libstdc++
chrono
Go to the documentation of this file.
1 // <chrono> -*- C++ -*-
2 
3 // Copyright (C) 2008-2015 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 
46 namespace std _GLIBCXX_VISIBILITY(default)
47 {
48  /**
49  * @defgroup chrono Time
50  * @ingroup utilities
51  *
52  * Classes and functions for time.
53  * @{
54  */
55 
56  /** @namespace std::chrono
57  * @brief ISO C++ 2011 entities sub-namespace for time and date.
58  */
59  namespace chrono
60  {
61  _GLIBCXX_BEGIN_NAMESPACE_VERSION
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  _GLIBCXX_END_NAMESPACE_VERSION
70  }
71 
72 _GLIBCXX_BEGIN_NAMESPACE_VERSION
73 
74  // 20.11.4.3 specialization of common_type (for duration, sfinae-friendly)
75 
76  template<typename _CT, typename _Period1, typename _Period2>
77  struct __duration_common_type_wrapper
78  {
79  private:
80  typedef __static_gcd<_Period1::num, _Period2::num> __gcd_num;
81  typedef __static_gcd<_Period1::den, _Period2::den> __gcd_den;
82  typedef typename _CT::type __cr;
83  typedef ratio<__gcd_num::value,
84  (_Period1::den / __gcd_den::value) * _Period2::den> __r;
85  public:
86  typedef __success_type<chrono::duration<__cr, __r>> type;
87  };
88 
89  template<typename _Period1, typename _Period2>
90  struct __duration_common_type_wrapper<__failure_type, _Period1, _Period2>
91  { typedef __failure_type type; };
92 
93  template<typename _Rep1, typename _Period1, typename _Rep2, typename _Period2>
94  struct common_type<chrono::duration<_Rep1, _Period1>,
95  chrono::duration<_Rep2, _Period2>>
96  : public __duration_common_type_wrapper<typename __member_type_wrapper<
97  common_type<_Rep1, _Rep2>>::type, _Period1, _Period2>::type
98  { };
99 
100  // 20.11.4.3 specialization of common_type (for time_point, sfinae-friendly)
101 
102  template<typename _CT, typename _Clock>
103  struct __timepoint_common_type_wrapper
104  {
105  typedef __success_type<chrono::time_point<_Clock, typename _CT::type>>
106  type;
107  };
108 
109  template<typename _Clock>
110  struct __timepoint_common_type_wrapper<__failure_type, _Clock>
111  { typedef __failure_type type; };
112 
113  template<typename _Clock, typename _Duration1, typename _Duration2>
114  struct common_type<chrono::time_point<_Clock, _Duration1>,
115  chrono::time_point<_Clock, _Duration2>>
116  : public __timepoint_common_type_wrapper<typename __member_type_wrapper<
117  common_type<_Duration1, _Duration2>>::type, _Clock>::type
118  { };
119 
120 _GLIBCXX_END_NAMESPACE_VERSION
121 
122  namespace chrono
123  {
124  _GLIBCXX_BEGIN_NAMESPACE_VERSION
125 
126  // Primary template for duration_cast impl.
127  template<typename _ToDur, typename _CF, typename _CR,
128  bool _NumIsOne = false, bool _DenIsOne = false>
129  struct __duration_cast_impl
130  {
131  template<typename _Rep, typename _Period>
132  static constexpr _ToDur
133  __cast(const duration<_Rep, _Period>& __d)
134  {
135  typedef typename _ToDur::rep __to_rep;
136  return _ToDur(static_cast<__to_rep>(static_cast<_CR>(__d.count())
137  * static_cast<_CR>(_CF::num)
138  / static_cast<_CR>(_CF::den)));
139  }
140  };
141 
142  template<typename _ToDur, typename _CF, typename _CR>
143  struct __duration_cast_impl<_ToDur, _CF, _CR, true, true>
144  {
145  template<typename _Rep, typename _Period>
146  static constexpr _ToDur
147  __cast(const duration<_Rep, _Period>& __d)
148  {
149  typedef typename _ToDur::rep __to_rep;
150  return _ToDur(static_cast<__to_rep>(__d.count()));
151  }
152  };
153 
154  template<typename _ToDur, typename _CF, typename _CR>
155  struct __duration_cast_impl<_ToDur, _CF, _CR, true, false>
156  {
157  template<typename _Rep, typename _Period>
158  static constexpr _ToDur
159  __cast(const duration<_Rep, _Period>& __d)
160  {
161  typedef typename _ToDur::rep __to_rep;
162  return _ToDur(static_cast<__to_rep>(
163  static_cast<_CR>(__d.count()) / static_cast<_CR>(_CF::den)));
164  }
165  };
166 
167  template<typename _ToDur, typename _CF, typename _CR>
168  struct __duration_cast_impl<_ToDur, _CF, _CR, false, true>
169  {
170  template<typename _Rep, typename _Period>
171  static constexpr _ToDur
172  __cast(const duration<_Rep, _Period>& __d)
173  {
174  typedef typename _ToDur::rep __to_rep;
175  return _ToDur(static_cast<__to_rep>(
176  static_cast<_CR>(__d.count()) * static_cast<_CR>(_CF::num)));
177  }
178  };
179 
180  template<typename _Tp>
181  struct __is_duration
182  : std::false_type
183  { };
184 
185  template<typename _Rep, typename _Period>
186  struct __is_duration<duration<_Rep, _Period>>
187  : std::true_type
188  { };
189 
190  /// duration_cast
191  template<typename _ToDur, typename _Rep, typename _Period>
192  constexpr typename enable_if<__is_duration<_ToDur>::value,
193  _ToDur>::type
194  duration_cast(const duration<_Rep, _Period>& __d)
195  {
196  typedef typename _ToDur::period __to_period;
197  typedef typename _ToDur::rep __to_rep;
198  typedef ratio_divide<_Period, __to_period> __cf;
199  typedef typename common_type<__to_rep, _Rep, intmax_t>::type
200  __cr;
201  typedef __duration_cast_impl<_ToDur, __cf, __cr,
202  __cf::num == 1, __cf::den == 1> __dc;
203  return __dc::__cast(__d);
204  }
205 
206  /// treat_as_floating_point
207  template<typename _Rep>
208  struct treat_as_floating_point
209  : is_floating_point<_Rep>
210  { };
211 
212  /// duration_values
213  template<typename _Rep>
214  struct duration_values
215  {
216  static constexpr _Rep
217  zero()
218  { return _Rep(0); }
219 
220  static constexpr _Rep
221  max()
222  { return numeric_limits<_Rep>::max(); }
223 
224  static constexpr _Rep
225  min()
226  { return numeric_limits<_Rep>::lowest(); }
227  };
228 
229  template<typename _Tp>
230  struct __is_ratio
231  : std::false_type
232  { };
233 
234  template<intmax_t _Num, intmax_t _Den>
235  struct __is_ratio<ratio<_Num, _Den>>
236  : std::true_type
237  { };
238 
239  /// duration
240  template<typename _Rep, typename _Period>
241  struct duration
242  {
243  typedef _Rep rep;
244  typedef _Period period;
245 
246  static_assert(!__is_duration<_Rep>::value, "rep cannot be a duration");
247  static_assert(__is_ratio<_Period>::value,
248  "period must be a specialization of ratio");
249  static_assert(_Period::num > 0, "period must be positive");
250 
251  // 20.11.5.1 construction / copy / destroy
252  constexpr duration() = default;
253 
254  // NB: Make constexpr implicit. This cannot be explicitly
255  // constexpr, as any UDT that is not a literal type with a
256  // constexpr copy constructor will be ill-formed.
257  duration(const duration&) = default;
258 
259  template<typename _Rep2, typename = typename
260  enable_if<is_convertible<_Rep2, rep>::value
261  && (treat_as_floating_point<rep>::value
262  || !treat_as_floating_point<_Rep2>::value)>::type>
263  constexpr explicit duration(const _Rep2& __rep)
264  : __r(static_cast<rep>(__rep)) { }
265 
266  template<typename _Rep2, typename _Period2, typename = typename
267  enable_if<treat_as_floating_point<rep>::value
268  || (ratio_divide<_Period2, period>::den == 1
269  && !treat_as_floating_point<_Rep2>::value)>::type>
270  constexpr duration(const duration<_Rep2, _Period2>& __d)
271  : __r(duration_cast<duration>(__d).count()) { }
272 
273  ~duration() = default;
274  duration& operator=(const duration&) = default;
275 
276  // 20.11.5.2 observer
277  constexpr rep
278  count() const
279  { return __r; }
280 
281  // 20.11.5.3 arithmetic
282  constexpr duration
283  operator+() const
284  { return *this; }
285 
286  constexpr duration
287  operator-() const
288  { return duration(-__r); }
289 
290  duration&
291  operator++()
292  {
293  ++__r;
294  return *this;
295  }
296 
297  duration
298  operator++(int)
299  { return duration(__r++); }
300 
301  duration&
302  operator--()
303  {
304  --__r;
305  return *this;
306  }
307 
308  duration
309  operator--(int)
310  { return duration(__r--); }
311 
312  duration&
313  operator+=(const duration& __d)
314  {
315  __r += __d.count();
316  return *this;
317  }
318 
319  duration&
320  operator-=(const duration& __d)
321  {
322  __r -= __d.count();
323  return *this;
324  }
325 
326  duration&
327  operator*=(const rep& __rhs)
328  {
329  __r *= __rhs;
330  return *this;
331  }
332 
333  duration&
334  operator/=(const rep& __rhs)
335  {
336  __r /= __rhs;
337  return *this;
338  }
339 
340  // DR 934.
341  template<typename _Rep2 = rep>
342  typename enable_if<!treat_as_floating_point<_Rep2>::value,
343  duration&>::type
344  operator%=(const rep& __rhs)
345  {
346  __r %= __rhs;
347  return *this;
348  }
349 
350  template<typename _Rep2 = rep>
351  typename enable_if<!treat_as_floating_point<_Rep2>::value,
352  duration&>::type
353  operator%=(const duration& __d)
354  {
355  __r %= __d.count();
356  return *this;
357  }
358 
359  // 20.11.5.4 special values
360  static constexpr duration
361  zero()
362  { return duration(duration_values<rep>::zero()); }
363 
364  static constexpr duration
365  min()
366  { return duration(duration_values<rep>::min()); }
367 
368  static constexpr duration
369  max()
370  { return duration(duration_values<rep>::max()); }
371 
372  private:
373  rep __r;
374  };
375 
376  template<typename _Rep1, typename _Period1,
377  typename _Rep2, typename _Period2>
378  constexpr typename common_type<duration<_Rep1, _Period1>,
379  duration<_Rep2, _Period2>>::type
380  operator+(const duration<_Rep1, _Period1>& __lhs,
381  const duration<_Rep2, _Period2>& __rhs)
382  {
383  typedef duration<_Rep1, _Period1> __dur1;
384  typedef duration<_Rep2, _Period2> __dur2;
385  typedef typename common_type<__dur1,__dur2>::type __cd;
386  return __cd(__cd(__lhs).count() + __cd(__rhs).count());
387  }
388 
389  template<typename _Rep1, typename _Period1,
390  typename _Rep2, typename _Period2>
391  constexpr typename common_type<duration<_Rep1, _Period1>,
392  duration<_Rep2, _Period2>>::type
393  operator-(const duration<_Rep1, _Period1>& __lhs,
394  const duration<_Rep2, _Period2>& __rhs)
395  {
396  typedef duration<_Rep1, _Period1> __dur1;
397  typedef duration<_Rep2, _Period2> __dur2;
398  typedef typename common_type<__dur1,__dur2>::type __cd;
399  return __cd(__cd(__lhs).count() - __cd(__rhs).count());
400  }
401 
402  template<typename _Rep1, typename _Rep2, bool =
403  is_convertible<_Rep2,
404  typename common_type<_Rep1, _Rep2>::type>::value>
405  struct __common_rep_type { };
406 
407  template<typename _Rep1, typename _Rep2>
408  struct __common_rep_type<_Rep1, _Rep2, true>
409  { typedef typename common_type<_Rep1, _Rep2>::type type; };
410 
411  template<typename _Rep1, typename _Period, typename _Rep2>
412  constexpr
413  duration<typename __common_rep_type<_Rep1, _Rep2>::type, _Period>
414  operator*(const duration<_Rep1, _Period>& __d, const _Rep2& __s)
415  {
416  typedef duration<typename common_type<_Rep1, _Rep2>::type, _Period>
417  __cd;
418  return __cd(__cd(__d).count() * __s);
419  }
420 
421  template<typename _Rep1, typename _Rep2, typename _Period>
422  constexpr
423  duration<typename __common_rep_type<_Rep2, _Rep1>::type, _Period>
424  operator*(const _Rep1& __s, const duration<_Rep2, _Period>& __d)
425  { return __d * __s; }
426 
427  template<typename _Rep1, typename _Period, typename _Rep2>
428  constexpr duration<typename __common_rep_type<_Rep1, typename
429  enable_if<!__is_duration<_Rep2>::value, _Rep2>::type>::type, _Period>
430  operator/(const duration<_Rep1, _Period>& __d, const _Rep2& __s)
431  {
432  typedef duration<typename common_type<_Rep1, _Rep2>::type, _Period>
433  __cd;
434  return __cd(__cd(__d).count() / __s);
435  }
436 
437  template<typename _Rep1, typename _Period1,
438  typename _Rep2, typename _Period2>
439  constexpr typename common_type<_Rep1, _Rep2>::type
440  operator/(const duration<_Rep1, _Period1>& __lhs,
441  const duration<_Rep2, _Period2>& __rhs)
442  {
443  typedef duration<_Rep1, _Period1> __dur1;
444  typedef duration<_Rep2, _Period2> __dur2;
445  typedef typename common_type<__dur1,__dur2>::type __cd;
446  return __cd(__lhs).count() / __cd(__rhs).count();
447  }
448 
449  // DR 934.
450  template<typename _Rep1, typename _Period, typename _Rep2>
451  constexpr duration<typename __common_rep_type<_Rep1, typename
452  enable_if<!__is_duration<_Rep2>::value, _Rep2>::type>::type, _Period>
453  operator%(const duration<_Rep1, _Period>& __d, const _Rep2& __s)
454  {
455  typedef duration<typename common_type<_Rep1, _Rep2>::type, _Period>
456  __cd;
457  return __cd(__cd(__d).count() % __s);
458  }
459 
460  template<typename _Rep1, typename _Period1,
461  typename _Rep2, typename _Period2>
462  constexpr typename common_type<duration<_Rep1, _Period1>,
463  duration<_Rep2, _Period2>>::type
464  operator%(const duration<_Rep1, _Period1>& __lhs,
465  const duration<_Rep2, _Period2>& __rhs)
466  {
467  typedef duration<_Rep1, _Period1> __dur1;
468  typedef duration<_Rep2, _Period2> __dur2;
469  typedef typename common_type<__dur1,__dur2>::type __cd;
470  return __cd(__cd(__lhs).count() % __cd(__rhs).count());
471  }
472 
473  // comparisons
474  template<typename _Rep1, typename _Period1,
475  typename _Rep2, typename _Period2>
476  constexpr bool
477  operator==(const duration<_Rep1, _Period1>& __lhs,
478  const duration<_Rep2, _Period2>& __rhs)
479  {
480  typedef duration<_Rep1, _Period1> __dur1;
481  typedef duration<_Rep2, _Period2> __dur2;
482  typedef typename common_type<__dur1,__dur2>::type __ct;
483  return __ct(__lhs).count() == __ct(__rhs).count();
484  }
485 
486  template<typename _Rep1, typename _Period1,
487  typename _Rep2, typename _Period2>
488  constexpr bool
489  operator<(const duration<_Rep1, _Period1>& __lhs,
490  const duration<_Rep2, _Period2>& __rhs)
491  {
492  typedef duration<_Rep1, _Period1> __dur1;
493  typedef duration<_Rep2, _Period2> __dur2;
494  typedef typename common_type<__dur1,__dur2>::type __ct;
495  return __ct(__lhs).count() < __ct(__rhs).count();
496  }
497 
498  template<typename _Rep1, typename _Period1,
499  typename _Rep2, typename _Period2>
500  constexpr bool
501  operator!=(const duration<_Rep1, _Period1>& __lhs,
502  const duration<_Rep2, _Period2>& __rhs)
503  { return !(__lhs == __rhs); }
504 
505  template<typename _Rep1, typename _Period1,
506  typename _Rep2, typename _Period2>
507  constexpr bool
508  operator<=(const duration<_Rep1, _Period1>& __lhs,
509  const duration<_Rep2, _Period2>& __rhs)
510  { return !(__rhs < __lhs); }
511 
512  template<typename _Rep1, typename _Period1,
513  typename _Rep2, typename _Period2>
514  constexpr bool
515  operator>(const duration<_Rep1, _Period1>& __lhs,
516  const duration<_Rep2, _Period2>& __rhs)
517  { return __rhs < __lhs; }
518 
519  template<typename _Rep1, typename _Period1,
520  typename _Rep2, typename _Period2>
521  constexpr bool
522  operator>=(const duration<_Rep1, _Period1>& __lhs,
523  const duration<_Rep2, _Period2>& __rhs)
524  { return !(__lhs < __rhs); }
525 
526  /// nanoseconds
527  typedef duration<int64_t, nano> nanoseconds;
528 
529  /// microseconds
530  typedef duration<int64_t, micro> microseconds;
531 
532  /// milliseconds
533  typedef duration<int64_t, milli> milliseconds;
534 
535  /// seconds
536  typedef duration<int64_t> seconds;
537 
538  /// minutes
539  typedef duration<int64_t, ratio< 60>> minutes;
540 
541  /// hours
542  typedef duration<int64_t, ratio<3600>> hours;
543 
544  /// time_point
545  template<typename _Clock, typename _Dur>
546  struct time_point
547  {
548  typedef _Clock clock;
549  typedef _Dur duration;
550  typedef typename duration::rep rep;
551  typedef typename duration::period period;
552 
553  constexpr time_point() : __d(duration::zero())
554  { }
555 
556  constexpr explicit time_point(const duration& __dur)
557  : __d(__dur)
558  { }
559 
560  // conversions
561  template<typename _Dur2>
562  constexpr time_point(const time_point<clock, _Dur2>& __t)
563  : __d(__t.time_since_epoch())
564  { }
565 
566  // observer
567  constexpr duration
568  time_since_epoch() const
569  { return __d; }
570 
571  // arithmetic
572  time_point&
573  operator+=(const duration& __dur)
574  {
575  __d += __dur;
576  return *this;
577  }
578 
579  time_point&
580  operator-=(const duration& __dur)
581  {
582  __d -= __dur;
583  return *this;
584  }
585 
586  // special values
587  static constexpr time_point
588  min()
589  { return time_point(duration::min()); }
590 
591  static constexpr time_point
592  max()
593  { return time_point(duration::max()); }
594 
595  private:
596  duration __d;
597  };
598 
599  /// time_point_cast
600  template<typename _ToDur, typename _Clock, typename _Dur>
601  constexpr typename enable_if<__is_duration<_ToDur>::value,
602  time_point<_Clock, _ToDur>>::type
603  time_point_cast(const time_point<_Clock, _Dur>& __t)
604  {
605  typedef time_point<_Clock, _ToDur> __time_point;
606  return __time_point(duration_cast<_ToDur>(__t.time_since_epoch()));
607  }
608 
609  template<typename _Clock, typename _Dur1,
610  typename _Rep2, typename _Period2>
611  constexpr time_point<_Clock,
612  typename common_type<_Dur1, duration<_Rep2, _Period2>>::type>
613  operator+(const time_point<_Clock, _Dur1>& __lhs,
614  const duration<_Rep2, _Period2>& __rhs)
615  {
616  typedef duration<_Rep2, _Period2> __dur2;
617  typedef typename common_type<_Dur1,__dur2>::type __ct;
618  typedef time_point<_Clock, __ct> __time_point;
619  return __time_point(__lhs.time_since_epoch() + __rhs);
620  }
621 
622  template<typename _Rep1, typename _Period1,
623  typename _Clock, typename _Dur2>
624  constexpr time_point<_Clock,
625  typename common_type<duration<_Rep1, _Period1>, _Dur2>::type>
626  operator+(const duration<_Rep1, _Period1>& __lhs,
627  const time_point<_Clock, _Dur2>& __rhs)
628  {
629  typedef duration<_Rep1, _Period1> __dur1;
630  typedef typename common_type<__dur1,_Dur2>::type __ct;
631  typedef time_point<_Clock, __ct> __time_point;
632  return __time_point(__rhs.time_since_epoch() + __lhs);
633  }
634 
635  template<typename _Clock, typename _Dur1,
636  typename _Rep2, typename _Period2>
637  constexpr time_point<_Clock,
638  typename common_type<_Dur1, duration<_Rep2, _Period2>>::type>
639  operator-(const time_point<_Clock, _Dur1>& __lhs,
640  const duration<_Rep2, _Period2>& __rhs)
641  {
642  typedef duration<_Rep2, _Period2> __dur2;
643  typedef typename common_type<_Dur1,__dur2>::type __ct;
644  typedef time_point<_Clock, __ct> __time_point;
645  return __time_point(__lhs.time_since_epoch() -__rhs);
646  }
647 
648  template<typename _Clock, typename _Dur1, typename _Dur2>
649  constexpr typename common_type<_Dur1, _Dur2>::type
650  operator-(const time_point<_Clock, _Dur1>& __lhs,
651  const time_point<_Clock, _Dur2>& __rhs)
652  { return __lhs.time_since_epoch() - __rhs.time_since_epoch(); }
653 
654  template<typename _Clock, typename _Dur1, typename _Dur2>
655  constexpr bool
656  operator==(const time_point<_Clock, _Dur1>& __lhs,
657  const time_point<_Clock, _Dur2>& __rhs)
658  { return __lhs.time_since_epoch() == __rhs.time_since_epoch(); }
659 
660  template<typename _Clock, typename _Dur1, typename _Dur2>
661  constexpr bool
662  operator!=(const time_point<_Clock, _Dur1>& __lhs,
663  const time_point<_Clock, _Dur2>& __rhs)
664  { return !(__lhs == __rhs); }
665 
666  template<typename _Clock, typename _Dur1, typename _Dur2>
667  constexpr bool
668  operator<(const time_point<_Clock, _Dur1>& __lhs,
669  const time_point<_Clock, _Dur2>& __rhs)
670  { return __lhs.time_since_epoch() < __rhs.time_since_epoch(); }
671 
672  template<typename _Clock, typename _Dur1, typename _Dur2>
673  constexpr bool
674  operator<=(const time_point<_Clock, _Dur1>& __lhs,
675  const time_point<_Clock, _Dur2>& __rhs)
676  { return !(__rhs < __lhs); }
677 
678  template<typename _Clock, typename _Dur1, typename _Dur2>
679  constexpr bool
680  operator>(const time_point<_Clock, _Dur1>& __lhs,
681  const time_point<_Clock, _Dur2>& __rhs)
682  { return __rhs < __lhs; }
683 
684  template<typename _Clock, typename _Dur1, typename _Dur2>
685  constexpr bool
686  operator>=(const time_point<_Clock, _Dur1>& __lhs,
687  const time_point<_Clock, _Dur2>& __rhs)
688  { return !(__lhs < __rhs); }
689 
690 
691  // Clocks.
692 
693  // Why nanosecond resolution as the default?
694  // Why have std::system_clock always count in the higest
695  // resolution (ie nanoseconds), even if on some OSes the low 3
696  // or 9 decimal digits will be always zero? This allows later
697  // implementations to change the system_clock::now()
698  // implementation any time to provide better resolution without
699  // changing function signature or units.
700 
701  // To support the (forward) evolution of the library's defined
702  // clocks, wrap inside inline namespace so that the current
703  // defintions of system_clock, steady_clock, and
704  // high_resolution_clock types are uniquely mangled. This way, new
705  // code can use the latests clocks, while the library can contain
706  // compatibility definitions for previous versions. At some
707  // point, when these clocks settle down, the inlined namespaces
708  // can be removed. XXX GLIBCXX_ABI Deprecated
709  inline namespace _V2 {
710 
711  /**
712  * @brief System clock.
713  *
714  * Time returned represents wall time from the system-wide clock.
715  */
716  struct system_clock
717  {
718  typedef chrono::nanoseconds duration;
719  typedef duration::rep rep;
720  typedef duration::period period;
721  typedef chrono::time_point<system_clock, duration> time_point;
722 
723  static_assert(system_clock::duration::min()
724  < system_clock::duration::zero(),
725  "a clock's minimum duration cannot be less than its epoch");
726 
727  static constexpr bool is_steady = false;
728 
729  static time_point
730  now() noexcept;
731 
732  // Map to C API
733  static std::time_t
734  to_time_t(const time_point& __t) noexcept
735  {
736  return std::time_t(duration_cast<chrono::seconds>
737  (__t.time_since_epoch()).count());
738  }
739 
740  static time_point
741  from_time_t(std::time_t __t) noexcept
742  {
743  typedef chrono::time_point<system_clock, seconds> __from;
744  return time_point_cast<system_clock::duration>
745  (__from(chrono::seconds(__t)));
746  }
747  };
748 
749 
750  /**
751  * @brief Monotonic clock
752  *
753  * Time returned has the property of only increasing at a uniform rate.
754  */
755  struct steady_clock
756  {
757  typedef chrono::nanoseconds duration;
758  typedef duration::rep rep;
759  typedef duration::period period;
760  typedef chrono::time_point<steady_clock, duration> time_point;
761 
762  static constexpr bool is_steady = true;
763 
764  static time_point
765  now() noexcept;
766  };
767 
768 
769  /**
770  * @brief Highest-resolution clock
771  *
772  * This is the clock "with the shortest tick period." Alias to
773  * std::system_clock until higher-than-nanosecond definitions
774  * become feasible.
775  */
776  using high_resolution_clock = system_clock;
777 
778  } // end inline namespace _V2
779 
780  _GLIBCXX_END_NAMESPACE_VERSION
781  } // namespace chrono
782 
783 #if __cplusplus > 201103L
784 
785 #define __cpp_lib_chrono_udls 201304
786 
787  inline namespace literals
788  {
789  inline namespace chrono_literals
790  {
791 
792  template<typename _Rep, unsigned long long _Val>
793  struct _Checked_integral_constant
794  : integral_constant<_Rep, static_cast<_Rep>(_Val)>
795  {
796  static_assert(_Checked_integral_constant::value >= 0
797  && _Checked_integral_constant::value == _Val,
798  "literal value cannot be represented by duration type");
799  };
800 
801  template<typename _Dur, char... _Digits>
802  constexpr _Dur __check_overflow()
803  {
804  using _Val = __parse_int::_Parse_int<_Digits...>;
805  using _Rep = typename _Dur::rep;
806  // TODO: should be simply integral_constant<_Rep, _Val::value>
807  // but GCC doesn't reject narrowing conversions to _Rep.
808  using _CheckedVal = _Checked_integral_constant<_Rep, _Val::value>;
809  return _Dur{_CheckedVal::value};
810  }
811 
812  constexpr chrono::duration<long double, ratio<3600,1>>
813  operator""h(long double __hours)
814  { return chrono::duration<long double, ratio<3600,1>>{__hours}; }
815 
816  template <char... _Digits>
817  constexpr chrono::hours
818  operator""h()
819  { return __check_overflow<chrono::hours, _Digits...>(); }
820 
821  constexpr chrono::duration<long double, ratio<60,1>>
822  operator""min(long double __mins)
823  { return chrono::duration<long double, ratio<60,1>>{__mins}; }
824 
825  template <char... _Digits>
826  constexpr chrono::minutes
827  operator""min()
828  { return __check_overflow<chrono::minutes, _Digits...>(); }
829 
830  constexpr chrono::duration<long double>
831  operator""s(long double __secs)
832  { return chrono::duration<long double>{__secs}; }
833 
834  template <char... _Digits>
835  constexpr chrono::seconds
836  operator""s()
837  { return __check_overflow<chrono::seconds, _Digits...>(); }
838 
839  constexpr chrono::duration<long double, milli>
840  operator""ms(long double __msecs)
841  { return chrono::duration<long double, milli>{__msecs}; }
842 
843  template <char... _Digits>
844  constexpr chrono::milliseconds
845  operator""ms()
846  { return __check_overflow<chrono::milliseconds, _Digits...>(); }
847 
848  constexpr chrono::duration<long double, micro>
849  operator""us(long double __usecs)
850  { return chrono::duration<long double, micro>{__usecs}; }
851 
852  template <char... _Digits>
853  constexpr chrono::microseconds
854  operator""us()
855  { return __check_overflow<chrono::microseconds, _Digits...>(); }
856 
857  constexpr chrono::duration<long double, nano>
858  operator""ns(long double __nsecs)
859  { return chrono::duration<long double, nano>{__nsecs}; }
860 
861  template <char... _Digits>
862  constexpr chrono::nanoseconds
863  operator""ns()
864  { return __check_overflow<chrono::nanoseconds, _Digits...>(); }
865 
866  } // inline namespace chrono_literals
867  } // inline namespace literals
868 
869  namespace chrono
870  {
871  _GLIBCXX_BEGIN_NAMESPACE_VERSION
872 
873  using namespace literals::chrono_literals;
874 
875  _GLIBCXX_END_NAMESPACE_VERSION
876  } // namespace chrono
877 
878 #endif // __cplusplus > 201103L
879 
880  // @} group chrono
881 } // namespace std
882 
883 #endif //_GLIBCXX_USE_C99_STDINT_TR1
884 
885 #endif // C++11
886 
887 #endif //_GLIBCXX_CHRONO