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      1 // -*- C++ -*-
      2 //===---------------------------- chrono ----------------------------------===//
      3 //
      4 //                     The LLVM Compiler Infrastructure
      5 //
      6 // This file is dual licensed under the MIT and the University of Illinois Open
      7 // Source Licenses. See LICENSE.TXT for details.
      8 //
      9 //===----------------------------------------------------------------------===//
     10 
     11 #ifndef _LIBCPP_CHRONO
     12 #define _LIBCPP_CHRONO
     13 
     14 /*
     15     chrono synopsis
     16 
     17 namespace std
     18 {
     19 namespace chrono
     20 {
     21 
     22 template <class ToDuration, class Rep, class Period>
     23 constexpr
     24 ToDuration
     25 duration_cast(const duration<Rep, Period>& fd);
     26 
     27 template <class Rep> struct treat_as_floating_point : is_floating_point<Rep> {};
     28 
     29 template <class Rep> constexpr bool treat_as_floating_point_v
     30     = treat_as_floating_point<Rep>::value;                       // C++17
     31 
     32 template <class Rep>
     33 struct duration_values
     34 {
     35 public:
     36     static constexpr Rep zero();
     37     static constexpr Rep max();
     38     static constexpr Rep min();
     39 };
     40 
     41 // duration
     42 
     43 template <class Rep, class Period = ratio<1>>
     44 class duration
     45 {
     46     static_assert(!__is_duration<Rep>::value, "A duration representation can not be a duration");
     47     static_assert(__is_ratio<Period>::value, "Second template parameter of duration must be a std::ratio");
     48     static_assert(Period::num > 0, "duration period must be positive");
     49 public:
     50     typedef Rep rep;
     51     typedef Period period;
     52 
     53     constexpr duration() = default;
     54     template <class Rep2>
     55         constexpr explicit duration(const Rep2& r,
     56             typename enable_if
     57             <
     58                is_convertible<Rep2, rep>::value &&
     59                (treat_as_floating_point<rep>::value ||
     60                !treat_as_floating_point<rep>::value && !treat_as_floating_point<Rep2>::value)
     61             >::type* = 0);
     62 
     63     // conversions
     64     template <class Rep2, class Period2>
     65         constexpr duration(const duration<Rep2, Period2>& d,
     66             typename enable_if
     67             <
     68                 treat_as_floating_point<rep>::value ||
     69                 ratio_divide<Period2, period>::type::den == 1
     70             >::type* = 0);
     71 
     72     // observer
     73 
     74     constexpr rep count() const;
     75 
     76     // arithmetic
     77 
     78     constexpr duration  operator+() const;
     79     constexpr duration  operator-() const;
     80     constexpr duration& operator++();
     81     constexpr duration  operator++(int);
     82     constexpr duration& operator--();
     83     constexpr duration  operator--(int);
     84 
     85     constexpr duration& operator+=(const duration& d);
     86     constexpr duration& operator-=(const duration& d);
     87 
     88     duration& operator*=(const rep& rhs);
     89     duration& operator/=(const rep& rhs);
     90 
     91     // special values
     92 
     93     static constexpr duration zero();
     94     static constexpr duration min();
     95     static constexpr duration max();
     96 };
     97 
     98 typedef duration<long long,         nano> nanoseconds;
     99 typedef duration<long long,        micro> microseconds;
    100 typedef duration<long long,        milli> milliseconds;
    101 typedef duration<long long              > seconds;
    102 typedef duration<     long, ratio<  60> > minutes;
    103 typedef duration<     long, ratio<3600> > hours;
    104 
    105 template <class Clock, class Duration = typename Clock::duration>
    106 class time_point
    107 {
    108 public:
    109     typedef Clock                     clock;
    110     typedef Duration                  duration;
    111     typedef typename duration::rep    rep;
    112     typedef typename duration::period period;
    113 private:
    114     duration d_;  // exposition only
    115 
    116 public:
    117     time_point();  // has value "epoch" // constexpr in C++14
    118     explicit time_point(const duration& d);  // same as time_point() + d // constexpr in C++14
    119 
    120     // conversions
    121     template <class Duration2>
    122        time_point(const time_point<clock, Duration2>& t); // constexpr in C++14
    123 
    124     // observer
    125 
    126     duration time_since_epoch() const; // constexpr in C++14
    127 
    128     // arithmetic
    129 
    130     time_point& operator+=(const duration& d);
    131     time_point& operator-=(const duration& d);
    132 
    133     // special values
    134 
    135     static constexpr time_point min();
    136     static constexpr time_point max();
    137 };
    138 
    139 } // chrono
    140 
    141 // common_type traits
    142 template <class Rep1, class Period1, class Rep2, class Period2>
    143   struct common_type<chrono::duration<Rep1, Period1>, chrono::duration<Rep2, Period2>>;
    144 
    145 template <class Clock, class Duration1, class Duration2>
    146   struct common_type<chrono::time_point<Clock, Duration1>, chrono::time_point<Clock, Duration2>>;
    147 
    148 namespace chrono {
    149 
    150 // duration arithmetic
    151 template <class Rep1, class Period1, class Rep2, class Period2>
    152   constexpr
    153   typename common_type<duration<Rep1, Period1>, duration<Rep2, Period2>>::type
    154   operator+(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
    155 template <class Rep1, class Period1, class Rep2, class Period2>
    156   constexpr
    157   typename common_type<duration<Rep1, Period1>, duration<Rep2, Period2>>::type
    158   operator-(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
    159 template <class Rep1, class Period, class Rep2>
    160   constexpr
    161   duration<typename common_type<Rep1, Rep2>::type, Period>
    162   operator*(const duration<Rep1, Period>& d, const Rep2& s);
    163 template <class Rep1, class Period, class Rep2>
    164   constexpr
    165   duration<typename common_type<Rep1, Rep2>::type, Period>
    166   operator*(const Rep1& s, const duration<Rep2, Period>& d);
    167 template <class Rep1, class Period, class Rep2>
    168   constexpr
    169   duration<typename common_type<Rep1, Rep2>::type, Period>
    170   operator/(const duration<Rep1, Period>& d, const Rep2& s);
    171 template <class Rep1, class Period1, class Rep2, class Period2>
    172   constexpr
    173   typename common_type<Rep1, Rep2>::type
    174   operator/(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
    175 
    176 // duration comparisons
    177 template <class Rep1, class Period1, class Rep2, class Period2>
    178    constexpr
    179    bool operator==(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
    180 template <class Rep1, class Period1, class Rep2, class Period2>
    181    constexpr
    182    bool operator!=(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
    183 template <class Rep1, class Period1, class Rep2, class Period2>
    184    constexpr
    185    bool operator< (const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
    186 template <class Rep1, class Period1, class Rep2, class Period2>
    187    constexpr
    188    bool operator<=(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
    189 template <class Rep1, class Period1, class Rep2, class Period2>
    190    constexpr
    191    bool operator> (const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
    192 template <class Rep1, class Period1, class Rep2, class Period2>
    193    constexpr
    194    bool operator>=(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
    195 
    196 // duration_cast
    197 template <class ToDuration, class Rep, class Period>
    198   ToDuration duration_cast(const duration<Rep, Period>& d);
    199 
    200 template <class ToDuration, class Rep, class Period>
    201     constexpr ToDuration floor(const duration<Rep, Period>& d);    // C++17
    202 template <class ToDuration, class Rep, class Period>
    203     constexpr ToDuration ceil(const duration<Rep, Period>& d);     // C++17
    204 template <class ToDuration, class Rep, class Period>
    205     constexpr ToDuration round(const duration<Rep, Period>& d);    // C++17
    206 
    207 // time_point arithmetic (all constexpr in C++14)
    208 template <class Clock, class Duration1, class Rep2, class Period2>
    209   time_point<Clock, typename common_type<Duration1, duration<Rep2, Period2>>::type>
    210   operator+(const time_point<Clock, Duration1>& lhs, const duration<Rep2, Period2>& rhs);
    211 template <class Rep1, class Period1, class Clock, class Duration2>
    212   time_point<Clock, typename common_type<duration<Rep1, Period1>, Duration2>::type>
    213   operator+(const duration<Rep1, Period1>& lhs, const time_point<Clock, Duration2>& rhs);
    214 template <class Clock, class Duration1, class Rep2, class Period2>
    215   time_point<Clock, typename common_type<Duration1, duration<Rep2, Period2>>::type>
    216   operator-(const time_point<Clock, Duration1>& lhs, const duration<Rep2, Period2>& rhs);
    217 template <class Clock, class Duration1, class Duration2>
    218   typename common_type<Duration1, Duration2>::type
    219   operator-(const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
    220 
    221 // time_point comparisons (all constexpr in C++14)
    222 template <class Clock, class Duration1, class Duration2>
    223    bool operator==(const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
    224 template <class Clock, class Duration1, class Duration2>
    225    bool operator!=(const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
    226 template <class Clock, class Duration1, class Duration2>
    227    bool operator< (const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
    228 template <class Clock, class Duration1, class Duration2>
    229    bool operator<=(const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
    230 template <class Clock, class Duration1, class Duration2>
    231    bool operator> (const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
    232 template <class Clock, class Duration1, class Duration2>
    233    bool operator>=(const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
    234 
    235 // time_point_cast (constexpr in C++14)
    236 
    237 template <class ToDuration, class Clock, class Duration>
    238   time_point<Clock, ToDuration> time_point_cast(const time_point<Clock, Duration>& t);
    239 
    240 template <class ToDuration, class Clock, class Duration>
    241     constexpr time_point<Clock, ToDuration>
    242     floor(const time_point<Clock, Duration>& tp);                  // C++17
    243 
    244 template <class ToDuration, class Clock, class Duration>
    245     constexpr time_point<Clock, ToDuration>
    246     ceil(const time_point<Clock, Duration>& tp);                   // C++17
    247 
    248 template <class ToDuration, class Clock, class Duration>
    249     constexpr time_point<Clock, ToDuration>
    250     round(const time_point<Clock, Duration>& tp);                  // C++17
    251 
    252 template <class Rep, class Period>
    253     constexpr duration<Rep, Period> abs(duration<Rep, Period> d);  // C++17
    254 // Clocks
    255 
    256 class system_clock
    257 {
    258 public:
    259     typedef microseconds                     duration;
    260     typedef duration::rep                    rep;
    261     typedef duration::period                 period;
    262     typedef chrono::time_point<system_clock> time_point;
    263     static const bool is_steady =            false; // constexpr in C++14
    264 
    265     static time_point now() noexcept;
    266     static time_t     to_time_t  (const time_point& __t) noexcept;
    267     static time_point from_time_t(time_t __t) noexcept;
    268 };
    269 
    270 class steady_clock
    271 {
    272 public:
    273     typedef nanoseconds                                   duration;
    274     typedef duration::rep                                 rep;
    275     typedef duration::period                              period;
    276     typedef chrono::time_point<steady_clock, duration>    time_point;
    277     static const bool is_steady =                         true; // constexpr in C++14
    278 
    279     static time_point now() noexcept;
    280 };
    281 
    282 typedef steady_clock high_resolution_clock;
    283 
    284 }  // chrono
    285 
    286 constexpr chrono::hours                                 operator "" h(unsigned long long); // C++14
    287 constexpr chrono::duration<unspecified , ratio<3600,1>> operator "" h(long double); // C++14
    288 constexpr chrono::minutes                               operator "" min(unsigned long long); // C++14
    289 constexpr chrono::duration<unspecified , ratio<60,1>>   operator "" min(long double); // C++14
    290 constexpr chrono::seconds                               operator "" s(unsigned long long); // C++14
    291 constexpr chrono::duration<unspecified >                operator "" s(long double); // C++14
    292 constexpr chrono::milliseconds                          operator "" ms(unsigned long long); // C++14
    293 constexpr chrono::duration<unspecified , milli>         operator "" ms(long double); // C++14
    294 constexpr chrono::microseconds                          operator "" us(unsigned long long); // C++14
    295 constexpr chrono::duration<unspecified , micro>         operator "" us(long double); // C++14
    296 constexpr chrono::nanoseconds                           operator "" ns(unsigned long long); // C++14
    297 constexpr chrono::duration<unspecified , nano>          operator "" ns(long double); // C++14
    298 
    299 }  // std
    300 */
    301 
    302 #include <__config>
    303 #include <ctime>
    304 #include <type_traits>
    305 #include <ratio>
    306 #include <limits>
    307 
    308 #include <__undef_min_max>
    309 
    310 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
    311 #pragma GCC system_header
    312 #endif
    313 
    314 _LIBCPP_BEGIN_NAMESPACE_STD
    315 
    316 namespace chrono
    317 {
    318 
    319 template <class _Rep, class _Period = ratio<1> > class _LIBCPP_TEMPLATE_VIS duration;
    320 
    321 template <class _Tp>
    322 struct __is_duration : false_type {};
    323 
    324 template <class _Rep, class _Period>
    325 struct __is_duration<duration<_Rep, _Period> > : true_type  {};
    326 
    327 template <class _Rep, class _Period>
    328 struct __is_duration<const duration<_Rep, _Period> > : true_type  {};
    329 
    330 template <class _Rep, class _Period>
    331 struct __is_duration<volatile duration<_Rep, _Period> > : true_type  {};
    332 
    333 template <class _Rep, class _Period>
    334 struct __is_duration<const volatile duration<_Rep, _Period> > : true_type  {};
    335 
    336 } // chrono
    337 
    338 template <class _Rep1, class _Period1, class _Rep2, class _Period2>
    339 struct _LIBCPP_TEMPLATE_VIS common_type<chrono::duration<_Rep1, _Period1>,
    340                                          chrono::duration<_Rep2, _Period2> >
    341 {
    342     typedef chrono::duration<typename common_type<_Rep1, _Rep2>::type,
    343                              typename __ratio_gcd<_Period1, _Period2>::type> type;
    344 };
    345 
    346 namespace chrono {
    347 
    348 // duration_cast
    349 
    350 template <class _FromDuration, class _ToDuration,
    351           class _Period = typename ratio_divide<typename _FromDuration::period, typename _ToDuration::period>::type,
    352           bool = _Period::num == 1,
    353           bool = _Period::den == 1>
    354 struct __duration_cast;
    355 
    356 template <class _FromDuration, class _ToDuration, class _Period>
    357 struct __duration_cast<_FromDuration, _ToDuration, _Period, true, true>
    358 {
    359     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
    360     _ToDuration operator()(const _FromDuration& __fd) const
    361     {
    362         return _ToDuration(static_cast<typename _ToDuration::rep>(__fd.count()));
    363     }
    364 };
    365 
    366 template <class _FromDuration, class _ToDuration, class _Period>
    367 struct __duration_cast<_FromDuration, _ToDuration, _Period, true, false>
    368 {
    369     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
    370     _ToDuration operator()(const _FromDuration& __fd) const
    371     {
    372         typedef typename common_type<typename _ToDuration::rep, typename _FromDuration::rep, intmax_t>::type _Ct;
    373         return _ToDuration(static_cast<typename _ToDuration::rep>(
    374                            static_cast<_Ct>(__fd.count()) / static_cast<_Ct>(_Period::den)));
    375     }
    376 };
    377 
    378 template <class _FromDuration, class _ToDuration, class _Period>
    379 struct __duration_cast<_FromDuration, _ToDuration, _Period, false, true>
    380 {
    381     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
    382     _ToDuration operator()(const _FromDuration& __fd) const
    383     {
    384         typedef typename common_type<typename _ToDuration::rep, typename _FromDuration::rep, intmax_t>::type _Ct;
    385         return _ToDuration(static_cast<typename _ToDuration::rep>(
    386                            static_cast<_Ct>(__fd.count()) * static_cast<_Ct>(_Period::num)));
    387     }
    388 };
    389 
    390 template <class _FromDuration, class _ToDuration, class _Period>
    391 struct __duration_cast<_FromDuration, _ToDuration, _Period, false, false>
    392 {
    393     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
    394     _ToDuration operator()(const _FromDuration& __fd) const
    395     {
    396         typedef typename common_type<typename _ToDuration::rep, typename _FromDuration::rep, intmax_t>::type _Ct;
    397         return _ToDuration(static_cast<typename _ToDuration::rep>(
    398                            static_cast<_Ct>(__fd.count()) * static_cast<_Ct>(_Period::num)
    399                                                           / static_cast<_Ct>(_Period::den)));
    400     }
    401 };
    402 
    403 template <class _ToDuration, class _Rep, class _Period>
    404 inline _LIBCPP_INLINE_VISIBILITY
    405 _LIBCPP_CONSTEXPR
    406 typename enable_if
    407 <
    408     __is_duration<_ToDuration>::value,
    409     _ToDuration
    410 >::type
    411 duration_cast(const duration<_Rep, _Period>& __fd)
    412 {
    413     return __duration_cast<duration<_Rep, _Period>, _ToDuration>()(__fd);
    414 }
    415 
    416 template <class _Rep>
    417 struct _LIBCPP_TEMPLATE_VIS treat_as_floating_point : is_floating_point<_Rep> {};
    418 
    419 #if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
    420 template <class _Rep> _LIBCPP_CONSTEXPR bool treat_as_floating_point_v
    421     = treat_as_floating_point<_Rep>::value;
    422 #endif
    423 
    424 template <class _Rep>
    425 struct _LIBCPP_TEMPLATE_VIS duration_values
    426 {
    427 public:
    428     _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR _Rep zero() {return _Rep(0);}
    429     _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR _Rep max()  {return numeric_limits<_Rep>::max();}
    430     _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR _Rep min()  {return numeric_limits<_Rep>::lowest();}
    431 };
    432 
    433 #if _LIBCPP_STD_VER > 14
    434 template <class _ToDuration, class _Rep, class _Period>
    435 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
    436 typename enable_if
    437 <
    438     __is_duration<_ToDuration>::value,
    439     _ToDuration
    440 >::type
    441 floor(const duration<_Rep, _Period>& __d)
    442 {
    443     _ToDuration __t = duration_cast<_ToDuration>(__d);
    444     if (__t > __d)
    445         __t = __t - _ToDuration{1};
    446     return __t;
    447 }
    448 
    449 template <class _ToDuration, class _Rep, class _Period>
    450 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
    451 typename enable_if
    452 <
    453     __is_duration<_ToDuration>::value,
    454     _ToDuration
    455 >::type
    456 ceil(const duration<_Rep, _Period>& __d)
    457 {
    458     _ToDuration __t = duration_cast<_ToDuration>(__d);
    459     if (__t < __d)
    460         __t = __t + _ToDuration{1};
    461     return __t;
    462 }
    463 
    464 template <class _ToDuration, class _Rep, class _Period>
    465 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
    466 typename enable_if
    467 <
    468     __is_duration<_ToDuration>::value,
    469     _ToDuration
    470 >::type
    471 round(const duration<_Rep, _Period>& __d)
    472 {
    473     _ToDuration __lower = floor<_ToDuration>(__d);
    474     _ToDuration __upper = __lower + _ToDuration{1};
    475     auto __lowerDiff = __d - __lower;
    476     auto __upperDiff = __upper - __d;
    477     if (__lowerDiff < __upperDiff)
    478         return __lower;
    479     if (__lowerDiff > __upperDiff)
    480         return __upper;
    481     return __lower.count() & 1 ? __upper : __lower;
    482 }
    483 #endif
    484 
    485 // duration
    486 
    487 template <class _Rep, class _Period>
    488 class _LIBCPP_TEMPLATE_VIS duration
    489 {
    490     static_assert(!__is_duration<_Rep>::value, "A duration representation can not be a duration");
    491     static_assert(__is_ratio<_Period>::value, "Second template parameter of duration must be a std::ratio");
    492     static_assert(_Period::num > 0, "duration period must be positive");
    493 
    494     template <class _R1, class _R2>
    495     struct __no_overflow
    496     {
    497     private:
    498         static const intmax_t __gcd_n1_n2 = __static_gcd<_R1::num, _R2::num>::value;
    499         static const intmax_t __gcd_d1_d2 = __static_gcd<_R1::den, _R2::den>::value;
    500         static const intmax_t __n1 = _R1::num / __gcd_n1_n2;
    501         static const intmax_t __d1 = _R1::den / __gcd_d1_d2;
    502         static const intmax_t __n2 = _R2::num / __gcd_n1_n2;
    503         static const intmax_t __d2 = _R2::den / __gcd_d1_d2;
    504         static const intmax_t max = -((intmax_t(1) << (sizeof(intmax_t) * CHAR_BIT - 1)) + 1);
    505 
    506         template <intmax_t _Xp, intmax_t _Yp, bool __overflow>
    507         struct __mul    // __overflow == false
    508         {
    509             static const intmax_t value = _Xp * _Yp;
    510         };
    511 
    512         template <intmax_t _Xp, intmax_t _Yp>
    513         struct __mul<_Xp, _Yp, true>
    514         {
    515             static const intmax_t value = 1;
    516         };
    517 
    518     public:
    519         static const bool value = (__n1 <= max / __d2) && (__n2 <= max / __d1);
    520         typedef ratio<__mul<__n1, __d2, !value>::value,
    521                       __mul<__n2, __d1, !value>::value> type;
    522     };
    523     
    524 public:
    525     typedef _Rep rep;
    526     typedef _Period period;
    527 private:
    528     rep __rep_;
    529 public:
    530 
    531     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
    532 #ifndef _LIBCPP_CXX03_LANG
    533         duration() = default;
    534 #else
    535         duration() {}
    536 #endif
    537 
    538     template <class _Rep2>
    539         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
    540         explicit duration(const _Rep2& __r,
    541             typename enable_if
    542             <
    543                is_convertible<_Rep2, rep>::value &&
    544                (treat_as_floating_point<rep>::value ||
    545                !treat_as_floating_point<_Rep2>::value)
    546             >::type* = 0)
    547                 : __rep_(__r) {}
    548 
    549     // conversions
    550     template <class _Rep2, class _Period2>
    551         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
    552         duration(const duration<_Rep2, _Period2>& __d,
    553             typename enable_if
    554             <
    555                 __no_overflow<_Period2, period>::value && (
    556                 treat_as_floating_point<rep>::value ||
    557                 (__no_overflow<_Period2, period>::type::den == 1 &&
    558                  !treat_as_floating_point<_Rep2>::value))
    559             >::type* = 0)
    560                 : __rep_(_VSTD::chrono::duration_cast<duration>(__d).count()) {}
    561 
    562     // observer
    563 
    564     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR rep count() const {return __rep_;}
    565 
    566     // arithmetic
    567 
    568     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR duration  operator+() const {return *this;}
    569     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR duration  operator-() const {return duration(-__rep_);}
    570     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 duration& operator++()      {++__rep_; return *this;}
    571     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 duration  operator++(int)   {return duration(__rep_++);}
    572     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 duration& operator--()      {--__rep_; return *this;}
    573     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 duration  operator--(int)   {return duration(__rep_--);}
    574 
    575     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 duration& operator+=(const duration& __d) {__rep_ += __d.count(); return *this;}
    576     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 duration& operator-=(const duration& __d) {__rep_ -= __d.count(); return *this;}
    577 
    578     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 duration& operator*=(const rep& rhs) {__rep_ *= rhs; return *this;}
    579     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 duration& operator/=(const rep& rhs) {__rep_ /= rhs; return *this;}
    580     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 duration& operator%=(const rep& rhs) {__rep_ %= rhs; return *this;}
    581     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 duration& operator%=(const duration& rhs) {__rep_ %= rhs.count(); return *this;}
    582 
    583     // special values
    584 
    585     _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR duration zero() {return duration(duration_values<rep>::zero());}
    586     _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR duration min()  {return duration(duration_values<rep>::min());}
    587     _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR duration max()  {return duration(duration_values<rep>::max());}
    588 };
    589 
    590 typedef duration<long long,         nano> nanoseconds;
    591 typedef duration<long long,        micro> microseconds;
    592 typedef duration<long long,        milli> milliseconds;
    593 typedef duration<long long              > seconds;
    594 typedef duration<     long, ratio<  60> > minutes;
    595 typedef duration<     long, ratio<3600> > hours;
    596 
    597 // Duration ==
    598 
    599 template <class _LhsDuration, class _RhsDuration>
    600 struct __duration_eq
    601 {
    602     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
    603     bool operator()(const _LhsDuration& __lhs, const _RhsDuration& __rhs) const
    604         {
    605             typedef typename common_type<_LhsDuration, _RhsDuration>::type _Ct;
    606             return _Ct(__lhs).count() == _Ct(__rhs).count();
    607         }
    608 };
    609 
    610 template <class _LhsDuration>
    611 struct __duration_eq<_LhsDuration, _LhsDuration>
    612 {
    613     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
    614     bool operator()(const _LhsDuration& __lhs, const _LhsDuration& __rhs) const
    615         {return __lhs.count() == __rhs.count();}
    616 };
    617 
    618 template <class _Rep1, class _Period1, class _Rep2, class _Period2>
    619 inline _LIBCPP_INLINE_VISIBILITY
    620 _LIBCPP_CONSTEXPR
    621 bool
    622 operator==(const duration<_Rep1, _Period1>& __lhs, const duration<_Rep2, _Period2>& __rhs)
    623 {
    624     return __duration_eq<duration<_Rep1, _Period1>, duration<_Rep2, _Period2> >()(__lhs, __rhs);
    625 }
    626 
    627 // Duration !=
    628 
    629 template <class _Rep1, class _Period1, class _Rep2, class _Period2>
    630 inline _LIBCPP_INLINE_VISIBILITY
    631 _LIBCPP_CONSTEXPR
    632 bool
    633 operator!=(const duration<_Rep1, _Period1>& __lhs, const duration<_Rep2, _Period2>& __rhs)
    634 {
    635     return !(__lhs == __rhs);
    636 }
    637 
    638 // Duration <
    639 
    640 template <class _LhsDuration, class _RhsDuration>
    641 struct __duration_lt
    642 {
    643     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
    644     bool operator()(const _LhsDuration& __lhs, const _RhsDuration& __rhs) const
    645         {
    646             typedef typename common_type<_LhsDuration, _RhsDuration>::type _Ct;
    647             return _Ct(__lhs).count() < _Ct(__rhs).count();
    648         }
    649 };
    650 
    651 template <class _LhsDuration>
    652 struct __duration_lt<_LhsDuration, _LhsDuration>
    653 {
    654     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
    655     bool operator()(const _LhsDuration& __lhs, const _LhsDuration& __rhs) const
    656         {return __lhs.count() < __rhs.count();}
    657 };
    658 
    659 template <class _Rep1, class _Period1, class _Rep2, class _Period2>
    660 inline _LIBCPP_INLINE_VISIBILITY
    661 _LIBCPP_CONSTEXPR
    662 bool
    663 operator< (const duration<_Rep1, _Period1>& __lhs, const duration<_Rep2, _Period2>& __rhs)
    664 {
    665     return __duration_lt<duration<_Rep1, _Period1>, duration<_Rep2, _Period2> >()(__lhs, __rhs);
    666 }
    667 
    668 // Duration >
    669 
    670 template <class _Rep1, class _Period1, class _Rep2, class _Period2>
    671 inline _LIBCPP_INLINE_VISIBILITY
    672 _LIBCPP_CONSTEXPR
    673 bool
    674 operator> (const duration<_Rep1, _Period1>& __lhs, const duration<_Rep2, _Period2>& __rhs)
    675 {
    676     return __rhs < __lhs;
    677 }
    678 
    679 // Duration <=
    680 
    681 template <class _Rep1, class _Period1, class _Rep2, class _Period2>
    682 inline _LIBCPP_INLINE_VISIBILITY
    683 _LIBCPP_CONSTEXPR
    684 bool
    685 operator<=(const duration<_Rep1, _Period1>& __lhs, const duration<_Rep2, _Period2>& __rhs)
    686 {
    687     return !(__rhs < __lhs);
    688 }
    689 
    690 // Duration >=
    691 
    692 template <class _Rep1, class _Period1, class _Rep2, class _Period2>
    693 inline _LIBCPP_INLINE_VISIBILITY
    694 _LIBCPP_CONSTEXPR
    695 bool
    696 operator>=(const duration<_Rep1, _Period1>& __lhs, const duration<_Rep2, _Period2>& __rhs)
    697 {
    698     return !(__lhs < __rhs);
    699 }
    700 
    701 // Duration +
    702 
    703 template <class _Rep1, class _Period1, class _Rep2, class _Period2>
    704 inline _LIBCPP_INLINE_VISIBILITY
    705 _LIBCPP_CONSTEXPR
    706 typename common_type<duration<_Rep1, _Period1>, duration<_Rep2, _Period2> >::type
    707 operator+(const duration<_Rep1, _Period1>& __lhs, const duration<_Rep2, _Period2>& __rhs)
    708 {
    709     typedef typename common_type<duration<_Rep1, _Period1>, duration<_Rep2, _Period2> >::type _Cd;
    710     return _Cd(_Cd(__lhs).count() + _Cd(__rhs).count());
    711 }
    712 
    713 // Duration -
    714 
    715 template <class _Rep1, class _Period1, class _Rep2, class _Period2>
    716 inline _LIBCPP_INLINE_VISIBILITY
    717 _LIBCPP_CONSTEXPR
    718 typename common_type<duration<_Rep1, _Period1>, duration<_Rep2, _Period2> >::type
    719 operator-(const duration<_Rep1, _Period1>& __lhs, const duration<_Rep2, _Period2>& __rhs)
    720 {
    721     typedef typename common_type<duration<_Rep1, _Period1>, duration<_Rep2, _Period2> >::type _Cd;
    722     return _Cd(_Cd(__lhs).count() - _Cd(__rhs).count());
    723 }
    724 
    725 // Duration *
    726 
    727 template <class _Rep1, class _Period, class _Rep2>
    728 inline _LIBCPP_INLINE_VISIBILITY
    729 _LIBCPP_CONSTEXPR
    730 typename enable_if
    731 <
    732     is_convertible<_Rep2, typename common_type<_Rep1, _Rep2>::type>::value,
    733     duration<typename common_type<_Rep1, _Rep2>::type, _Period>
    734 >::type
    735 operator*(const duration<_Rep1, _Period>& __d, const _Rep2& __s)
    736 {
    737     typedef typename common_type<_Rep1, _Rep2>::type _Cr;
    738     typedef duration<_Cr, _Period> _Cd;
    739     return _Cd(_Cd(__d).count() * static_cast<_Cr>(__s));
    740 }
    741 
    742 template <class _Rep1, class _Period, class _Rep2>
    743 inline _LIBCPP_INLINE_VISIBILITY
    744 _LIBCPP_CONSTEXPR
    745 typename enable_if
    746 <
    747     is_convertible<_Rep1, typename common_type<_Rep1, _Rep2>::type>::value,
    748     duration<typename common_type<_Rep1, _Rep2>::type, _Period>
    749 >::type
    750 operator*(const _Rep1& __s, const duration<_Rep2, _Period>& __d)
    751 {
    752     return __d * __s;
    753 }
    754 
    755 // Duration /
    756 
    757 template <class _Duration, class _Rep, bool = __is_duration<_Rep>::value>
    758 struct __duration_divide_result
    759 {
    760 };
    761 
    762 template <class _Duration, class _Rep2,
    763     bool = is_convertible<_Rep2,
    764                           typename common_type<typename _Duration::rep, _Rep2>::type>::value>
    765 struct __duration_divide_imp
    766 {
    767 };
    768 
    769 template <class _Rep1, class _Period, class _Rep2>
    770 struct __duration_divide_imp<duration<_Rep1, _Period>, _Rep2, true>
    771 {
    772     typedef duration<typename common_type<_Rep1, _Rep2>::type, _Period> type;
    773 };
    774 
    775 template <class _Rep1, class _Period, class _Rep2>
    776 struct __duration_divide_result<duration<_Rep1, _Period>, _Rep2, false>
    777     : __duration_divide_imp<duration<_Rep1, _Period>, _Rep2>
    778 {
    779 };
    780 
    781 template <class _Rep1, class _Period, class _Rep2>
    782 inline _LIBCPP_INLINE_VISIBILITY
    783 _LIBCPP_CONSTEXPR
    784 typename __duration_divide_result<duration<_Rep1, _Period>, _Rep2>::type
    785 operator/(const duration<_Rep1, _Period>& __d, const _Rep2& __s)
    786 {
    787     typedef typename common_type<_Rep1, _Rep2>::type _Cr;
    788     typedef duration<_Cr, _Period> _Cd;
    789     return _Cd(_Cd(__d).count() / static_cast<_Cr>(__s));
    790 }
    791 
    792 template <class _Rep1, class _Period1, class _Rep2, class _Period2>
    793 inline _LIBCPP_INLINE_VISIBILITY
    794 _LIBCPP_CONSTEXPR
    795 typename common_type<_Rep1, _Rep2>::type
    796 operator/(const duration<_Rep1, _Period1>& __lhs, const duration<_Rep2, _Period2>& __rhs)
    797 {
    798     typedef typename common_type<duration<_Rep1, _Period1>, duration<_Rep2, _Period2> >::type _Ct;
    799     return _Ct(__lhs).count() / _Ct(__rhs).count();
    800 }
    801 
    802 // Duration %
    803 
    804 template <class _Rep1, class _Period, class _Rep2>
    805 inline _LIBCPP_INLINE_VISIBILITY
    806 _LIBCPP_CONSTEXPR
    807 typename __duration_divide_result<duration<_Rep1, _Period>, _Rep2>::type
    808 operator%(const duration<_Rep1, _Period>& __d, const _Rep2& __s)
    809 {
    810     typedef typename common_type<_Rep1, _Rep2>::type _Cr;
    811     typedef duration<_Cr, _Period> _Cd;
    812     return _Cd(_Cd(__d).count() % static_cast<_Cr>(__s));
    813 }
    814 
    815 template <class _Rep1, class _Period1, class _Rep2, class _Period2>
    816 inline _LIBCPP_INLINE_VISIBILITY
    817 _LIBCPP_CONSTEXPR
    818 typename common_type<duration<_Rep1, _Period1>, duration<_Rep2, _Period2> >::type
    819 operator%(const duration<_Rep1, _Period1>& __lhs, const duration<_Rep2, _Period2>& __rhs)
    820 {
    821     typedef typename common_type<_Rep1, _Rep2>::type _Cr;
    822     typedef typename common_type<duration<_Rep1, _Period1>, duration<_Rep2, _Period2> >::type _Cd;
    823     return _Cd(static_cast<_Cr>(_Cd(__lhs).count()) % static_cast<_Cr>(_Cd(__rhs).count()));
    824 }
    825 
    826 //////////////////////////////////////////////////////////
    827 ///////////////////// time_point /////////////////////////
    828 //////////////////////////////////////////////////////////
    829 
    830 template <class _Clock, class _Duration = typename _Clock::duration>
    831 class _LIBCPP_TEMPLATE_VIS time_point
    832 {
    833     static_assert(__is_duration<_Duration>::value,
    834                   "Second template parameter of time_point must be a std::chrono::duration");
    835 public:
    836     typedef _Clock                    clock;
    837     typedef _Duration                 duration;
    838     typedef typename duration::rep    rep;
    839     typedef typename duration::period period;
    840 private:
    841     duration __d_;
    842 
    843 public:
    844     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 time_point() : __d_(duration::zero()) {}
    845     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 explicit time_point(const duration& __d) : __d_(__d) {}
    846 
    847     // conversions
    848     template <class _Duration2>
    849     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    850     time_point(const time_point<clock, _Duration2>& t,
    851         typename enable_if
    852         <
    853             is_convertible<_Duration2, duration>::value
    854         >::type* = 0)
    855             : __d_(t.time_since_epoch()) {}
    856 
    857     // observer
    858 
    859     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 duration time_since_epoch() const {return __d_;}
    860 
    861     // arithmetic
    862 
    863     _LIBCPP_INLINE_VISIBILITY time_point& operator+=(const duration& __d) {__d_ += __d; return *this;}
    864     _LIBCPP_INLINE_VISIBILITY time_point& operator-=(const duration& __d) {__d_ -= __d; return *this;}
    865 
    866     // special values
    867 
    868     _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR time_point min() {return time_point(duration::min());}
    869     _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR time_point max() {return time_point(duration::max());}
    870 };
    871 
    872 } // chrono
    873 
    874 template <class _Clock, class _Duration1, class _Duration2>
    875 struct _LIBCPP_TEMPLATE_VIS common_type<chrono::time_point<_Clock, _Duration1>,
    876                                          chrono::time_point<_Clock, _Duration2> >
    877 {
    878     typedef chrono::time_point<_Clock, typename common_type<_Duration1, _Duration2>::type> type;
    879 };
    880 
    881 namespace chrono {
    882 
    883 template <class _ToDuration, class _Clock, class _Duration>
    884 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    885 time_point<_Clock, _ToDuration>
    886 time_point_cast(const time_point<_Clock, _Duration>& __t)
    887 {
    888     return time_point<_Clock, _ToDuration>(_VSTD::chrono::duration_cast<_ToDuration>(__t.time_since_epoch()));
    889 }
    890 
    891 #if _LIBCPP_STD_VER > 14
    892 template <class _ToDuration, class _Clock, class _Duration>
    893 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
    894 typename enable_if
    895 <
    896     __is_duration<_ToDuration>::value,
    897     time_point<_Clock, _ToDuration>
    898 >::type
    899 floor(const time_point<_Clock, _Duration>& __t)
    900 {
    901     return time_point<_Clock, _ToDuration>{floor<_ToDuration>(__t.time_since_epoch())};
    902 }
    903 
    904 template <class _ToDuration, class _Clock, class _Duration>
    905 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
    906 typename enable_if
    907 <
    908     __is_duration<_ToDuration>::value,
    909     time_point<_Clock, _ToDuration>
    910 >::type
    911 ceil(const time_point<_Clock, _Duration>& __t)
    912 {
    913     return time_point<_Clock, _ToDuration>{ceil<_ToDuration>(__t.time_since_epoch())};
    914 }
    915 
    916 template <class _ToDuration, class _Clock, class _Duration>
    917 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
    918 typename enable_if
    919 <
    920     __is_duration<_ToDuration>::value,
    921     time_point<_Clock, _ToDuration>
    922 >::type
    923 round(const time_point<_Clock, _Duration>& __t)
    924 {
    925     return time_point<_Clock, _ToDuration>{round<_ToDuration>(__t.time_since_epoch())};
    926 }
    927 
    928 template <class _Rep, class _Period>
    929 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
    930 typename enable_if
    931 <
    932     numeric_limits<_Rep>::is_signed,
    933     duration<_Rep, _Period>
    934 >::type
    935 abs(duration<_Rep, _Period> __d)
    936 {
    937     return __d >= __d.zero() ? __d : -__d;
    938 }
    939 #endif
    940 
    941 // time_point ==
    942 
    943 template <class _Clock, class _Duration1, class _Duration2>
    944 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    945 bool
    946 operator==(const time_point<_Clock, _Duration1>& __lhs, const time_point<_Clock, _Duration2>& __rhs)
    947 {
    948     return __lhs.time_since_epoch() == __rhs.time_since_epoch();
    949 }
    950 
    951 // time_point !=
    952 
    953 template <class _Clock, class _Duration1, class _Duration2>
    954 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    955 bool
    956 operator!=(const time_point<_Clock, _Duration1>& __lhs, const time_point<_Clock, _Duration2>& __rhs)
    957 {
    958     return !(__lhs == __rhs);
    959 }
    960 
    961 // time_point <
    962 
    963 template <class _Clock, class _Duration1, class _Duration2>
    964 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    965 bool
    966 operator<(const time_point<_Clock, _Duration1>& __lhs, const time_point<_Clock, _Duration2>& __rhs)
    967 {
    968     return __lhs.time_since_epoch() < __rhs.time_since_epoch();
    969 }
    970 
    971 // time_point >
    972 
    973 template <class _Clock, class _Duration1, class _Duration2>
    974 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    975 bool
    976 operator>(const time_point<_Clock, _Duration1>& __lhs, const time_point<_Clock, _Duration2>& __rhs)
    977 {
    978     return __rhs < __lhs;
    979 }
    980 
    981 // time_point <=
    982 
    983 template <class _Clock, class _Duration1, class _Duration2>
    984 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    985 bool
    986 operator<=(const time_point<_Clock, _Duration1>& __lhs, const time_point<_Clock, _Duration2>& __rhs)
    987 {
    988     return !(__rhs < __lhs);
    989 }
    990 
    991 // time_point >=
    992 
    993 template <class _Clock, class _Duration1, class _Duration2>
    994 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    995 bool
    996 operator>=(const time_point<_Clock, _Duration1>& __lhs, const time_point<_Clock, _Duration2>& __rhs)
    997 {
    998     return !(__lhs < __rhs);
    999 }
   1000 
   1001 // time_point operator+(time_point x, duration y);
   1002 
   1003 template <class _Clock, class _Duration1, class _Rep2, class _Period2>
   1004 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
   1005 time_point<_Clock, typename common_type<_Duration1, duration<_Rep2, _Period2> >::type>
   1006 operator+(const time_point<_Clock, _Duration1>& __lhs, const duration<_Rep2, _Period2>& __rhs)
   1007 {
   1008     typedef time_point<_Clock, typename common_type<_Duration1, duration<_Rep2, _Period2> >::type> _Tr;
   1009     return _Tr (__lhs.time_since_epoch() + __rhs);
   1010 }
   1011 
   1012 // time_point operator+(duration x, time_point y);
   1013 
   1014 template <class _Rep1, class _Period1, class _Clock, class _Duration2>
   1015 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
   1016 time_point<_Clock, typename common_type<duration<_Rep1, _Period1>, _Duration2>::type>
   1017 operator+(const duration<_Rep1, _Period1>& __lhs, const time_point<_Clock, _Duration2>& __rhs)
   1018 {
   1019     return __rhs + __lhs;
   1020 }
   1021 
   1022 // time_point operator-(time_point x, duration y);
   1023 
   1024 template <class _Clock, class _Duration1, class _Rep2, class _Period2>
   1025 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
   1026 time_point<_Clock, typename common_type<_Duration1, duration<_Rep2, _Period2> >::type>
   1027 operator-(const time_point<_Clock, _Duration1>& __lhs, const duration<_Rep2, _Period2>& __rhs)
   1028 {
   1029     typedef time_point<_Clock, typename common_type<_Duration1, duration<_Rep2, _Period2> >::type> _Ret;
   1030     return _Ret(__lhs.time_since_epoch() -__rhs);
   1031 }
   1032 
   1033 // duration operator-(time_point x, time_point y);
   1034 
   1035 template <class _Clock, class _Duration1, class _Duration2>
   1036 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
   1037 typename common_type<_Duration1, _Duration2>::type
   1038 operator-(const time_point<_Clock, _Duration1>& __lhs, const time_point<_Clock, _Duration2>& __rhs)
   1039 {
   1040     return __lhs.time_since_epoch() - __rhs.time_since_epoch();
   1041 }
   1042 
   1043 //////////////////////////////////////////////////////////
   1044 /////////////////////// clocks ///////////////////////////
   1045 //////////////////////////////////////////////////////////
   1046 
   1047 class _LIBCPP_TYPE_VIS system_clock
   1048 {
   1049 public:
   1050     typedef microseconds                     duration;
   1051     typedef duration::rep                    rep;
   1052     typedef duration::period                 period;
   1053     typedef chrono::time_point<system_clock> time_point;
   1054     static _LIBCPP_CONSTEXPR_AFTER_CXX11 const bool is_steady = false;
   1055 
   1056     static time_point now() _NOEXCEPT;
   1057     static time_t     to_time_t  (const time_point& __t) _NOEXCEPT;
   1058     static time_point from_time_t(time_t __t) _NOEXCEPT;
   1059 };
   1060 
   1061 #ifndef _LIBCPP_HAS_NO_MONOTONIC_CLOCK
   1062 class _LIBCPP_TYPE_VIS steady_clock
   1063 {
   1064 public:
   1065     typedef nanoseconds                                   duration;
   1066     typedef duration::rep                                 rep;
   1067     typedef duration::period                              period;
   1068     typedef chrono::time_point<steady_clock, duration>    time_point;
   1069     static _LIBCPP_CONSTEXPR_AFTER_CXX11 const bool is_steady = true;
   1070 
   1071     static time_point now() _NOEXCEPT;
   1072 };
   1073 
   1074 typedef steady_clock high_resolution_clock;
   1075 #else
   1076 typedef system_clock high_resolution_clock;
   1077 #endif
   1078 
   1079 } // chrono
   1080 
   1081 #if _LIBCPP_STD_VER > 11
   1082 // Suffixes for duration literals [time.duration.literals]
   1083 inline namespace literals
   1084 { 
   1085   inline namespace chrono_literals
   1086   {
   1087 
   1088     constexpr chrono::hours operator"" h(unsigned long long __h)
   1089     {
   1090         return chrono::hours(static_cast<chrono::hours::rep>(__h));
   1091     }
   1092 
   1093     constexpr chrono::duration<long double, ratio<3600,1>> operator"" h(long double __h)
   1094     {
   1095         return chrono::duration<long double, ratio<3600,1>>(__h);
   1096     }
   1097 
   1098 
   1099     constexpr chrono::minutes operator"" min(unsigned long long __m)
   1100     {
   1101         return chrono::minutes(static_cast<chrono::minutes::rep>(__m));
   1102     }
   1103 
   1104     constexpr chrono::duration<long double, ratio<60,1>> operator"" min(long double __m)
   1105     {
   1106         return chrono::duration<long double, ratio<60,1>> (__m);
   1107     }
   1108 
   1109 
   1110     constexpr chrono::seconds operator"" s(unsigned long long __s)
   1111     {
   1112         return chrono::seconds(static_cast<chrono::seconds::rep>(__s));
   1113     }
   1114 
   1115     constexpr chrono::duration<long double> operator"" s(long double __s)
   1116     {
   1117         return chrono::duration<long double> (__s);
   1118     }
   1119 
   1120 
   1121     constexpr chrono::milliseconds operator"" ms(unsigned long long __ms)
   1122     {
   1123         return chrono::milliseconds(static_cast<chrono::milliseconds::rep>(__ms));
   1124     }
   1125 
   1126     constexpr chrono::duration<long double, milli> operator"" ms(long double __ms)
   1127     {
   1128         return chrono::duration<long double, milli>(__ms);
   1129     }
   1130 
   1131 
   1132     constexpr chrono::microseconds operator"" us(unsigned long long __us)
   1133     {
   1134         return chrono::microseconds(static_cast<chrono::microseconds::rep>(__us));
   1135     }
   1136 
   1137     constexpr chrono::duration<long double, micro> operator"" us(long double __us)
   1138     {
   1139         return chrono::duration<long double, micro> (__us);
   1140     }
   1141     
   1142 
   1143     constexpr chrono::nanoseconds operator"" ns(unsigned long long __ns)
   1144     {
   1145         return chrono::nanoseconds(static_cast<chrono::nanoseconds::rep>(__ns));
   1146     }
   1147 
   1148     constexpr chrono::duration<long double, nano> operator"" ns(long double __ns)
   1149     {
   1150         return chrono::duration<long double, nano> (__ns);
   1151     }
   1152 
   1153 }}
   1154 
   1155 namespace chrono { // hoist the literals into namespace std::chrono
   1156    using namespace literals::chrono_literals;
   1157 }
   1158 
   1159 #endif
   1160 
   1161 _LIBCPP_END_NAMESPACE_STD
   1162 
   1163 #endif  // _LIBCPP_CHRONO
   1164