plus.pass.cpp (2352B)
1 //===----------------------------------------------------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is dual licensed under the MIT and the University of Illinois Open 6 // Source Licenses. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // UNSUPPORTED: c++98, c++03, c++11, c++14, c++17 10 11 // <chrono> 12 // class month; 13 14 // constexpr month operator+(const month& x, const months& y) noexcept; 15 // Returns: month(int{x} + y.count()). 16 // 17 // constexpr month operator+(const months& x, const month& y) noexcept; 18 // Returns: 19 // month{modulo(static_cast<long long>(int{x}) + (y.count() - 1), 12) + 1} 20 // where modulo(n, 12) computes the remainder of n divided by 12 using Euclidean division. 21 // [Note: Given a divisor of 12, Euclidean division truncates towards negative infinity 22 // and always produces a remainder in the range of [0, 11]. 23 // Assuming no overflow in the signed summation, this operation results in a month 24 // holding a value in the range [1, 12] even if !x.ok(). —end note] 25 // [Example: February + months{11} == January. —end example] 26 27 28 29 #include <chrono> 30 #include <type_traits> 31 #include <cassert> 32 33 #include "test_macros.h" 34 35 template <typename M, typename Ms> 36 constexpr bool testConstexpr() 37 { 38 M m{1}; 39 Ms offset{4}; 40 if (m + offset != M{5}) return false; 41 if (offset + m != M{5}) return false; 42 // Check the example 43 if (M{2} + Ms{11} != M{1}) return false; 44 return true; 45 } 46 47 int main() 48 { 49 using month = std::chrono::month; 50 using months = std::chrono::months; 51 52 ASSERT_NOEXCEPT(std::declval<month>() + std::declval<months>()); 53 ASSERT_NOEXCEPT(std::declval<months>() + std::declval<month>()); 54 55 ASSERT_SAME_TYPE(month, decltype(std::declval<month>() + std::declval<months>())); 56 ASSERT_SAME_TYPE(month, decltype(std::declval<months>() + std::declval<month>() )); 57 58 static_assert(testConstexpr<month, months>(), ""); 59 60 month my{2}; 61 for (unsigned i = 0; i <= 15; ++i) 62 { 63 month m1 = my + months{i}; 64 month m2 = months{i} + my; 65 assert(m1 == m2); 66 unsigned exp = i + 2; 67 while (exp > 12) 68 exp -= 12; 69 assert(static_cast<unsigned>(m1) == exp); 70 assert(static_cast<unsigned>(m2) == exp); 71 } 72 }