libcxx/test/std/time/time.hms/time.hms.members/width.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 // <chrono>
  10
  11 // template <class Duration>
  12 // class hh_mm_ss
  13 // {
  14 // public:
  15 //     static unsigned constexpr fractional_width = see below;
  16 //     using precision                            = see below;
  17 //
  18 //  fractional_width is the number of fractional decimal digits represented by precision.
  19 //  fractional_width has the value of the smallest possible integer in the range [0, 18]
  20 //    such that precision will exactly represent all values of Duration.
  21 //  If no such value of fractional_width exists, then fractional_width is 6.
  22
  23
  24 #include <chrono>
  25 #include <cassert>
  26 #include <ratio>
  27
  28 #include "test_macros.h"
  29
  30 template <typename Duration, unsigned width>
  31 constexpr bool check_width()
  32 {
  33     using HMS = std::chrono::hh_mm_ss<Duration>;
  34     return HMS::fractional_width == width;
  35 }
  36
  37 int main(int, char**)
  38 {
  39     using microfortnights = std::chrono::duration<int, std::ratio<756, 625>>;
  40
  41     static_assert( check_width<std::chrono::hours,                               0>(), "");
  42     static_assert( check_width<std::chrono::minutes,                             0>(), "");
  43     static_assert( check_width<std::chrono::seconds,                             0>(), "");
  44     static_assert( check_width<std::chrono::milliseconds,                        3>(), "");
  45     static_assert( check_width<std::chrono::microseconds,                        6>(), "");
  46     static_assert( check_width<std::chrono::nanoseconds,                         9>(), "");
  47     static_assert( check_width<std::chrono::duration<int, std::ratio<  1,   2>>, 1>(), "");
  48     static_assert( check_width<std::chrono::duration<int, std::ratio<  1,   3>>, 6>(), "");
  49     static_assert( check_width<std::chrono::duration<int, std::ratio<  1,   4>>, 2>(), "");
  50     static_assert( check_width<std::chrono::duration<int, std::ratio<  1,   5>>, 1>(), "");
  51     static_assert( check_width<std::chrono::duration<int, std::ratio<  1,   6>>, 6>(), "");
  52     static_assert( check_width<std::chrono::duration<int, std::ratio<  1,   7>>, 6>(), "");
  53     static_assert( check_width<std::chrono::duration<int, std::ratio<  1,   8>>, 3>(), "");
  54     static_assert( check_width<std::chrono::duration<int, std::ratio<  1,   9>>, 6>(), "");
  55     static_assert( check_width<std::chrono::duration<int, std::ratio<  1,  10>>, 1>(), "");
  56     static_assert( check_width<microfortnights,                                  4>(), "");
  57
  58     return 0;
  59 }