xref: /freebsd/contrib/llvm-project/libcxx/include/future (revision 6be3386466ab79a84b48429ae66244f21526d3df)
1// -*- C++ -*-
2//===--------------------------- future -----------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP_FUTURE
11#define _LIBCPP_FUTURE
12
13/*
14    future synopsis
15
16namespace std
17{
18
19enum class future_errc
20{
21    future_already_retrieved = 1,
22    promise_already_satisfied,
23    no_state,
24    broken_promise
25};
26
27enum class launch
28{
29    async = 1,
30    deferred = 2,
31    any = async | deferred
32};
33
34enum class future_status
35{
36    ready,
37    timeout,
38    deferred
39};
40
41template <> struct is_error_code_enum<future_errc> : public true_type { };
42error_code make_error_code(future_errc e) noexcept;
43error_condition make_error_condition(future_errc e) noexcept;
44
45const error_category& future_category() noexcept;
46
47class future_error
48    : public logic_error
49{
50public:
51    future_error(error_code ec);  // exposition only
52    explicit future_error(future_errc); // C++17
53    const error_code& code() const noexcept;
54    const char*       what() const noexcept;
55};
56
57template <class R>
58class promise
59{
60public:
61    promise();
62    template <class Allocator>
63        promise(allocator_arg_t, const Allocator& a);
64    promise(promise&& rhs) noexcept;
65    promise(const promise& rhs) = delete;
66    ~promise();
67
68    // assignment
69    promise& operator=(promise&& rhs) noexcept;
70    promise& operator=(const promise& rhs) = delete;
71    void swap(promise& other) noexcept;
72
73    // retrieving the result
74    future<R> get_future();
75
76    // setting the result
77    void set_value(const R& r);
78    void set_value(R&& r);
79    void set_exception(exception_ptr p);
80
81    // setting the result with deferred notification
82    void set_value_at_thread_exit(const R& r);
83    void set_value_at_thread_exit(R&& r);
84    void set_exception_at_thread_exit(exception_ptr p);
85};
86
87template <class R>
88class promise<R&>
89{
90public:
91    promise();
92    template <class Allocator>
93        promise(allocator_arg_t, const Allocator& a);
94    promise(promise&& rhs) noexcept;
95    promise(const promise& rhs) = delete;
96    ~promise();
97
98    // assignment
99    promise& operator=(promise&& rhs) noexcept;
100    promise& operator=(const promise& rhs) = delete;
101    void swap(promise& other) noexcept;
102
103    // retrieving the result
104    future<R&> get_future();
105
106    // setting the result
107    void set_value(R& r);
108    void set_exception(exception_ptr p);
109
110    // setting the result with deferred notification
111    void set_value_at_thread_exit(R&);
112    void set_exception_at_thread_exit(exception_ptr p);
113};
114
115template <>
116class promise<void>
117{
118public:
119    promise();
120    template <class Allocator>
121        promise(allocator_arg_t, const Allocator& a);
122    promise(promise&& rhs) noexcept;
123    promise(const promise& rhs) = delete;
124    ~promise();
125
126    // assignment
127    promise& operator=(promise&& rhs) noexcept;
128    promise& operator=(const promise& rhs) = delete;
129    void swap(promise& other) noexcept;
130
131    // retrieving the result
132    future<void> get_future();
133
134    // setting the result
135    void set_value();
136    void set_exception(exception_ptr p);
137
138    // setting the result with deferred notification
139    void set_value_at_thread_exit();
140    void set_exception_at_thread_exit(exception_ptr p);
141};
142
143template <class R> void swap(promise<R>& x, promise<R>& y) noexcept;
144
145template <class R, class Alloc>
146    struct uses_allocator<promise<R>, Alloc> : public true_type {};
147
148template <class R>
149class future
150{
151public:
152    future() noexcept;
153    future(future&&) noexcept;
154    future(const future& rhs) = delete;
155    ~future();
156    future& operator=(const future& rhs) = delete;
157    future& operator=(future&&) noexcept;
158    shared_future<R> share() noexcept;
159
160    // retrieving the value
161    R get();
162
163    // functions to check state
164    bool valid() const noexcept;
165
166    void wait() const;
167    template <class Rep, class Period>
168        future_status
169        wait_for(const chrono::duration<Rep, Period>& rel_time) const;
170    template <class Clock, class Duration>
171        future_status
172        wait_until(const chrono::time_point<Clock, Duration>& abs_time) const;
173};
174
175template <class R>
176class future<R&>
177{
178public:
179    future() noexcept;
180    future(future&&) noexcept;
181    future(const future& rhs) = delete;
182    ~future();
183    future& operator=(const future& rhs) = delete;
184    future& operator=(future&&) noexcept;
185    shared_future<R&> share() noexcept;
186
187    // retrieving the value
188    R& get();
189
190    // functions to check state
191    bool valid() const noexcept;
192
193    void wait() const;
194    template <class Rep, class Period>
195        future_status
196        wait_for(const chrono::duration<Rep, Period>& rel_time) const;
197    template <class Clock, class Duration>
198        future_status
199        wait_until(const chrono::time_point<Clock, Duration>& abs_time) const;
200};
201
202template <>
203class future<void>
204{
205public:
206    future() noexcept;
207    future(future&&) noexcept;
208    future(const future& rhs) = delete;
209    ~future();
210    future& operator=(const future& rhs) = delete;
211    future& operator=(future&&) noexcept;
212    shared_future<void> share() noexcept;
213
214    // retrieving the value
215    void get();
216
217    // functions to check state
218    bool valid() const noexcept;
219
220    void wait() const;
221    template <class Rep, class Period>
222        future_status
223        wait_for(const chrono::duration<Rep, Period>& rel_time) const;
224    template <class Clock, class Duration>
225        future_status
226        wait_until(const chrono::time_point<Clock, Duration>& abs_time) const;
227};
228
229template <class R>
230class shared_future
231{
232public:
233    shared_future() noexcept;
234    shared_future(const shared_future& rhs);
235    shared_future(future<R>&&) noexcept;
236    shared_future(shared_future&& rhs) noexcept;
237    ~shared_future();
238    shared_future& operator=(const shared_future& rhs);
239    shared_future& operator=(shared_future&& rhs) noexcept;
240
241    // retrieving the value
242    const R& get() const;
243
244    // functions to check state
245    bool valid() const noexcept;
246
247    void wait() const;
248    template <class Rep, class Period>
249        future_status
250        wait_for(const chrono::duration<Rep, Period>& rel_time) const;
251    template <class Clock, class Duration>
252        future_status
253        wait_until(const chrono::time_point<Clock, Duration>& abs_time) const;
254};
255
256template <class R>
257class shared_future<R&>
258{
259public:
260    shared_future() noexcept;
261    shared_future(const shared_future& rhs);
262    shared_future(future<R&>&&) noexcept;
263    shared_future(shared_future&& rhs) noexcept;
264    ~shared_future();
265    shared_future& operator=(const shared_future& rhs);
266    shared_future& operator=(shared_future&& rhs) noexcept;
267
268    // retrieving the value
269    R& get() const;
270
271    // functions to check state
272    bool valid() const noexcept;
273
274    void wait() const;
275    template <class Rep, class Period>
276        future_status
277        wait_for(const chrono::duration<Rep, Period>& rel_time) const;
278    template <class Clock, class Duration>
279        future_status
280        wait_until(const chrono::time_point<Clock, Duration>& abs_time) const;
281};
282
283template <>
284class shared_future<void>
285{
286public:
287    shared_future() noexcept;
288    shared_future(const shared_future& rhs);
289    shared_future(future<void>&&) noexcept;
290    shared_future(shared_future&& rhs) noexcept;
291    ~shared_future();
292    shared_future& operator=(const shared_future& rhs);
293    shared_future& operator=(shared_future&& rhs) noexcept;
294
295    // retrieving the value
296    void get() const;
297
298    // functions to check state
299    bool valid() const noexcept;
300
301    void wait() const;
302    template <class Rep, class Period>
303        future_status
304        wait_for(const chrono::duration<Rep, Period>& rel_time) const;
305    template <class Clock, class Duration>
306        future_status
307        wait_until(const chrono::time_point<Clock, Duration>& abs_time) const;
308};
309
310template <class F, class... Args>
311  future<typename result_of<typename decay<F>::type(typename decay<Args>::type...)>::type>
312  async(F&& f, Args&&... args);
313
314template <class F, class... Args>
315  future<typename result_of<typename decay<F>::type(typename decay<Args>::type...)>::type>
316  async(launch policy, F&& f, Args&&... args);
317
318template <class> class packaged_task; // undefined
319
320template <class R, class... ArgTypes>
321class packaged_task<R(ArgTypes...)>
322{
323public:
324    typedef R result_type; // extension
325
326    // construction and destruction
327    packaged_task() noexcept;
328    template <class F>
329        explicit packaged_task(F&& f);
330    template <class F, class Allocator>
331        packaged_task(allocator_arg_t, const Allocator& a, F&& f);
332    ~packaged_task();
333
334    // no copy
335    packaged_task(const packaged_task&) = delete;
336    packaged_task& operator=(const packaged_task&) = delete;
337
338    // move support
339    packaged_task(packaged_task&& other) noexcept;
340    packaged_task& operator=(packaged_task&& other) noexcept;
341    void swap(packaged_task& other) noexcept;
342
343    bool valid() const noexcept;
344
345    // result retrieval
346    future<R> get_future();
347
348    // execution
349    void operator()(ArgTypes... );
350    void make_ready_at_thread_exit(ArgTypes...);
351
352    void reset();
353};
354
355template <class R>
356  void swap(packaged_task<R(ArgTypes...)&, packaged_task<R(ArgTypes...)>&) noexcept;
357
358template <class R, class Alloc> struct uses_allocator<packaged_task<R>, Alloc>;
359
360}  // std
361
362*/
363
364#include <__config>
365#include <system_error>
366#include <memory>
367#include <chrono>
368#include <exception>
369#include <mutex>
370#include <thread>
371
372#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
373#pragma GCC system_header
374#endif
375
376#ifdef _LIBCPP_HAS_NO_THREADS
377#error <future> is not supported on this single threaded system
378#else // !_LIBCPP_HAS_NO_THREADS
379
380_LIBCPP_BEGIN_NAMESPACE_STD
381
382//enum class future_errc
383_LIBCPP_DECLARE_STRONG_ENUM(future_errc)
384{
385    future_already_retrieved = 1,
386    promise_already_satisfied,
387    no_state,
388    broken_promise
389};
390_LIBCPP_DECLARE_STRONG_ENUM_EPILOG(future_errc)
391
392template <>
393struct _LIBCPP_TEMPLATE_VIS is_error_code_enum<future_errc> : public true_type {};
394
395#ifdef _LIBCPP_HAS_NO_STRONG_ENUMS
396template <>
397struct _LIBCPP_TEMPLATE_VIS is_error_code_enum<future_errc::__lx> : public true_type { };
398#endif
399
400//enum class launch
401_LIBCPP_DECLARE_STRONG_ENUM(launch)
402{
403    async = 1,
404    deferred = 2,
405    any = async | deferred
406};
407_LIBCPP_DECLARE_STRONG_ENUM_EPILOG(launch)
408
409#ifndef _LIBCPP_HAS_NO_STRONG_ENUMS
410
411typedef underlying_type<launch>::type __launch_underlying_type;
412
413inline _LIBCPP_INLINE_VISIBILITY
414_LIBCPP_CONSTEXPR
415launch
416operator&(launch __x, launch __y)
417{
418    return static_cast<launch>(static_cast<__launch_underlying_type>(__x) &
419                               static_cast<__launch_underlying_type>(__y));
420}
421
422inline _LIBCPP_INLINE_VISIBILITY
423_LIBCPP_CONSTEXPR
424launch
425operator|(launch __x, launch __y)
426{
427    return static_cast<launch>(static_cast<__launch_underlying_type>(__x) |
428                               static_cast<__launch_underlying_type>(__y));
429}
430
431inline _LIBCPP_INLINE_VISIBILITY
432_LIBCPP_CONSTEXPR
433launch
434operator^(launch __x, launch __y)
435{
436    return static_cast<launch>(static_cast<__launch_underlying_type>(__x) ^
437                               static_cast<__launch_underlying_type>(__y));
438}
439
440inline _LIBCPP_INLINE_VISIBILITY
441_LIBCPP_CONSTEXPR
442launch
443operator~(launch __x)
444{
445    return static_cast<launch>(~static_cast<__launch_underlying_type>(__x) & 3);
446}
447
448inline _LIBCPP_INLINE_VISIBILITY
449launch&
450operator&=(launch& __x, launch __y)
451{
452    __x = __x & __y; return __x;
453}
454
455inline _LIBCPP_INLINE_VISIBILITY
456launch&
457operator|=(launch& __x, launch __y)
458{
459    __x = __x | __y; return __x;
460}
461
462inline _LIBCPP_INLINE_VISIBILITY
463launch&
464operator^=(launch& __x, launch __y)
465{
466    __x = __x ^ __y; return __x;
467}
468
469#endif  // !_LIBCPP_HAS_NO_STRONG_ENUMS
470
471//enum class future_status
472_LIBCPP_DECLARE_STRONG_ENUM(future_status)
473{
474    ready,
475    timeout,
476    deferred
477};
478_LIBCPP_DECLARE_STRONG_ENUM_EPILOG(future_status)
479
480_LIBCPP_FUNC_VIS
481const error_category& future_category() _NOEXCEPT;
482
483inline _LIBCPP_INLINE_VISIBILITY
484error_code
485make_error_code(future_errc __e) _NOEXCEPT
486{
487    return error_code(static_cast<int>(__e), future_category());
488}
489
490inline _LIBCPP_INLINE_VISIBILITY
491error_condition
492make_error_condition(future_errc __e) _NOEXCEPT
493{
494    return error_condition(static_cast<int>(__e), future_category());
495}
496
497class _LIBCPP_EXCEPTION_ABI _LIBCPP_AVAILABILITY_FUTURE_ERROR future_error
498    : public logic_error
499{
500    error_code __ec_;
501public:
502    future_error(error_code __ec);
503#if _LIBCPP_STD_VERS > 14
504    explicit future_error(future_errc _Ev) : logic_error(), __ec_(make_error_code(_Ev)) {}
505#endif
506    _LIBCPP_INLINE_VISIBILITY
507    const error_code& code() const _NOEXCEPT {return __ec_;}
508
509    future_error(const future_error&) _NOEXCEPT = default;
510    virtual ~future_error() _NOEXCEPT;
511};
512
513_LIBCPP_NORETURN inline _LIBCPP_INLINE_VISIBILITY
514#ifndef _LIBCPP_NO_EXCEPTIONS
515_LIBCPP_AVAILABILITY_FUTURE_ERROR
516#endif
517void __throw_future_error(future_errc _Ev)
518{
519#ifndef _LIBCPP_NO_EXCEPTIONS
520    throw future_error(make_error_code(_Ev));
521#else
522    ((void)_Ev);
523    _VSTD::abort();
524#endif
525}
526
527class _LIBCPP_TYPE_VIS _LIBCPP_AVAILABILITY_FUTURE __assoc_sub_state
528    : public __shared_count
529{
530protected:
531    exception_ptr __exception_;
532    mutable mutex __mut_;
533    mutable condition_variable __cv_;
534    unsigned __state_;
535
536    virtual void __on_zero_shared() _NOEXCEPT;
537    void __sub_wait(unique_lock<mutex>& __lk);
538public:
539    enum
540    {
541        __constructed = 1,
542        __future_attached = 2,
543        ready = 4,
544        deferred = 8
545    };
546
547    _LIBCPP_INLINE_VISIBILITY
548    __assoc_sub_state() : __state_(0) {}
549
550    _LIBCPP_INLINE_VISIBILITY
551    bool __has_value() const
552        {return (__state_ & __constructed) || (__exception_ != nullptr);}
553
554    _LIBCPP_INLINE_VISIBILITY
555    void __attach_future() {
556        lock_guard<mutex> __lk(__mut_);
557        bool __has_future_attached = (__state_ & __future_attached) != 0;
558        if (__has_future_attached)
559            __throw_future_error(future_errc::future_already_retrieved);
560        this->__add_shared();
561        __state_ |= __future_attached;
562    }
563
564    _LIBCPP_INLINE_VISIBILITY
565    void __set_deferred() {__state_ |= deferred;}
566
567    void __make_ready();
568    _LIBCPP_INLINE_VISIBILITY
569    bool __is_ready() const {return (__state_ & ready) != 0;}
570
571    void set_value();
572    void set_value_at_thread_exit();
573
574    void set_exception(exception_ptr __p);
575    void set_exception_at_thread_exit(exception_ptr __p);
576
577    void copy();
578
579    void wait();
580    template <class _Rep, class _Period>
581        future_status
582        _LIBCPP_INLINE_VISIBILITY
583        wait_for(const chrono::duration<_Rep, _Period>& __rel_time) const;
584    template <class _Clock, class _Duration>
585        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
586        future_status
587        wait_until(const chrono::time_point<_Clock, _Duration>& __abs_time) const;
588
589    virtual void __execute();
590};
591
592template <class _Clock, class _Duration>
593future_status
594__assoc_sub_state::wait_until(const chrono::time_point<_Clock, _Duration>& __abs_time) const
595{
596    unique_lock<mutex> __lk(__mut_);
597    if (__state_ & deferred)
598        return future_status::deferred;
599    while (!(__state_ & ready) && _Clock::now() < __abs_time)
600        __cv_.wait_until(__lk, __abs_time);
601    if (__state_ & ready)
602        return future_status::ready;
603    return future_status::timeout;
604}
605
606template <class _Rep, class _Period>
607inline
608future_status
609__assoc_sub_state::wait_for(const chrono::duration<_Rep, _Period>& __rel_time) const
610{
611    return wait_until(chrono::steady_clock::now() + __rel_time);
612}
613
614template <class _Rp>
615class _LIBCPP_AVAILABILITY_FUTURE _LIBCPP_HIDDEN __assoc_state
616    : public __assoc_sub_state
617{
618    typedef __assoc_sub_state base;
619    typedef typename aligned_storage<sizeof(_Rp), alignment_of<_Rp>::value>::type _Up;
620protected:
621    _Up __value_;
622
623    virtual void __on_zero_shared() _NOEXCEPT;
624public:
625
626    template <class _Arg>
627#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
628        void set_value(_Arg&& __arg);
629#else
630        void set_value(_Arg& __arg);
631#endif
632
633    template <class _Arg>
634#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
635        void set_value_at_thread_exit(_Arg&& __arg);
636#else
637        void set_value_at_thread_exit(_Arg& __arg);
638#endif
639
640    _Rp move();
641    typename add_lvalue_reference<_Rp>::type copy();
642};
643
644template <class _Rp>
645void
646__assoc_state<_Rp>::__on_zero_shared() _NOEXCEPT
647{
648    if (this->__state_ & base::__constructed)
649        reinterpret_cast<_Rp*>(&__value_)->~_Rp();
650    delete this;
651}
652
653template <class _Rp>
654template <class _Arg>
655_LIBCPP_AVAILABILITY_FUTURE
656void
657#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
658__assoc_state<_Rp>::set_value(_Arg&& __arg)
659#else
660__assoc_state<_Rp>::set_value(_Arg& __arg)
661#endif
662{
663    unique_lock<mutex> __lk(this->__mut_);
664    if (this->__has_value())
665        __throw_future_error(future_errc::promise_already_satisfied);
666    ::new(&__value_) _Rp(_VSTD::forward<_Arg>(__arg));
667    this->__state_ |= base::__constructed | base::ready;
668    __cv_.notify_all();
669}
670
671template <class _Rp>
672template <class _Arg>
673void
674#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
675__assoc_state<_Rp>::set_value_at_thread_exit(_Arg&& __arg)
676#else
677__assoc_state<_Rp>::set_value_at_thread_exit(_Arg& __arg)
678#endif
679{
680    unique_lock<mutex> __lk(this->__mut_);
681    if (this->__has_value())
682        __throw_future_error(future_errc::promise_already_satisfied);
683    ::new(&__value_) _Rp(_VSTD::forward<_Arg>(__arg));
684    this->__state_ |= base::__constructed;
685    __thread_local_data()->__make_ready_at_thread_exit(this);
686}
687
688template <class _Rp>
689_Rp
690__assoc_state<_Rp>::move()
691{
692    unique_lock<mutex> __lk(this->__mut_);
693    this->__sub_wait(__lk);
694    if (this->__exception_ != nullptr)
695        rethrow_exception(this->__exception_);
696    return _VSTD::move(*reinterpret_cast<_Rp*>(&__value_));
697}
698
699template <class _Rp>
700typename add_lvalue_reference<_Rp>::type
701__assoc_state<_Rp>::copy()
702{
703    unique_lock<mutex> __lk(this->__mut_);
704    this->__sub_wait(__lk);
705    if (this->__exception_ != nullptr)
706        rethrow_exception(this->__exception_);
707    return *reinterpret_cast<_Rp*>(&__value_);
708}
709
710template <class _Rp>
711class _LIBCPP_AVAILABILITY_FUTURE __assoc_state<_Rp&>
712    : public __assoc_sub_state
713{
714    typedef __assoc_sub_state base;
715    typedef _Rp* _Up;
716protected:
717    _Up __value_;
718
719    virtual void __on_zero_shared() _NOEXCEPT;
720public:
721
722    void set_value(_Rp& __arg);
723    void set_value_at_thread_exit(_Rp& __arg);
724
725    _Rp& copy();
726};
727
728template <class _Rp>
729void
730__assoc_state<_Rp&>::__on_zero_shared() _NOEXCEPT
731{
732    delete this;
733}
734
735template <class _Rp>
736void
737__assoc_state<_Rp&>::set_value(_Rp& __arg)
738{
739    unique_lock<mutex> __lk(this->__mut_);
740    if (this->__has_value())
741        __throw_future_error(future_errc::promise_already_satisfied);
742    __value_ = _VSTD::addressof(__arg);
743    this->__state_ |= base::__constructed | base::ready;
744    __cv_.notify_all();
745}
746
747template <class _Rp>
748void
749__assoc_state<_Rp&>::set_value_at_thread_exit(_Rp& __arg)
750{
751    unique_lock<mutex> __lk(this->__mut_);
752    if (this->__has_value())
753        __throw_future_error(future_errc::promise_already_satisfied);
754    __value_ = _VSTD::addressof(__arg);
755    this->__state_ |= base::__constructed;
756    __thread_local_data()->__make_ready_at_thread_exit(this);
757}
758
759template <class _Rp>
760_Rp&
761__assoc_state<_Rp&>::copy()
762{
763    unique_lock<mutex> __lk(this->__mut_);
764    this->__sub_wait(__lk);
765    if (this->__exception_ != nullptr)
766        rethrow_exception(this->__exception_);
767    return *__value_;
768}
769
770template <class _Rp, class _Alloc>
771class _LIBCPP_AVAILABILITY_FUTURE __assoc_state_alloc
772    : public __assoc_state<_Rp>
773{
774    typedef __assoc_state<_Rp> base;
775    _Alloc __alloc_;
776
777    virtual void __on_zero_shared() _NOEXCEPT;
778public:
779    _LIBCPP_INLINE_VISIBILITY
780    explicit __assoc_state_alloc(const _Alloc& __a)
781        : __alloc_(__a) {}
782};
783
784template <class _Rp, class _Alloc>
785void
786__assoc_state_alloc<_Rp, _Alloc>::__on_zero_shared() _NOEXCEPT
787{
788    if (this->__state_ & base::__constructed)
789        reinterpret_cast<_Rp*>(_VSTD::addressof(this->__value_))->~_Rp();
790    typedef typename __allocator_traits_rebind<_Alloc, __assoc_state_alloc>::type _Al;
791    typedef allocator_traits<_Al> _ATraits;
792    typedef pointer_traits<typename _ATraits::pointer> _PTraits;
793    _Al __a(__alloc_);
794    this->~__assoc_state_alloc();
795    __a.deallocate(_PTraits::pointer_to(*this), 1);
796}
797
798template <class _Rp, class _Alloc>
799class _LIBCPP_AVAILABILITY_FUTURE __assoc_state_alloc<_Rp&, _Alloc>
800    : public __assoc_state<_Rp&>
801{
802    typedef __assoc_state<_Rp&> base;
803    _Alloc __alloc_;
804
805    virtual void __on_zero_shared() _NOEXCEPT;
806public:
807    _LIBCPP_INLINE_VISIBILITY
808    explicit __assoc_state_alloc(const _Alloc& __a)
809        : __alloc_(__a) {}
810};
811
812template <class _Rp, class _Alloc>
813void
814__assoc_state_alloc<_Rp&, _Alloc>::__on_zero_shared() _NOEXCEPT
815{
816    typedef typename __allocator_traits_rebind<_Alloc, __assoc_state_alloc>::type _Al;
817    typedef allocator_traits<_Al> _ATraits;
818    typedef pointer_traits<typename _ATraits::pointer> _PTraits;
819    _Al __a(__alloc_);
820    this->~__assoc_state_alloc();
821    __a.deallocate(_PTraits::pointer_to(*this), 1);
822}
823
824template <class _Alloc>
825class _LIBCPP_AVAILABILITY_FUTURE __assoc_sub_state_alloc
826    : public __assoc_sub_state
827{
828    typedef __assoc_sub_state base;
829    _Alloc __alloc_;
830
831    virtual void __on_zero_shared() _NOEXCEPT;
832public:
833    _LIBCPP_INLINE_VISIBILITY
834    explicit __assoc_sub_state_alloc(const _Alloc& __a)
835        : __alloc_(__a) {}
836};
837
838template <class _Alloc>
839void
840__assoc_sub_state_alloc<_Alloc>::__on_zero_shared() _NOEXCEPT
841{
842    typedef typename __allocator_traits_rebind<_Alloc, __assoc_sub_state_alloc>::type _Al;
843    typedef allocator_traits<_Al> _ATraits;
844    typedef pointer_traits<typename _ATraits::pointer> _PTraits;
845    _Al __a(__alloc_);
846    this->~__assoc_sub_state_alloc();
847    __a.deallocate(_PTraits::pointer_to(*this), 1);
848}
849
850template <class _Rp, class _Fp>
851class _LIBCPP_AVAILABILITY_FUTURE __deferred_assoc_state
852    : public __assoc_state<_Rp>
853{
854    typedef __assoc_state<_Rp> base;
855
856    _Fp __func_;
857
858public:
859#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
860    _LIBCPP_INLINE_VISIBILITY
861    explicit __deferred_assoc_state(_Fp&& __f);
862#endif
863
864    virtual void __execute();
865};
866
867#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
868
869template <class _Rp, class _Fp>
870inline
871__deferred_assoc_state<_Rp, _Fp>::__deferred_assoc_state(_Fp&& __f)
872    : __func_(_VSTD::forward<_Fp>(__f))
873{
874    this->__set_deferred();
875}
876
877#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
878
879template <class _Rp, class _Fp>
880void
881__deferred_assoc_state<_Rp, _Fp>::__execute()
882{
883#ifndef _LIBCPP_NO_EXCEPTIONS
884    try
885    {
886#endif  // _LIBCPP_NO_EXCEPTIONS
887        this->set_value(__func_());
888#ifndef _LIBCPP_NO_EXCEPTIONS
889    }
890    catch (...)
891    {
892        this->set_exception(current_exception());
893    }
894#endif  // _LIBCPP_NO_EXCEPTIONS
895}
896
897template <class _Fp>
898class _LIBCPP_AVAILABILITY_FUTURE __deferred_assoc_state<void, _Fp>
899    : public __assoc_sub_state
900{
901    typedef __assoc_sub_state base;
902
903    _Fp __func_;
904
905public:
906#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
907    _LIBCPP_INLINE_VISIBILITY
908    explicit __deferred_assoc_state(_Fp&& __f);
909#endif
910
911    virtual void __execute();
912};
913
914#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
915
916template <class _Fp>
917inline
918__deferred_assoc_state<void, _Fp>::__deferred_assoc_state(_Fp&& __f)
919    : __func_(_VSTD::forward<_Fp>(__f))
920{
921    this->__set_deferred();
922}
923
924#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
925
926template <class _Fp>
927void
928__deferred_assoc_state<void, _Fp>::__execute()
929{
930#ifndef _LIBCPP_NO_EXCEPTIONS
931    try
932    {
933#endif  // _LIBCPP_NO_EXCEPTIONS
934        __func_();
935        this->set_value();
936#ifndef _LIBCPP_NO_EXCEPTIONS
937    }
938    catch (...)
939    {
940        this->set_exception(current_exception());
941    }
942#endif  // _LIBCPP_NO_EXCEPTIONS
943}
944
945template <class _Rp, class _Fp>
946class _LIBCPP_AVAILABILITY_FUTURE __async_assoc_state
947    : public __assoc_state<_Rp>
948{
949    typedef __assoc_state<_Rp> base;
950
951    _Fp __func_;
952
953    virtual void __on_zero_shared() _NOEXCEPT;
954public:
955#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
956    _LIBCPP_INLINE_VISIBILITY
957    explicit __async_assoc_state(_Fp&& __f);
958#endif
959
960    virtual void __execute();
961};
962
963#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
964
965template <class _Rp, class _Fp>
966inline
967__async_assoc_state<_Rp, _Fp>::__async_assoc_state(_Fp&& __f)
968    : __func_(_VSTD::forward<_Fp>(__f))
969{
970}
971
972#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
973
974template <class _Rp, class _Fp>
975void
976__async_assoc_state<_Rp, _Fp>::__execute()
977{
978#ifndef _LIBCPP_NO_EXCEPTIONS
979    try
980    {
981#endif  // _LIBCPP_NO_EXCEPTIONS
982        this->set_value(__func_());
983#ifndef _LIBCPP_NO_EXCEPTIONS
984    }
985    catch (...)
986    {
987        this->set_exception(current_exception());
988    }
989#endif  // _LIBCPP_NO_EXCEPTIONS
990}
991
992template <class _Rp, class _Fp>
993void
994__async_assoc_state<_Rp, _Fp>::__on_zero_shared() _NOEXCEPT
995{
996    this->wait();
997    base::__on_zero_shared();
998}
999
1000template <class _Fp>
1001class _LIBCPP_AVAILABILITY_FUTURE __async_assoc_state<void, _Fp>
1002    : public __assoc_sub_state
1003{
1004    typedef __assoc_sub_state base;
1005
1006    _Fp __func_;
1007
1008    virtual void __on_zero_shared() _NOEXCEPT;
1009public:
1010#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1011    _LIBCPP_INLINE_VISIBILITY
1012    explicit __async_assoc_state(_Fp&& __f);
1013#endif
1014
1015    virtual void __execute();
1016};
1017
1018#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1019
1020template <class _Fp>
1021inline
1022__async_assoc_state<void, _Fp>::__async_assoc_state(_Fp&& __f)
1023    : __func_(_VSTD::forward<_Fp>(__f))
1024{
1025}
1026
1027#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1028
1029template <class _Fp>
1030void
1031__async_assoc_state<void, _Fp>::__execute()
1032{
1033#ifndef _LIBCPP_NO_EXCEPTIONS
1034    try
1035    {
1036#endif  // _LIBCPP_NO_EXCEPTIONS
1037        __func_();
1038        this->set_value();
1039#ifndef _LIBCPP_NO_EXCEPTIONS
1040    }
1041    catch (...)
1042    {
1043        this->set_exception(current_exception());
1044    }
1045#endif  // _LIBCPP_NO_EXCEPTIONS
1046}
1047
1048template <class _Fp>
1049void
1050__async_assoc_state<void, _Fp>::__on_zero_shared() _NOEXCEPT
1051{
1052    this->wait();
1053    base::__on_zero_shared();
1054}
1055
1056template <class _Rp> class _LIBCPP_TEMPLATE_VIS promise;
1057template <class _Rp> class _LIBCPP_TEMPLATE_VIS shared_future;
1058
1059// future
1060
1061template <class _Rp> class _LIBCPP_TEMPLATE_VIS future;
1062
1063template <class _Rp, class _Fp>
1064_LIBCPP_INLINE_VISIBILITY future<_Rp>
1065#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1066__make_deferred_assoc_state(_Fp&& __f);
1067#else
1068__make_deferred_assoc_state(_Fp __f);
1069#endif
1070
1071template <class _Rp, class _Fp>
1072_LIBCPP_INLINE_VISIBILITY future<_Rp>
1073#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1074__make_async_assoc_state(_Fp&& __f);
1075#else
1076__make_async_assoc_state(_Fp __f);
1077#endif
1078
1079template <class _Rp>
1080class _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FUTURE future
1081{
1082    __assoc_state<_Rp>* __state_;
1083
1084    explicit future(__assoc_state<_Rp>* __state);
1085
1086    template <class> friend class promise;
1087    template <class> friend class shared_future;
1088
1089#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1090    template <class _R1, class _Fp>
1091        friend future<_R1> __make_deferred_assoc_state(_Fp&& __f);
1092    template <class _R1, class _Fp>
1093        friend future<_R1> __make_async_assoc_state(_Fp&& __f);
1094#else
1095    template <class _R1, class _Fp>
1096        friend future<_R1> __make_deferred_assoc_state(_Fp __f);
1097    template <class _R1, class _Fp>
1098        friend future<_R1> __make_async_assoc_state(_Fp __f);
1099#endif
1100
1101public:
1102    _LIBCPP_INLINE_VISIBILITY
1103    future() _NOEXCEPT : __state_(nullptr) {}
1104#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1105    _LIBCPP_INLINE_VISIBILITY
1106    future(future&& __rhs) _NOEXCEPT
1107        : __state_(__rhs.__state_) {__rhs.__state_ = nullptr;}
1108    future(const future&) = delete;
1109    future& operator=(const future&) = delete;
1110    _LIBCPP_INLINE_VISIBILITY
1111    future& operator=(future&& __rhs) _NOEXCEPT
1112        {
1113            future(std::move(__rhs)).swap(*this);
1114            return *this;
1115        }
1116#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1117private:
1118    future(const future&);
1119    future& operator=(const future&);
1120public:
1121#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1122    ~future();
1123    _LIBCPP_INLINE_VISIBILITY
1124    shared_future<_Rp> share() _NOEXCEPT;
1125
1126    // retrieving the value
1127    _Rp get();
1128
1129    _LIBCPP_INLINE_VISIBILITY
1130    void swap(future& __rhs) _NOEXCEPT {_VSTD::swap(__state_, __rhs.__state_);}
1131
1132    // functions to check state
1133    _LIBCPP_INLINE_VISIBILITY
1134    bool valid() const _NOEXCEPT {return __state_ != nullptr;}
1135
1136    _LIBCPP_INLINE_VISIBILITY
1137    void wait() const {__state_->wait();}
1138    template <class _Rep, class _Period>
1139        _LIBCPP_INLINE_VISIBILITY
1140        future_status
1141        wait_for(const chrono::duration<_Rep, _Period>& __rel_time) const
1142            {return __state_->wait_for(__rel_time);}
1143    template <class _Clock, class _Duration>
1144        _LIBCPP_INLINE_VISIBILITY
1145        future_status
1146        wait_until(const chrono::time_point<_Clock, _Duration>& __abs_time) const
1147            {return __state_->wait_until(__abs_time);}
1148};
1149
1150template <class _Rp>
1151future<_Rp>::future(__assoc_state<_Rp>* __state)
1152    : __state_(__state)
1153{
1154    __state_->__attach_future();
1155}
1156
1157struct __release_shared_count
1158{
1159    void operator()(__shared_count* p) {p->__release_shared();}
1160};
1161
1162template <class _Rp>
1163future<_Rp>::~future()
1164{
1165    if (__state_)
1166        __state_->__release_shared();
1167}
1168
1169template <class _Rp>
1170_Rp
1171future<_Rp>::get()
1172{
1173    unique_ptr<__shared_count, __release_shared_count> __(__state_);
1174    __assoc_state<_Rp>* __s = __state_;
1175    __state_ = nullptr;
1176    return __s->move();
1177}
1178
1179template <class _Rp>
1180class _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FUTURE future<_Rp&>
1181{
1182    __assoc_state<_Rp&>* __state_;
1183
1184    explicit future(__assoc_state<_Rp&>* __state);
1185
1186    template <class> friend class promise;
1187    template <class> friend class shared_future;
1188
1189#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1190    template <class _R1, class _Fp>
1191        friend future<_R1> __make_deferred_assoc_state(_Fp&& __f);
1192    template <class _R1, class _Fp>
1193        friend future<_R1> __make_async_assoc_state(_Fp&& __f);
1194#else
1195    template <class _R1, class _Fp>
1196        friend future<_R1> __make_deferred_assoc_state(_Fp __f);
1197    template <class _R1, class _Fp>
1198        friend future<_R1> __make_async_assoc_state(_Fp __f);
1199#endif
1200
1201public:
1202    _LIBCPP_INLINE_VISIBILITY
1203    future() _NOEXCEPT : __state_(nullptr) {}
1204#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1205    _LIBCPP_INLINE_VISIBILITY
1206    future(future&& __rhs) _NOEXCEPT
1207        : __state_(__rhs.__state_) {__rhs.__state_ = nullptr;}
1208    future(const future&) = delete;
1209    future& operator=(const future&) = delete;
1210    _LIBCPP_INLINE_VISIBILITY
1211    future& operator=(future&& __rhs) _NOEXCEPT
1212        {
1213            future(std::move(__rhs)).swap(*this);
1214            return *this;
1215        }
1216#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1217private:
1218    future(const future&);
1219    future& operator=(const future&);
1220public:
1221#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1222    ~future();
1223    _LIBCPP_INLINE_VISIBILITY
1224    shared_future<_Rp&> share() _NOEXCEPT;
1225
1226    // retrieving the value
1227    _Rp& get();
1228
1229    _LIBCPP_INLINE_VISIBILITY
1230    void swap(future& __rhs) _NOEXCEPT {_VSTD::swap(__state_, __rhs.__state_);}
1231
1232    // functions to check state
1233    _LIBCPP_INLINE_VISIBILITY
1234    bool valid() const _NOEXCEPT {return __state_ != nullptr;}
1235
1236    _LIBCPP_INLINE_VISIBILITY
1237    void wait() const {__state_->wait();}
1238    template <class _Rep, class _Period>
1239        _LIBCPP_INLINE_VISIBILITY
1240        future_status
1241        wait_for(const chrono::duration<_Rep, _Period>& __rel_time) const
1242            {return __state_->wait_for(__rel_time);}
1243    template <class _Clock, class _Duration>
1244        _LIBCPP_INLINE_VISIBILITY
1245        future_status
1246        wait_until(const chrono::time_point<_Clock, _Duration>& __abs_time) const
1247            {return __state_->wait_until(__abs_time);}
1248};
1249
1250template <class _Rp>
1251future<_Rp&>::future(__assoc_state<_Rp&>* __state)
1252    : __state_(__state)
1253{
1254    __state_->__attach_future();
1255}
1256
1257template <class _Rp>
1258future<_Rp&>::~future()
1259{
1260    if (__state_)
1261        __state_->__release_shared();
1262}
1263
1264template <class _Rp>
1265_Rp&
1266future<_Rp&>::get()
1267{
1268    unique_ptr<__shared_count, __release_shared_count> __(__state_);
1269    __assoc_state<_Rp&>* __s = __state_;
1270    __state_ = nullptr;
1271    return __s->copy();
1272}
1273
1274template <>
1275class _LIBCPP_TYPE_VIS _LIBCPP_AVAILABILITY_FUTURE future<void>
1276{
1277    __assoc_sub_state* __state_;
1278
1279    explicit future(__assoc_sub_state* __state);
1280
1281    template <class> friend class promise;
1282    template <class> friend class shared_future;
1283
1284#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1285    template <class _R1, class _Fp>
1286        friend future<_R1> __make_deferred_assoc_state(_Fp&& __f);
1287    template <class _R1, class _Fp>
1288        friend future<_R1> __make_async_assoc_state(_Fp&& __f);
1289#else
1290    template <class _R1, class _Fp>
1291        friend future<_R1> __make_deferred_assoc_state(_Fp __f);
1292    template <class _R1, class _Fp>
1293        friend future<_R1> __make_async_assoc_state(_Fp __f);
1294#endif
1295
1296public:
1297    _LIBCPP_INLINE_VISIBILITY
1298    future() _NOEXCEPT : __state_(nullptr) {}
1299#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1300    _LIBCPP_INLINE_VISIBILITY
1301    future(future&& __rhs) _NOEXCEPT
1302        : __state_(__rhs.__state_) {__rhs.__state_ = nullptr;}
1303    future(const future&) = delete;
1304    future& operator=(const future&) = delete;
1305    _LIBCPP_INLINE_VISIBILITY
1306    future& operator=(future&& __rhs) _NOEXCEPT
1307        {
1308            future(std::move(__rhs)).swap(*this);
1309            return *this;
1310        }
1311#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1312private:
1313    future(const future&);
1314    future& operator=(const future&);
1315public:
1316#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1317    ~future();
1318    _LIBCPP_INLINE_VISIBILITY
1319    shared_future<void> share() _NOEXCEPT;
1320
1321    // retrieving the value
1322    void get();
1323
1324    _LIBCPP_INLINE_VISIBILITY
1325    void swap(future& __rhs) _NOEXCEPT {_VSTD::swap(__state_, __rhs.__state_);}
1326
1327    // functions to check state
1328    _LIBCPP_INLINE_VISIBILITY
1329    bool valid() const _NOEXCEPT {return __state_ != nullptr;}
1330
1331    _LIBCPP_INLINE_VISIBILITY
1332    void wait() const {__state_->wait();}
1333    template <class _Rep, class _Period>
1334        _LIBCPP_INLINE_VISIBILITY
1335        future_status
1336        wait_for(const chrono::duration<_Rep, _Period>& __rel_time) const
1337            {return __state_->wait_for(__rel_time);}
1338    template <class _Clock, class _Duration>
1339        _LIBCPP_INLINE_VISIBILITY
1340        future_status
1341        wait_until(const chrono::time_point<_Clock, _Duration>& __abs_time) const
1342            {return __state_->wait_until(__abs_time);}
1343};
1344
1345template <class _Rp>
1346inline _LIBCPP_INLINE_VISIBILITY
1347void
1348swap(future<_Rp>& __x, future<_Rp>& __y) _NOEXCEPT
1349{
1350    __x.swap(__y);
1351}
1352
1353// promise<R>
1354
1355template <class _Callable> class packaged_task;
1356
1357template <class _Rp>
1358class _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FUTURE promise
1359{
1360    __assoc_state<_Rp>* __state_;
1361
1362    _LIBCPP_INLINE_VISIBILITY
1363    explicit promise(nullptr_t) _NOEXCEPT : __state_(nullptr) {}
1364
1365    template <class> friend class packaged_task;
1366public:
1367    promise();
1368    template <class _Alloc>
1369        promise(allocator_arg_t, const _Alloc& __a);
1370#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1371    _LIBCPP_INLINE_VISIBILITY
1372    promise(promise&& __rhs) _NOEXCEPT
1373        : __state_(__rhs.__state_) {__rhs.__state_ = nullptr;}
1374    promise(const promise& __rhs) = delete;
1375#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1376private:
1377    promise(const promise& __rhs);
1378public:
1379#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1380    ~promise();
1381
1382    // assignment
1383#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1384    _LIBCPP_INLINE_VISIBILITY
1385    promise& operator=(promise&& __rhs) _NOEXCEPT
1386        {
1387            promise(std::move(__rhs)).swap(*this);
1388            return *this;
1389        }
1390    promise& operator=(const promise& __rhs) = delete;
1391#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1392private:
1393    promise& operator=(const promise& __rhs);
1394public:
1395#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1396    _LIBCPP_INLINE_VISIBILITY
1397    void swap(promise& __rhs) _NOEXCEPT {_VSTD::swap(__state_, __rhs.__state_);}
1398
1399    // retrieving the result
1400    future<_Rp> get_future();
1401
1402    // setting the result
1403    void set_value(const _Rp& __r);
1404#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1405    void set_value(_Rp&& __r);
1406#endif
1407    void set_exception(exception_ptr __p);
1408
1409    // setting the result with deferred notification
1410    void set_value_at_thread_exit(const _Rp& __r);
1411#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1412    void set_value_at_thread_exit(_Rp&& __r);
1413#endif
1414    void set_exception_at_thread_exit(exception_ptr __p);
1415};
1416
1417template <class _Rp>
1418promise<_Rp>::promise()
1419    : __state_(new __assoc_state<_Rp>)
1420{
1421}
1422
1423template <class _Rp>
1424template <class _Alloc>
1425promise<_Rp>::promise(allocator_arg_t, const _Alloc& __a0)
1426{
1427    typedef __assoc_state_alloc<_Rp, _Alloc> _State;
1428    typedef typename __allocator_traits_rebind<_Alloc, _State>::type _A2;
1429    typedef __allocator_destructor<_A2> _D2;
1430    _A2 __a(__a0);
1431    unique_ptr<_State, _D2> __hold(__a.allocate(1), _D2(__a, 1));
1432    ::new(static_cast<void*>(_VSTD::addressof(*__hold.get()))) _State(__a0);
1433    __state_ = _VSTD::addressof(*__hold.release());
1434}
1435
1436template <class _Rp>
1437promise<_Rp>::~promise()
1438{
1439    if (__state_)
1440    {
1441        if (!__state_->__has_value() && __state_->use_count() > 1)
1442            __state_->set_exception(make_exception_ptr(
1443                      future_error(make_error_code(future_errc::broken_promise))
1444                                                      ));
1445        __state_->__release_shared();
1446    }
1447}
1448
1449template <class _Rp>
1450future<_Rp>
1451promise<_Rp>::get_future()
1452{
1453    if (__state_ == nullptr)
1454        __throw_future_error(future_errc::no_state);
1455    return future<_Rp>(__state_);
1456}
1457
1458template <class _Rp>
1459void
1460promise<_Rp>::set_value(const _Rp& __r)
1461{
1462    if (__state_ == nullptr)
1463        __throw_future_error(future_errc::no_state);
1464    __state_->set_value(__r);
1465}
1466
1467#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1468
1469template <class _Rp>
1470void
1471promise<_Rp>::set_value(_Rp&& __r)
1472{
1473    if (__state_ == nullptr)
1474        __throw_future_error(future_errc::no_state);
1475    __state_->set_value(_VSTD::move(__r));
1476}
1477
1478#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1479
1480template <class _Rp>
1481void
1482promise<_Rp>::set_exception(exception_ptr __p)
1483{
1484    _LIBCPP_ASSERT( __p != nullptr, "promise::set_exception: received nullptr" );
1485    if (__state_ == nullptr)
1486        __throw_future_error(future_errc::no_state);
1487    __state_->set_exception(__p);
1488}
1489
1490template <class _Rp>
1491void
1492promise<_Rp>::set_value_at_thread_exit(const _Rp& __r)
1493{
1494    if (__state_ == nullptr)
1495        __throw_future_error(future_errc::no_state);
1496    __state_->set_value_at_thread_exit(__r);
1497}
1498
1499#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1500
1501template <class _Rp>
1502void
1503promise<_Rp>::set_value_at_thread_exit(_Rp&& __r)
1504{
1505    if (__state_ == nullptr)
1506        __throw_future_error(future_errc::no_state);
1507    __state_->set_value_at_thread_exit(_VSTD::move(__r));
1508}
1509
1510#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1511
1512template <class _Rp>
1513void
1514promise<_Rp>::set_exception_at_thread_exit(exception_ptr __p)
1515{
1516    _LIBCPP_ASSERT( __p != nullptr, "promise::set_exception_at_thread_exit: received nullptr" );
1517    if (__state_ == nullptr)
1518        __throw_future_error(future_errc::no_state);
1519    __state_->set_exception_at_thread_exit(__p);
1520}
1521
1522// promise<R&>
1523
1524template <class _Rp>
1525class _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FUTURE promise<_Rp&>
1526{
1527    __assoc_state<_Rp&>* __state_;
1528
1529    _LIBCPP_INLINE_VISIBILITY
1530    explicit promise(nullptr_t) _NOEXCEPT : __state_(nullptr) {}
1531
1532    template <class> friend class packaged_task;
1533
1534public:
1535    promise();
1536    template <class _Allocator>
1537        promise(allocator_arg_t, const _Allocator& __a);
1538#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1539    _LIBCPP_INLINE_VISIBILITY
1540    promise(promise&& __rhs) _NOEXCEPT
1541        : __state_(__rhs.__state_) {__rhs.__state_ = nullptr;}
1542    promise(const promise& __rhs) = delete;
1543#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1544private:
1545    promise(const promise& __rhs);
1546public:
1547#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1548    ~promise();
1549
1550    // assignment
1551#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1552    _LIBCPP_INLINE_VISIBILITY
1553    promise& operator=(promise&& __rhs) _NOEXCEPT
1554        {
1555            promise(std::move(__rhs)).swap(*this);
1556            return *this;
1557        }
1558    promise& operator=(const promise& __rhs) = delete;
1559#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1560private:
1561    promise& operator=(const promise& __rhs);
1562public:
1563#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1564    _LIBCPP_INLINE_VISIBILITY
1565    void swap(promise& __rhs) _NOEXCEPT {_VSTD::swap(__state_, __rhs.__state_);}
1566
1567    // retrieving the result
1568    future<_Rp&> get_future();
1569
1570    // setting the result
1571    void set_value(_Rp& __r);
1572    void set_exception(exception_ptr __p);
1573
1574    // setting the result with deferred notification
1575    void set_value_at_thread_exit(_Rp&);
1576    void set_exception_at_thread_exit(exception_ptr __p);
1577};
1578
1579template <class _Rp>
1580promise<_Rp&>::promise()
1581    : __state_(new __assoc_state<_Rp&>)
1582{
1583}
1584
1585template <class _Rp>
1586template <class _Alloc>
1587promise<_Rp&>::promise(allocator_arg_t, const _Alloc& __a0)
1588{
1589    typedef __assoc_state_alloc<_Rp&, _Alloc> _State;
1590    typedef typename __allocator_traits_rebind<_Alloc, _State>::type _A2;
1591    typedef __allocator_destructor<_A2> _D2;
1592    _A2 __a(__a0);
1593    unique_ptr<_State, _D2> __hold(__a.allocate(1), _D2(__a, 1));
1594    ::new(static_cast<void*>(_VSTD::addressof(*__hold.get()))) _State(__a0);
1595    __state_ = _VSTD::addressof(*__hold.release());
1596}
1597
1598template <class _Rp>
1599promise<_Rp&>::~promise()
1600{
1601    if (__state_)
1602    {
1603        if (!__state_->__has_value() && __state_->use_count() > 1)
1604            __state_->set_exception(make_exception_ptr(
1605                      future_error(make_error_code(future_errc::broken_promise))
1606                                                      ));
1607        __state_->__release_shared();
1608    }
1609}
1610
1611template <class _Rp>
1612future<_Rp&>
1613promise<_Rp&>::get_future()
1614{
1615    if (__state_ == nullptr)
1616        __throw_future_error(future_errc::no_state);
1617    return future<_Rp&>(__state_);
1618}
1619
1620template <class _Rp>
1621void
1622promise<_Rp&>::set_value(_Rp& __r)
1623{
1624    if (__state_ == nullptr)
1625        __throw_future_error(future_errc::no_state);
1626    __state_->set_value(__r);
1627}
1628
1629template <class _Rp>
1630void
1631promise<_Rp&>::set_exception(exception_ptr __p)
1632{
1633    _LIBCPP_ASSERT( __p != nullptr, "promise::set_exception: received nullptr" );
1634    if (__state_ == nullptr)
1635        __throw_future_error(future_errc::no_state);
1636    __state_->set_exception(__p);
1637}
1638
1639template <class _Rp>
1640void
1641promise<_Rp&>::set_value_at_thread_exit(_Rp& __r)
1642{
1643    if (__state_ == nullptr)
1644        __throw_future_error(future_errc::no_state);
1645    __state_->set_value_at_thread_exit(__r);
1646}
1647
1648template <class _Rp>
1649void
1650promise<_Rp&>::set_exception_at_thread_exit(exception_ptr __p)
1651{
1652    _LIBCPP_ASSERT( __p != nullptr, "promise::set_exception_at_thread_exit: received nullptr" );
1653    if (__state_ == nullptr)
1654        __throw_future_error(future_errc::no_state);
1655    __state_->set_exception_at_thread_exit(__p);
1656}
1657
1658// promise<void>
1659
1660template <>
1661class _LIBCPP_TYPE_VIS _LIBCPP_AVAILABILITY_FUTURE promise<void>
1662{
1663    __assoc_sub_state* __state_;
1664
1665    _LIBCPP_INLINE_VISIBILITY
1666    explicit promise(nullptr_t) _NOEXCEPT : __state_(nullptr) {}
1667
1668    template <class> friend class packaged_task;
1669
1670public:
1671    promise();
1672    template <class _Allocator>
1673        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1674        promise(allocator_arg_t, const _Allocator& __a);
1675#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1676    _LIBCPP_INLINE_VISIBILITY
1677    promise(promise&& __rhs) _NOEXCEPT
1678        : __state_(__rhs.__state_) {__rhs.__state_ = nullptr;}
1679    promise(const promise& __rhs) = delete;
1680#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1681private:
1682    promise(const promise& __rhs);
1683public:
1684#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1685    ~promise();
1686
1687    // assignment
1688#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
1689    _LIBCPP_INLINE_VISIBILITY
1690    promise& operator=(promise&& __rhs) _NOEXCEPT
1691        {
1692            promise(std::move(__rhs)).swap(*this);
1693            return *this;
1694        }
1695    promise& operator=(const promise& __rhs) = delete;
1696#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1697private:
1698    promise& operator=(const promise& __rhs);
1699public:
1700#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
1701    _LIBCPP_INLINE_VISIBILITY
1702    void swap(promise& __rhs) _NOEXCEPT {_VSTD::swap(__state_, __rhs.__state_);}
1703
1704    // retrieving the result
1705    future<void> get_future();
1706
1707    // setting the result
1708    void set_value();
1709    void set_exception(exception_ptr __p);
1710
1711    // setting the result with deferred notification
1712    void set_value_at_thread_exit();
1713    void set_exception_at_thread_exit(exception_ptr __p);
1714};
1715
1716template <class _Alloc>
1717promise<void>::promise(allocator_arg_t, const _Alloc& __a0)
1718{
1719    typedef __assoc_sub_state_alloc<_Alloc> _State;
1720    typedef typename __allocator_traits_rebind<_Alloc, _State>::type _A2;
1721    typedef __allocator_destructor<_A2> _D2;
1722    _A2 __a(__a0);
1723    unique_ptr<_State, _D2> __hold(__a.allocate(1), _D2(__a, 1));
1724    ::new(static_cast<void*>(_VSTD::addressof(*__hold.get()))) _State(__a0);
1725    __state_ = _VSTD::addressof(*__hold.release());
1726}
1727
1728template <class _Rp>
1729inline _LIBCPP_INLINE_VISIBILITY
1730void
1731swap(promise<_Rp>& __x, promise<_Rp>& __y) _NOEXCEPT
1732{
1733    __x.swap(__y);
1734}
1735
1736template <class _Rp, class _Alloc>
1737    struct _LIBCPP_TEMPLATE_VIS uses_allocator<promise<_Rp>, _Alloc>
1738        : public true_type {};
1739
1740#ifndef _LIBCPP_HAS_NO_VARIADICS
1741
1742// packaged_task
1743
1744template<class _Fp> class __packaged_task_base;
1745
1746template<class _Rp, class ..._ArgTypes>
1747class _LIBCPP_AVAILABILITY_FUTURE __packaged_task_base<_Rp(_ArgTypes...)>
1748{
1749    __packaged_task_base(const __packaged_task_base&);
1750    __packaged_task_base& operator=(const __packaged_task_base&);
1751public:
1752    _LIBCPP_INLINE_VISIBILITY
1753    __packaged_task_base() {}
1754    _LIBCPP_INLINE_VISIBILITY
1755    virtual ~__packaged_task_base() {}
1756    virtual void __move_to(__packaged_task_base*) _NOEXCEPT = 0;
1757    virtual void destroy() = 0;
1758    virtual void destroy_deallocate() = 0;
1759    virtual _Rp operator()(_ArgTypes&& ...) = 0;
1760};
1761
1762template<class _FD, class _Alloc, class _FB> class __packaged_task_func;
1763
1764template<class _Fp, class _Alloc, class _Rp, class ..._ArgTypes>
1765class _LIBCPP_AVAILABILITY_FUTURE __packaged_task_func<_Fp, _Alloc, _Rp(_ArgTypes...)>
1766    : public  __packaged_task_base<_Rp(_ArgTypes...)>
1767{
1768    __compressed_pair<_Fp, _Alloc> __f_;
1769public:
1770    _LIBCPP_INLINE_VISIBILITY
1771    explicit __packaged_task_func(const _Fp& __f) : __f_(__f, __default_init_tag()) {}
1772    _LIBCPP_INLINE_VISIBILITY
1773    explicit __packaged_task_func(_Fp&& __f) : __f_(_VSTD::move(__f), __default_init_tag()) {}
1774    _LIBCPP_INLINE_VISIBILITY
1775    __packaged_task_func(const _Fp& __f, const _Alloc& __a)
1776        : __f_(__f, __a) {}
1777    _LIBCPP_INLINE_VISIBILITY
1778    __packaged_task_func(_Fp&& __f, const _Alloc& __a)
1779        : __f_(_VSTD::move(__f), __a) {}
1780    virtual void __move_to(__packaged_task_base<_Rp(_ArgTypes...)>*) _NOEXCEPT;
1781    virtual void destroy();
1782    virtual void destroy_deallocate();
1783    virtual _Rp operator()(_ArgTypes&& ... __args);
1784};
1785
1786template<class _Fp, class _Alloc, class _Rp, class ..._ArgTypes>
1787void
1788__packaged_task_func<_Fp, _Alloc, _Rp(_ArgTypes...)>::__move_to(
1789                              __packaged_task_base<_Rp(_ArgTypes...)>* __p) _NOEXCEPT
1790{
1791    ::new (__p) __packaged_task_func(_VSTD::move(__f_.first()), _VSTD::move(__f_.second()));
1792}
1793
1794template<class _Fp, class _Alloc, class _Rp, class ..._ArgTypes>
1795void
1796__packaged_task_func<_Fp, _Alloc, _Rp(_ArgTypes...)>::destroy()
1797{
1798    __f_.~__compressed_pair<_Fp, _Alloc>();
1799}
1800
1801template<class _Fp, class _Alloc, class _Rp, class ..._ArgTypes>
1802void
1803__packaged_task_func<_Fp, _Alloc, _Rp(_ArgTypes...)>::destroy_deallocate()
1804{
1805    typedef typename __allocator_traits_rebind<_Alloc, __packaged_task_func>::type _Ap;
1806    typedef allocator_traits<_Ap> _ATraits;
1807    typedef pointer_traits<typename _ATraits::pointer> _PTraits;
1808    _Ap __a(__f_.second());
1809    __f_.~__compressed_pair<_Fp, _Alloc>();
1810    __a.deallocate(_PTraits::pointer_to(*this), 1);
1811}
1812
1813template<class _Fp, class _Alloc, class _Rp, class ..._ArgTypes>
1814_Rp
1815__packaged_task_func<_Fp, _Alloc, _Rp(_ArgTypes...)>::operator()(_ArgTypes&& ... __arg)
1816{
1817    return __invoke(__f_.first(), _VSTD::forward<_ArgTypes>(__arg)...);
1818}
1819
1820template <class _Callable> class __packaged_task_function;
1821
1822template<class _Rp, class ..._ArgTypes>
1823class _LIBCPP_AVAILABILITY_FUTURE __packaged_task_function<_Rp(_ArgTypes...)>
1824{
1825    typedef __packaged_task_base<_Rp(_ArgTypes...)> __base;
1826    typename aligned_storage<3*sizeof(void*)>::type __buf_;
1827    __base* __f_;
1828
1829public:
1830    typedef _Rp result_type;
1831
1832    // construct/copy/destroy:
1833    _LIBCPP_INLINE_VISIBILITY
1834    __packaged_task_function() _NOEXCEPT : __f_(nullptr) {}
1835    template<class _Fp>
1836      __packaged_task_function(_Fp&& __f);
1837    template<class _Fp, class _Alloc>
1838      __packaged_task_function(allocator_arg_t, const _Alloc& __a, _Fp&& __f);
1839
1840    __packaged_task_function(__packaged_task_function&&) _NOEXCEPT;
1841    __packaged_task_function& operator=(__packaged_task_function&&) _NOEXCEPT;
1842
1843    __packaged_task_function(const __packaged_task_function&) =  delete;
1844    __packaged_task_function& operator=(const __packaged_task_function&) =  delete;
1845
1846    ~__packaged_task_function();
1847
1848    void swap(__packaged_task_function&) _NOEXCEPT;
1849
1850    _LIBCPP_INLINE_VISIBILITY
1851    _Rp operator()(_ArgTypes...) const;
1852};
1853
1854template<class _Rp, class ..._ArgTypes>
1855__packaged_task_function<_Rp(_ArgTypes...)>::__packaged_task_function(__packaged_task_function&& __f) _NOEXCEPT
1856{
1857    if (__f.__f_ == nullptr)
1858        __f_ = nullptr;
1859    else if (__f.__f_ == (__base*)&__f.__buf_)
1860    {
1861        __f_ = (__base*)&__buf_;
1862        __f.__f_->__move_to(__f_);
1863    }
1864    else
1865    {
1866        __f_ = __f.__f_;
1867        __f.__f_ = nullptr;
1868    }
1869}
1870
1871template<class _Rp, class ..._ArgTypes>
1872template <class _Fp>
1873__packaged_task_function<_Rp(_ArgTypes...)>::__packaged_task_function(_Fp&& __f)
1874    : __f_(nullptr)
1875{
1876    typedef typename remove_reference<typename decay<_Fp>::type>::type _FR;
1877    typedef __packaged_task_func<_FR, allocator<_FR>, _Rp(_ArgTypes...)> _FF;
1878    if (sizeof(_FF) <= sizeof(__buf_))
1879    {
1880        __f_ = (__base*)&__buf_;
1881        ::new (__f_) _FF(_VSTD::forward<_Fp>(__f));
1882    }
1883    else
1884    {
1885        typedef allocator<_FF> _Ap;
1886        _Ap __a;
1887        typedef __allocator_destructor<_Ap> _Dp;
1888        unique_ptr<__base, _Dp> __hold(__a.allocate(1), _Dp(__a, 1));
1889        ::new (__hold.get()) _FF(_VSTD::forward<_Fp>(__f), allocator<_FR>(__a));
1890        __f_ = __hold.release();
1891    }
1892}
1893
1894template<class _Rp, class ..._ArgTypes>
1895template <class _Fp, class _Alloc>
1896__packaged_task_function<_Rp(_ArgTypes...)>::__packaged_task_function(
1897                                  allocator_arg_t, const _Alloc& __a0, _Fp&& __f)
1898    : __f_(nullptr)
1899{
1900    typedef typename remove_reference<typename decay<_Fp>::type>::type _FR;
1901    typedef __packaged_task_func<_FR, _Alloc, _Rp(_ArgTypes...)> _FF;
1902    if (sizeof(_FF) <= sizeof(__buf_))
1903    {
1904        __f_ = (__base*)&__buf_;
1905        ::new (__f_) _FF(_VSTD::forward<_Fp>(__f));
1906    }
1907    else
1908    {
1909        typedef typename __allocator_traits_rebind<_Alloc, _FF>::type _Ap;
1910        _Ap __a(__a0);
1911        typedef __allocator_destructor<_Ap> _Dp;
1912        unique_ptr<__base, _Dp> __hold(__a.allocate(1), _Dp(__a, 1));
1913        ::new (static_cast<void*>(_VSTD::addressof(*__hold.get())))
1914            _FF(_VSTD::forward<_Fp>(__f), _Alloc(__a));
1915        __f_ = _VSTD::addressof(*__hold.release());
1916    }
1917}
1918
1919template<class _Rp, class ..._ArgTypes>
1920__packaged_task_function<_Rp(_ArgTypes...)>&
1921__packaged_task_function<_Rp(_ArgTypes...)>::operator=(__packaged_task_function&& __f) _NOEXCEPT
1922{
1923    if (__f_ == (__base*)&__buf_)
1924        __f_->destroy();
1925    else if (__f_)
1926        __f_->destroy_deallocate();
1927    __f_ = nullptr;
1928    if (__f.__f_ == nullptr)
1929        __f_ = nullptr;
1930    else if (__f.__f_ == (__base*)&__f.__buf_)
1931    {
1932        __f_ = (__base*)&__buf_;
1933        __f.__f_->__move_to(__f_);
1934    }
1935    else
1936    {
1937        __f_ = __f.__f_;
1938        __f.__f_ = nullptr;
1939    }
1940    return *this;
1941}
1942
1943template<class _Rp, class ..._ArgTypes>
1944__packaged_task_function<_Rp(_ArgTypes...)>::~__packaged_task_function()
1945{
1946    if (__f_ == (__base*)&__buf_)
1947        __f_->destroy();
1948    else if (__f_)
1949        __f_->destroy_deallocate();
1950}
1951
1952template<class _Rp, class ..._ArgTypes>
1953void
1954__packaged_task_function<_Rp(_ArgTypes...)>::swap(__packaged_task_function& __f) _NOEXCEPT
1955{
1956    if (__f_ == (__base*)&__buf_ && __f.__f_ == (__base*)&__f.__buf_)
1957    {
1958        typename aligned_storage<sizeof(__buf_)>::type __tempbuf;
1959        __base* __t = (__base*)&__tempbuf;
1960        __f_->__move_to(__t);
1961        __f_->destroy();
1962        __f_ = nullptr;
1963        __f.__f_->__move_to((__base*)&__buf_);
1964        __f.__f_->destroy();
1965        __f.__f_ = nullptr;
1966        __f_ = (__base*)&__buf_;
1967        __t->__move_to((__base*)&__f.__buf_);
1968        __t->destroy();
1969        __f.__f_ = (__base*)&__f.__buf_;
1970    }
1971    else if (__f_ == (__base*)&__buf_)
1972    {
1973        __f_->__move_to((__base*)&__f.__buf_);
1974        __f_->destroy();
1975        __f_ = __f.__f_;
1976        __f.__f_ = (__base*)&__f.__buf_;
1977    }
1978    else if (__f.__f_ == (__base*)&__f.__buf_)
1979    {
1980        __f.__f_->__move_to((__base*)&__buf_);
1981        __f.__f_->destroy();
1982        __f.__f_ = __f_;
1983        __f_ = (__base*)&__buf_;
1984    }
1985    else
1986        _VSTD::swap(__f_, __f.__f_);
1987}
1988
1989template<class _Rp, class ..._ArgTypes>
1990inline
1991_Rp
1992__packaged_task_function<_Rp(_ArgTypes...)>::operator()(_ArgTypes... __arg) const
1993{
1994    return (*__f_)(_VSTD::forward<_ArgTypes>(__arg)...);
1995}
1996
1997template<class _Rp, class ..._ArgTypes>
1998class _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FUTURE packaged_task<_Rp(_ArgTypes...)>
1999{
2000public:
2001    typedef _Rp result_type; // extension
2002
2003private:
2004    __packaged_task_function<result_type(_ArgTypes...)> __f_;
2005    promise<result_type>                                __p_;
2006
2007public:
2008    // construction and destruction
2009    _LIBCPP_INLINE_VISIBILITY
2010    packaged_task() _NOEXCEPT : __p_(nullptr) {}
2011    template <class _Fp,
2012              class = typename enable_if
2013              <
2014                  !is_same<
2015                      typename __uncvref<_Fp>::type,
2016                      packaged_task
2017                      >::value
2018                  >::type
2019             >
2020        _LIBCPP_INLINE_VISIBILITY
2021        explicit packaged_task(_Fp&& __f) : __f_(_VSTD::forward<_Fp>(__f)) {}
2022    template <class _Fp, class _Allocator,
2023              class = typename enable_if
2024              <
2025                  !is_same<
2026                      typename __uncvref<_Fp>::type,
2027                      packaged_task
2028                      >::value
2029                  >::type
2030              >
2031        _LIBCPP_INLINE_VISIBILITY
2032        packaged_task(allocator_arg_t, const _Allocator& __a, _Fp&& __f)
2033             : __f_(allocator_arg, __a, _VSTD::forward<_Fp>(__f)),
2034               __p_(allocator_arg, __a) {}
2035    // ~packaged_task() = default;
2036
2037    // no copy
2038    packaged_task(const packaged_task&) = delete;
2039    packaged_task& operator=(const packaged_task&) = delete;
2040
2041    // move support
2042    _LIBCPP_INLINE_VISIBILITY
2043    packaged_task(packaged_task&& __other) _NOEXCEPT
2044        : __f_(_VSTD::move(__other.__f_)), __p_(_VSTD::move(__other.__p_)) {}
2045    _LIBCPP_INLINE_VISIBILITY
2046    packaged_task& operator=(packaged_task&& __other) _NOEXCEPT
2047    {
2048        __f_ = _VSTD::move(__other.__f_);
2049        __p_ = _VSTD::move(__other.__p_);
2050        return *this;
2051    }
2052    _LIBCPP_INLINE_VISIBILITY
2053    void swap(packaged_task& __other) _NOEXCEPT
2054    {
2055        __f_.swap(__other.__f_);
2056        __p_.swap(__other.__p_);
2057    }
2058
2059    _LIBCPP_INLINE_VISIBILITY
2060    bool valid() const _NOEXCEPT {return __p_.__state_ != nullptr;}
2061
2062    // result retrieval
2063    _LIBCPP_INLINE_VISIBILITY
2064    future<result_type> get_future() {return __p_.get_future();}
2065
2066    // execution
2067    void operator()(_ArgTypes... __args);
2068    void make_ready_at_thread_exit(_ArgTypes... __args);
2069
2070    void reset();
2071};
2072
2073template<class _Rp, class ..._ArgTypes>
2074void
2075packaged_task<_Rp(_ArgTypes...)>::operator()(_ArgTypes... __args)
2076{
2077    if (__p_.__state_ == nullptr)
2078        __throw_future_error(future_errc::no_state);
2079    if (__p_.__state_->__has_value())
2080        __throw_future_error(future_errc::promise_already_satisfied);
2081#ifndef _LIBCPP_NO_EXCEPTIONS
2082    try
2083    {
2084#endif  // _LIBCPP_NO_EXCEPTIONS
2085        __p_.set_value(__f_(_VSTD::forward<_ArgTypes>(__args)...));
2086#ifndef _LIBCPP_NO_EXCEPTIONS
2087    }
2088    catch (...)
2089    {
2090        __p_.set_exception(current_exception());
2091    }
2092#endif  // _LIBCPP_NO_EXCEPTIONS
2093}
2094
2095template<class _Rp, class ..._ArgTypes>
2096void
2097packaged_task<_Rp(_ArgTypes...)>::make_ready_at_thread_exit(_ArgTypes... __args)
2098{
2099    if (__p_.__state_ == nullptr)
2100        __throw_future_error(future_errc::no_state);
2101    if (__p_.__state_->__has_value())
2102        __throw_future_error(future_errc::promise_already_satisfied);
2103#ifndef _LIBCPP_NO_EXCEPTIONS
2104    try
2105    {
2106#endif  // _LIBCPP_NO_EXCEPTIONS
2107        __p_.set_value_at_thread_exit(__f_(_VSTD::forward<_ArgTypes>(__args)...));
2108#ifndef _LIBCPP_NO_EXCEPTIONS
2109    }
2110    catch (...)
2111    {
2112        __p_.set_exception_at_thread_exit(current_exception());
2113    }
2114#endif  // _LIBCPP_NO_EXCEPTIONS
2115}
2116
2117template<class _Rp, class ..._ArgTypes>
2118void
2119packaged_task<_Rp(_ArgTypes...)>::reset()
2120{
2121    if (!valid())
2122        __throw_future_error(future_errc::no_state);
2123    __p_ = promise<result_type>();
2124}
2125
2126template<class ..._ArgTypes>
2127class _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FUTURE packaged_task<void(_ArgTypes...)>
2128{
2129public:
2130    typedef void result_type; // extension
2131
2132private:
2133    __packaged_task_function<result_type(_ArgTypes...)> __f_;
2134    promise<result_type>                                __p_;
2135
2136public:
2137    // construction and destruction
2138    _LIBCPP_INLINE_VISIBILITY
2139    packaged_task() _NOEXCEPT : __p_(nullptr) {}
2140    template <class _Fp,
2141              class = typename enable_if
2142              <
2143                  !is_same<
2144                      typename __uncvref<_Fp>::type,
2145                      packaged_task
2146                      >::value
2147                  >::type
2148              >
2149        _LIBCPP_INLINE_VISIBILITY
2150        explicit packaged_task(_Fp&& __f) : __f_(_VSTD::forward<_Fp>(__f)) {}
2151    template <class _Fp, class _Allocator,
2152              class = typename enable_if
2153              <
2154                  !is_same<
2155                      typename __uncvref<_Fp>::type,
2156                      packaged_task
2157                      >::value
2158                  >::type
2159              >
2160        _LIBCPP_INLINE_VISIBILITY
2161        packaged_task(allocator_arg_t, const _Allocator& __a, _Fp&& __f)
2162             : __f_(allocator_arg, __a, _VSTD::forward<_Fp>(__f)),
2163               __p_(allocator_arg, __a) {}
2164    // ~packaged_task() = default;
2165
2166    // no copy
2167    packaged_task(const packaged_task&) = delete;
2168    packaged_task& operator=(const packaged_task&) = delete;
2169
2170    // move support
2171    _LIBCPP_INLINE_VISIBILITY
2172    packaged_task(packaged_task&& __other) _NOEXCEPT
2173        : __f_(_VSTD::move(__other.__f_)), __p_(_VSTD::move(__other.__p_)) {}
2174    _LIBCPP_INLINE_VISIBILITY
2175    packaged_task& operator=(packaged_task&& __other) _NOEXCEPT
2176    {
2177        __f_ = _VSTD::move(__other.__f_);
2178        __p_ = _VSTD::move(__other.__p_);
2179        return *this;
2180    }
2181    _LIBCPP_INLINE_VISIBILITY
2182    void swap(packaged_task& __other) _NOEXCEPT
2183    {
2184        __f_.swap(__other.__f_);
2185        __p_.swap(__other.__p_);
2186    }
2187
2188    _LIBCPP_INLINE_VISIBILITY
2189    bool valid() const _NOEXCEPT {return __p_.__state_ != nullptr;}
2190
2191    // result retrieval
2192    _LIBCPP_INLINE_VISIBILITY
2193    future<result_type> get_future() {return __p_.get_future();}
2194
2195    // execution
2196    void operator()(_ArgTypes... __args);
2197    void make_ready_at_thread_exit(_ArgTypes... __args);
2198
2199    void reset();
2200};
2201
2202template<class ..._ArgTypes>
2203void
2204packaged_task<void(_ArgTypes...)>::operator()(_ArgTypes... __args)
2205{
2206    if (__p_.__state_ == nullptr)
2207        __throw_future_error(future_errc::no_state);
2208    if (__p_.__state_->__has_value())
2209        __throw_future_error(future_errc::promise_already_satisfied);
2210#ifndef _LIBCPP_NO_EXCEPTIONS
2211    try
2212    {
2213#endif  // _LIBCPP_NO_EXCEPTIONS
2214        __f_(_VSTD::forward<_ArgTypes>(__args)...);
2215        __p_.set_value();
2216#ifndef _LIBCPP_NO_EXCEPTIONS
2217    }
2218    catch (...)
2219    {
2220        __p_.set_exception(current_exception());
2221    }
2222#endif  // _LIBCPP_NO_EXCEPTIONS
2223}
2224
2225template<class ..._ArgTypes>
2226void
2227packaged_task<void(_ArgTypes...)>::make_ready_at_thread_exit(_ArgTypes... __args)
2228{
2229    if (__p_.__state_ == nullptr)
2230        __throw_future_error(future_errc::no_state);
2231    if (__p_.__state_->__has_value())
2232        __throw_future_error(future_errc::promise_already_satisfied);
2233#ifndef _LIBCPP_NO_EXCEPTIONS
2234    try
2235    {
2236#endif  // _LIBCPP_NO_EXCEPTIONS
2237        __f_(_VSTD::forward<_ArgTypes>(__args)...);
2238        __p_.set_value_at_thread_exit();
2239#ifndef _LIBCPP_NO_EXCEPTIONS
2240    }
2241    catch (...)
2242    {
2243        __p_.set_exception_at_thread_exit(current_exception());
2244    }
2245#endif  // _LIBCPP_NO_EXCEPTIONS
2246}
2247
2248template<class ..._ArgTypes>
2249void
2250packaged_task<void(_ArgTypes...)>::reset()
2251{
2252    if (!valid())
2253        __throw_future_error(future_errc::no_state);
2254    __p_ = promise<result_type>();
2255}
2256
2257template <class _Callable>
2258inline _LIBCPP_INLINE_VISIBILITY
2259void
2260swap(packaged_task<_Callable>& __x, packaged_task<_Callable>& __y) _NOEXCEPT
2261{
2262    __x.swap(__y);
2263}
2264
2265template <class _Callable, class _Alloc>
2266struct _LIBCPP_TEMPLATE_VIS uses_allocator<packaged_task<_Callable>, _Alloc>
2267    : public true_type {};
2268
2269template <class _Rp, class _Fp>
2270_LIBCPP_INLINE_VISIBILITY future<_Rp>
2271#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
2272__make_deferred_assoc_state(_Fp&& __f)
2273#else
2274__make_deferred_assoc_state(_Fp __f)
2275#endif
2276{
2277    unique_ptr<__deferred_assoc_state<_Rp, _Fp>, __release_shared_count>
2278        __h(new __deferred_assoc_state<_Rp, _Fp>(_VSTD::forward<_Fp>(__f)));
2279    return future<_Rp>(__h.get());
2280}
2281
2282template <class _Rp, class _Fp>
2283_LIBCPP_INLINE_VISIBILITY future<_Rp>
2284#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
2285__make_async_assoc_state(_Fp&& __f)
2286#else
2287__make_async_assoc_state(_Fp __f)
2288#endif
2289{
2290    unique_ptr<__async_assoc_state<_Rp, _Fp>, __release_shared_count>
2291        __h(new __async_assoc_state<_Rp, _Fp>(_VSTD::forward<_Fp>(__f)));
2292    _VSTD::thread(&__async_assoc_state<_Rp, _Fp>::__execute, __h.get()).detach();
2293    return future<_Rp>(__h.get());
2294}
2295
2296template <class _Fp, class... _Args>
2297class _LIBCPP_HIDDEN __async_func
2298{
2299    tuple<_Fp, _Args...> __f_;
2300
2301public:
2302    typedef typename __invoke_of<_Fp, _Args...>::type _Rp;
2303
2304    _LIBCPP_INLINE_VISIBILITY
2305    explicit __async_func(_Fp&& __f, _Args&&... __args)
2306        : __f_(_VSTD::move(__f), _VSTD::move(__args)...) {}
2307
2308    _LIBCPP_INLINE_VISIBILITY
2309    __async_func(__async_func&& __f) : __f_(_VSTD::move(__f.__f_)) {}
2310
2311    _Rp operator()()
2312    {
2313        typedef typename __make_tuple_indices<1+sizeof...(_Args), 1>::type _Index;
2314        return __execute(_Index());
2315    }
2316private:
2317    template <size_t ..._Indices>
2318    _Rp
2319    __execute(__tuple_indices<_Indices...>)
2320    {
2321        return __invoke(_VSTD::move(_VSTD::get<0>(__f_)), _VSTD::move(_VSTD::get<_Indices>(__f_))...);
2322    }
2323};
2324
2325inline _LIBCPP_INLINE_VISIBILITY bool __does_policy_contain(launch __policy, launch __value )
2326{ return (int(__policy) & int(__value)) != 0; }
2327
2328template <class _Fp, class... _Args>
2329_LIBCPP_NODISCARD_AFTER_CXX17
2330future<typename __invoke_of<typename decay<_Fp>::type, typename decay<_Args>::type...>::type>
2331async(launch __policy, _Fp&& __f, _Args&&... __args)
2332{
2333    typedef __async_func<typename decay<_Fp>::type, typename decay<_Args>::type...> _BF;
2334    typedef typename _BF::_Rp _Rp;
2335
2336#ifndef _LIBCPP_NO_EXCEPTIONS
2337    try
2338    {
2339#endif
2340        if (__does_policy_contain(__policy, launch::async))
2341        return _VSTD::__make_async_assoc_state<_Rp>(_BF(__decay_copy(_VSTD::forward<_Fp>(__f)),
2342                                                     __decay_copy(_VSTD::forward<_Args>(__args))...));
2343#ifndef _LIBCPP_NO_EXCEPTIONS
2344    }
2345    catch ( ... ) { if (__policy == launch::async) throw ; }
2346#endif
2347
2348    if (__does_policy_contain(__policy, launch::deferred))
2349        return _VSTD::__make_deferred_assoc_state<_Rp>(_BF(__decay_copy(_VSTD::forward<_Fp>(__f)),
2350                                                        __decay_copy(_VSTD::forward<_Args>(__args))...));
2351    return future<_Rp>{};
2352}
2353
2354template <class _Fp, class... _Args>
2355_LIBCPP_NODISCARD_AFTER_CXX17 inline _LIBCPP_INLINE_VISIBILITY
2356future<typename __invoke_of<typename decay<_Fp>::type, typename decay<_Args>::type...>::type>
2357async(_Fp&& __f, _Args&&... __args)
2358{
2359    return _VSTD::async(launch::any, _VSTD::forward<_Fp>(__f),
2360                                    _VSTD::forward<_Args>(__args)...);
2361}
2362
2363#endif  // _LIBCPP_HAS_NO_VARIADICS
2364
2365// shared_future
2366
2367template <class _Rp>
2368class _LIBCPP_TEMPLATE_VIS shared_future
2369{
2370    __assoc_state<_Rp>* __state_;
2371
2372public:
2373    _LIBCPP_INLINE_VISIBILITY
2374    shared_future() _NOEXCEPT : __state_(nullptr) {}
2375    _LIBCPP_INLINE_VISIBILITY
2376    shared_future(const shared_future& __rhs)  _NOEXCEPT : __state_(__rhs.__state_)
2377        {if (__state_) __state_->__add_shared();}
2378#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
2379    _LIBCPP_INLINE_VISIBILITY
2380    shared_future(future<_Rp>&& __f) _NOEXCEPT : __state_(__f.__state_)
2381        {__f.__state_ = nullptr;}
2382    _LIBCPP_INLINE_VISIBILITY
2383    shared_future(shared_future&& __rhs) _NOEXCEPT : __state_(__rhs.__state_)
2384        {__rhs.__state_ = nullptr;}
2385#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
2386    ~shared_future();
2387    shared_future& operator=(const shared_future& __rhs) _NOEXCEPT;
2388#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
2389    _LIBCPP_INLINE_VISIBILITY
2390    shared_future& operator=(shared_future&& __rhs) _NOEXCEPT
2391        {
2392            shared_future(std::move(__rhs)).swap(*this);
2393            return *this;
2394        }
2395#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
2396
2397    // retrieving the value
2398    _LIBCPP_INLINE_VISIBILITY
2399    const _Rp& get() const {return __state_->copy();}
2400
2401    _LIBCPP_INLINE_VISIBILITY
2402    void swap(shared_future& __rhs) _NOEXCEPT {_VSTD::swap(__state_, __rhs.__state_);}
2403
2404    // functions to check state
2405    _LIBCPP_INLINE_VISIBILITY
2406    bool valid() const _NOEXCEPT {return __state_ != nullptr;}
2407
2408    _LIBCPP_INLINE_VISIBILITY
2409    void wait() const {__state_->wait();}
2410    template <class _Rep, class _Period>
2411        _LIBCPP_INLINE_VISIBILITY
2412        future_status
2413        wait_for(const chrono::duration<_Rep, _Period>& __rel_time) const
2414            {return __state_->wait_for(__rel_time);}
2415    template <class _Clock, class _Duration>
2416        _LIBCPP_INLINE_VISIBILITY
2417        future_status
2418        wait_until(const chrono::time_point<_Clock, _Duration>& __abs_time) const
2419            {return __state_->wait_until(__abs_time);}
2420};
2421
2422template <class _Rp>
2423shared_future<_Rp>::~shared_future()
2424{
2425    if (__state_)
2426        __state_->__release_shared();
2427}
2428
2429template <class _Rp>
2430shared_future<_Rp>&
2431shared_future<_Rp>::operator=(const shared_future& __rhs) _NOEXCEPT
2432{
2433    if (__rhs.__state_)
2434        __rhs.__state_->__add_shared();
2435    if (__state_)
2436        __state_->__release_shared();
2437    __state_ = __rhs.__state_;
2438    return *this;
2439}
2440
2441template <class _Rp>
2442class _LIBCPP_TEMPLATE_VIS shared_future<_Rp&>
2443{
2444    __assoc_state<_Rp&>* __state_;
2445
2446public:
2447    _LIBCPP_INLINE_VISIBILITY
2448    shared_future() _NOEXCEPT : __state_(nullptr) {}
2449    _LIBCPP_INLINE_VISIBILITY
2450    shared_future(const shared_future& __rhs) : __state_(__rhs.__state_)
2451        {if (__state_) __state_->__add_shared();}
2452#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
2453    _LIBCPP_INLINE_VISIBILITY
2454    shared_future(future<_Rp&>&& __f) _NOEXCEPT : __state_(__f.__state_)
2455        {__f.__state_ = nullptr;}
2456    _LIBCPP_INLINE_VISIBILITY
2457    shared_future(shared_future&& __rhs) _NOEXCEPT : __state_(__rhs.__state_)
2458        {__rhs.__state_ = nullptr;}
2459#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
2460    ~shared_future();
2461    shared_future& operator=(const shared_future& __rhs);
2462#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
2463    _LIBCPP_INLINE_VISIBILITY
2464    shared_future& operator=(shared_future&& __rhs) _NOEXCEPT
2465        {
2466            shared_future(std::move(__rhs)).swap(*this);
2467            return *this;
2468        }
2469#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
2470
2471    // retrieving the value
2472    _LIBCPP_INLINE_VISIBILITY
2473    _Rp& get() const {return __state_->copy();}
2474
2475    _LIBCPP_INLINE_VISIBILITY
2476    void swap(shared_future& __rhs) _NOEXCEPT {_VSTD::swap(__state_, __rhs.__state_);}
2477
2478    // functions to check state
2479    _LIBCPP_INLINE_VISIBILITY
2480    bool valid() const _NOEXCEPT {return __state_ != nullptr;}
2481
2482    _LIBCPP_INLINE_VISIBILITY
2483    void wait() const {__state_->wait();}
2484    template <class _Rep, class _Period>
2485        _LIBCPP_INLINE_VISIBILITY
2486        future_status
2487        wait_for(const chrono::duration<_Rep, _Period>& __rel_time) const
2488            {return __state_->wait_for(__rel_time);}
2489    template <class _Clock, class _Duration>
2490        _LIBCPP_INLINE_VISIBILITY
2491        future_status
2492        wait_until(const chrono::time_point<_Clock, _Duration>& __abs_time) const
2493            {return __state_->wait_until(__abs_time);}
2494};
2495
2496template <class _Rp>
2497shared_future<_Rp&>::~shared_future()
2498{
2499    if (__state_)
2500        __state_->__release_shared();
2501}
2502
2503template <class _Rp>
2504shared_future<_Rp&>&
2505shared_future<_Rp&>::operator=(const shared_future& __rhs)
2506{
2507    if (__rhs.__state_)
2508        __rhs.__state_->__add_shared();
2509    if (__state_)
2510        __state_->__release_shared();
2511    __state_ = __rhs.__state_;
2512    return *this;
2513}
2514
2515template <>
2516class _LIBCPP_TYPE_VIS _LIBCPP_AVAILABILITY_FUTURE shared_future<void>
2517{
2518    __assoc_sub_state* __state_;
2519
2520public:
2521    _LIBCPP_INLINE_VISIBILITY
2522    shared_future() _NOEXCEPT : __state_(nullptr) {}
2523    _LIBCPP_INLINE_VISIBILITY
2524    shared_future(const shared_future& __rhs) : __state_(__rhs.__state_)
2525        {if (__state_) __state_->__add_shared();}
2526#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
2527    _LIBCPP_INLINE_VISIBILITY
2528    shared_future(future<void>&& __f) _NOEXCEPT : __state_(__f.__state_)
2529        {__f.__state_ = nullptr;}
2530    _LIBCPP_INLINE_VISIBILITY
2531    shared_future(shared_future&& __rhs) _NOEXCEPT : __state_(__rhs.__state_)
2532        {__rhs.__state_ = nullptr;}
2533#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
2534    ~shared_future();
2535    shared_future& operator=(const shared_future& __rhs);
2536#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
2537    _LIBCPP_INLINE_VISIBILITY
2538    shared_future& operator=(shared_future&& __rhs) _NOEXCEPT
2539        {
2540            shared_future(std::move(__rhs)).swap(*this);
2541            return *this;
2542        }
2543#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
2544
2545    // retrieving the value
2546    _LIBCPP_INLINE_VISIBILITY
2547    void get() const {__state_->copy();}
2548
2549    _LIBCPP_INLINE_VISIBILITY
2550    void swap(shared_future& __rhs) _NOEXCEPT {_VSTD::swap(__state_, __rhs.__state_);}
2551
2552    // functions to check state
2553    _LIBCPP_INLINE_VISIBILITY
2554    bool valid() const _NOEXCEPT {return __state_ != nullptr;}
2555
2556    _LIBCPP_INLINE_VISIBILITY
2557    void wait() const {__state_->wait();}
2558    template <class _Rep, class _Period>
2559        _LIBCPP_INLINE_VISIBILITY
2560        future_status
2561        wait_for(const chrono::duration<_Rep, _Period>& __rel_time) const
2562            {return __state_->wait_for(__rel_time);}
2563    template <class _Clock, class _Duration>
2564        _LIBCPP_INLINE_VISIBILITY
2565        future_status
2566        wait_until(const chrono::time_point<_Clock, _Duration>& __abs_time) const
2567            {return __state_->wait_until(__abs_time);}
2568};
2569
2570template <class _Rp>
2571inline _LIBCPP_INLINE_VISIBILITY
2572void
2573swap(shared_future<_Rp>& __x, shared_future<_Rp>& __y) _NOEXCEPT
2574{
2575    __x.swap(__y);
2576}
2577
2578template <class _Rp>
2579inline
2580shared_future<_Rp>
2581future<_Rp>::share() _NOEXCEPT
2582{
2583    return shared_future<_Rp>(_VSTD::move(*this));
2584}
2585
2586template <class _Rp>
2587inline
2588shared_future<_Rp&>
2589future<_Rp&>::share() _NOEXCEPT
2590{
2591    return shared_future<_Rp&>(_VSTD::move(*this));
2592}
2593
2594#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
2595
2596inline
2597shared_future<void>
2598future<void>::share() _NOEXCEPT
2599{
2600    return shared_future<void>(_VSTD::move(*this));
2601}
2602
2603#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
2604
2605_LIBCPP_END_NAMESPACE_STD
2606
2607#endif // !_LIBCPP_HAS_NO_THREADS
2608
2609#endif  // _LIBCPP_FUTURE
2610