libstdc++-v3/include/std/chrono

   1 // <chrono> -*- C++ -*-
   2
   3 // Copyright (C) 2008-2016 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 #if __cplusplus > 201402L
 213     template <typename _Rep>
 214       constexpr bool treat_as_floating_point_v =
 215         treat_as_floating_point<_Rep>::value;
 216 #endif // C++17
 217
 218 #if __cplusplus > 201402L
 219 # define __cpp_lib_chrono 201510
 220
 221     template<typename _ToDur, typename _Rep, typename _Period>
 222       constexpr enable_if_t<__is_duration<_ToDur>::value, _ToDur>
 223       floor(const duration<_Rep, _Period>& __d)
 224       {
 225         auto __to = chrono::duration_cast<_ToDur>(__d);
 226         if (__to > __d)
 227           --__to;
 228         return __to;
 229       }
 230
 231     template<typename _ToDur, typename _Rep, typename _Period>
 232       constexpr enable_if_t<__is_duration<_ToDur>::value, _ToDur>
 233       ceil(const duration<_Rep, _Period>& __d)
 234       {
 235         auto __to = chrono::duration_cast<_ToDur>(__d);
 236         if (__to < __d)
 237           return __to + _ToDur{1};
 238         return __to;
 239       }
 240
 241     template <typename _ToDur, typename _Rep, typename _Period>
 242       constexpr enable_if_t<
 243         __and_<__is_duration<_ToDur>,
 244                __not_<treat_as_floating_point<typename _ToDur::rep>>>::value,
 245         _ToDur>
 246       round(const duration<_Rep, _Period>& __d)
 247       {
 248         _ToDur __t0 = chrono::floor<_ToDur>(__d);
 249         _ToDur __t1 = __t0 + _ToDur{1};
 250         auto __diff0 = __d - __t0;
 251         auto __diff1 = __t1 - __d;
 252         if (__diff0 == __diff1)
 253         {
 254             if (__t0.count() & 1)
 255                 return __t1;
 256             return __t0;
 257         }
 258         else if (__diff0 < __diff1)
 259             return __t0;
 260         return __t1;
 261       }
 262
 263     template<typename _Rep, typename _Period>
 264       constexpr
 265       enable_if_t<numeric_limits<_Rep>::is_signed, duration<_Rep, _Period>>
 266       abs(duration<_Rep, _Period> __d)
 267       {
 268         if (__d >= __d.zero())
 269           return __d;
 270         return -__d;
 271       }
 272 #endif // C++17
 273
 274     /// duration_values
 275     template<typename _Rep>
 276       struct duration_values
 277       {
 278         static constexpr _Rep
 279         zero()
 280         { return _Rep(0); }
 281
 282         static constexpr _Rep
 283         max()
 284         { return numeric_limits<_Rep>::max(); }
 285
 286         static constexpr _Rep
 287         min()
 288         { return numeric_limits<_Rep>::lowest(); }
 289       };
 290
 291     template<typename _Tp>
 292       struct __is_ratio
 293       : std::false_type
 294       { };
 295
 296     template<intmax_t _Num, intmax_t _Den>
 297       struct __is_ratio<ratio<_Num, _Den>>
 298       : std::true_type
 299       { };
 300
 301     /// duration
 302     template<typename _Rep, typename _Period>
 303       struct duration
 304       {
 305         typedef _Rep                                            rep;
 306         typedef _Period                                         period;
 307
 308         static_assert(!__is_duration<_Rep>::value, "rep cannot be a duration");
 309         static_assert(__is_ratio<_Period>::value,
 310                       "period must be a specialization of ratio");
 311         static_assert(_Period::num > 0, "period must be positive");
 312
 313         // 20.11.5.1 construction / copy / destroy
 314         constexpr duration() = default;
 315
 316         // NB: Make constexpr implicit. This cannot be explicitly
 317         // constexpr, as any UDT that is not a literal type with a
 318         // constexpr copy constructor will be ill-formed.
 319         duration(const duration&) = default;
 320
 321         template<typename _Rep2, typename = typename
 322                enable_if<is_convertible<_Rep2, rep>::value
 323                          && (treat_as_floating_point<rep>::value
 324                              || !treat_as_floating_point<_Rep2>::value)>::type>
 325           constexpr explicit duration(const _Rep2& __rep)
 326           : __r(static_cast<rep>(__rep)) { }
 327
 328         template<typename _Rep2, typename _Period2, typename = typename
 329                enable_if<treat_as_floating_point<rep>::value
 330                          || (ratio_divide<_Period2, period>::den == 1
 331                              && !treat_as_floating_point<_Rep2>::value)>::type>
 332           constexpr duration(const duration<_Rep2, _Period2>& __d)
 333           : __r(duration_cast<duration>(__d).count()) { }
 334
 335         ~duration() = default;
 336         duration& operator=(const duration&) = default;
 337
 338         // 20.11.5.2 observer
 339         constexpr rep
 340         count() const
 341         { return __r; }
 342
 343         // 20.11.5.3 arithmetic
 344         constexpr duration
 345         operator+() const
 346         { return *this; }
 347
 348         constexpr duration
 349         operator-() const
 350         { return duration(-__r); }
 351
 352         duration&
 353         operator++()
 354         {
 355           ++__r;
 356           return *this;
 357         }
 358
 359         duration
 360         operator++(int)
 361         { return duration(__r++); }
 362
 363         duration&
 364         operator--()
 365         {
 366           --__r;
 367           return *this;
 368         }
 369
 370         duration
 371         operator--(int)
 372         { return duration(__r--); }
 373
 374         duration&
 375         operator+=(const duration& __d)
 376         {
 377           __r += __d.count();
 378           return *this;
 379         }
 380
 381         duration&
 382         operator-=(const duration& __d)
 383         {
 384           __r -= __d.count();
 385           return *this;
 386         }
 387
 388         duration&
 389         operator*=(const rep& __rhs)
 390         {
 391           __r *= __rhs;
 392           return *this;
 393         }
 394
 395         duration&
 396         operator/=(const rep& __rhs)
 397         {
 398           __r /= __rhs;
 399           return *this;
 400         }
 401
 402         // DR 934.
 403         template<typename _Rep2 = rep>
 404           typename enable_if<!treat_as_floating_point<_Rep2>::value,
 405                              duration&>::type
 406           operator%=(const rep& __rhs)
 407           {
 408             __r %= __rhs;
 409             return *this;
 410           }
 411
 412         template<typename _Rep2 = rep>
 413           typename enable_if<!treat_as_floating_point<_Rep2>::value,
 414                              duration&>::type
 415           operator%=(const duration& __d)
 416           {
 417             __r %= __d.count();
 418             return *this;
 419           }
 420
 421         // 20.11.5.4 special values
 422         static constexpr duration
 423         zero()
 424         { return duration(duration_values<rep>::zero()); }
 425
 426         static constexpr duration
 427         min()
 428         { return duration(duration_values<rep>::min()); }
 429
 430         static constexpr duration
 431         max()
 432         { return duration(duration_values<rep>::max()); }
 433
 434       private:
 435         rep __r;
 436       };
 437
 438     template<typename _Rep1, typename _Period1,
 439              typename _Rep2, typename _Period2>
 440       constexpr typename common_type<duration<_Rep1, _Period1>,
 441                                      duration<_Rep2, _Period2>>::type
 442       operator+(const duration<_Rep1, _Period1>& __lhs,
 443                 const duration<_Rep2, _Period2>& __rhs)
 444       {
 445         typedef duration<_Rep1, _Period1>                       __dur1;
 446         typedef duration<_Rep2, _Period2>                       __dur2;
 447         typedef typename common_type<__dur1,__dur2>::type       __cd;
 448         return __cd(__cd(__lhs).count() + __cd(__rhs).count());
 449       }
 450
 451     template<typename _Rep1, typename _Period1,
 452              typename _Rep2, typename _Period2>
 453       constexpr typename common_type<duration<_Rep1, _Period1>,
 454                                      duration<_Rep2, _Period2>>::type
 455       operator-(const duration<_Rep1, _Period1>& __lhs,
 456                 const duration<_Rep2, _Period2>& __rhs)
 457       {
 458         typedef duration<_Rep1, _Period1>                       __dur1;
 459         typedef duration<_Rep2, _Period2>                       __dur2;
 460         typedef typename common_type<__dur1,__dur2>::type       __cd;
 461         return __cd(__cd(__lhs).count() - __cd(__rhs).count());
 462       }
 463
 464     template<typename _Rep1, typename _Rep2, bool =
 465              is_convertible<_Rep2,
 466                             typename common_type<_Rep1, _Rep2>::type>::value>
 467       struct __common_rep_type { };
 468
 469     template<typename _Rep1, typename _Rep2>
 470       struct __common_rep_type<_Rep1, _Rep2, true>
 471       { typedef typename common_type<_Rep1, _Rep2>::type type; };
 472
 473     template<typename _Rep1, typename _Period, typename _Rep2>
 474       constexpr
 475       duration<typename __common_rep_type<_Rep1, _Rep2>::type, _Period>
 476       operator*(const duration<_Rep1, _Period>& __d, const _Rep2& __s)
 477       {
 478         typedef duration<typename common_type<_Rep1, _Rep2>::type, _Period>
 479           __cd;
 480         return __cd(__cd(__d).count() * __s);
 481       }
 482
 483     template<typename _Rep1, typename _Rep2, typename _Period>
 484       constexpr
 485       duration<typename __common_rep_type<_Rep2, _Rep1>::type, _Period>
 486       operator*(const _Rep1& __s, const duration<_Rep2, _Period>& __d)
 487       { return __d * __s; }
 488
 489     template<typename _Rep1, typename _Period, typename _Rep2>
 490       constexpr duration<typename __common_rep_type<_Rep1, typename
 491         enable_if<!__is_duration<_Rep2>::value, _Rep2>::type>::type, _Period>
 492       operator/(const duration<_Rep1, _Period>& __d, const _Rep2& __s)
 493       {
 494         typedef duration<typename common_type<_Rep1, _Rep2>::type, _Period>
 495           __cd;
 496         return __cd(__cd(__d).count() / __s);
 497       }
 498
 499     template<typename _Rep1, typename _Period1,
 500              typename _Rep2, typename _Period2>
 501       constexpr typename common_type<_Rep1, _Rep2>::type
 502       operator/(const duration<_Rep1, _Period1>& __lhs,
 503                 const duration<_Rep2, _Period2>& __rhs)
 504       {
 505         typedef duration<_Rep1, _Period1>                       __dur1;
 506         typedef duration<_Rep2, _Period2>                       __dur2;
 507         typedef typename common_type<__dur1,__dur2>::type       __cd;
 508         return __cd(__lhs).count() / __cd(__rhs).count();
 509       }
 510
 511     // DR 934.
 512     template<typename _Rep1, typename _Period, typename _Rep2>
 513       constexpr duration<typename __common_rep_type<_Rep1, typename
 514         enable_if<!__is_duration<_Rep2>::value, _Rep2>::type>::type, _Period>
 515       operator%(const duration<_Rep1, _Period>& __d, const _Rep2& __s)
 516       {
 517         typedef duration<typename common_type<_Rep1, _Rep2>::type, _Period>
 518           __cd;
 519         return __cd(__cd(__d).count() % __s);
 520       }
 521
 522     template<typename _Rep1, typename _Period1,
 523              typename _Rep2, typename _Period2>
 524       constexpr typename common_type<duration<_Rep1, _Period1>,
 525                                      duration<_Rep2, _Period2>>::type
 526       operator%(const duration<_Rep1, _Period1>& __lhs,
 527                 const duration<_Rep2, _Period2>& __rhs)
 528       {
 529         typedef duration<_Rep1, _Period1>                       __dur1;
 530         typedef duration<_Rep2, _Period2>                       __dur2;
 531         typedef typename common_type<__dur1,__dur2>::type       __cd;
 532         return __cd(__cd(__lhs).count() % __cd(__rhs).count());
 533       }
 534
 535     // comparisons
 536     template<typename _Rep1, typename _Period1,
 537              typename _Rep2, typename _Period2>
 538       constexpr bool
 539       operator==(const duration<_Rep1, _Period1>& __lhs,
 540                  const duration<_Rep2, _Period2>& __rhs)
 541       {
 542         typedef duration<_Rep1, _Period1>                       __dur1;
 543         typedef duration<_Rep2, _Period2>                       __dur2;
 544         typedef typename common_type<__dur1,__dur2>::type       __ct;
 545         return __ct(__lhs).count() == __ct(__rhs).count();
 546       }
 547
 548     template<typename _Rep1, typename _Period1,
 549              typename _Rep2, typename _Period2>
 550       constexpr bool
 551       operator<(const duration<_Rep1, _Period1>& __lhs,
 552                 const duration<_Rep2, _Period2>& __rhs)
 553       {
 554         typedef duration<_Rep1, _Period1>                       __dur1;
 555         typedef duration<_Rep2, _Period2>                       __dur2;
 556         typedef typename common_type<__dur1,__dur2>::type       __ct;
 557         return __ct(__lhs).count() < __ct(__rhs).count();
 558       }
 559
 560     template<typename _Rep1, typename _Period1,
 561              typename _Rep2, typename _Period2>
 562       constexpr bool
 563       operator!=(const duration<_Rep1, _Period1>& __lhs,
 564                  const duration<_Rep2, _Period2>& __rhs)
 565       { return !(__lhs == __rhs); }
 566
 567     template<typename _Rep1, typename _Period1,
 568              typename _Rep2, typename _Period2>
 569       constexpr bool
 570       operator<=(const duration<_Rep1, _Period1>& __lhs,
 571                  const duration<_Rep2, _Period2>& __rhs)
 572       { return !(__rhs < __lhs); }
 573
 574     template<typename _Rep1, typename _Period1,
 575              typename _Rep2, typename _Period2>
 576       constexpr bool
 577       operator>(const duration<_Rep1, _Period1>& __lhs,
 578                 const duration<_Rep2, _Period2>& __rhs)
 579       { return __rhs < __lhs; }
 580
 581     template<typename _Rep1, typename _Period1,
 582              typename _Rep2, typename _Period2>
 583       constexpr bool
 584       operator>=(const duration<_Rep1, _Period1>& __lhs,
 585                  const duration<_Rep2, _Period2>& __rhs)
 586       { return !(__lhs < __rhs); }
 587
 588     /// nanoseconds
 589     typedef duration<int64_t, nano>         nanoseconds;
 590
 591     /// microseconds
 592     typedef duration<int64_t, micro>        microseconds;
 593
 594     /// milliseconds
 595     typedef duration<int64_t, milli>        milliseconds;
 596
 597     /// seconds
 598     typedef duration<int64_t>               seconds;
 599
 600     /// minutes
 601     typedef duration<int64_t, ratio< 60>>   minutes;
 602
 603     /// hours
 604     typedef duration<int64_t, ratio<3600>>  hours;
 605
 606     /// time_point
 607     template<typename _Clock, typename _Dur>
 608       struct time_point
 609       {
 610         typedef _Clock                                          clock;
 611         typedef _Dur                                            duration;
 612         typedef typename duration::rep                          rep;
 613         typedef typename duration::period                       period;
 614
 615         constexpr time_point() : __d(duration::zero())
 616         { }
 617
 618         constexpr explicit time_point(const duration& __dur)
 619         : __d(__dur)
 620         { }
 621
 622         // conversions
 623         template<typename _Dur2>
 624           constexpr time_point(const time_point<clock, _Dur2>& __t)
 625           : __d(__t.time_since_epoch())
 626           { }
 627
 628         // observer
 629         constexpr duration
 630         time_since_epoch() const
 631         { return __d; }
 632
 633         // arithmetic
 634         time_point&
 635         operator+=(const duration& __dur)
 636         {
 637           __d += __dur;
 638           return *this;
 639         }
 640
 641         time_point&
 642         operator-=(const duration& __dur)
 643         {
 644           __d -= __dur;
 645           return *this;
 646         }
 647
 648         // special values
 649         static constexpr time_point
 650         min()
 651         { return time_point(duration::min()); }
 652
 653         static constexpr time_point
 654         max()
 655         { return time_point(duration::max()); }
 656
 657       private:
 658         duration __d;
 659       };
 660
 661     /// time_point_cast
 662     template<typename _ToDur, typename _Clock, typename _Dur>
 663       constexpr typename enable_if<__is_duration<_ToDur>::value,
 664                                    time_point<_Clock, _ToDur>>::type
 665       time_point_cast(const time_point<_Clock, _Dur>& __t)
 666       {
 667         typedef time_point<_Clock, _ToDur>                      __time_point;
 668         return __time_point(duration_cast<_ToDur>(__t.time_since_epoch()));
 669       }
 670
 671 #if __cplusplus > 201402L
 672     template<typename _ToDur, typename _Clock, typename _Dur>
 673       constexpr
 674       enable_if_t<__is_duration<_ToDur>::value, time_point<_Clock, _ToDur>>
 675       floor(const time_point<_Clock, _Dur>& __tp)
 676       {
 677         return time_point<_Clock, _ToDur>{
 678             chrono::floor<_ToDur>(__tp.time_since_epoch())};
 679       }
 680
 681     template<typename _ToDur, typename _Clock, typename _Dur>
 682       constexpr
 683       enable_if_t<__is_duration<_ToDur>::value, time_point<_Clock, _ToDur>>
 684       ceil(const time_point<_Clock, _Dur>& __tp)
 685       {
 686         return time_point<_Clock, _ToDur>{
 687             chrono::ceil<_ToDur>(__tp.time_since_epoch())};
 688       }
 689
 690     template<typename _ToDur, typename _Clock, typename _Dur>
 691       constexpr enable_if_t<
 692         __and_<__is_duration<_ToDur>,
 693                __not_<treat_as_floating_point<typename _ToDur::rep>>>::value,
 694         time_point<_Clock, _ToDur>>
 695       round(const time_point<_Clock, _Dur>& __tp)
 696       {
 697         return time_point<_Clock, _ToDur>{
 698             chrono::round<_ToDur>(__tp.time_since_epoch())};
 699       }
 700 #endif // C++17
 701
 702     template<typename _Clock, typename _Dur1,
 703              typename _Rep2, typename _Period2>
 704       constexpr time_point<_Clock,
 705         typename common_type<_Dur1, duration<_Rep2, _Period2>>::type>
 706       operator+(const time_point<_Clock, _Dur1>& __lhs,
 707                 const duration<_Rep2, _Period2>& __rhs)
 708       {
 709         typedef duration<_Rep2, _Period2>                       __dur2;
 710         typedef typename common_type<_Dur1,__dur2>::type        __ct;
 711         typedef time_point<_Clock, __ct>                        __time_point;
 712         return __time_point(__lhs.time_since_epoch() + __rhs);
 713       }
 714
 715     template<typename _Rep1, typename _Period1,
 716              typename _Clock, typename _Dur2>
 717       constexpr time_point<_Clock,
 718         typename common_type<duration<_Rep1, _Period1>, _Dur2>::type>
 719       operator+(const duration<_Rep1, _Period1>& __lhs,
 720                 const time_point<_Clock, _Dur2>& __rhs)
 721       {
 722         typedef duration<_Rep1, _Period1>                       __dur1;
 723         typedef typename common_type<__dur1,_Dur2>::type        __ct;
 724         typedef time_point<_Clock, __ct>                        __time_point;
 725         return __time_point(__rhs.time_since_epoch() + __lhs);
 726       }
 727
 728     template<typename _Clock, typename _Dur1,
 729              typename _Rep2, typename _Period2>
 730       constexpr time_point<_Clock,
 731         typename common_type<_Dur1, duration<_Rep2, _Period2>>::type>
 732       operator-(const time_point<_Clock, _Dur1>& __lhs,
 733                 const duration<_Rep2, _Period2>& __rhs)
 734       {
 735         typedef duration<_Rep2, _Period2>                       __dur2;
 736         typedef typename common_type<_Dur1,__dur2>::type        __ct;
 737         typedef time_point<_Clock, __ct>                        __time_point;
 738         return __time_point(__lhs.time_since_epoch() -__rhs);
 739       }
 740
 741     template<typename _Clock, typename _Dur1, typename _Dur2>
 742       constexpr typename common_type<_Dur1, _Dur2>::type
 743       operator-(const time_point<_Clock, _Dur1>& __lhs,
 744                 const time_point<_Clock, _Dur2>& __rhs)
 745       { return __lhs.time_since_epoch() - __rhs.time_since_epoch(); }
 746
 747     template<typename _Clock, typename _Dur1, typename _Dur2>
 748       constexpr bool
 749       operator==(const time_point<_Clock, _Dur1>& __lhs,
 750                  const time_point<_Clock, _Dur2>& __rhs)
 751       { return __lhs.time_since_epoch() == __rhs.time_since_epoch(); }
 752
 753     template<typename _Clock, typename _Dur1, typename _Dur2>
 754       constexpr bool
 755       operator!=(const time_point<_Clock, _Dur1>& __lhs,
 756                  const time_point<_Clock, _Dur2>& __rhs)
 757       { return !(__lhs == __rhs); }
 758
 759     template<typename _Clock, typename _Dur1, typename _Dur2>
 760       constexpr bool
 761       operator<(const time_point<_Clock, _Dur1>& __lhs,
 762                 const time_point<_Clock, _Dur2>& __rhs)
 763       { return  __lhs.time_since_epoch() < __rhs.time_since_epoch(); }
 764
 765     template<typename _Clock, typename _Dur1, typename _Dur2>
 766       constexpr bool
 767       operator<=(const time_point<_Clock, _Dur1>& __lhs,
 768                  const time_point<_Clock, _Dur2>& __rhs)
 769       { return !(__rhs < __lhs); }
 770
 771     template<typename _Clock, typename _Dur1, typename _Dur2>
 772       constexpr bool
 773       operator>(const time_point<_Clock, _Dur1>& __lhs,
 774                 const time_point<_Clock, _Dur2>& __rhs)
 775       { return __rhs < __lhs; }
 776
 777     template<typename _Clock, typename _Dur1, typename _Dur2>
 778       constexpr bool
 779       operator>=(const time_point<_Clock, _Dur1>& __lhs,
 780                  const time_point<_Clock, _Dur2>& __rhs)
 781       { return !(__lhs < __rhs); }
 782
 783
 784     // Clocks.
 785
 786     // Why nanosecond resolution as the default?
 787     // Why have std::system_clock always count in the highest
 788     // resolution (ie nanoseconds), even if on some OSes the low 3
 789     // or 9 decimal digits will be always zero? This allows later
 790     // implementations to change the system_clock::now()
 791     // implementation any time to provide better resolution without
 792     // changing function signature or units.
 793
 794     // To support the (forward) evolution of the library's defined
 795     // clocks, wrap inside inline namespace so that the current
 796     // defintions of system_clock, steady_clock, and
 797     // high_resolution_clock types are uniquely mangled. This way, new
 798     // code can use the latests clocks, while the library can contain
 799     // compatibility definitions for previous versions.  At some
 800     // point, when these clocks settle down, the inlined namespaces
 801     // can be removed.  XXX GLIBCXX_ABI Deprecated
 802     inline namespace _V2 {
 803
 804     /**
 805      *  @brief System clock.
 806      *
 807      *  Time returned represents wall time from the system-wide clock.
 808     */
 809     struct system_clock
 810     {
 811       typedef chrono::nanoseconds                               duration;
 812       typedef duration::rep                                     rep;
 813       typedef duration::period                                  period;
 814       typedef chrono::time_point<system_clock, duration>        time_point;
 815
 816       static_assert(system_clock::duration::min()
 817                     < system_clock::duration::zero(),
 818                     "a clock's minimum duration cannot be less than its epoch");
 819
 820       static constexpr bool is_steady = false;
 821
 822       static time_point
 823       now() noexcept;
 824
 825       // Map to C API
 826       static std::time_t
 827       to_time_t(const time_point& __t) noexcept
 828       {
 829         return std::time_t(duration_cast<chrono::seconds>
 830                            (__t.time_since_epoch()).count());
 831       }
 832
 833       static time_point
 834       from_time_t(std::time_t __t) noexcept
 835       {
 836         typedef chrono::time_point<system_clock, seconds>       __from;
 837         return time_point_cast<system_clock::duration>
 838                (__from(chrono::seconds(__t)));
 839       }
 840     };
 841
 842
 843     /**
 844      *  @brief Monotonic clock
 845      *
 846      *  Time returned has the property of only increasing at a uniform rate.
 847     */
 848     struct steady_clock
 849     {
 850       typedef chrono::nanoseconds                               duration;
 851       typedef duration::rep                                     rep;
 852       typedef duration::period                                  period;
 853       typedef chrono::time_point<steady_clock, duration>        time_point;
 854
 855       static constexpr bool is_steady = true;
 856
 857       static time_point
 858       now() noexcept;
 859     };
 860
 861
 862     /**
 863      *  @brief Highest-resolution clock
 864      *
 865      *  This is the clock "with the shortest tick period." Alias to
 866      *  std::system_clock until higher-than-nanosecond definitions
 867      *  become feasible.
 868     */
 869     using high_resolution_clock = system_clock;
 870
 871     } // end inline namespace _V2
 872
 873   _GLIBCXX_END_NAMESPACE_VERSION
 874   } // namespace chrono
 875
 876 #if __cplusplus > 201103L
 877
 878 #define __cpp_lib_chrono_udls 201304
 879
 880   inline namespace literals
 881   {
 882   inline namespace chrono_literals
 883   {
 884   _GLIBCXX_BEGIN_NAMESPACE_VERSION
 885
 886     template<typename _Rep, unsigned long long _Val>
 887       struct _Checked_integral_constant
 888       : integral_constant<_Rep, static_cast<_Rep>(_Val)>
 889       {
 890         static_assert(_Checked_integral_constant::value >= 0
 891                       && _Checked_integral_constant::value == _Val,
 892                       "literal value cannot be represented by duration type");
 893       };
 894
 895     template<typename _Dur, char... _Digits>
 896       constexpr _Dur __check_overflow()
 897       {
 898         using _Val = __parse_int::_Parse_int<_Digits...>;
 899         using _Rep = typename _Dur::rep;
 900         // TODO: should be simply integral_constant<_Rep, _Val::value>
 901         // but GCC doesn't reject narrowing conversions to _Rep.
 902         using _CheckedVal = _Checked_integral_constant<_Rep, _Val::value>;
 903         return _Dur{_CheckedVal::value};
 904       }
 905
 906     constexpr chrono::duration<long double, ratio<3600,1>>
 907     operator""h(long double __hours)
 908     { return chrono::duration<long double, ratio<3600,1>>{__hours}; }
 909
 910     template <char... _Digits>
 911       constexpr chrono::hours
 912       operator""h()
 913       { return __check_overflow<chrono::hours, _Digits...>(); }
 914
 915     constexpr chrono::duration<long double, ratio<60,1>>
 916     operator""min(long double __mins)
 917     { return chrono::duration<long double, ratio<60,1>>{__mins}; }
 918
 919     template <char... _Digits>
 920       constexpr chrono::minutes
 921       operator""min()
 922       { return __check_overflow<chrono::minutes, _Digits...>(); }
 923
 924     constexpr chrono::duration<long double>
 925     operator""s(long double __secs)
 926     { return chrono::duration<long double>{__secs}; }
 927
 928     template <char... _Digits>
 929       constexpr chrono::seconds
 930       operator""s()
 931       { return __check_overflow<chrono::seconds, _Digits...>(); }
 932
 933     constexpr chrono::duration<long double, milli>
 934     operator""ms(long double __msecs)
 935     { return chrono::duration<long double, milli>{__msecs}; }
 936
 937     template <char... _Digits>
 938       constexpr chrono::milliseconds
 939       operator""ms()
 940       { return __check_overflow<chrono::milliseconds, _Digits...>(); }
 941
 942     constexpr chrono::duration<long double, micro>
 943     operator""us(long double __usecs)
 944     { return chrono::duration<long double, micro>{__usecs}; }
 945
 946     template <char... _Digits>
 947       constexpr chrono::microseconds
 948       operator""us()
 949       { return __check_overflow<chrono::microseconds, _Digits...>(); }
 950
 951     constexpr chrono::duration<long double, nano>
 952     operator""ns(long double __nsecs)
 953     { return chrono::duration<long double, nano>{__nsecs}; }
 954
 955     template <char... _Digits>
 956       constexpr chrono::nanoseconds
 957       operator""ns()
 958       { return __check_overflow<chrono::nanoseconds, _Digits...>(); }
 959
 960   _GLIBCXX_END_NAMESPACE_VERSION
 961   } // inline namespace chrono_literals
 962   } // inline namespace literals
 963
 964   namespace chrono
 965   {
 966   _GLIBCXX_BEGIN_NAMESPACE_VERSION
 967
 968   using namespace literals::chrono_literals;
 969
 970   _GLIBCXX_END_NAMESPACE_VERSION
 971   } // namespace chrono
 972
 973 #endif // __cplusplus > 201103L
 974
 975   // @} group chrono
 976 } // namespace std
 977
 978 #endif //_GLIBCXX_USE_C99_STDINT_TR1
 979
 980 #endif // C++11
 981
 982 #endif //_GLIBCXX_CHRONO