libcxx/test/std/time/time.cal/time.cal.ymd/time.cal.ymd.members/op.local_days.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 // UNSUPPORTED: c++03, c++11, c++14, c++17
   9
  10 // <chrono>
  11 // class year_month_day;
  12
  13 // constexpr operator local_days() const noexcept;
  14 //
  15 // Returns: If ok(), returns a local_days holding a count of days from the
  16 //   local_days epoch to *this (a negative value if *this represents a date
  17 //   prior to the sys_days epoch). Otherwise, if y_.ok() && m_.ok() is true,
  18 //   returns a sys_days which is offset from sys_days{y_/m_/last} by the
  19 //   number of days d_ is offset from sys_days{y_/m_/last}.day(). Otherwise
  20 //   the value returned is unspecified.
  21 //
  22 // Remarks: A local_days in the range [days{-12687428}, days{11248737}] which
  23 //   is converted to a year_month_day shall have the same value when
  24 //   converted back to a sys_days.
  25 //
  26 // [Example:
  27 //   static_assert(year_month_day{local_days{2017y/January/0}}  == 2016y/December/31);
  28 //   static_assert(year_month_day{local_days{2017y/January/31}} == 2017y/January/31);
  29 //   static_assert(year_month_day{local_days{2017y/January/32}} == 2017y/February/1);
  30 // -end example]
  31
  32 #include <chrono>
  33 #include <type_traits>
  34 #include <cassert>
  35
  36 #include "test_macros.h"
  37
  38 void RunTheExample()
  39 {
  40     using namespace std::chrono;
  41
  42     static_assert(year_month_day{local_days{year{2017}/January/0}}  == year{2016}/December/31);
  43     static_assert(year_month_day{local_days{year{2017}/January/31}} == year{2017}/January/31);
  44     static_assert(year_month_day{local_days{year{2017}/January/32}} == year{2017}/February/1);
  45 }
  46
  47 int main(int, char**)
  48 {
  49     using year           = std::chrono::year;
  50     using month          = std::chrono::month;
  51     using day            = std::chrono::day;
  52     using local_days       = std::chrono::local_days;
  53     using days           = std::chrono::days;
  54     using year_month_day = std::chrono::year_month_day;
  55
  56     ASSERT_NOEXCEPT(local_days(std::declval<year_month_day>()));
  57     RunTheExample();
  58
  59     {
  60     constexpr year_month_day ymd{year{1970}, month{1}, day{1}};
  61     constexpr local_days sd{ymd};
  62
  63     static_assert( sd.time_since_epoch() == days{0}, "");
  64     static_assert( year_month_day{sd} == ymd, ""); // and back
  65     }
  66
  67     {
  68     constexpr year_month_day ymd{year{2000}, month{2}, day{2}};
  69     constexpr local_days sd{ymd};
  70
  71     static_assert( sd.time_since_epoch() == days{10957+32}, "");
  72     static_assert( year_month_day{sd} == ymd, ""); // and back
  73     }
  74
  75     // There's one more leap day between 1/1/40 and 1/1/70
  76     // when compared to 1/1/70 -> 1/1/2000
  77     {
  78     constexpr year_month_day ymd{year{1940}, month{1}, day{2}};
  79     constexpr local_days sd{ymd};
  80
  81     static_assert( sd.time_since_epoch() == days{-10957}, "");
  82     static_assert( year_month_day{sd} == ymd, ""); // and back
  83     }
  84
  85     {
  86     year_month_day ymd{year{1939}, month{11}, day{29}};
  87     local_days sd{ymd};
  88
  89     assert( sd.time_since_epoch() == days{-(10957+34)});
  90     assert( year_month_day{sd} == ymd); // and back
  91     }
  92
  93     return 0;
  94 }