xref: /dragonfly/contrib/gcc-8.0/libstdc++-v3/include/std/chrono (revision 95059079af47f9a66a175f374f2da1a5020e3255)
1// <chrono> -*- C++ -*-
2
3// Copyright (C) 2008-2018 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library.  This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14// GNU General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23// <http://www.gnu.org/licenses/>.
24
25/** @file include/chrono
26 *  This is a Standard C++ Library header.
27 */
28
29#ifndef _GLIBCXX_CHRONO
30#define _GLIBCXX_CHRONO 1
31
32#pragma GCC system_header
33
34#if __cplusplus < 201103L
35# include <bits/c++0x_warning.h>
36#else
37
38#include <ratio>
39#include <type_traits>
40#include <limits>
41#include <ctime>
42#include <bits/parse_numbers.h> // for literals support.
43
44#ifdef _GLIBCXX_USE_C99_STDINT_TR1
45
46namespace std _GLIBCXX_VISIBILITY(default)
47{
48_GLIBCXX_BEGIN_NAMESPACE_VERSION
49
50  /**
51   * @defgroup chrono Time
52   * @ingroup utilities
53   *
54   * Classes and functions for time.
55   * @{
56   */
57
58  /** @namespace std::chrono
59   *  @brief ISO C++ 2011 entities sub-namespace for time and date.
60   */
61  namespace chrono
62  {
63    template<typename _Rep, typename _Period = ratio<1>>
64      struct duration;
65
66    template<typename _Clock, typename _Dur = typename _Clock::duration>
67      struct time_point;
68  }
69
70  // 20.11.4.3 specialization of common_type (for duration, sfinae-friendly)
71
72  template<typename _CT, typename _Period1, typename _Period2>
73    struct __duration_common_type_wrapper
74    {
75    private:
76      typedef __static_gcd<_Period1::num, _Period2::num> __gcd_num;
77      typedef __static_gcd<_Period1::den, _Period2::den> __gcd_den;
78      typedef typename _CT::type __cr;
79      typedef ratio<__gcd_num::value,
80        (_Period1::den / __gcd_den::value) * _Period2::den> __r;
81    public:
82      typedef __success_type<chrono::duration<__cr, __r>> type;
83    };
84
85  template<typename _Period1, typename _Period2>
86    struct __duration_common_type_wrapper<__failure_type, _Period1, _Period2>
87    { typedef __failure_type type; };
88
89  template<typename _Rep1, typename _Period1, typename _Rep2, typename _Period2>
90    struct common_type<chrono::duration<_Rep1, _Period1>,
91             chrono::duration<_Rep2, _Period2>>
92    : public __duration_common_type_wrapper<typename __member_type_wrapper<
93             common_type<_Rep1, _Rep2>>::type, _Period1, _Period2>::type
94    { };
95
96  // 20.11.4.3 specialization of common_type (for time_point, sfinae-friendly)
97
98  template<typename _CT, typename _Clock>
99    struct __timepoint_common_type_wrapper
100    {
101      typedef __success_type<chrono::time_point<_Clock, typename _CT::type>>
102        type;
103    };
104
105  template<typename _Clock>
106    struct __timepoint_common_type_wrapper<__failure_type, _Clock>
107    { typedef __failure_type type; };
108
109  template<typename _Clock, typename _Duration1, typename _Duration2>
110    struct common_type<chrono::time_point<_Clock, _Duration1>,
111             chrono::time_point<_Clock, _Duration2>>
112    : public __timepoint_common_type_wrapper<typename __member_type_wrapper<
113             common_type<_Duration1, _Duration2>>::type, _Clock>::type
114    { };
115
116  namespace chrono
117  {
118    // Primary template for duration_cast impl.
119    template<typename _ToDur, typename _CF, typename _CR,
120               bool _NumIsOne = false, bool _DenIsOne = false>
121      struct __duration_cast_impl
122      {
123          template<typename _Rep, typename _Period>
124            static constexpr _ToDur
125            __cast(const duration<_Rep, _Period>& __d)
126            {
127              typedef typename _ToDur::rep                            __to_rep;
128              return _ToDur(static_cast<__to_rep>(static_cast<_CR>(__d.count())
129                * static_cast<_CR>(_CF::num)
130                / static_cast<_CR>(_CF::den)));
131            }
132      };
133
134    template<typename _ToDur, typename _CF, typename _CR>
135      struct __duration_cast_impl<_ToDur, _CF, _CR, true, true>
136      {
137          template<typename _Rep, typename _Period>
138            static constexpr _ToDur
139            __cast(const duration<_Rep, _Period>& __d)
140            {
141              typedef typename _ToDur::rep                            __to_rep;
142              return _ToDur(static_cast<__to_rep>(__d.count()));
143            }
144      };
145
146    template<typename _ToDur, typename _CF, typename _CR>
147      struct __duration_cast_impl<_ToDur, _CF, _CR, true, false>
148      {
149          template<typename _Rep, typename _Period>
150            static constexpr _ToDur
151            __cast(const duration<_Rep, _Period>& __d)
152            {
153              typedef typename _ToDur::rep                            __to_rep;
154              return _ToDur(static_cast<__to_rep>(
155                static_cast<_CR>(__d.count()) / static_cast<_CR>(_CF::den)));
156            }
157      };
158
159    template<typename _ToDur, typename _CF, typename _CR>
160      struct __duration_cast_impl<_ToDur, _CF, _CR, false, true>
161      {
162          template<typename _Rep, typename _Period>
163            static constexpr _ToDur
164            __cast(const duration<_Rep, _Period>& __d)
165            {
166              typedef typename _ToDur::rep                            __to_rep;
167              return _ToDur(static_cast<__to_rep>(
168                static_cast<_CR>(__d.count()) * static_cast<_CR>(_CF::num)));
169            }
170      };
171
172    template<typename _Tp>
173      struct __is_duration
174      : std::false_type
175      { };
176
177    template<typename _Rep, typename _Period>
178      struct __is_duration<duration<_Rep, _Period>>
179      : std::true_type
180      { };
181
182    template<typename _Tp>
183      using __enable_if_is_duration
184          = typename enable_if<__is_duration<_Tp>::value, _Tp>::type;
185
186    template<typename _Tp>
187      using __disable_if_is_duration
188          = typename enable_if<!__is_duration<_Tp>::value, _Tp>::type;
189
190    /// duration_cast
191    template<typename _ToDur, typename _Rep, typename _Period>
192      constexpr __enable_if_is_duration<_ToDur>
193      duration_cast(const duration<_Rep, _Period>& __d)
194      {
195          typedef typename _ToDur::period                                       __to_period;
196          typedef typename _ToDur::rep                                __to_rep;
197          typedef ratio_divide<_Period, __to_period>                  __cf;
198          typedef typename common_type<__to_rep, _Rep, intmax_t>::type
199                                                                                __cr;
200          typedef  __duration_cast_impl<_ToDur, __cf, __cr,
201                                              __cf::num == 1, __cf::den == 1> __dc;
202          return __dc::__cast(__d);
203      }
204
205    /// treat_as_floating_point
206    template<typename _Rep>
207      struct treat_as_floating_point
208      : is_floating_point<_Rep>
209      { };
210
211#if __cplusplus > 201402L
212    template <typename _Rep>
213      inline constexpr bool treat_as_floating_point_v =
214        treat_as_floating_point<_Rep>::value;
215#endif // C++17
216
217#if __cplusplus >= 201703L
218# define __cpp_lib_chrono 201611
219
220    template<typename _ToDur, typename _Rep, typename _Period>
221      constexpr __enable_if_is_duration<_ToDur>
222      floor(const duration<_Rep, _Period>& __d)
223      {
224          auto __to = chrono::duration_cast<_ToDur>(__d);
225          if (__to > __d)
226            return __to - _ToDur{1};
227          return __to;
228      }
229
230    template<typename _ToDur, typename _Rep, typename _Period>
231      constexpr __enable_if_is_duration<_ToDur>
232      ceil(const duration<_Rep, _Period>& __d)
233      {
234          auto __to = chrono::duration_cast<_ToDur>(__d);
235          if (__to < __d)
236            return __to + _ToDur{1};
237          return __to;
238      }
239
240    template <typename _ToDur, typename _Rep, typename _Period>
241      constexpr enable_if_t<
242          __and_<__is_duration<_ToDur>,
243                 __not_<treat_as_floating_point<typename _ToDur::rep>>>::value,
244          _ToDur>
245      round(const duration<_Rep, _Period>& __d)
246      {
247          _ToDur __t0 = chrono::floor<_ToDur>(__d);
248          _ToDur __t1 = __t0 + _ToDur{1};
249          auto __diff0 = __d - __t0;
250          auto __diff1 = __t1 - __d;
251          if (__diff0 == __diff1)
252          {
253              if (__t0.count() & 1)
254                    return __t1;
255              return __t0;
256          }
257          else if (__diff0 < __diff1)
258              return __t0;
259          return __t1;
260      }
261
262    template<typename _Rep, typename _Period>
263      constexpr
264      enable_if_t<numeric_limits<_Rep>::is_signed, duration<_Rep, _Period>>
265      abs(duration<_Rep, _Period> __d)
266      {
267          if (__d >= __d.zero())
268            return __d;
269          return -__d;
270      }
271#endif // C++17
272
273    /// duration_values
274    template<typename _Rep>
275      struct duration_values
276      {
277          static constexpr _Rep
278          zero() noexcept
279          { return _Rep(0); }
280
281          static constexpr _Rep
282          max() noexcept
283          { return numeric_limits<_Rep>::max(); }
284
285          static constexpr _Rep
286          min() noexcept
287          { return numeric_limits<_Rep>::lowest(); }
288      };
289
290    template<typename _Tp>
291      struct __is_ratio
292      : std::false_type
293      { };
294
295    template<intmax_t _Num, intmax_t _Den>
296      struct __is_ratio<ratio<_Num, _Den>>
297      : std::true_type
298      { };
299
300    /// duration
301    template<typename _Rep, typename _Period>
302      struct duration
303      {
304      private:
305          template<typename _Rep2>
306            using __is_float = treat_as_floating_point<_Rep2>;
307
308          // _Period2 is an exact multiple of _Period
309          template<typename _Period2>
310            using __is_harmonic
311              = __bool_constant<ratio_divide<_Period2, _Period>::den == 1>;
312
313      public:
314
315          typedef _Rep                                                          rep;
316          typedef _Period                                             period;
317
318          static_assert(!__is_duration<_Rep>::value, "rep cannot be a duration");
319          static_assert(__is_ratio<_Period>::value,
320                          "period must be a specialization of ratio");
321          static_assert(_Period::num > 0, "period must be positive");
322
323          // 20.11.5.1 construction / copy / destroy
324          constexpr duration() = default;
325
326          duration(const duration&) = default;
327
328          // _GLIBCXX_RESOLVE_LIB_DEFECTS
329          // 3050. Conversion specification problem in chrono::duration
330          template<typename _Rep2, typename = _Require<
331                     is_convertible<const _Rep2&, rep>,
332                     __or_<__is_float<rep>, __not_<__is_float<_Rep2>>>>>
333            constexpr explicit duration(const _Rep2& __rep)
334            : __r(static_cast<rep>(__rep)) { }
335
336          template<typename _Rep2, typename _Period2, typename = _Require<
337                     __or_<__is_float<rep>,
338                           __and_<__is_harmonic<_Period2>,
339                                    __not_<__is_float<_Rep2>>>>>>
340            constexpr duration(const duration<_Rep2, _Period2>& __d)
341            : __r(duration_cast<duration>(__d).count()) { }
342
343          ~duration() = default;
344          duration& operator=(const duration&) = default;
345
346          // 20.11.5.2 observer
347          constexpr rep
348          count() const
349          { return __r; }
350
351          // 20.11.5.3 arithmetic
352          constexpr duration
353          operator+() const
354          { return *this; }
355
356          constexpr duration
357          operator-() const
358          { return duration(-__r); }
359
360          _GLIBCXX17_CONSTEXPR duration&
361          operator++()
362          {
363            ++__r;
364            return *this;
365          }
366
367          _GLIBCXX17_CONSTEXPR duration
368          operator++(int)
369          { return duration(__r++); }
370
371          _GLIBCXX17_CONSTEXPR duration&
372          operator--()
373          {
374            --__r;
375            return *this;
376          }
377
378          _GLIBCXX17_CONSTEXPR duration
379          operator--(int)
380          { return duration(__r--); }
381
382          _GLIBCXX17_CONSTEXPR duration&
383          operator+=(const duration& __d)
384          {
385            __r += __d.count();
386            return *this;
387          }
388
389          _GLIBCXX17_CONSTEXPR duration&
390          operator-=(const duration& __d)
391          {
392            __r -= __d.count();
393            return *this;
394          }
395
396          _GLIBCXX17_CONSTEXPR duration&
397          operator*=(const rep& __rhs)
398          {
399            __r *= __rhs;
400            return *this;
401          }
402
403          _GLIBCXX17_CONSTEXPR duration&
404          operator/=(const rep& __rhs)
405          {
406            __r /= __rhs;
407            return *this;
408          }
409
410          // DR 934.
411          template<typename _Rep2 = rep>
412            _GLIBCXX17_CONSTEXPR
413            typename enable_if<!treat_as_floating_point<_Rep2>::value,
414                                   duration&>::type
415            operator%=(const rep& __rhs)
416            {
417              __r %= __rhs;
418              return *this;
419            }
420
421          template<typename _Rep2 = rep>
422            _GLIBCXX17_CONSTEXPR
423            typename enable_if<!treat_as_floating_point<_Rep2>::value,
424                                   duration&>::type
425            operator%=(const duration& __d)
426            {
427              __r %= __d.count();
428              return *this;
429            }
430
431          // 20.11.5.4 special values
432          static constexpr duration
433          zero() noexcept
434          { return duration(duration_values<rep>::zero()); }
435
436          static constexpr duration
437          min() noexcept
438          { return duration(duration_values<rep>::min()); }
439
440          static constexpr duration
441          max() noexcept
442          { return duration(duration_values<rep>::max()); }
443
444      private:
445          rep __r;
446      };
447
448    template<typename _Rep1, typename _Period1,
449               typename _Rep2, typename _Period2>
450      constexpr typename common_type<duration<_Rep1, _Period1>,
451                                             duration<_Rep2, _Period2>>::type
452      operator+(const duration<_Rep1, _Period1>& __lhs,
453                    const duration<_Rep2, _Period2>& __rhs)
454      {
455          typedef duration<_Rep1, _Period1>                           __dur1;
456          typedef duration<_Rep2, _Period2>                           __dur2;
457          typedef typename common_type<__dur1,__dur2>::type __cd;
458          return __cd(__cd(__lhs).count() + __cd(__rhs).count());
459      }
460
461    template<typename _Rep1, typename _Period1,
462               typename _Rep2, typename _Period2>
463      constexpr typename common_type<duration<_Rep1, _Period1>,
464                                             duration<_Rep2, _Period2>>::type
465      operator-(const duration<_Rep1, _Period1>& __lhs,
466                    const duration<_Rep2, _Period2>& __rhs)
467      {
468          typedef duration<_Rep1, _Period1>                           __dur1;
469          typedef duration<_Rep2, _Period2>                           __dur2;
470          typedef typename common_type<__dur1,__dur2>::type __cd;
471          return __cd(__cd(__lhs).count() - __cd(__rhs).count());
472      }
473
474    // SFINAE helper to obtain common_type<_Rep1, _Rep2> only if _Rep2
475    // is implicitly convertible to it.
476    // _GLIBCXX_RESOLVE_LIB_DEFECTS
477    // 3050. Conversion specification problem in chrono::duration constructor
478    template<typename _Rep1, typename _Rep2,
479               typename _CRep = typename common_type<_Rep1, _Rep2>::type>
480      using __common_rep_t = typename
481          enable_if<is_convertible<const _Rep2&, _CRep>::value, _CRep>::type;
482
483    template<typename _Rep1, typename _Period, typename _Rep2>
484      constexpr duration<__common_rep_t<_Rep1, _Rep2>, _Period>
485      operator*(const duration<_Rep1, _Period>& __d, const _Rep2& __s)
486      {
487          typedef duration<typename common_type<_Rep1, _Rep2>::type, _Period>
488            __cd;
489          return __cd(__cd(__d).count() * __s);
490      }
491
492    template<typename _Rep1, typename _Rep2, typename _Period>
493      constexpr duration<__common_rep_t<_Rep2, _Rep1>, _Period>
494      operator*(const _Rep1& __s, const duration<_Rep2, _Period>& __d)
495      { return __d * __s; }
496
497    template<typename _Rep1, typename _Period, typename _Rep2>
498      constexpr
499      duration<__common_rep_t<_Rep1, __disable_if_is_duration<_Rep2>>, _Period>
500      operator/(const duration<_Rep1, _Period>& __d, const _Rep2& __s)
501      {
502          typedef duration<typename common_type<_Rep1, _Rep2>::type, _Period>
503            __cd;
504          return __cd(__cd(__d).count() / __s);
505      }
506
507    template<typename _Rep1, typename _Period1,
508               typename _Rep2, typename _Period2>
509      constexpr typename common_type<_Rep1, _Rep2>::type
510      operator/(const duration<_Rep1, _Period1>& __lhs,
511                    const duration<_Rep2, _Period2>& __rhs)
512      {
513          typedef duration<_Rep1, _Period1>                           __dur1;
514          typedef duration<_Rep2, _Period2>                           __dur2;
515          typedef typename common_type<__dur1,__dur2>::type __cd;
516          return __cd(__lhs).count() / __cd(__rhs).count();
517      }
518
519    // DR 934.
520    template<typename _Rep1, typename _Period, typename _Rep2>
521      constexpr
522      duration<__common_rep_t<_Rep1, __disable_if_is_duration<_Rep2>>, _Period>
523      operator%(const duration<_Rep1, _Period>& __d, const _Rep2& __s)
524      {
525          typedef duration<typename common_type<_Rep1, _Rep2>::type, _Period>
526            __cd;
527          return __cd(__cd(__d).count() % __s);
528      }
529
530    template<typename _Rep1, typename _Period1,
531               typename _Rep2, typename _Period2>
532      constexpr typename common_type<duration<_Rep1, _Period1>,
533                                             duration<_Rep2, _Period2>>::type
534      operator%(const duration<_Rep1, _Period1>& __lhs,
535                    const duration<_Rep2, _Period2>& __rhs)
536      {
537          typedef duration<_Rep1, _Period1>                           __dur1;
538          typedef duration<_Rep2, _Period2>                           __dur2;
539          typedef typename common_type<__dur1,__dur2>::type __cd;
540          return __cd(__cd(__lhs).count() % __cd(__rhs).count());
541      }
542
543    // comparisons
544    template<typename _Rep1, typename _Period1,
545               typename _Rep2, typename _Period2>
546      constexpr bool
547      operator==(const duration<_Rep1, _Period1>& __lhs,
548                     const duration<_Rep2, _Period2>& __rhs)
549      {
550          typedef duration<_Rep1, _Period1>                           __dur1;
551          typedef duration<_Rep2, _Period2>                           __dur2;
552          typedef typename common_type<__dur1,__dur2>::type __ct;
553          return __ct(__lhs).count() == __ct(__rhs).count();
554      }
555
556    template<typename _Rep1, typename _Period1,
557               typename _Rep2, typename _Period2>
558      constexpr bool
559      operator<(const duration<_Rep1, _Period1>& __lhs,
560                    const duration<_Rep2, _Period2>& __rhs)
561      {
562          typedef duration<_Rep1, _Period1>                           __dur1;
563          typedef duration<_Rep2, _Period2>                           __dur2;
564          typedef typename common_type<__dur1,__dur2>::type __ct;
565          return __ct(__lhs).count() < __ct(__rhs).count();
566      }
567
568    template<typename _Rep1, typename _Period1,
569               typename _Rep2, typename _Period2>
570      constexpr bool
571      operator!=(const duration<_Rep1, _Period1>& __lhs,
572                     const duration<_Rep2, _Period2>& __rhs)
573      { return !(__lhs == __rhs); }
574
575    template<typename _Rep1, typename _Period1,
576               typename _Rep2, typename _Period2>
577      constexpr bool
578      operator<=(const duration<_Rep1, _Period1>& __lhs,
579                     const duration<_Rep2, _Period2>& __rhs)
580      { return !(__rhs < __lhs); }
581
582    template<typename _Rep1, typename _Period1,
583               typename _Rep2, typename _Period2>
584      constexpr bool
585      operator>(const duration<_Rep1, _Period1>& __lhs,
586                    const duration<_Rep2, _Period2>& __rhs)
587      { return __rhs < __lhs; }
588
589    template<typename _Rep1, typename _Period1,
590               typename _Rep2, typename _Period2>
591      constexpr bool
592      operator>=(const duration<_Rep1, _Period1>& __lhs,
593                     const duration<_Rep2, _Period2>& __rhs)
594      { return !(__lhs < __rhs); }
595
596    /// nanoseconds
597    typedef duration<int64_t, nano>         nanoseconds;
598
599    /// microseconds
600    typedef duration<int64_t, micro>        microseconds;
601
602    /// milliseconds
603    typedef duration<int64_t, milli>        milliseconds;
604
605    /// seconds
606    typedef duration<int64_t>                         seconds;
607
608    /// minutes
609    typedef duration<int64_t, ratio< 60>>   minutes;
610
611    /// hours
612    typedef duration<int64_t, ratio<3600>>  hours;
613
614    /// time_point
615    template<typename _Clock, typename _Dur>
616      struct time_point
617      {
618          typedef _Clock                                                        clock;
619          typedef _Dur                                                          duration;
620          typedef typename duration::rep                                        rep;
621          typedef typename duration::period                           period;
622
623          constexpr time_point() : __d(duration::zero())
624          { }
625
626          constexpr explicit time_point(const duration& __dur)
627          : __d(__dur)
628          { }
629
630          // conversions
631          template<typename _Dur2,
632                     typename = _Require<is_convertible<_Dur2, _Dur>>>
633            constexpr time_point(const time_point<clock, _Dur2>& __t)
634            : __d(__t.time_since_epoch())
635            { }
636
637          // observer
638          constexpr duration
639          time_since_epoch() const
640          { return __d; }
641
642          // arithmetic
643          _GLIBCXX17_CONSTEXPR time_point&
644          operator+=(const duration& __dur)
645          {
646            __d += __dur;
647            return *this;
648          }
649
650          _GLIBCXX17_CONSTEXPR time_point&
651          operator-=(const duration& __dur)
652          {
653            __d -= __dur;
654            return *this;
655          }
656
657          // special values
658          static constexpr time_point
659          min() noexcept
660          { return time_point(duration::min()); }
661
662          static constexpr time_point
663          max() noexcept
664          { return time_point(duration::max()); }
665
666      private:
667          duration __d;
668      };
669
670    /// time_point_cast
671    template<typename _ToDur, typename _Clock, typename _Dur>
672      constexpr typename enable_if<__is_duration<_ToDur>::value,
673                                           time_point<_Clock, _ToDur>>::type
674      time_point_cast(const time_point<_Clock, _Dur>& __t)
675      {
676          typedef time_point<_Clock, _ToDur>                          __time_point;
677          return __time_point(duration_cast<_ToDur>(__t.time_since_epoch()));
678      }
679
680#if __cplusplus > 201402L
681    template<typename _ToDur, typename _Clock, typename _Dur>
682      constexpr
683      enable_if_t<__is_duration<_ToDur>::value, time_point<_Clock, _ToDur>>
684      floor(const time_point<_Clock, _Dur>& __tp)
685      {
686          return time_point<_Clock, _ToDur>{
687              chrono::floor<_ToDur>(__tp.time_since_epoch())};
688      }
689
690    template<typename _ToDur, typename _Clock, typename _Dur>
691      constexpr
692      enable_if_t<__is_duration<_ToDur>::value, time_point<_Clock, _ToDur>>
693      ceil(const time_point<_Clock, _Dur>& __tp)
694      {
695          return time_point<_Clock, _ToDur>{
696              chrono::ceil<_ToDur>(__tp.time_since_epoch())};
697      }
698
699    template<typename _ToDur, typename _Clock, typename _Dur>
700      constexpr enable_if_t<
701          __and_<__is_duration<_ToDur>,
702                 __not_<treat_as_floating_point<typename _ToDur::rep>>>::value,
703          time_point<_Clock, _ToDur>>
704      round(const time_point<_Clock, _Dur>& __tp)
705      {
706          return time_point<_Clock, _ToDur>{
707              chrono::round<_ToDur>(__tp.time_since_epoch())};
708      }
709#endif // C++17
710
711    template<typename _Clock, typename _Dur1,
712               typename _Rep2, typename _Period2>
713      constexpr time_point<_Clock,
714          typename common_type<_Dur1, duration<_Rep2, _Period2>>::type>
715      operator+(const time_point<_Clock, _Dur1>& __lhs,
716                    const duration<_Rep2, _Period2>& __rhs)
717      {
718          typedef duration<_Rep2, _Period2>                           __dur2;
719          typedef typename common_type<_Dur1,__dur2>::type  __ct;
720          typedef time_point<_Clock, __ct>                            __time_point;
721          return __time_point(__lhs.time_since_epoch() + __rhs);
722      }
723
724    template<typename _Rep1, typename _Period1,
725               typename _Clock, typename _Dur2>
726      constexpr time_point<_Clock,
727          typename common_type<duration<_Rep1, _Period1>, _Dur2>::type>
728      operator+(const duration<_Rep1, _Period1>& __lhs,
729                    const time_point<_Clock, _Dur2>& __rhs)
730      {
731          typedef duration<_Rep1, _Period1>                           __dur1;
732          typedef typename common_type<__dur1,_Dur2>::type  __ct;
733          typedef time_point<_Clock, __ct>                            __time_point;
734          return __time_point(__rhs.time_since_epoch() + __lhs);
735      }
736
737    template<typename _Clock, typename _Dur1,
738               typename _Rep2, typename _Period2>
739      constexpr time_point<_Clock,
740          typename common_type<_Dur1, duration<_Rep2, _Period2>>::type>
741      operator-(const time_point<_Clock, _Dur1>& __lhs,
742                    const duration<_Rep2, _Period2>& __rhs)
743      {
744          typedef duration<_Rep2, _Period2>                           __dur2;
745          typedef typename common_type<_Dur1,__dur2>::type  __ct;
746          typedef time_point<_Clock, __ct>                            __time_point;
747          return __time_point(__lhs.time_since_epoch() -__rhs);
748      }
749
750    template<typename _Clock, typename _Dur1, typename _Dur2>
751      constexpr typename common_type<_Dur1, _Dur2>::type
752      operator-(const time_point<_Clock, _Dur1>& __lhs,
753                    const time_point<_Clock, _Dur2>& __rhs)
754      { return __lhs.time_since_epoch() - __rhs.time_since_epoch(); }
755
756    template<typename _Clock, typename _Dur1, typename _Dur2>
757      constexpr bool
758      operator==(const time_point<_Clock, _Dur1>& __lhs,
759                     const time_point<_Clock, _Dur2>& __rhs)
760      { return __lhs.time_since_epoch() == __rhs.time_since_epoch(); }
761
762    template<typename _Clock, typename _Dur1, typename _Dur2>
763      constexpr bool
764      operator!=(const time_point<_Clock, _Dur1>& __lhs,
765                     const time_point<_Clock, _Dur2>& __rhs)
766      { return !(__lhs == __rhs); }
767
768    template<typename _Clock, typename _Dur1, typename _Dur2>
769      constexpr bool
770      operator<(const time_point<_Clock, _Dur1>& __lhs,
771                    const time_point<_Clock, _Dur2>& __rhs)
772      { return  __lhs.time_since_epoch() < __rhs.time_since_epoch(); }
773
774    template<typename _Clock, typename _Dur1, typename _Dur2>
775      constexpr bool
776      operator<=(const time_point<_Clock, _Dur1>& __lhs,
777                     const time_point<_Clock, _Dur2>& __rhs)
778      { return !(__rhs < __lhs); }
779
780    template<typename _Clock, typename _Dur1, typename _Dur2>
781      constexpr bool
782      operator>(const time_point<_Clock, _Dur1>& __lhs,
783                    const time_point<_Clock, _Dur2>& __rhs)
784      { return __rhs < __lhs; }
785
786    template<typename _Clock, typename _Dur1, typename _Dur2>
787      constexpr bool
788      operator>=(const time_point<_Clock, _Dur1>& __lhs,
789                     const time_point<_Clock, _Dur2>& __rhs)
790      { return !(__lhs < __rhs); }
791
792
793    // Clocks.
794
795    // Why nanosecond resolution as the default?
796    // Why have std::system_clock always count in the highest
797    // resolution (ie nanoseconds), even if on some OSes the low 3
798    // or 9 decimal digits will be always zero? This allows later
799    // implementations to change the system_clock::now()
800    // implementation any time to provide better resolution without
801    // changing function signature or units.
802
803    // To support the (forward) evolution of the library's defined
804    // clocks, wrap inside inline namespace so that the current
805    // defintions of system_clock, steady_clock, and
806    // high_resolution_clock types are uniquely mangled. This way, new
807    // code can use the latests clocks, while the library can contain
808    // compatibility definitions for previous versions.  At some
809    // point, when these clocks settle down, the inlined namespaces
810    // can be removed.  XXX GLIBCXX_ABI Deprecated
811    inline namespace _V2 {
812
813    /**
814     *  @brief System clock.
815     *
816     *  Time returned represents wall time from the system-wide clock.
817    */
818    struct system_clock
819    {
820      typedef chrono::nanoseconds                                     duration;
821      typedef duration::rep                                                     rep;
822      typedef duration::period                                                  period;
823      typedef chrono::time_point<system_clock, duration>    time_point;
824
825      static_assert(system_clock::duration::min()
826                        < system_clock::duration::zero(),
827                        "a clock's minimum duration cannot be less than its epoch");
828
829      static constexpr bool is_steady = false;
830
831      static time_point
832      now() noexcept;
833
834      // Map to C API
835      static std::time_t
836      to_time_t(const time_point& __t) noexcept
837      {
838          return std::time_t(duration_cast<chrono::seconds>
839                                 (__t.time_since_epoch()).count());
840      }
841
842      static time_point
843      from_time_t(std::time_t __t) noexcept
844      {
845          typedef chrono::time_point<system_clock, seconds> __from;
846          return time_point_cast<system_clock::duration>
847                 (__from(chrono::seconds(__t)));
848      }
849    };
850
851
852    /**
853     *  @brief Monotonic clock
854     *
855     *  Time returned has the property of only increasing at a uniform rate.
856    */
857    struct steady_clock
858    {
859      typedef chrono::nanoseconds                                     duration;
860      typedef duration::rep                                           rep;
861      typedef duration::period                                                  period;
862      typedef chrono::time_point<steady_clock, duration>    time_point;
863
864      static constexpr bool is_steady = true;
865
866      static time_point
867      now() noexcept;
868    };
869
870
871    /**
872     *  @brief Highest-resolution clock
873     *
874     *  This is the clock "with the shortest tick period." Alias to
875     *  std::system_clock until higher-than-nanosecond definitions
876     *  become feasible.
877    */
878    using high_resolution_clock = system_clock;
879
880    } // end inline namespace _V2
881  } // namespace chrono
882
883#if __cplusplus > 201103L
884
885#define __cpp_lib_chrono_udls 201304
886
887  inline namespace literals
888  {
889  inline namespace chrono_literals
890  {
891#pragma GCC diagnostic push
892#pragma GCC diagnostic ignored "-Wliteral-suffix"
893    template<typename _Rep, unsigned long long _Val>
894      struct _Checked_integral_constant
895      : integral_constant<_Rep, static_cast<_Rep>(_Val)>
896      {
897          static_assert(_Checked_integral_constant::value >= 0
898                          && _Checked_integral_constant::value == _Val,
899                          "literal value cannot be represented by duration type");
900      };
901
902    template<typename _Dur, char... _Digits>
903      constexpr _Dur __check_overflow()
904      {
905          using _Val = __parse_int::_Parse_int<_Digits...>;
906          using _Rep = typename _Dur::rep;
907          // TODO: should be simply integral_constant<_Rep, _Val::value>
908          // but GCC doesn't reject narrowing conversions to _Rep.
909          using _CheckedVal = _Checked_integral_constant<_Rep, _Val::value>;
910          return _Dur{_CheckedVal::value};
911      }
912
913    constexpr chrono::duration<long double, ratio<3600,1>>
914    operator""h(long double __hours)
915    { return chrono::duration<long double, ratio<3600,1>>{__hours}; }
916
917    template <char... _Digits>
918      constexpr chrono::hours
919      operator""h()
920      { return __check_overflow<chrono::hours, _Digits...>(); }
921
922    constexpr chrono::duration<long double, ratio<60,1>>
923    operator""min(long double __mins)
924    { return chrono::duration<long double, ratio<60,1>>{__mins}; }
925
926    template <char... _Digits>
927      constexpr chrono::minutes
928      operator""min()
929      { return __check_overflow<chrono::minutes, _Digits...>(); }
930
931    constexpr chrono::duration<long double>
932    operator""s(long double __secs)
933    { return chrono::duration<long double>{__secs}; }
934
935    template <char... _Digits>
936      constexpr chrono::seconds
937      operator""s()
938      { return __check_overflow<chrono::seconds, _Digits...>(); }
939
940    constexpr chrono::duration<long double, milli>
941    operator""ms(long double __msecs)
942    { return chrono::duration<long double, milli>{__msecs}; }
943
944    template <char... _Digits>
945      constexpr chrono::milliseconds
946      operator""ms()
947      { return __check_overflow<chrono::milliseconds, _Digits...>(); }
948
949    constexpr chrono::duration<long double, micro>
950    operator""us(long double __usecs)
951    { return chrono::duration<long double, micro>{__usecs}; }
952
953    template <char... _Digits>
954      constexpr chrono::microseconds
955      operator""us()
956      { return __check_overflow<chrono::microseconds, _Digits...>(); }
957
958    constexpr chrono::duration<long double, nano>
959    operator""ns(long double __nsecs)
960    { return chrono::duration<long double, nano>{__nsecs}; }
961
962    template <char... _Digits>
963      constexpr chrono::nanoseconds
964      operator""ns()
965      { return __check_overflow<chrono::nanoseconds, _Digits...>(); }
966
967#pragma GCC diagnostic pop
968  } // inline namespace chrono_literals
969  } // inline namespace literals
970
971  namespace chrono
972  {
973    using namespace literals::chrono_literals;
974  } // namespace chrono
975
976#endif // C++14
977
978  // @} group chrono
979
980_GLIBCXX_END_NAMESPACE_VERSION
981} // namespace std
982
983#endif //_GLIBCXX_USE_C99_STDINT_TR1
984
985#endif // C++11
986
987#endif //_GLIBCXX_CHRONO
988