-
Notifications
You must be signed in to change notification settings - Fork 28
/
Copy pathoptional
1238 lines (1048 loc) · 37.2 KB
/
optional
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
// <optional> -*- C++ -*-
// Copyright (C) 2013-2020 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file include/optional
* This is a Standard C++ Library header.
*/
#ifndef _GLIBCXX_OPTIONAL
#define _GLIBCXX_OPTIONAL 1
#pragma GCC system_header
#if __cplusplus >= 201703L
#include <utility>
#include <type_traits>
#include <bits/functexcept.h>
#include <new>
#include <initializer_list>
#include <bits/exception_defines.h>
#include <bits/functional_hash.h>
#include <bits/enable_special_members.h>
#if __cplusplus > 201703L
# include <compare>
#endif
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @addtogroup utilities
* @{
*/
#define __cpp_lib_optional 201606L
template<typename _Tp>
class optional;
/// Tag type to disengage optional objects.
struct nullopt_t
{
// Do not user-declare default constructor at all for
// optional_value = {} syntax to work.
// nullopt_t() = delete;
// Used for constructing nullopt.
enum class _Construct { _Token };
// Must be constexpr for nullopt_t to be literal.
explicit constexpr nullopt_t(_Construct) { }
};
/// Tag to disengage optional objects.
inline constexpr nullopt_t nullopt { nullopt_t::_Construct::_Token };
// This class template manages construction/destruction of
// the contained value for a std::optional.
template <typename _Tp>
struct _Optional_payload_base
{
using _Stored_type = remove_const_t<_Tp>;
_Optional_payload_base() = default;
~_Optional_payload_base() = default;
template<typename... _Args>
constexpr
_Optional_payload_base(in_place_t __tag, _Args&&... __args)
: _M_payload(__tag, std::forward<_Args>(__args)...),
_M_engaged(true)
{ }
template<typename _Up, typename... _Args>
constexpr
_Optional_payload_base(std::initializer_list<_Up> __il,
_Args&&... __args)
: _M_payload(__il, std::forward<_Args>(__args)...),
_M_engaged(true)
{ }
// Constructor used by _Optional_base copy constructor when the
// contained value is not trivially copy constructible.
constexpr
_Optional_payload_base(bool __engaged,
const _Optional_payload_base& __other)
{
if (__other._M_engaged)
this->_M_construct(__other._M_get());
}
// Constructor used by _Optional_base move constructor when the
// contained value is not trivially move constructible.
constexpr
_Optional_payload_base(bool __engaged,
_Optional_payload_base&& __other)
{
if (__other._M_engaged)
this->_M_construct(std::move(__other._M_get()));
}
// Copy constructor is only used to when the contained value is
// trivially copy constructible.
_Optional_payload_base(const _Optional_payload_base&) = default;
// Move constructor is only used to when the contained value is
// trivially copy constructible.
_Optional_payload_base(_Optional_payload_base&&) = default;
_Optional_payload_base&
operator=(const _Optional_payload_base&) = default;
_Optional_payload_base&
operator=(_Optional_payload_base&&) = default;
// used to perform non-trivial copy assignment.
constexpr void
_M_copy_assign(const _Optional_payload_base& __other)
{
if (this->_M_engaged && __other._M_engaged)
this->_M_get() = __other._M_get();
else
{
if (__other._M_engaged)
this->_M_construct(__other._M_get());
else
this->_M_reset();
}
}
// used to perform non-trivial move assignment.
constexpr void
_M_move_assign(_Optional_payload_base&& __other)
noexcept(__and_v<is_nothrow_move_constructible<_Tp>,
is_nothrow_move_assignable<_Tp>>)
{
if (this->_M_engaged && __other._M_engaged)
this->_M_get() = std::move(__other._M_get());
else
{
if (__other._M_engaged)
this->_M_construct(std::move(__other._M_get()));
else
this->_M_reset();
}
}
struct _Empty_byte { };
template<typename _Up, bool = is_trivially_destructible_v<_Up>>
union _Storage
{
constexpr _Storage() noexcept : _M_empty() { }
template<typename... _Args>
constexpr
_Storage(in_place_t, _Args&&... __args)
: _M_value(std::forward<_Args>(__args)...)
{ }
template<typename _Vp, typename... _Args>
constexpr
_Storage(std::initializer_list<_Vp> __il, _Args&&... __args)
: _M_value(__il, std::forward<_Args>(__args)...)
{ }
_Empty_byte _M_empty;
_Up _M_value;
};
template<typename _Up>
union _Storage<_Up, false>
{
constexpr _Storage() noexcept : _M_empty() { }
template<typename... _Args>
constexpr
_Storage(in_place_t, _Args&&... __args)
: _M_value(std::forward<_Args>(__args)...)
{ }
template<typename _Vp, typename... _Args>
constexpr
_Storage(std::initializer_list<_Vp> __il, _Args&&... __args)
: _M_value(__il, std::forward<_Args>(__args)...)
{ }
// User-provided destructor is needed when _Up has non-trivial dtor.
~_Storage() { }
_Empty_byte _M_empty;
_Up _M_value;
};
_Storage<_Stored_type> _M_payload;
bool _M_engaged = false;
template<typename... _Args>
void
_M_construct(_Args&&... __args)
noexcept(is_nothrow_constructible_v<_Stored_type, _Args...>)
{
::new ((void *) std::__addressof(this->_M_payload))
_Stored_type(std::forward<_Args>(__args)...);
this->_M_engaged = true;
}
constexpr void
_M_destroy() noexcept
{
_M_engaged = false;
_M_payload._M_value.~_Stored_type();
}
// The _M_get() operations have _M_engaged as a precondition.
// They exist to access the contained value with the appropriate
// const-qualification, because _M_payload has had the const removed.
constexpr _Tp&
_M_get() noexcept
{ return this->_M_payload._M_value; }
constexpr const _Tp&
_M_get() const noexcept
{ return this->_M_payload._M_value; }
// _M_reset is a 'safe' operation with no precondition.
constexpr void
_M_reset() noexcept
{
if (this->_M_engaged)
_M_destroy();
}
};
// Class template that manages the payload for optionals.
template <typename _Tp,
bool /*_HasTrivialDestructor*/ =
is_trivially_destructible_v<_Tp>,
bool /*_HasTrivialCopy */ =
is_trivially_copy_assignable_v<_Tp>
&& is_trivially_copy_constructible_v<_Tp>,
bool /*_HasTrivialMove */ =
is_trivially_move_assignable_v<_Tp>
&& is_trivially_move_constructible_v<_Tp>>
struct _Optional_payload;
// Payload for potentially-constexpr optionals (trivial copy/move/destroy).
template <typename _Tp>
struct _Optional_payload<_Tp, true, true, true>
: _Optional_payload_base<_Tp>
{
using _Optional_payload_base<_Tp>::_Optional_payload_base;
_Optional_payload() = default;
};
// Payload for optionals with non-trivial copy construction/assignment.
template <typename _Tp>
struct _Optional_payload<_Tp, true, false, true>
: _Optional_payload_base<_Tp>
{
using _Optional_payload_base<_Tp>::_Optional_payload_base;
_Optional_payload() = default;
~_Optional_payload() = default;
_Optional_payload(const _Optional_payload&) = default;
_Optional_payload(_Optional_payload&&) = default;
_Optional_payload& operator=(_Optional_payload&&) = default;
// Non-trivial copy assignment.
constexpr
_Optional_payload&
operator=(const _Optional_payload& __other)
{
this->_M_copy_assign(__other);
return *this;
}
};
// Payload for optionals with non-trivial move construction/assignment.
template <typename _Tp>
struct _Optional_payload<_Tp, true, true, false>
: _Optional_payload_base<_Tp>
{
using _Optional_payload_base<_Tp>::_Optional_payload_base;
_Optional_payload() = default;
~_Optional_payload() = default;
_Optional_payload(const _Optional_payload&) = default;
_Optional_payload(_Optional_payload&&) = default;
_Optional_payload& operator=(const _Optional_payload&) = default;
// Non-trivial move assignment.
constexpr
_Optional_payload&
operator=(_Optional_payload&& __other)
noexcept(__and_v<is_nothrow_move_constructible<_Tp>,
is_nothrow_move_assignable<_Tp>>)
{
this->_M_move_assign(std::move(__other));
return *this;
}
};
// Payload for optionals with non-trivial copy and move assignment.
template <typename _Tp>
struct _Optional_payload<_Tp, true, false, false>
: _Optional_payload_base<_Tp>
{
using _Optional_payload_base<_Tp>::_Optional_payload_base;
_Optional_payload() = default;
~_Optional_payload() = default;
_Optional_payload(const _Optional_payload&) = default;
_Optional_payload(_Optional_payload&&) = default;
// Non-trivial copy assignment.
constexpr
_Optional_payload&
operator=(const _Optional_payload& __other)
{
this->_M_copy_assign(__other);
return *this;
}
// Non-trivial move assignment.
constexpr
_Optional_payload&
operator=(_Optional_payload&& __other)
noexcept(__and_v<is_nothrow_move_constructible<_Tp>,
is_nothrow_move_assignable<_Tp>>)
{
this->_M_move_assign(std::move(__other));
return *this;
}
};
// Payload for optionals with non-trivial destructors.
template <typename _Tp, bool _Copy, bool _Move>
struct _Optional_payload<_Tp, false, _Copy, _Move>
: _Optional_payload<_Tp, true, false, false>
{
// Base class implements all the constructors and assignment operators:
using _Optional_payload<_Tp, true, false, false>::_Optional_payload;
_Optional_payload() = default;
_Optional_payload(const _Optional_payload&) = default;
_Optional_payload(_Optional_payload&&) = default;
_Optional_payload& operator=(const _Optional_payload&) = default;
_Optional_payload& operator=(_Optional_payload&&) = default;
// Destructor needs to destroy the contained value:
~_Optional_payload() { this->_M_reset(); }
};
// Common base class for _Optional_base<T> to avoid repeating these
// member functions in each specialization.
template<typename _Tp, typename _Dp>
class _Optional_base_impl
{
protected:
using _Stored_type = remove_const_t<_Tp>;
// The _M_construct operation has !_M_engaged as a precondition
// while _M_destruct has _M_engaged as a precondition.
template<typename... _Args>
void
_M_construct(_Args&&... __args)
noexcept(is_nothrow_constructible_v<_Stored_type, _Args...>)
{
::new
(std::__addressof(static_cast<_Dp*>(this)->_M_payload._M_payload))
_Stored_type(std::forward<_Args>(__args)...);
static_cast<_Dp*>(this)->_M_payload._M_engaged = true;
}
void
_M_destruct() noexcept
{ static_cast<_Dp*>(this)->_M_payload._M_destroy(); }
// _M_reset is a 'safe' operation with no precondition.
constexpr void
_M_reset() noexcept
{ static_cast<_Dp*>(this)->_M_payload._M_reset(); }
constexpr bool _M_is_engaged() const noexcept
{ return static_cast<const _Dp*>(this)->_M_payload._M_engaged; }
// The _M_get operations have _M_engaged as a precondition.
constexpr _Tp&
_M_get() noexcept
{
__glibcxx_assert(this->_M_is_engaged());
return static_cast<_Dp*>(this)->_M_payload._M_get();
}
constexpr const _Tp&
_M_get() const noexcept
{
__glibcxx_assert(this->_M_is_engaged());
return static_cast<const _Dp*>(this)->_M_payload._M_get();
}
};
/**
* @brief Class template that provides copy/move constructors of optional.
*
* Such a separate base class template is necessary in order to
* conditionally make copy/move constructors trivial.
*
* When the contained value is trivially copy/move constructible,
* the copy/move constructors of _Optional_base will invoke the
* trivial copy/move constructor of _Optional_payload. Otherwise,
* they will invoke _Optional_payload(bool, const _Optional_payload&)
* or _Optional_payload(bool, _Optional_payload&&) to initialize
* the contained value, if copying/moving an engaged optional.
*
* Whether the other special members are trivial is determined by the
* _Optional_payload<_Tp> specialization used for the _M_payload member.
*
* @see optional, _Enable_special_members
*/
template<typename _Tp,
bool = is_trivially_copy_constructible_v<_Tp>,
bool = is_trivially_move_constructible_v<_Tp>>
struct _Optional_base
: _Optional_base_impl<_Tp, _Optional_base<_Tp>>
{
// Constructors for disengaged optionals.
constexpr _Optional_base() = default;
// Constructors for engaged optionals.
template<typename... _Args,
enable_if_t<is_constructible_v<_Tp, _Args&&...>, bool> = false>
constexpr explicit _Optional_base(in_place_t, _Args&&... __args)
: _M_payload(in_place,
std::forward<_Args>(__args)...) { }
template<typename _Up, typename... _Args,
enable_if_t<is_constructible_v<_Tp,
initializer_list<_Up>&,
_Args&&...>, bool> = false>
constexpr explicit _Optional_base(in_place_t,
initializer_list<_Up> __il,
_Args&&... __args)
: _M_payload(in_place,
__il, std::forward<_Args>(__args)...)
{ }
// Copy and move constructors.
constexpr _Optional_base(const _Optional_base& __other)
: _M_payload(__other._M_payload._M_engaged,
__other._M_payload)
{ }
constexpr _Optional_base(_Optional_base&& __other)
noexcept(is_nothrow_move_constructible_v<_Tp>)
: _M_payload(__other._M_payload._M_engaged,
std::move(__other._M_payload))
{ }
// Assignment operators.
_Optional_base& operator=(const _Optional_base&) = default;
_Optional_base& operator=(_Optional_base&&) = default;
_Optional_payload<_Tp> _M_payload;
};
template<typename _Tp>
struct _Optional_base<_Tp, false, true>
: _Optional_base_impl<_Tp, _Optional_base<_Tp>>
{
// Constructors for disengaged optionals.
constexpr _Optional_base() = default;
// Constructors for engaged optionals.
template<typename... _Args,
enable_if_t<is_constructible_v<_Tp, _Args&&...>, bool> = false>
constexpr explicit _Optional_base(in_place_t, _Args&&... __args)
: _M_payload(in_place,
std::forward<_Args>(__args)...) { }
template<typename _Up, typename... _Args,
enable_if_t<is_constructible_v<_Tp,
initializer_list<_Up>&,
_Args&&...>, bool> = false>
constexpr explicit _Optional_base(in_place_t,
initializer_list<_Up> __il,
_Args&&... __args)
: _M_payload(in_place,
__il, std::forward<_Args>(__args)...)
{ }
// Copy and move constructors.
constexpr _Optional_base(const _Optional_base& __other)
: _M_payload(__other._M_payload._M_engaged,
__other._M_payload)
{ }
constexpr _Optional_base(_Optional_base&& __other) = default;
// Assignment operators.
_Optional_base& operator=(const _Optional_base&) = default;
_Optional_base& operator=(_Optional_base&&) = default;
_Optional_payload<_Tp> _M_payload;
};
template<typename _Tp>
struct _Optional_base<_Tp, true, false>
: _Optional_base_impl<_Tp, _Optional_base<_Tp>>
{
// Constructors for disengaged optionals.
constexpr _Optional_base() = default;
// Constructors for engaged optionals.
template<typename... _Args,
enable_if_t<is_constructible_v<_Tp, _Args&&...>, bool> = false>
constexpr explicit _Optional_base(in_place_t, _Args&&... __args)
: _M_payload(in_place,
std::forward<_Args>(__args)...) { }
template<typename _Up, typename... _Args,
enable_if_t<is_constructible_v<_Tp,
initializer_list<_Up>&,
_Args&&...>, bool> = false>
constexpr explicit _Optional_base(in_place_t,
initializer_list<_Up> __il,
_Args&&... __args)
: _M_payload(in_place,
__il, std::forward<_Args>(__args)...)
{ }
// Copy and move constructors.
constexpr _Optional_base(const _Optional_base& __other) = default;
constexpr _Optional_base(_Optional_base&& __other)
noexcept(is_nothrow_move_constructible_v<_Tp>)
: _M_payload(__other._M_payload._M_engaged,
std::move(__other._M_payload))
{ }
// Assignment operators.
_Optional_base& operator=(const _Optional_base&) = default;
_Optional_base& operator=(_Optional_base&&) = default;
_Optional_payload<_Tp> _M_payload;
};
template<typename _Tp>
struct _Optional_base<_Tp, true, true>
: _Optional_base_impl<_Tp, _Optional_base<_Tp>>
{
// Constructors for disengaged optionals.
constexpr _Optional_base() = default;
// Constructors for engaged optionals.
template<typename... _Args,
enable_if_t<is_constructible_v<_Tp, _Args&&...>, bool> = false>
constexpr explicit _Optional_base(in_place_t, _Args&&... __args)
: _M_payload(in_place,
std::forward<_Args>(__args)...) { }
template<typename _Up, typename... _Args,
enable_if_t<is_constructible_v<_Tp,
initializer_list<_Up>&,
_Args&&...>, bool> = false>
constexpr explicit _Optional_base(in_place_t,
initializer_list<_Up> __il,
_Args&&... __args)
: _M_payload(in_place,
__il, std::forward<_Args>(__args)...)
{ }
// Copy and move constructors.
constexpr _Optional_base(const _Optional_base& __other) = default;
constexpr _Optional_base(_Optional_base&& __other) = default;
// Assignment operators.
_Optional_base& operator=(const _Optional_base&) = default;
_Optional_base& operator=(_Optional_base&&) = default;
_Optional_payload<_Tp> _M_payload;
};
template<typename _Tp>
class optional;
template<typename _Tp, typename _Up>
using __converts_from_optional =
__or_<is_constructible<_Tp, const optional<_Up>&>,
is_constructible<_Tp, optional<_Up>&>,
is_constructible<_Tp, const optional<_Up>&&>,
is_constructible<_Tp, optional<_Up>&&>,
is_convertible<const optional<_Up>&, _Tp>,
is_convertible<optional<_Up>&, _Tp>,
is_convertible<const optional<_Up>&&, _Tp>,
is_convertible<optional<_Up>&&, _Tp>>;
template<typename _Tp, typename _Up>
using __assigns_from_optional =
__or_<is_assignable<_Tp&, const optional<_Up>&>,
is_assignable<_Tp&, optional<_Up>&>,
is_assignable<_Tp&, const optional<_Up>&&>,
is_assignable<_Tp&, optional<_Up>&&>>;
/**
* @brief Class template for optional values.
*/
template<typename _Tp>
class optional
: private _Optional_base<_Tp>,
private _Enable_copy_move<
// Copy constructor.
is_copy_constructible_v<_Tp>,
// Copy assignment.
__and_v<is_copy_constructible<_Tp>, is_copy_assignable<_Tp>>,
// Move constructor.
is_move_constructible_v<_Tp>,
// Move assignment.
__and_v<is_move_constructible<_Tp>, is_move_assignable<_Tp>>,
// Unique tag type.
optional<_Tp>>
{
static_assert(!is_same_v<remove_cv_t<_Tp>, nullopt_t>);
static_assert(!is_same_v<remove_cv_t<_Tp>, in_place_t>);
static_assert(!is_reference_v<_Tp>);
private:
using _Base = _Optional_base<_Tp>;
// SFINAE helpers
template<typename _Up>
using __not_self = __not_<is_same<optional, __remove_cvref_t<_Up>>>;
template<typename _Up>
using __not_tag = __not_<is_same<in_place_t, __remove_cvref_t<_Up>>>;
template<typename... _Cond>
using _Requires = enable_if_t<__and_v<_Cond...>, bool>;
public:
using value_type = _Tp;
constexpr optional() = default;
constexpr optional(nullopt_t) noexcept { }
// Converting constructors for engaged optionals.
template<typename _Up = _Tp,
_Requires<__not_self<_Up>, __not_tag<_Up>,
is_constructible<_Tp, _Up&&>,
is_convertible<_Up&&, _Tp>> = true>
constexpr
optional(_Up&& __t)
: _Base(std::in_place, std::forward<_Up>(__t)) { }
template<typename _Up = _Tp,
_Requires<__not_self<_Up>, __not_tag<_Up>,
is_constructible<_Tp, _Up&&>,
__not_<is_convertible<_Up&&, _Tp>>> = false>
explicit constexpr
optional(_Up&& __t)
: _Base(std::in_place, std::forward<_Up>(__t)) { }
template<typename _Up,
_Requires<__not_<is_same<_Tp, _Up>>,
is_constructible<_Tp, const _Up&>,
is_convertible<const _Up&, _Tp>,
__not_<__converts_from_optional<_Tp, _Up>>> = true>
constexpr
optional(const optional<_Up>& __t)
{
if (__t)
emplace(*__t);
}
template<typename _Up,
_Requires<__not_<is_same<_Tp, _Up>>,
is_constructible<_Tp, const _Up&>,
__not_<is_convertible<const _Up&, _Tp>>,
__not_<__converts_from_optional<_Tp, _Up>>> = false>
explicit constexpr
optional(const optional<_Up>& __t)
{
if (__t)
emplace(*__t);
}
template <typename _Up,
_Requires<__not_<is_same<_Tp, _Up>>,
is_constructible<_Tp, _Up&&>,
is_convertible<_Up&&, _Tp>,
__not_<__converts_from_optional<_Tp, _Up>>> = true>
constexpr
optional(optional<_Up>&& __t)
{
if (__t)
emplace(std::move(*__t));
}
template <typename _Up,
_Requires<__not_<is_same<_Tp, _Up>>,
is_constructible<_Tp, _Up&&>,
__not_<is_convertible<_Up&&, _Tp>>,
__not_<__converts_from_optional<_Tp, _Up>>> = false>
explicit constexpr
optional(optional<_Up>&& __t)
{
if (__t)
emplace(std::move(*__t));
}
template<typename... _Args,
_Requires<is_constructible<_Tp, _Args&&...>> = false>
explicit constexpr
optional(in_place_t, _Args&&... __args)
: _Base(std::in_place, std::forward<_Args>(__args)...) { }
template<typename _Up, typename... _Args,
_Requires<is_constructible<_Tp,
initializer_list<_Up>&,
_Args&&...>> = false>
explicit constexpr
optional(in_place_t, initializer_list<_Up> __il, _Args&&... __args)
: _Base(std::in_place, __il, std::forward<_Args>(__args)...) { }
// Assignment operators.
optional&
operator=(nullopt_t) noexcept
{
this->_M_reset();
return *this;
}
template<typename _Up = _Tp>
enable_if_t<__and_v<__not_self<_Up>,
__not_<__and_<is_scalar<_Tp>,
is_same<_Tp, decay_t<_Up>>>>,
is_constructible<_Tp, _Up>,
is_assignable<_Tp&, _Up>>,
optional&>
operator=(_Up&& __u)
{
if (this->_M_is_engaged())
this->_M_get() = std::forward<_Up>(__u);
else
this->_M_construct(std::forward<_Up>(__u));
return *this;
}
template<typename _Up>
enable_if_t<__and_v<__not_<is_same<_Tp, _Up>>,
is_constructible<_Tp, const _Up&>,
is_assignable<_Tp&, _Up>,
__not_<__converts_from_optional<_Tp, _Up>>,
__not_<__assigns_from_optional<_Tp, _Up>>>,
optional&>
operator=(const optional<_Up>& __u)
{
if (__u)
{
if (this->_M_is_engaged())
this->_M_get() = *__u;
else
this->_M_construct(*__u);
}
else
{
this->_M_reset();
}
return *this;
}
template<typename _Up>
enable_if_t<__and_v<__not_<is_same<_Tp, _Up>>,
is_constructible<_Tp, _Up>,
is_assignable<_Tp&, _Up>,
__not_<__converts_from_optional<_Tp, _Up>>,
__not_<__assigns_from_optional<_Tp, _Up>>>,
optional&>
operator=(optional<_Up>&& __u)
{
if (__u)
{
if (this->_M_is_engaged())
this->_M_get() = std::move(*__u);
else
this->_M_construct(std::move(*__u));
}
else
{
this->_M_reset();
}
return *this;
}
template<typename... _Args>
enable_if_t<is_constructible_v<_Tp, _Args&&...>, _Tp&>
emplace(_Args&&... __args)
{
this->_M_reset();
this->_M_construct(std::forward<_Args>(__args)...);
return this->_M_get();
}
template<typename _Up, typename... _Args>
enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&,
_Args&&...>, _Tp&>
emplace(initializer_list<_Up> __il, _Args&&... __args)
{
this->_M_reset();
this->_M_construct(__il, std::forward<_Args>(__args)...);
return this->_M_get();
}
// Destructor is implicit, implemented in _Optional_base.
// Swap.
void
swap(optional& __other)
noexcept(is_nothrow_move_constructible_v<_Tp>
&& is_nothrow_swappable_v<_Tp>)
{
using std::swap;
if (this->_M_is_engaged() && __other._M_is_engaged())
swap(this->_M_get(), __other._M_get());
else if (this->_M_is_engaged())
{
__other._M_construct(std::move(this->_M_get()));
this->_M_destruct();
}
else if (__other._M_is_engaged())
{
this->_M_construct(std::move(__other._M_get()));
__other._M_destruct();
}
}
// Observers.
constexpr const _Tp*
operator->() const
{ return std::__addressof(this->_M_get()); }
constexpr _Tp*
operator->()
{ return std::__addressof(this->_M_get()); }
constexpr const _Tp&
operator*() const&
{ return this->_M_get(); }
constexpr _Tp&
operator*()&
{ return this->_M_get(); }
constexpr _Tp&&
operator*()&&
{ return std::move(this->_M_get()); }
constexpr const _Tp&&
operator*() const&&
{ return std::move(this->_M_get()); }
constexpr explicit operator bool() const noexcept
{ return this->_M_is_engaged(); }
constexpr bool has_value() const noexcept
{ return this->_M_is_engaged(); }
constexpr const _Tp&
value() const&
{
return this->_M_is_engaged()
? this->_M_get()
: (__throw_bad_optional_access(), this->_M_get());
}
constexpr _Tp&
value()&
{
return this->_M_is_engaged()
? this->_M_get()
: (__throw_bad_optional_access(), this->_M_get());
}
constexpr _Tp&&
value()&&
{
return this->_M_is_engaged()
? std::move(this->_M_get())
: (__throw_bad_optional_access(), std::move(this->_M_get()));
}
constexpr const _Tp&&
value() const&&
{
return this->_M_is_engaged()
? std::move(this->_M_get())
: (__throw_bad_optional_access(), std::move(this->_M_get()));
}
template<typename _Up>
constexpr _Tp
value_or(_Up&& __u) const&
{
static_assert(is_copy_constructible_v<_Tp>);
static_assert(is_convertible_v<_Up&&, _Tp>);
return this->_M_is_engaged()
? this->_M_get() : static_cast<_Tp>(std::forward<_Up>(__u));
}
template<typename _Up>
constexpr _Tp
value_or(_Up&& __u) &&
{
static_assert(is_move_constructible_v<_Tp>);
static_assert(is_convertible_v<_Up&&, _Tp>);
return this->_M_is_engaged()
? std::move(this->_M_get())
: static_cast<_Tp>(std::forward<_Up>(__u));
}
void reset() noexcept { this->_M_reset(); }
};
template<typename _Tp>
using __optional_relop_t =
enable_if_t<is_convertible<_Tp, bool>::value, bool>;
// Comparisons between optional values.
template<typename _Tp, typename _Up>
constexpr auto
operator==(const optional<_Tp>& __lhs, const optional<_Up>& __rhs)
-> __optional_relop_t<decltype(declval<_Tp>() == declval<_Up>())>
{
return static_cast<bool>(__lhs) == static_cast<bool>(__rhs)
&& (!__lhs || *__lhs == *__rhs);
}
template<typename _Tp, typename _Up>
constexpr auto
operator!=(const optional<_Tp>& __lhs, const optional<_Up>& __rhs)
-> __optional_relop_t<decltype(declval<_Tp>() != declval<_Up>())>
{
return static_cast<bool>(__lhs) != static_cast<bool>(__rhs)
|| (static_cast<bool>(__lhs) && *__lhs != *__rhs);
}
template<typename _Tp, typename _Up>
constexpr auto
operator<(const optional<_Tp>& __lhs, const optional<_Up>& __rhs)
-> __optional_relop_t<decltype(declval<_Tp>() < declval<_Up>())>
{
return static_cast<bool>(__rhs) && (!__lhs || *__lhs < *__rhs);
}
template<typename _Tp, typename _Up>
constexpr auto
operator>(const optional<_Tp>& __lhs, const optional<_Up>& __rhs)
-> __optional_relop_t<decltype(declval<_Tp>() > declval<_Up>())>
{
return static_cast<bool>(__lhs) && (!__rhs || *__lhs > *__rhs);
}
template<typename _Tp, typename _Up>
constexpr auto
operator<=(const optional<_Tp>& __lhs, const optional<_Up>& __rhs)
-> __optional_relop_t<decltype(declval<_Tp>() <= declval<_Up>())>
{
return !__lhs || (static_cast<bool>(__rhs) && *__lhs <= *__rhs);
}
template<typename _Tp, typename _Up>