libcxx/test/std/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/minus.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 weekday;
  12
  13 // constexpr weekday operator-(const weekday& x, const days& y) noexcept;
  14 //   Returns: x + -y.
  15 //
  16 // constexpr days operator-(const weekday& x, const weekday& y) noexcept;
  17 // Returns: If x.ok() == true and y.ok() == true, returns a value d in the range
  18 //    [days{0}, days{6}] satisfying y + d == x.
  19 // Otherwise the value returned is unspecified.
  20 // [Example: Sunday - Monday == days{6}. -end example]
  21
  22 #include <chrono>
  23 #include <type_traits>
  24 #include <cassert>
  25
  26 #include "test_macros.h"
  27 #include "../../euclidian.h"
  28
  29 using weekday = std::chrono::weekday;
  30 using days    = std::chrono::days;
  31
  32 constexpr bool test() {
  33   for (unsigned i = 0; i <= 6; ++i)
  34     for (unsigned j = 0; j <= 6; ++j) {
  35       weekday wd = weekday{i} - days{j};
  36       assert(wd + days{j} == weekday{i});
  37       assert((wd.c_encoding() == euclidian_subtraction<unsigned, 0, 6>(i, j)));
  38     }
  39
  40   for (unsigned i = 0; i <= 6; ++i)
  41     for (unsigned j = 0; j <= 6; ++j) {
  42       days d = weekday{j} - weekday{i};
  43       assert(weekday{i} + d == weekday{j});
  44     }
  45
  46   //  Check the example
  47   assert(weekday{0} - weekday{1} == days{6});
  48
  49   return true;
  50 }
  51
  52 int main(int, char**) {
  53   ASSERT_NOEXCEPT(std::declval<weekday>() - std::declval<days>());
  54   ASSERT_SAME_TYPE(weekday, decltype(std::declval<weekday>() - std::declval<days>()));
  55
  56   ASSERT_NOEXCEPT(std::declval<weekday>() - std::declval<weekday>());
  57   ASSERT_SAME_TYPE(days, decltype(std::declval<weekday>() - std::declval<weekday>()));
  58
  59   test();
  60   static_assert(test());
  61
  62   return 0;
  63 }