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
10// UNSUPPORTED: c++98, c++03, c++11
11// <utility>
12
13// exchange
14
15// template<class T, class U=T>
16//    constexpr T            // constexpr after C++17
17//    exchange(T& obj, U&& new_value);
18
19#include <utility>
20#include <cassert>
21#include <string>
22
23#include "test_macros.h"
24
25#if TEST_STD_VER > 17
26TEST_CONSTEXPR bool test_constexpr() {
27    int v = 12;
28
29    if (12 != std::exchange(v,23) || v != 23)
30        return false;
31
32    if (23 != std::exchange(v,static_cast<short>(67)) || v != 67)
33        return false;
34
35    if (67 != std::exchange<int, short>(v, {}) || v != 0)
36        return false;
37    return true;
38    }
39#endif
40
41
42
43int main()
44{
45    {
46    int v = 12;
47    assert ( std::exchange ( v, 23 ) == 12 );
48    assert ( v == 23 );
49    assert ( std::exchange ( v, static_cast<short>(67) ) == 23 );
50    assert ( v == 67 );
51
52    assert ((std::exchange<int, short> ( v, {} )) == 67 );
53    assert ( v == 0 );
54
55    }
56
57    {
58    bool b = false;
59    assert ( !std::exchange ( b, true ));
60    assert ( b );
61    }
62
63    {
64    const std::string s1 ( "Hi Mom!" );
65    const std::string s2 ( "Yo Dad!" );
66    std::string s3 = s1; // Mom
67    assert ( std::exchange ( s3, s2 ) == s1 );
68    assert ( s3 == s2 );
69    assert ( std::exchange ( s3, "Hi Mom!" ) == s2 );
70    assert ( s3 == s1 );
71
72    s3 = s2; // Dad
73    assert ( std::exchange ( s3, {} ) == s2 );
74    assert ( s3.size () == 0 );
75
76    s3 = s2; // Dad
77    assert ( std::exchange ( s3, "" ) == s2 );
78    assert ( s3.size () == 0 );
79    }
80
81#if TEST_STD_VER > 17
82    static_assert(test_constexpr());
83#endif
84}
85