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 // utilities
11 
12 // exchange
13 
14 #include <utility>
15 #include <cassert>
16 #include <string>
17 
main()18 int main()
19 {
20 #if _LIBCPP_STD_VER > 11
21     {
22     int v = 12;
23     assert ( std::exchange ( v, 23 ) == 12 );
24     assert ( v == 23 );
25     assert ( std::exchange ( v, 67.2 ) == 23 );
26     assert ( v == 67 );
27 
28     assert ((std::exchange<int, float> ( v, {} )) == 67 );
29     assert ( v == 0 );
30 
31     }
32 
33     {
34     bool b = false;
35     assert ( !std::exchange ( b, true ));
36     assert ( b );
37     }
38 
39     {
40     const std::string s1 ( "Hi Mom!" );
41     const std::string s2 ( "Yo Dad!" );
42     std::string s3 = s1; // Mom
43     assert ( std::exchange ( s3, s2 ) == s1 );
44     assert ( s3 == s2 );
45     assert ( std::exchange ( s3, "Hi Mom!" ) == s2 );
46     assert ( s3 == s1 );
47 
48     s3 = s2; // Dad
49     assert ( std::exchange ( s3, {} ) == s2 );
50     assert ( s3.size () == 0 );
51 
52     s3 = s2; // Dad
53     assert ( std::exchange ( s3, "" ) == s2 );
54     assert ( s3.size () == 0 );
55     }
56 
57 #endif
58 }
59