source: s10k/CommonLibs/cpp17optional/optional.hpp@ 1085

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1// Copyright (C) 2011 - 2012 Andrzej Krzemienski.
2//
3// Use, modification, and distribution is subject to the Boost Software
4// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
5// http://www.boost.org/LICENSE_1_0.txt)
6//
7// The idea and interface is based on Boost.Optional library
8// authored by Fernando Luis Cacciola Carballal
9
10# ifndef ___OPTIONAL_HPP___
11# define ___OPTIONAL_HPP___
12
13# include <utility>
14# include <type_traits>
15# include <initializer_list>
16# include <cassert>
17# include <functional>
18# include <string>
19# include <stdexcept>
20
21# define TR2_OPTIONAL_REQUIRES(...) typename enable_if<__VA_ARGS__::value, bool>::type = false
22
23# if defined __GNUC__ // NOTE: GNUC is also defined for Clang
24# if (__GNUC__ == 4) && (__GNUC_MINOR__ >= 8)
25# define TR2_OPTIONAL_GCC_4_8_AND_HIGHER___
26# elif (__GNUC__ > 4)
27# define TR2_OPTIONAL_GCC_4_8_AND_HIGHER___
28# endif
29#
30# if (__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)
31# define TR2_OPTIONAL_GCC_4_7_AND_HIGHER___
32# elif (__GNUC__ > 4)
33# define TR2_OPTIONAL_GCC_4_7_AND_HIGHER___
34# endif
35#
36# if (__GNUC__ == 4) && (__GNUC_MINOR__ == 8) && (__GNUC_PATCHLEVEL__ >= 1)
37# define TR2_OPTIONAL_GCC_4_8_1_AND_HIGHER___
38# elif (__GNUC__ == 4) && (__GNUC_MINOR__ >= 9)
39# define TR2_OPTIONAL_GCC_4_8_1_AND_HIGHER___
40# elif (__GNUC__ > 4)
41# define TR2_OPTIONAL_GCC_4_8_1_AND_HIGHER___
42# endif
43# endif
44#
45# if defined __clang_major__
46# if (__clang_major__ == 3 && __clang_minor__ >= 5)
47# define TR2_OPTIONAL_CLANG_3_5_AND_HIGHTER_
48# elif (__clang_major__ > 3)
49# define TR2_OPTIONAL_CLANG_3_5_AND_HIGHTER_
50# endif
51# if defined TR2_OPTIONAL_CLANG_3_5_AND_HIGHTER_
52# define TR2_OPTIONAL_CLANG_3_4_2_AND_HIGHER_
53# elif (__clang_major__ == 3 && __clang_minor__ == 4 && __clang_patchlevel__ >= 2)
54# define TR2_OPTIONAL_CLANG_3_4_2_AND_HIGHER_
55# endif
56# endif
57#
58# if defined _MSC_VER
59# if (_MSC_VER >= 1900)
60# define TR2_OPTIONAL_MSVC_2015_AND_HIGHER___
61# endif
62# endif
63
64# if defined __clang__
65# if (__clang_major__ > 2) || (__clang_major__ == 2) && (__clang_minor__ >= 9)
66# define OPTIONAL_HAS_THIS_RVALUE_REFS 1
67# else
68# define OPTIONAL_HAS_THIS_RVALUE_REFS 0
69# endif
70# elif defined TR2_OPTIONAL_GCC_4_8_1_AND_HIGHER___
71# define OPTIONAL_HAS_THIS_RVALUE_REFS 1
72# elif defined TR2_OPTIONAL_MSVC_2015_AND_HIGHER___
73# define OPTIONAL_HAS_THIS_RVALUE_REFS 1
74# else
75# define OPTIONAL_HAS_THIS_RVALUE_REFS 0
76# endif
77
78
79# if defined TR2_OPTIONAL_GCC_4_8_1_AND_HIGHER___
80# define OPTIONAL_HAS_CONSTEXPR_INIT_LIST 1
81# define OPTIONAL_CONSTEXPR_INIT_LIST constexpr
82# else
83# define OPTIONAL_HAS_CONSTEXPR_INIT_LIST 0
84# define OPTIONAL_CONSTEXPR_INIT_LIST
85# endif
86
87# if defined TR2_OPTIONAL_CLANG_3_5_AND_HIGHTER_ && (defined __cplusplus) && (__cplusplus != 201103L)
88# define OPTIONAL_HAS_MOVE_ACCESSORS 1
89# else
90# define OPTIONAL_HAS_MOVE_ACCESSORS 0
91# endif
92
93# // In C++11 constexpr implies const, so we need to make non-const members also non-constexpr
94# if (defined __cplusplus) && (__cplusplus == 201103L)
95# define OPTIONAL_MUTABLE_CONSTEXPR
96# else
97# define OPTIONAL_MUTABLE_CONSTEXPR constexpr
98# endif
99
100namespace std{
101
102namespace experimental{
103
104// BEGIN workaround for missing is_trivially_destructible
105# if defined TR2_OPTIONAL_GCC_4_8_AND_HIGHER___
106 // leave it: it is already there
107# elif defined TR2_OPTIONAL_CLANG_3_4_2_AND_HIGHER_
108 // leave it: it is already there
109# elif defined TR2_OPTIONAL_MSVC_2015_AND_HIGHER___
110 // leave it: it is already there
111# elif defined TR2_OPTIONAL_DISABLE_EMULATION_OF_TYPE_TRAITS
112 // leave it: the user doesn't want it
113# else
114 template <typename T>
115 using is_trivially_destructible = std::has_trivial_destructor<T>;
116# endif
117// END workaround for missing is_trivially_destructible
118
119# if (defined TR2_OPTIONAL_GCC_4_7_AND_HIGHER___)
120 // leave it; our metafunctions are already defined.
121# elif defined TR2_OPTIONAL_CLANG_3_4_2_AND_HIGHER_
122 // leave it; our metafunctions are already defined.
123# elif defined TR2_OPTIONAL_MSVC_2015_AND_HIGHER___
124 // leave it: it is already there
125# elif defined TR2_OPTIONAL_DISABLE_EMULATION_OF_TYPE_TRAITS
126 // leave it: the user doesn't want it
127# else
128
129
130// workaround for missing traits in GCC and CLANG
131template <class T>
132struct is_nothrow_move_constructible
133{
134 constexpr static bool value = std::is_nothrow_constructible<T, T&&>::value;
135};
136
137
138template <class T, class U>
139struct is_assignable
140{
141 template <class X, class Y>
142 constexpr static bool has_assign(...) { return false; }
143
144 template <class X, class Y, size_t S = sizeof((std::declval<X>() = std::declval<Y>(), true)) >
145 // the comma operator is necessary for the cases where operator= returns void
146 constexpr static bool has_assign(bool) { return true; }
147
148 constexpr static bool value = has_assign<T, U>(true);
149};
150
151
152template <class T>
153struct is_nothrow_move_assignable
154{
155 template <class X, bool has_any_move_assign>
156 struct has_nothrow_move_assign {
157 constexpr static bool value = false;
158 };
159
160 template <class X>
161 struct has_nothrow_move_assign<X, true> {
162 constexpr static bool value = noexcept( std::declval<X&>() = std::declval<X&&>() );
163 };
164
165 constexpr static bool value = has_nothrow_move_assign<T, is_assignable<T&, T&&>::value>::value;
166};
167// end workaround
168
169
170# endif
171
172
173
174// 20.5.4, optional for object types
175template <class T> class optional;
176
177// 20.5.5, optional for lvalue reference types
178template <class T> class optional<T&>;
179
180
181// workaround: std utility functions aren't constexpr yet
182template <class T> inline constexpr T&& constexpr_forward(typename std::remove_reference<T>::type& t) noexcept
183{
184 return static_cast<T&&>(t);
185}
186
187template <class T> inline constexpr T&& constexpr_forward(typename std::remove_reference<T>::type&& t) noexcept
188{
189 static_assert(!std::is_lvalue_reference<T>::value, "!!");
190 return static_cast<T&&>(t);
191}
192
193template <class T> inline constexpr typename std::remove_reference<T>::type&& constexpr_move(T&& t) noexcept
194{
195 return static_cast<typename std::remove_reference<T>::type&&>(t);
196}
197
198
199#if defined NDEBUG
200# define TR2_OPTIONAL_ASSERTED_EXPRESSION(CHECK, EXPR) (EXPR)
201#else
202# define TR2_OPTIONAL_ASSERTED_EXPRESSION(CHECK, EXPR) ((CHECK) ? (EXPR) : ([]{assert(!#CHECK);}(), (EXPR)))
203#endif
204
205
206namespace detail_
207{
208
209// static_addressof: a constexpr version of addressof
210template <typename T>
211struct has_overloaded_addressof
212{
213 template <class X>
214 constexpr static bool has_overload(...) { return false; }
215
216 template <class X, size_t S = sizeof(std::declval<X&>().operator&()) >
217 constexpr static bool has_overload(bool) { return true; }
218
219 constexpr static bool value = has_overload<T>(true);
220};
221
222template <typename T, TR2_OPTIONAL_REQUIRES(!has_overloaded_addressof<T>)>
223constexpr T* static_addressof(T& ref)
224{
225 return &ref;
226}
227
228template <typename T, TR2_OPTIONAL_REQUIRES(has_overloaded_addressof<T>)>
229T* static_addressof(T& ref)
230{
231 return std::addressof(ref);
232}
233
234
235// the call to convert<A>(b) has return type A and converts b to type A iff b decltype(b) is implicitly convertible to A
236template <class U>
237constexpr U convert(U v) { return v; }
238
239} // namespace detail
240
241
242constexpr struct trivial_init_t{} trivial_init{};
243
244
245// 20.5.6, In-place construction
246constexpr struct in_place_t{} in_place{};
247
248
249// 20.5.7, Disengaged state indicator
250struct nullopt_t
251{
252 struct init{};
253 constexpr explicit nullopt_t(init){}
254};
255constexpr nullopt_t nullopt{nullopt_t::init()};
256
257
258// 20.5.8, class bad_optional_access
259class bad_optional_access : public logic_error {
260public:
261 explicit bad_optional_access(const string& what_arg) : logic_error{what_arg} {}
262 explicit bad_optional_access(const char* what_arg) : logic_error{what_arg} {}
263};
264
265
266template <class T>
267union storage_t
268{
269 unsigned char dummy_;
270 T value_;
271
272 constexpr storage_t( trivial_init_t ) noexcept : dummy_() {};
273
274 template <class... Args>
275 constexpr storage_t( Args&&... args ) : value_(constexpr_forward<Args>(args)...) {}
276
277 ~storage_t(){}
278};
279
280
281template <class T>
282union constexpr_storage_t
283{
284 unsigned char dummy_;
285 T value_;
286
287 constexpr constexpr_storage_t( trivial_init_t ) noexcept : dummy_() {};
288
289 template <class... Args>
290 constexpr constexpr_storage_t( Args&&... args ) : value_(constexpr_forward<Args>(args)...) {}
291
292 ~constexpr_storage_t() = default;
293};
294
295
296template <class T>
297struct optional_base
298{
299 bool init_;
300 storage_t<T> storage_;
301
302 constexpr optional_base() noexcept : init_(false), storage_(trivial_init) {};
303
304 explicit constexpr optional_base(const T& v) : init_(true), storage_(v) {}
305
306 explicit constexpr optional_base(T&& v) : init_(true), storage_(constexpr_move(v)) {}
307
308 template <class... Args> explicit optional_base(in_place_t, Args&&... args)
309 : init_(true), storage_(constexpr_forward<Args>(args)...) {}
310
311 template <class U, class... Args, TR2_OPTIONAL_REQUIRES(is_constructible<T, std::initializer_list<U>>)>
312 explicit optional_base(in_place_t, std::initializer_list<U> il, Args&&... args)
313 : init_(true), storage_(il, std::forward<Args>(args)...) {}
314
315 ~optional_base() { if (init_) storage_.value_.T::~T(); }
316};
317
318
319template <class T>
320struct constexpr_optional_base
321{
322 bool init_;
323 constexpr_storage_t<T> storage_;
324
325 constexpr constexpr_optional_base() noexcept : init_(false), storage_(trivial_init) {};
326
327 explicit constexpr constexpr_optional_base(const T& v) : init_(true), storage_(v) {}
328
329 explicit constexpr constexpr_optional_base(T&& v) : init_(true), storage_(constexpr_move(v)) {}
330
331 template <class... Args> explicit constexpr constexpr_optional_base(in_place_t, Args&&... args)
332 : init_(true), storage_(constexpr_forward<Args>(args)...) {}
333
334 template <class U, class... Args, TR2_OPTIONAL_REQUIRES(is_constructible<T, std::initializer_list<U>>)>
335 OPTIONAL_CONSTEXPR_INIT_LIST explicit constexpr_optional_base(in_place_t, std::initializer_list<U> il, Args&&... args)
336 : init_(true), storage_(il, std::forward<Args>(args)...) {}
337
338 ~constexpr_optional_base() = default;
339};
340
341template <class T>
342using OptionalBase = typename std::conditional<
343 is_trivially_destructible<T>::value, // if possible
344 constexpr_optional_base<typename std::remove_const<T>::type>, // use base with trivial destructor
345 optional_base<typename std::remove_const<T>::type>
346>::type;
347
348
349
350template <class T>
351class optional : private OptionalBase<T>
352{
353 static_assert( !std::is_same<typename std::decay<T>::type, nullopt_t>::value, "bad T" );
354 static_assert( !std::is_same<typename std::decay<T>::type, in_place_t>::value, "bad T" );
355
356
357 constexpr bool initialized() const noexcept { return OptionalBase<T>::init_; }
358 typename std::remove_const<T>::type* dataptr() { return std::addressof(OptionalBase<T>::storage_.value_); }
359 constexpr const T* dataptr() const { return detail_::static_addressof(OptionalBase<T>::storage_.value_); }
360
361# if OPTIONAL_HAS_THIS_RVALUE_REFS == 1
362 constexpr const T& contained_val() const& { return OptionalBase<T>::storage_.value_; }
363# if OPTIONAL_HAS_MOVE_ACCESSORS == 1
364 OPTIONAL_MUTABLE_CONSTEXPR T&& contained_val() && { return std::move(OptionalBase<T>::storage_.value_); }
365 OPTIONAL_MUTABLE_CONSTEXPR T& contained_val() & { return OptionalBase<T>::storage_.value_; }
366# else
367 T& contained_val() & { return OptionalBase<T>::storage_.value_; }
368 T&& contained_val() && { return std::move(OptionalBase<T>::storage_.value_); }
369# endif
370# else
371 constexpr const T& contained_val() const { return OptionalBase<T>::storage_.value_; }
372 T& contained_val() { return OptionalBase<T>::storage_.value_; }
373# endif
374
375 void clear() noexcept {
376 if (initialized()) dataptr()->T::~T();
377 OptionalBase<T>::init_ = false;
378 }
379
380 template <class... Args>
381 void initialize(Args&&... args) noexcept(noexcept(T(std::forward<Args>(args)...)))
382 {
383 assert(!OptionalBase<T>::init_);
384 ::new (static_cast<void*>(dataptr())) T(std::forward<Args>(args)...);
385 OptionalBase<T>::init_ = true;
386 }
387
388 template <class U, class... Args>
389 void initialize(std::initializer_list<U> il, Args&&... args) noexcept(noexcept(T(il, std::forward<Args>(args)...)))
390 {
391 assert(!OptionalBase<T>::init_);
392 ::new (static_cast<void*>(dataptr())) T(il, std::forward<Args>(args)...);
393 OptionalBase<T>::init_ = true;
394 }
395
396public:
397 typedef T value_type;
398
399 // 20.5.5.1, constructors
400 constexpr optional() noexcept : OptionalBase<T>() {};
401 constexpr optional(nullopt_t) noexcept : OptionalBase<T>() {};
402
403 optional(const optional& rhs)
404 : OptionalBase<T>()
405 {
406 if (rhs.initialized()) {
407 ::new (static_cast<void*>(dataptr())) T(*rhs);
408 OptionalBase<T>::init_ = true;
409 }
410 }
411
412 optional(optional&& rhs) noexcept(is_nothrow_move_constructible<T>::value)
413 : OptionalBase<T>()
414 {
415 if (rhs.initialized()) {
416 ::new (static_cast<void*>(dataptr())) T(std::move(*rhs));
417 OptionalBase<T>::init_ = true;
418 }
419 }
420
421 constexpr optional(const T& v) : OptionalBase<T>(v) {}
422
423 constexpr optional(T&& v) : OptionalBase<T>(constexpr_move(v)) {}
424
425 template <class... Args>
426 explicit constexpr optional(in_place_t, Args&&... args)
427 : OptionalBase<T>(in_place_t{}, constexpr_forward<Args>(args)...) {}
428
429 template <class U, class... Args, TR2_OPTIONAL_REQUIRES(is_constructible<T, std::initializer_list<U>>)>
430 OPTIONAL_CONSTEXPR_INIT_LIST explicit optional(in_place_t, std::initializer_list<U> il, Args&&... args)
431 : OptionalBase<T>(in_place_t{}, il, constexpr_forward<Args>(args)...) {}
432
433 // 20.5.4.2, Destructor
434 ~optional() = default;
435
436 // 20.5.4.3, assignment
437 optional& operator=(nullopt_t) noexcept
438 {
439 clear();
440 return *this;
441 }
442
443 optional& operator=(const optional& rhs)
444 {
445 if (initialized() == true && rhs.initialized() == false) clear();
446 else if (initialized() == false && rhs.initialized() == true) initialize(*rhs);
447 else if (initialized() == true && rhs.initialized() == true) contained_val() = *rhs;
448 return *this;
449 }
450
451 optional& operator=(optional&& rhs)
452 noexcept(is_nothrow_move_assignable<T>::value && is_nothrow_move_constructible<T>::value)
453 {
454 if (initialized() == true && rhs.initialized() == false) clear();
455 else if (initialized() == false && rhs.initialized() == true) initialize(std::move(*rhs));
456 else if (initialized() == true && rhs.initialized() == true) contained_val() = std::move(*rhs);
457 return *this;
458 }
459
460 template <class U>
461 auto operator=(U&& v)
462 -> typename enable_if
463 <
464 is_same<typename decay<U>::type, T>::value,
465 optional&
466 >::type
467 {
468 if (initialized()) { contained_val() = std::forward<U>(v); }
469 else { initialize(std::forward<U>(v)); }
470 return *this;
471 }
472
473
474 template <class... Args>
475 void emplace(Args&&... args)
476 {
477 clear();
478 initialize(std::forward<Args>(args)...);
479 }
480
481 template <class U, class... Args>
482 void emplace(initializer_list<U> il, Args&&... args)
483 {
484 clear();
485 initialize<U, Args...>(il, std::forward<Args>(args)...);
486 }
487
488 // 20.5.4.4, Swap
489 void swap(optional<T>& rhs) noexcept(is_nothrow_move_constructible<T>::value && noexcept(swap(declval<T&>(), declval<T&>())))
490 {
491 if (initialized() == true && rhs.initialized() == false) { rhs.initialize(std::move(**this)); clear(); }
492 else if (initialized() == false && rhs.initialized() == true) { initialize(std::move(*rhs)); rhs.clear(); }
493 else if (initialized() == true && rhs.initialized() == true) { using std::swap; swap(**this, *rhs); }
494 }
495
496 // 20.5.4.5, Observers
497
498 explicit constexpr operator bool() const noexcept { return initialized(); }
499 constexpr bool has_value() const noexcept { return initialized(); }
500
501 constexpr T const* operator ->() const {
502 return TR2_OPTIONAL_ASSERTED_EXPRESSION(initialized(), dataptr());
503 }
504
505# if OPTIONAL_HAS_MOVE_ACCESSORS == 1
506
507 OPTIONAL_MUTABLE_CONSTEXPR T* operator ->() {
508 assert (initialized());
509 return dataptr();
510 }
511
512 constexpr T const& operator *() const& {
513 return TR2_OPTIONAL_ASSERTED_EXPRESSION(initialized(), contained_val());
514 }
515
516 OPTIONAL_MUTABLE_CONSTEXPR T& operator *() & {
517 assert (initialized());
518 return contained_val();
519 }
520
521 OPTIONAL_MUTABLE_CONSTEXPR T&& operator *() && {
522 assert (initialized());
523 return constexpr_move(contained_val());
524 }
525
526 constexpr T const& value() const& {
527 return initialized() ? contained_val() : (throw bad_optional_access("bad optional access"), contained_val());
528 }
529
530 OPTIONAL_MUTABLE_CONSTEXPR T& value() & {
531 return initialized() ? contained_val() : (throw bad_optional_access("bad optional access"), contained_val());
532 }
533
534 OPTIONAL_MUTABLE_CONSTEXPR T&& value() && {
535 if (!initialized()) throw bad_optional_access("bad optional access");
536 return std::move(contained_val());
537 }
538
539# else
540
541 T* operator ->() {
542 assert (initialized());
543 return dataptr();
544 }
545
546 constexpr T const& operator *() const {
547 return TR2_OPTIONAL_ASSERTED_EXPRESSION(initialized(), contained_val());
548 }
549
550 T& operator *() {
551 assert (initialized());
552 return contained_val();
553 }
554
555 constexpr T const& value() const {
556 return initialized() ? contained_val() : (throw bad_optional_access("bad optional access"), contained_val());
557 }
558
559 T& value() {
560 return initialized() ? contained_val() : (throw bad_optional_access("bad optional access"), contained_val());
561 }
562
563# endif
564
565# if OPTIONAL_HAS_THIS_RVALUE_REFS == 1
566
567 template <class V>
568 constexpr T value_or(V&& v) const&
569 {
570 return *this ? **this : detail_::convert<T>(constexpr_forward<V>(v));
571 }
572
573# if OPTIONAL_HAS_MOVE_ACCESSORS == 1
574
575 template <class V>
576 OPTIONAL_MUTABLE_CONSTEXPR T value_or(V&& v) &&
577 {
578 return *this ? constexpr_move(const_cast<optional<T>&>(*this).contained_val()) : detail_::convert<T>(constexpr_forward<V>(v));
579 }
580
581# else
582
583 template <class V>
584 T value_or(V&& v) &&
585 {
586 return *this ? constexpr_move(const_cast<optional<T>&>(*this).contained_val()) : detail_::convert<T>(constexpr_forward<V>(v));
587 }
588
589# endif
590
591# else
592
593 template <class V>
594 constexpr T value_or(V&& v) const
595 {
596 return *this ? **this : detail_::convert<T>(constexpr_forward<V>(v));
597 }
598
599# endif
600
601 // 20.6.3.6, modifiers
602 void reset() noexcept { clear(); }
603};
604
605
606template <class T>
607class optional<T&>
608{
609 static_assert( !std::is_same<T, nullopt_t>::value, "bad T" );
610 static_assert( !std::is_same<T, in_place_t>::value, "bad T" );
611 T* ref;
612
613public:
614
615 // 20.5.5.1, construction/destruction
616 constexpr optional() noexcept : ref(nullptr) {}
617
618 constexpr optional(nullopt_t) noexcept : ref(nullptr) {}
619
620 constexpr optional(T& v) noexcept : ref(detail_::static_addressof(v)) {}
621
622 optional(T&&) = delete;
623
624 constexpr optional(const optional& rhs) noexcept : ref(rhs.ref) {}
625
626 explicit constexpr optional(in_place_t, T& v) noexcept : ref(detail_::static_addressof(v)) {}
627
628 explicit optional(in_place_t, T&&) = delete;
629
630 ~optional() = default;
631
632 // 20.5.5.2, mutation
633 optional& operator=(nullopt_t) noexcept {
634 ref = nullptr;
635 return *this;
636 }
637
638 // optional& operator=(const optional& rhs) noexcept {
639 // ref = rhs.ref;
640 // return *this;
641 // }
642
643 // optional& operator=(optional&& rhs) noexcept {
644 // ref = rhs.ref;
645 // return *this;
646 // }
647
648 template <typename U>
649 auto operator=(U&& rhs) noexcept
650 -> typename enable_if
651 <
652 is_same<typename decay<U>::type, optional<T&>>::value,
653 optional&
654 >::type
655 {
656 ref = rhs.ref;
657 return *this;
658 }
659
660 template <typename U>
661 auto operator=(U&& rhs) noexcept
662 -> typename enable_if
663 <
664 !is_same<typename decay<U>::type, optional<T&>>::value,
665 optional&
666 >::type
667 = delete;
668
669 void emplace(T& v) noexcept {
670 ref = detail_::static_addressof(v);
671 }
672
673 void emplace(T&&) = delete;
674
675
676 void swap(optional<T&>& rhs) noexcept
677 {
678 std::swap(ref, rhs.ref);
679 }
680
681 // 20.5.5.3, observers
682 constexpr T* operator->() const {
683 return TR2_OPTIONAL_ASSERTED_EXPRESSION(ref, ref);
684 }
685
686 constexpr T& operator*() const {
687 return TR2_OPTIONAL_ASSERTED_EXPRESSION(ref, *ref);
688 }
689
690 constexpr T& value() const {
691 return ref ? *ref : (throw bad_optional_access("bad optional access"), *ref);
692 }
693
694 explicit constexpr operator bool() const noexcept {
695 return ref != nullptr;
696 }
697
698 constexpr bool has_value() const noexcept {
699 return ref != nullptr;
700 }
701
702 template <class V>
703 constexpr typename decay<T>::type value_or(V&& v) const
704 {
705 return *this ? **this : detail_::convert<typename decay<T>::type>(constexpr_forward<V>(v));
706 }
707
708 // x.x.x.x, modifiers
709 void reset() noexcept { ref = nullptr; }
710};
711
712
713template <class T>
714class optional<T&&>
715{
716 static_assert( sizeof(T) == 0, "optional rvalue references disallowed" );
717};
718
719
720// 20.5.8, Relational operators
721template <class T> constexpr bool operator==(const optional<T>& x, const optional<T>& y)
722{
723 return bool(x) != bool(y) ? false : bool(x) == false ? true : *x == *y;
724}
725
726template <class T> constexpr bool operator!=(const optional<T>& x, const optional<T>& y)
727{
728 return !(x == y);
729}
730
731template <class T> constexpr bool operator<(const optional<T>& x, const optional<T>& y)
732{
733 return (!y) ? false : (!x) ? true : *x < *y;
734}
735
736template <class T> constexpr bool operator>(const optional<T>& x, const optional<T>& y)
737{
738 return (y < x);
739}
740
741template <class T> constexpr bool operator<=(const optional<T>& x, const optional<T>& y)
742{
743 return !(y < x);
744}
745
746template <class T> constexpr bool operator>=(const optional<T>& x, const optional<T>& y)
747{
748 return !(x < y);
749}
750
751
752// 20.5.9, Comparison with nullopt
753template <class T> constexpr bool operator==(const optional<T>& x, nullopt_t) noexcept
754{
755 return (!x);
756}
757
758template <class T> constexpr bool operator==(nullopt_t, const optional<T>& x) noexcept
759{
760 return (!x);
761}
762
763template <class T> constexpr bool operator!=(const optional<T>& x, nullopt_t) noexcept
764{
765 return bool(x);
766}
767
768template <class T> constexpr bool operator!=(nullopt_t, const optional<T>& x) noexcept
769{
770 return bool(x);
771}
772
773template <class T> constexpr bool operator<(const optional<T>&, nullopt_t) noexcept
774{
775 return false;
776}
777
778template <class T> constexpr bool operator<(nullopt_t, const optional<T>& x) noexcept
779{
780 return bool(x);
781}
782
783template <class T> constexpr bool operator<=(const optional<T>& x, nullopt_t) noexcept
784{
785 return (!x);
786}
787
788template <class T> constexpr bool operator<=(nullopt_t, const optional<T>&) noexcept
789{
790 return true;
791}
792
793template <class T> constexpr bool operator>(const optional<T>& x, nullopt_t) noexcept
794{
795 return bool(x);
796}
797
798template <class T> constexpr bool operator>(nullopt_t, const optional<T>&) noexcept
799{
800 return false;
801}
802
803template <class T> constexpr bool operator>=(const optional<T>&, nullopt_t) noexcept
804{
805 return true;
806}
807
808template <class T> constexpr bool operator>=(nullopt_t, const optional<T>& x) noexcept
809{
810 return (!x);
811}
812
813
814
815// 20.5.10, Comparison with T
816template <class T> constexpr bool operator==(const optional<T>& x, const T& v)
817{
818 return bool(x) ? *x == v : false;
819}
820
821template <class T> constexpr bool operator==(const T& v, const optional<T>& x)
822{
823 return bool(x) ? v == *x : false;
824}
825
826template <class T> constexpr bool operator!=(const optional<T>& x, const T& v)
827{
828 return bool(x) ? *x != v : true;
829}
830
831template <class T> constexpr bool operator!=(const T& v, const optional<T>& x)
832{
833 return bool(x) ? v != *x : true;
834}
835
836template <class T> constexpr bool operator<(const optional<T>& x, const T& v)
837{
838 return bool(x) ? *x < v : true;
839}
840
841template <class T> constexpr bool operator>(const T& v, const optional<T>& x)
842{
843 return bool(x) ? v > *x : true;
844}
845
846template <class T> constexpr bool operator>(const optional<T>& x, const T& v)
847{
848 return bool(x) ? *x > v : false;
849}
850
851template <class T> constexpr bool operator<(const T& v, const optional<T>& x)
852{
853 return bool(x) ? v < *x : false;
854}
855
856template <class T> constexpr bool operator>=(const optional<T>& x, const T& v)
857{
858 return bool(x) ? *x >= v : false;
859}
860
861template <class T> constexpr bool operator<=(const T& v, const optional<T>& x)
862{
863 return bool(x) ? v <= *x : false;
864}
865
866template <class T> constexpr bool operator<=(const optional<T>& x, const T& v)
867{
868 return bool(x) ? *x <= v : true;
869}
870
871template <class T> constexpr bool operator>=(const T& v, const optional<T>& x)
872{
873 return bool(x) ? v >= *x : true;
874}
875
876
877// Comparison of optional<T&> with T
878template <class T> constexpr bool operator==(const optional<T&>& x, const T& v)
879{
880 return bool(x) ? *x == v : false;
881}
882
883template <class T> constexpr bool operator==(const T& v, const optional<T&>& x)
884{
885 return bool(x) ? v == *x : false;
886}
887
888template <class T> constexpr bool operator!=(const optional<T&>& x, const T& v)
889{
890 return bool(x) ? *x != v : true;
891}
892
893template <class T> constexpr bool operator!=(const T& v, const optional<T&>& x)
894{
895 return bool(x) ? v != *x : true;
896}
897
898template <class T> constexpr bool operator<(const optional<T&>& x, const T& v)
899{
900 return bool(x) ? *x < v : true;
901}
902
903template <class T> constexpr bool operator>(const T& v, const optional<T&>& x)
904{
905 return bool(x) ? v > *x : true;
906}
907
908template <class T> constexpr bool operator>(const optional<T&>& x, const T& v)
909{
910 return bool(x) ? *x > v : false;
911}
912
913template <class T> constexpr bool operator<(const T& v, const optional<T&>& x)
914{
915 return bool(x) ? v < *x : false;
916}
917
918template <class T> constexpr bool operator>=(const optional<T&>& x, const T& v)
919{
920 return bool(x) ? *x >= v : false;
921}
922
923template <class T> constexpr bool operator<=(const T& v, const optional<T&>& x)
924{
925 return bool(x) ? v <= *x : false;
926}
927
928template <class T> constexpr bool operator<=(const optional<T&>& x, const T& v)
929{
930 return bool(x) ? *x <= v : true;
931}
932
933template <class T> constexpr bool operator>=(const T& v, const optional<T&>& x)
934{
935 return bool(x) ? v >= *x : true;
936}
937
938// Comparison of optional<T const&> with T
939template <class T> constexpr bool operator==(const optional<const T&>& x, const T& v)
940{
941 return bool(x) ? *x == v : false;
942}
943
944template <class T> constexpr bool operator==(const T& v, const optional<const T&>& x)
945{
946 return bool(x) ? v == *x : false;
947}
948
949template <class T> constexpr bool operator!=(const optional<const T&>& x, const T& v)
950{
951 return bool(x) ? *x != v : true;
952}
953
954template <class T> constexpr bool operator!=(const T& v, const optional<const T&>& x)
955{
956 return bool(x) ? v != *x : true;
957}
958
959template <class T> constexpr bool operator<(const optional<const T&>& x, const T& v)
960{
961 return bool(x) ? *x < v : true;
962}
963
964template <class T> constexpr bool operator>(const T& v, const optional<const T&>& x)
965{
966 return bool(x) ? v > *x : true;
967}
968
969template <class T> constexpr bool operator>(const optional<const T&>& x, const T& v)
970{
971 return bool(x) ? *x > v : false;
972}
973
974template <class T> constexpr bool operator<(const T& v, const optional<const T&>& x)
975{
976 return bool(x) ? v < *x : false;
977}
978
979template <class T> constexpr bool operator>=(const optional<const T&>& x, const T& v)
980{
981 return bool(x) ? *x >= v : false;
982}
983
984template <class T> constexpr bool operator<=(const T& v, const optional<const T&>& x)
985{
986 return bool(x) ? v <= *x : false;
987}
988
989template <class T> constexpr bool operator<=(const optional<const T&>& x, const T& v)
990{
991 return bool(x) ? *x <= v : true;
992}
993
994template <class T> constexpr bool operator>=(const T& v, const optional<const T&>& x)
995{
996 return bool(x) ? v >= *x : true;
997}
998
999
1000// 20.5.12, Specialized algorithms
1001template <class T>
1002void swap(optional<T>& x, optional<T>& y) noexcept(noexcept(x.swap(y)))
1003{
1004 x.swap(y);
1005}
1006
1007
1008template <class T>
1009constexpr optional<typename decay<T>::type> make_optional(T&& v)
1010{
1011 return optional<typename decay<T>::type>(constexpr_forward<T>(v));
1012}
1013
1014template <class X>
1015constexpr optional<X&> make_optional(reference_wrapper<X> v)
1016{
1017 return optional<X&>(v.get());
1018}
1019
1020
1021} // namespace experimental
1022} // namespace std
1023
1024namespace std
1025{
1026 template <typename T>
1027 struct hash<std::experimental::optional<T>>
1028 {
1029 typedef typename hash<T>::result_type result_type;
1030 typedef std::experimental::optional<T> argument_type;
1031
1032 constexpr result_type operator()(argument_type const& arg) const {
1033 return arg ? std::hash<T>{}(*arg) : result_type{};
1034 }
1035 };
1036
1037 template <typename T>
1038 struct hash<std::experimental::optional<T&>>
1039 {
1040 typedef typename hash<T>::result_type result_type;
1041 typedef std::experimental::optional<T&> argument_type;
1042
1043 constexpr result_type operator()(argument_type const& arg) const {
1044 return arg ? std::hash<T>{}(*arg) : result_type{};
1045 }
1046 };
1047}
1048
1049# undef TR2_OPTIONAL_REQUIRES
1050# undef TR2_OPTIONAL_ASSERTED_EXPRESSION
1051
1052# endif //___OPTIONAL_HPP___
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