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73 lines
2.3 KiB
C++
73 lines
2.3 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
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// <chrono>
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// class month;
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// constexpr month operator+(const month& x, const months& y) noexcept;
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// Returns: month(int{x} + y.count()).
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//
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// constexpr month operator+(const months& x, const month& y) noexcept;
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// Returns:
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// month{modulo(static_cast<long long>(int{x}) + (y.count() - 1), 12) + 1}
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// where modulo(n, 12) computes the remainder of n divided by 12 using Euclidean division.
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// [Note: Given a divisor of 12, Euclidean division truncates towards negative infinity
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// and always produces a remainder in the range of [0, 11].
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// Assuming no overflow in the signed summation, this operation results in a month
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// holding a value in the range [1, 12] even if !x.ok(). —end note]
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// [Example: February + months{11} == January. —end example]
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#include <chrono>
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#include <type_traits>
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#include <cassert>
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#include "test_macros.h"
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template <typename M, typename Ms>
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constexpr bool testConstexpr()
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{
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M m{1};
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Ms offset{4};
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if (m + offset != M{5}) return false;
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if (offset + m != M{5}) return false;
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// Check the example
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if (M{2} + Ms{11} != M{1}) return false;
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return true;
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}
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int main()
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{
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using month = std::chrono::month;
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using months = std::chrono::months;
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ASSERT_NOEXCEPT(std::declval<month>() + std::declval<months>());
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ASSERT_NOEXCEPT(std::declval<months>() + std::declval<month>());
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ASSERT_SAME_TYPE(month, decltype(std::declval<month>() + std::declval<months>()));
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ASSERT_SAME_TYPE(month, decltype(std::declval<months>() + std::declval<month>() ));
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static_assert(testConstexpr<month, months>(), "");
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month my{2};
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for (unsigned i = 0; i <= 15; ++i)
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{
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month m1 = my + months{i};
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month m2 = months{i} + my;
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assert(m1 == m2);
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unsigned exp = i + 2;
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while (exp > 12)
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exp -= 12;
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assert(static_cast<unsigned>(m1) == exp);
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assert(static_cast<unsigned>(m2) == exp);
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}
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}
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