86 lines
1.9 KiB
C++
86 lines
1.9 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++03, c++11
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// <utility>
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// exchange
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// template<class T, class U=T>
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// constexpr T // constexpr after C++17
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// exchange(T& obj, U&& new_value);
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#include <utility>
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#include <cassert>
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#include <string>
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#include "test_macros.h"
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#if TEST_STD_VER > 17
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TEST_CONSTEXPR bool test_constexpr() {
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int v = 12;
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if (12 != std::exchange(v,23) || v != 23)
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return false;
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if (23 != std::exchange(v,static_cast<short>(67)) || v != 67)
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return false;
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if (67 != std::exchange<int, short>(v, {}) || v != 0)
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return false;
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return true;
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}
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#endif
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int main(int, char**)
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{
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{
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int v = 12;
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assert ( std::exchange ( v, 23 ) == 12 );
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assert ( v == 23 );
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assert ( std::exchange ( v, static_cast<short>(67) ) == 23 );
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assert ( v == 67 );
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assert ((std::exchange<int, short> ( v, {} )) == 67 );
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assert ( v == 0 );
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}
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{
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bool b = false;
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assert ( !std::exchange ( b, true ));
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assert ( b );
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}
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{
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const std::string s1 ( "Hi Mom!" );
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const std::string s2 ( "Yo Dad!" );
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std::string s3 = s1; // Mom
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assert ( std::exchange ( s3, s2 ) == s1 );
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assert ( s3 == s2 );
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assert ( std::exchange ( s3, "Hi Mom!" ) == s2 );
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assert ( s3 == s1 );
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s3 = s2; // Dad
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assert ( std::exchange ( s3, {} ) == s2 );
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assert ( s3.size () == 0 );
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s3 = s2; // Dad
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assert ( std::exchange ( s3, "" ) == s2 );
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assert ( s3.size () == 0 );
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}
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#if TEST_STD_VER > 17
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static_assert(test_constexpr());
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#endif
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return 0;
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}
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