<_Tp> _M_payload; |
635 | }; |
636 | |
637 | template<typename _Tp> |
638 | class optional; |
639 | |
640 | template<typename _Tp, typename _Up> |
641 | using __converts_from_optional = |
642 | __or_<is_constructible<_Tp, const optional<_Up>&>, |
643 | is_constructible<_Tp, optional<_Up>&>, |
644 | is_constructible<_Tp, const optional<_Up>&&>, |
645 | is_constructible<_Tp, optional<_Up>&&>, |
646 | is_convertible<const optional<_Up>&, _Tp>, |
647 | is_convertible<optional<_Up>&, _Tp>, |
648 | is_convertible<const optional<_Up>&&, _Tp>, |
649 | is_convertible<optional<_Up>&&, _Tp>>; |
650 | |
651 | template<typename _Tp, typename _Up> |
652 | using __assigns_from_optional = |
653 | __or_<is_assignable<_Tp&, const optional<_Up>&>, |
654 | is_assignable<_Tp&, optional<_Up>&>, |
655 | is_assignable<_Tp&, const optional<_Up>&&>, |
656 | is_assignable<_Tp&, optional<_Up>&&>>; |
657 | |
658 | /** |
659 | * @brief Class template for optional values. |
660 | */ |
661 | template<typename _Tp> |
662 | class optional |
663 | : private _Optional_base<_Tp>, |
664 | private _Enable_copy_move< |
665 | // Copy constructor. |
666 | is_copy_constructible_v<_Tp>, |
667 | // Copy assignment. |
668 | __and_v<is_copy_constructible<_Tp>, is_copy_assignable<_Tp>>, |
669 | // Move constructor. |
670 | is_move_constructible_v<_Tp>, |
671 | // Move assignment. |
672 | __and_v<is_move_constructible<_Tp>, is_move_assignable<_Tp>>, |
673 | // Unique tag type. |
674 | optional<_Tp>> |
675 | { |
676 | static_assert(!is_same_v<remove_cv_t<_Tp>, nullopt_t>); |
677 | static_assert(!is_same_v<remove_cv_t<_Tp>, in_place_t>); |
678 | static_assert(!is_reference_v<_Tp>); |
679 | |
680 | private: |
681 | using _Base = _Optional_base<_Tp>; |
682 | |
683 | // SFINAE helpers |
684 | template<typename _Up> |
685 | using __not_self = __not_<is_same<optional, __remove_cvref_t<_Up>>>; |
686 | template<typename _Up> |
687 | using __not_tag = __not_<is_same<in_place_t, __remove_cvref_t<_Up>>>; |
688 | template<typename... _Cond> |
689 | using _Requires = enable_if_t<__and_v<_Cond...>, bool>; |
690 | |
691 | public: |
692 | using value_type = _Tp; |
693 | |
694 | constexpr optional() noexcept { } |
695 | |
696 | constexpr optional(nullopt_t) noexcept { } |
697 | |
698 | // Converting constructors for engaged optionals. |
699 | template<typename _Up = _Tp, |
700 | _Requires<__not_self<_Up>, __not_tag<_Up>, |
701 | is_constructible<_Tp, _Up>, |
702 | is_convertible<_Up, _Tp>> = true> |
703 | constexpr |
704 | optional(_Up&& __t) |
705 | noexcept(is_nothrow_constructible_v<_Tp, _Up>) |
706 | : _Base(std::in_place, std::forward<_Up>(__t)) { } |
707 | |
708 | template<typename _Up = _Tp, |
709 | _Requires<__not_self<_Up>, __not_tag<_Up>, |
710 | is_constructible<_Tp, _Up>, |
711 | __not_<is_convertible<_Up, _Tp>>> = false> |
712 | explicit constexpr |
713 | optional(_Up&& __t) |
714 | noexcept(is_nothrow_constructible_v<_Tp, _Up>) |
715 | : _Base(std::in_place, std::forward<_Up>(__t)) { } |
716 | |
717 | template<typename _Up, |
718 | _Requires<__not_<is_same<_Tp, _Up>>, |
719 | is_constructible<_Tp, const _Up&>, |
720 | is_convertible<const _Up&, _Tp>, |
721 | __not_<__converts_from_optional<_Tp, _Up>>> = true> |
722 | constexpr |
723 | optional(const optional<_Up>& __t) |
724 | noexcept(is_nothrow_constructible_v<_Tp, const _Up&>) |
725 | { |
726 | if (__t) |
727 | emplace(*__t); |
728 | } |
729 | |
730 | template<typename _Up, |
731 | _Requires<__not_<is_same<_Tp, _Up>>, |
732 | is_constructible<_Tp, const _Up&>, |
733 | __not_<is_convertible<const _Up&, _Tp>>, |
734 | __not_<__converts_from_optional<_Tp, _Up>>> = false> |
735 | explicit constexpr |
736 | optional(const optional<_Up>& __t) |
737 | noexcept(is_nothrow_constructible_v<_Tp, const _Up&>) |
738 | { |
739 | if (__t) |
740 | emplace(*__t); |
741 | } |
742 | |
743 | template<typename _Up, |
744 | _Requires<__not_<is_same<_Tp, _Up>>, |
745 | is_constructible<_Tp, _Up>, |
746 | is_convertible<_Up, _Tp>, |
747 | __not_<__converts_from_optional<_Tp, _Up>>> = true> |
748 | constexpr |
749 | optional(optional<_Up>&& __t) |
750 | noexcept(is_nothrow_constructible_v<_Tp, _Up>) |
751 | { |
752 | if (__t) |
753 | emplace(std::move(*__t)); |
754 | } |
755 | |
756 | template<typename _Up, |
757 | _Requires<__not_<is_same<_Tp, _Up>>, |
758 | is_constructible<_Tp, _Up>, |
759 | __not_<is_convertible<_Up, _Tp>>, |
760 | __not_<__converts_from_optional<_Tp, _Up>>> = false> |
761 | explicit constexpr |
762 | optional(optional<_Up>&& __t) |
763 | noexcept(is_nothrow_constructible_v<_Tp, _Up>) |
764 | { |
765 | if (__t) |
766 | emplace(std::move(*__t)); |
767 | } |
768 | |
769 | template<typename... _Args, |
770 | _Requires<is_constructible<_Tp, _Args...>> = false> |
771 | explicit constexpr |
772 | optional(in_place_t, _Args&&... __args) |
773 | noexcept(is_nothrow_constructible_v<_Tp, _Args...>) |
774 | : _Base(std::in_place, std::forward<_Args>(__args)...) { } |
775 | |
776 | template<typename _Up, typename... _Args, |
777 | _Requires<is_constructible<_Tp, |
778 | initializer_list<_Up>&, |
779 | _Args...>> = false> |
780 | explicit constexpr |
781 | optional(in_place_t, initializer_list<_Up> __il, _Args&&... __args) |
782 | noexcept(is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, |
783 | _Args...>) |
784 | : _Base(std::in_place, __il, std::forward<_Args>(__args)...) { } |
785 | |
786 | |
787 | // Assignment operators. |
788 | _GLIBCXX20_CONSTEXPR optional& |
789 | operator=(nullopt_t) noexcept |
790 | { |
791 | this->_M_reset(); |
792 | return *this; |
793 | } |
794 | |
795 | template<typename _Up = _Tp> |
796 | _GLIBCXX20_CONSTEXPR |
797 | enable_if_t<__and_v<__not_self<_Up>, |
798 | __not_<__and_<is_scalar<_Tp>, |
799 | is_same<_Tp, decay_t<_Up>>>>, |
800 | is_constructible<_Tp, _Up>, |
801 | is_assignable<_Tp&, _Up>>, |
802 | optional&> |
803 | operator=(_Up&& __u) |
804 | noexcept(__and_v<is_nothrow_constructible<_Tp, _Up>, |
805 | is_nothrow_assignable<_Tp&, _Up>>) |
806 | { |
807 | if (this->_M_is_engaged()) |
808 | this->_M_get() = std::forward<_Up>(__u); |
809 | else |
810 | this->_M_construct(std::forward<_Up>(__u)); |
811 | |
812 | return *this; |
813 | } |
814 | |
815 | template<typename _Up> |
816 | _GLIBCXX20_CONSTEXPR |
817 | enable_if_t<__and_v<__not_<is_same<_Tp, _Up>>, |
818 | is_constructible<_Tp, const _Up&>, |
819 | is_assignable<_Tp&, const _Up&>, |
820 | __not_<__converts_from_optional<_Tp, _Up>>, |
821 | __not_<__assigns_from_optional<_Tp, _Up>>>, |
822 | optional&> |
823 | operator=(const optional<_Up>& __u) |
824 | noexcept(__and_v<is_nothrow_constructible<_Tp, const _Up&>, |
825 | is_nothrow_assignable<_Tp&, const _Up&>>) |
826 | { |
827 | if (__u) |
828 | { |
829 | if (this->_M_is_engaged()) |
830 | this->_M_get() = *__u; |
831 | else |
832 | this->_M_construct(*__u); |
833 | } |
834 | else |
835 | { |
836 | this->_M_reset(); |
837 | } |
838 | return *this; |
839 | } |
840 | |
841 | template<typename _Up> |
842 | _GLIBCXX20_CONSTEXPR |
843 | enable_if_t<__and_v<__not_<is_same<_Tp, _Up>>, |
844 | is_constructible<_Tp, _Up>, |
845 | is_assignable<_Tp&, _Up>, |
846 | __not_<__converts_from_optional<_Tp, _Up>>, |
847 | __not_<__assigns_from_optional<_Tp, _Up>>>, |
848 | optional&> |
849 | operator=(optional<_Up>&& __u) |
850 | noexcept(__and_v<is_nothrow_constructible<_Tp, _Up>, |
851 | is_nothrow_assignable<_Tp&, _Up>>) |
852 | { |
853 | if (__u) |
854 | { |
855 | if (this->_M_is_engaged()) |
856 | this->_M_get() = std::move(*__u); |
857 | else |
858 | this->_M_construct(std::move(*__u)); |
859 | } |
860 | else |
861 | { |
862 | this->_M_reset(); |
863 | } |
864 | |
865 | return *this; |
866 | } |
867 | |
868 | template<typename... _Args> |
869 | _GLIBCXX20_CONSTEXPR |
870 | enable_if_t<is_constructible_v<_Tp, _Args...>, _Tp&> |
871 | emplace(_Args&&... __args) |
872 | noexcept(is_nothrow_constructible_v<_Tp, _Args...>) |
873 | { |
874 | this->_M_reset(); |
875 | this->_M_construct(std::forward<_Args>(__args)...); |
876 | return this->_M_get(); |
877 | } |
878 | |
879 | template<typename _Up, typename... _Args> |
880 | _GLIBCXX20_CONSTEXPR |
881 | enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, |
882 | _Tp&> |
883 | emplace(initializer_list<_Up> __il, _Args&&... __args) |
884 | noexcept(is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, |
885 | _Args...>) |
886 | { |
887 | this->_M_reset(); |
888 | this->_M_construct(__il, std::forward<_Args>(__args)...); |
889 | return this->_M_get(); |
890 | } |
891 | |
892 | // Destructor is implicit, implemented in _Optional_base. |
893 | |
894 | // Swap. |
895 | _GLIBCXX20_CONSTEXPR void |
896 | swap(optional& __other) |
897 | noexcept(is_nothrow_move_constructible_v<_Tp> |
898 | && is_nothrow_swappable_v<_Tp>) |
899 | { |
900 | using std::swap; |
901 | |
902 | if (this->_M_is_engaged() && __other._M_is_engaged()) |
903 | swap(this->_M_get(), __other._M_get()); |
904 | else if (this->_M_is_engaged()) |
905 | { |
906 | __other._M_construct(std::move(this->_M_get())); |
907 | this->_M_destruct(); |
908 | } |
909 | else if (__other._M_is_engaged()) |
910 | { |
911 | this->_M_construct(std::move(__other._M_get())); |
912 | __other._M_destruct(); |
913 | } |
914 | } |
915 | |
916 | // Observers. |
917 | constexpr const _Tp* |
918 | operator->() const noexcept |
919 | { return std::__addressof(this->_M_get()); } |
920 | |
921 | constexpr _Tp* |
922 | operator->() noexcept |
923 | { return std::__addressof(this->_M_get()); } |
924 | |
925 | constexpr const _Tp& |
926 | operator*() const& noexcept |
927 | { return this->_M_get(); } |
928 | |
929 | constexpr _Tp& |
930 | operator*()& noexcept |
931 | { return this->_M_get(); } |
932 | |
933 | constexpr _Tp&& |
934 | operator*()&& noexcept |
935 | { return std::move(this->_M_get()); } |
936 | |
937 | constexpr const _Tp&& |
938 | operator*() const&& noexcept |
939 | { return std::move(this->_M_get()); } |
940 | |
941 | constexpr explicit operator bool() const noexcept |
942 | { return this->_M_is_engaged(); } |
943 | |
944 | constexpr bool has_value() const noexcept |
945 | { return this->_M_is_engaged(); } |
946 | |
947 | constexpr const _Tp& |
948 | value() const& |
949 | { |
950 | if (this->_M_is_engaged()) |
951 | return this->_M_get(); |
952 | __throw_bad_optional_access(); |
953 | } |
954 | |
955 | constexpr _Tp& |
956 | value()& |
957 | { |
958 | if (this->_M_is_engaged()) |
959 | return this->_M_get(); |
960 | __throw_bad_optional_access(); |
961 | } |
962 | |
963 | constexpr _Tp&& |
964 | value()&& |
965 | { |
966 | if (this->_M_is_engaged()) |
967 | return std::move(this->_M_get()); |
968 | __throw_bad_optional_access(); |
969 | } |
970 | |
971 | constexpr const _Tp&& |
972 | value() const&& |
973 | { |
974 | if (this->_M_is_engaged()) |
975 | return std::move(this->_M_get()); |
976 | __throw_bad_optional_access(); |
977 | } |
978 | |
979 | template<typename _Up> |
980 | constexpr _Tp |
981 | value_or(_Up&& __u) const& |
982 | { |
983 | static_assert(is_copy_constructible_v<_Tp>); |
984 | static_assert(is_convertible_v<_Up&&, _Tp>); |
985 | |
986 | if (this->_M_is_engaged()) |
987 | return this->_M_get(); |
988 | else |
989 | return static_cast<_Tp>(std::forward<_Up>(__u)); |
990 | } |
991 | |
992 | template<typename _Up> |
993 | constexpr _Tp |
994 | value_or(_Up&& __u) && |
995 | { |
996 | static_assert(is_move_constructible_v<_Tp>); |
997 | static_assert(is_convertible_v<_Up&&, _Tp>); |
998 | |
999 | if (this->_M_is_engaged()) |
1000 | return std::move(this->_M_get()); |
1001 | else |
1002 | return static_cast<_Tp>(std::forward<_Up>(__u)); |
1003 | } |
1004 | |
1005 | _GLIBCXX20_CONSTEXPR void reset() noexcept { this->_M_reset(); } |
1006 | }; |
1007 | |
1008 | template<typename _Tp> |
1009 | using __optional_relop_t = |
1010 | enable_if_t<is_convertible<_Tp, bool>::value, bool>; |
1011 | |
1012 | template<typename _Tp, typename _Up> |
1013 | using __optional_eq_t = __optional_relop_t< |
1014 | decltype(std::declval<const _Tp&>() == std::declval<const _Up&>()) |
1015 | >; |
1016 | |
1017 | template<typename _Tp, typename _Up> |
1018 | using __optional_ne_t = __optional_relop_t< |
1019 | decltype(std::declval<const _Tp&>() != std::declval<const _Up&>()) |
1020 | >; |
1021 | |
1022 | template<typename _Tp, typename _Up> |
1023 | using __optional_lt_t = __optional_relop_t< |
1024 | decltype(std::declval<const _Tp&>() < std::declval<const _Up&>()) |
1025 | >; |
1026 | |
1027 | template<typename _Tp, typename _Up> |
1028 | using __optional_gt_t = __optional_relop_t< |
1029 | decltype(std::declval<const _Tp&>() > std::declval<const _Up&>()) |
1030 | >; |
1031 | |
1032 | template<typename _Tp, typename _Up> |
1033 | using __optional_le_t = __optional_relop_t< |
1034 | decltype(std::declval<const _Tp&>() <= std::declval<const _Up&>()) |
1035 | >; |
1036 | |
1037 | template<typename _Tp, typename _Up> |
1038 | using __optional_ge_t = __optional_relop_t< |
1039 | decltype(std::declval<const _Tp&>() >= std::declval<const _Up&>()) |
1040 | >; |
1041 | |
1042 | // Comparisons between optional values. |
1043 | template<typename _Tp, typename _Up> |
1044 | constexpr auto |
1045 | operator==(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
1046 | -> __optional_eq_t<_Tp, _Up> |
1047 | { |
1048 | return static_cast<bool>(__lhs) == static_cast<bool>(__rhs) |
1049 | && (!__lhs || *__lhs == *__rhs); |
1050 | } |
1051 | |
1052 | template<typename _Tp, typename _Up> |
1053 | constexpr auto |
1054 | operator!=(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
1055 | -> __optional_ne_t<_Tp, _Up> |
1056 | { |
1057 | return static_cast<bool>(__lhs) != static_cast<bool>(__rhs) |
1058 | || (static_cast<bool>(__lhs) && *__lhs != *__rhs); |
1059 | } |
1060 | |
1061 | template<typename _Tp, typename _Up> |
1062 | constexpr auto |
1063 | operator<(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
1064 | -> __optional_lt_t<_Tp, _Up> |
1065 | { |
1066 | return static_cast<bool>(__rhs) && (!__lhs || *__lhs < *__rhs); |
1067 | } |
1068 | |
1069 | template<typename _Tp, typename _Up> |
1070 | constexpr auto |
1071 | operator>(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
1072 | -> __optional_gt_t<_Tp, _Up> |
1073 | { |
1074 | return static_cast<bool>(__lhs) && (!__rhs || *__lhs > *__rhs); |
1075 | } |
1076 | |
1077 | template<typename _Tp, typename _Up> |
1078 | constexpr auto |
1079 | operator<=(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
1080 | -> __optional_le_t<_Tp, _Up> |
1081 | { |
1082 | return !__lhs || (static_cast<bool>(__rhs) && *__lhs <= *__rhs); |
1083 | } |
1084 | |
1085 | template<typename _Tp, typename _Up> |
1086 | constexpr auto |
1087 | operator>=(const optional<_Tp>& __lhs, const optional<_Up>& __rhs) |
1088 | -> __optional_ge_t<_Tp, _Up> |
1089 | { |
1090 | return !__rhs || (static_cast<bool>(__lhs) && *__lhs >= *__rhs); |
1091 | } |
1092 | |
1093 | #ifdef __cpp_lib_three_way_comparison |
1094 | template<typename _Tp, three_way_comparable_with<_Tp> _Up> |
1095 | constexpr compare_three_way_result_t<_Tp, _Up> |
1096 | operator<=>(const optional<_Tp>& __x, const optional<_Up>& __y) |
1097 | { |
1098 | return __x && __y ? *__x <=> *__y : bool(__x) <=> bool(__y); |
1099 | } |
1100 | #endif |
1101 | |
1102 | // Comparisons with nullopt. |
1103 | template<typename _Tp> |
1104 | constexpr bool |
1105 | operator==(const optional<_Tp>& __lhs, nullopt_t) noexcept |
1106 | { return !__lhs; } |
1107 | |
1108 | #ifdef __cpp_lib_three_way_comparison |
1109 | template<typename _Tp> |
1110 | constexpr strong_ordering |
1111 | operator<=>(const optional<_Tp>& __x, nullopt_t) noexcept |
1112 | { return bool(__x) <=> false; } |
1113 | #else |
1114 | template<typename _Tp> |
1115 | constexpr bool |
1116 | operator==(nullopt_t, const optional<_Tp>& __rhs) noexcept |
1117 | { return !__rhs; } |
1118 | |
1119 | template<typename _Tp> |
1120 | constexpr bool |
1121 | operator!=(const optional<_Tp>& __lhs, nullopt_t) noexcept |
1122 | { return static_cast<bool>(__lhs); } |
1123 | |
1124 | template<typename _Tp> |
1125 | constexpr bool |
1126 | operator!=(nullopt_t, const optional<_Tp>& __rhs) noexcept |
1127 | { return static_cast<bool>(__rhs); } |
1128 | |
1129 | template<typename _Tp> |
1130 | constexpr bool |
1131 | operator<(const optional<_Tp>& /* __lhs */, nullopt_t) noexcept |
1132 | { return false; } |
1133 | |
1134 | template<typename _Tp> |
1135 | constexpr bool |
1136 | operator<(nullopt_t, const optional<_Tp>& __rhs) noexcept |
1137 | { return static_cast<bool>(__rhs); } |
1138 | |
1139 | template<typename _Tp> |
1140 | constexpr bool |
1141 | operator>(const optional<_Tp>& __lhs, nullopt_t) noexcept |
1142 | { return static_cast<bool>(__lhs); } |
1143 | |
1144 | template<typename _Tp> |
1145 | constexpr bool |
1146 | operator>(nullopt_t, const optional<_Tp>& /* __rhs */) noexcept |
1147 | { return false; } |
1148 | |
1149 | template<typename _Tp> |
1150 | constexpr bool |
1151 | operator<=(const optional<_Tp>& __lhs, nullopt_t) noexcept |
1152 | { return !__lhs; } |
1153 | |
1154 | template<typename _Tp> |
1155 | constexpr bool |
1156 | operator<=(nullopt_t, const optional<_Tp>& /* __rhs */) noexcept |
1157 | { return true; } |
1158 | |
1159 | template<typename _Tp> |
1160 | constexpr bool |
1161 | operator>=(const optional<_Tp>& /* __lhs */, nullopt_t) noexcept |
1162 | { return true; } |
1163 | |
1164 | template<typename _Tp> |
1165 | constexpr bool |
1166 | operator>=(nullopt_t, const optional<_Tp>& __rhs) noexcept |
1167 | { return !__rhs; } |
1168 | #endif // three-way-comparison |
1169 | |
1170 | // Comparisons with value type. |
1171 | template<typename _Tp, typename _Up> |
1172 | constexpr auto |
1173 | operator==(const optional<_Tp>& __lhs, const _Up& __rhs) |
1174 | -> __optional_eq_t<_Tp, _Up> |
1175 | { return __lhs && *__lhs == __rhs; } |
1176 | |
1177 | template<typename _Tp, typename _Up> |
1178 | constexpr auto |
1179 | operator==(const _Up& __lhs, const optional<_Tp>& __rhs) |
1180 | -> __optional_eq_t<_Up, _Tp> |
1181 | { return __rhs && __lhs == *__rhs; } |
1182 | |
1183 | template<typename _Tp, typename _Up> |
1184 | constexpr auto |
1185 | operator!=(const optional<_Tp>& __lhs, const _Up& __rhs) |
1186 | -> __optional_ne_t<_Tp, _Up> |
1187 | { return !__lhs || *__lhs != __rhs; } |
1188 | |
1189 | template<typename _Tp, typename _Up> |
1190 | constexpr auto |
1191 | operator!=(const _Up& __lhs, const optional<_Tp>& __rhs) |
1192 | -> __optional_ne_t<_Up, _Tp> |
1193 | { return !__rhs || __lhs != *__rhs; } |
1194 | |
1195 | template<typename _Tp, typename _Up> |
1196 | constexpr auto |
1197 | operator<(const optional<_Tp>& __lhs, const _Up& __rhs) |
1198 | -> __optional_lt_t<_Tp, _Up> |
1199 | { return !__lhs || *__lhs < __rhs; } |
1200 | |
1201 | template<typename _Tp, typename _Up> |
1202 | constexpr auto |
1203 | operator<(const _Up& __lhs, const optional<_Tp>& __rhs) |
1204 | -> __optional_lt_t<_Up, _Tp> |
1205 | { return __rhs && __lhs < *__rhs; } |
1206 | |
1207 | template<typename _Tp, typename _Up> |
1208 | constexpr auto |
1209 | operator>(const optional<_Tp>& __lhs, const _Up& __rhs) |
1210 | -> __optional_gt_t<_Tp, _Up> |
1211 | { return __lhs && *__lhs > __rhs; } |
1212 | |
1213 | template<typename _Tp, typename _Up> |
1214 | constexpr auto |
1215 | operator>(const _Up& __lhs, const optional<_Tp>& __rhs) |
1216 | -> __optional_gt_t<_Up, _Tp> |
1217 | { return !__rhs || __lhs > *__rhs; } |
1218 | |
1219 | template<typename _Tp, typename _Up> |
1220 | constexpr auto |
1221 | operator<=(const optional<_Tp>& __lhs, const _Up& __rhs) |
1222 | -> __optional_le_t<_Tp, _Up> |
1223 | { return !__lhs || *__lhs <= __rhs; } |
1224 | |
1225 | template<typename _Tp, typename _Up> |
1226 | constexpr auto |
1227 | operator<=(const _Up& __lhs, const optional<_Tp>& __rhs) |
1228 | -> __optional_le_t<_Up, _Tp> |
1229 | { return __rhs && __lhs <= *__rhs; } |
1230 | |
1231 | template<typename _Tp, typename _Up> |
1232 | constexpr auto |
1233 | operator>=(const optional<_Tp>& __lhs, const _Up& __rhs) |
1234 | -> __optional_ge_t<_Tp, _Up> |
1235 | { return __lhs && *__lhs >= __rhs; } |
1236 | |
1237 | template<typename _Tp, typename _Up> |
1238 | constexpr auto |
1239 | operator>=(const _Up& __lhs, const optional<_Tp>& __rhs) |
1240 | -> __optional_ge_t<_Up, _Tp> |
1241 | { return !__rhs || __lhs >= *__rhs; } |
1242 | |
1243 | #ifdef __cpp_lib_three_way_comparison |
1244 | template<typename _Tp> |
1245 | inline constexpr bool __is_optional_v = false; |
1246 | template<typename _Tp> |
1247 | inline constexpr bool __is_optional_v<optional<_Tp>> = true; |
1248 | |
1249 | template<typename _Tp, typename _Up> |
1250 | requires (!__is_optional_v<_Up>) |
1251 | && three_way_comparable_with<_Tp, _Up> |
1252 | constexpr compare_three_way_result_t<_Tp, _Up> |
1253 | operator<=>(const optional<_Tp>& __x, const _Up& __v) |
1254 | { return bool(__x) ? *__x <=> __v : strong_ordering::less; } |
1255 | #endif |
1256 | |
1257 | // Swap and creation functions. |
1258 | |
1259 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
1260 | // 2748. swappable traits for optionals |
1261 | template<typename _Tp> |
1262 | _GLIBCXX20_CONSTEXPR |
1263 | inline enable_if_t<is_move_constructible_v<_Tp> && is_swappable_v<_Tp>> |
1264 | swap(optional<_Tp>& __lhs, optional<_Tp>& __rhs) |
1265 | noexcept(noexcept(__lhs.swap(__rhs))) |
1266 | { __lhs.swap(__rhs); } |
1267 | |
1268 | template<typename _Tp> |
1269 | enable_if_t<!(is_move_constructible_v<_Tp> && is_swappable_v<_Tp>)> |
1270 | swap(optional<_Tp>&, optional<_Tp>&) = delete; |
1271 | |
1272 | template<typename _Tp> |
1273 | constexpr |
1274 | enable_if_t<is_constructible_v<decay_t<_Tp>, _Tp>, |
1275 | optional<decay_t<_Tp>>> |
1276 | make_optional(_Tp&& __t) |
1277 | noexcept(is_nothrow_constructible_v<optional<decay_t<_Tp>>, _Tp>) |
1278 | { return optional<decay_t<_Tp>>{ std::forward<_Tp>(__t) }; } |
1279 | |
1280 | template<typename _Tp, typename... _Args> |
1281 | constexpr |
1282 | enable_if_t<is_constructible_v<_Tp, _Args...>, |
1283 | optional<_Tp>> |
1284 | make_optional(_Args&&... __args) |
1285 | noexcept(is_nothrow_constructible_v<_Tp, _Args...>) |
1286 | { return optional<_Tp>{ in_place, std::forward<_Args>(__args)... }; } |
1287 | |
1288 | template<typename _Tp, typename _Up, typename... _Args> |
1289 | constexpr |
1290 | enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, |
1291 | optional<_Tp>> |
1292 | make_optional(initializer_list<_Up> __il, _Args&&... __args) |
1293 | noexcept(is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, _Args...>) |
1294 | { return optional<_Tp>{ in_place, __il, std::forward<_Args>(__args)... }; } |
1295 | |
1296 | // Hash. |
1297 | |
1298 | template<typename _Tp, typename _Up = remove_const_t<_Tp>, |
1299 | bool = __poison_hash<_Up>::__enable_hash_call> |
1300 | struct __optional_hash_call_base |
1301 | { |
1302 | size_t |
1303 | operator()(const optional<_Tp>& __t) const |
1304 | noexcept(noexcept(hash<_Up>{}(*__t))) |
1305 | { |
1306 | // We pick an arbitrary hash for disengaged optionals which hopefully |
1307 | // usual values of _Tp won't typically hash to. |
1308 | constexpr size_t __magic_disengaged_hash = static_cast<size_t>(-3333); |
1309 | return __t ? hash<_Up>{}(*__t) : __magic_disengaged_hash; |
1310 | } |
1311 | }; |
1312 | |
1313 | template<typename _Tp, typename _Up> |
1314 | struct __optional_hash_call_base<_Tp, _Up, false> {}; |
1315 | |
1316 | template<typename _Tp> |
1317 | struct hash<optional<_Tp>> |
1318 | : private __poison_hash<remove_const_t<_Tp>>, |
1319 | public __optional_hash_call_base<_Tp> |
1320 | { |
1321 | using result_type [[__deprecated__]] = size_t; |
1322 | using argument_type [[__deprecated__]] = optional<_Tp>; |
1323 | }; |
1324 | |
1325 | template<typename _Tp> |
1326 | struct __is_fast_hash<hash<optional<_Tp>>> : __is_fast_hash<hash<_Tp>> |
1327 | { }; |
1328 | |
1329 | /// @} |
1330 | |
1331 | #if __cpp_deduction_guides >= 201606 |
1332 | template <typename _Tp> optional(_Tp) -> optional<_Tp>; |
1333 | #endif |
1334 | |
1335 | _GLIBCXX_END_NAMESPACE_VERSION |
1336 | } // namespace std |
1337 | |
1338 | #endif // C++17 |
1339 | |
1340 | #endif // _GLIBCXX_OPTIONAL |
1341 | |