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 // <fstream>
11 
12 // template <class charT, class traits = char_traits<charT> >
13 // class basic_fstream
14 
15 // void swap(basic_fstream& rhs);
16 
17 #include <fstream>
18 #include <utility>
19 #include <cassert>
20 #include "platform_support.h"
21 
get_temp_file_names()22 std::pair<std::string, std::string> get_temp_file_names() {
23   std::pair<std::string, std::string> names;
24   names.first = get_temp_file_name();
25 
26   // Create the file so the next call to `get_temp_file_name()` doesn't
27   // return the same file.
28   std::FILE *fd1 = std::fopen(names.first.c_str(), "w");
29 
30   names.second = get_temp_file_name();
31   assert(names.first != names.second);
32 
33   std::fclose(fd1);
34   std::remove(names.first.c_str());
35 
36   return names;
37 }
38 
main()39 int main()
40 {
41     std::pair<std::string, std::string> temp_files = get_temp_file_names();
42     std::string& temp1 = temp_files.first;
43     std::string& temp2 = temp_files.second;
44     assert(temp1 != temp2);
45     {
46         std::fstream fs1(temp1.c_str(), std::ios_base::in | std::ios_base::out
47                                                   | std::ios_base::trunc);
48         std::fstream fs2(temp2.c_str(), std::ios_base::in | std::ios_base::out
49                                                   | std::ios_base::trunc);
50         fs1 << 1 << ' ' << 2;
51         fs2 << 2 << ' ' << 1;
52         fs1.seekg(0);
53         fs1.swap(fs2);
54         fs1.seekg(0);
55         int i;
56         fs1 >> i;
57         assert(i == 2);
58         fs1 >> i;
59         assert(i == 1);
60         i = 0;
61         fs2 >> i;
62         assert(i == 1);
63         fs2 >> i;
64         assert(i == 2);
65     }
66     std::remove(temp1.c_str());
67     std::remove(temp2.c_str());
68     {
69         std::wfstream fs1(temp1.c_str(), std::ios_base::in | std::ios_base::out
70                                                    | std::ios_base::trunc);
71         std::wfstream fs2(temp2.c_str(), std::ios_base::in | std::ios_base::out
72                                                    | std::ios_base::trunc);
73         fs1 << 1 << ' ' << 2;
74         fs2 << 2 << ' ' << 1;
75         fs1.seekg(0);
76         fs1.swap(fs2);
77         fs1.seekg(0);
78         int i;
79         fs1 >> i;
80         assert(i == 2);
81         fs1 >> i;
82         assert(i == 1);
83         i = 0;
84         fs2 >> i;
85         assert(i == 1);
86         fs2 >> i;
87         assert(i == 2);
88     }
89     std::remove(temp1.c_str());
90     std::remove(temp2.c_str());
91 }
92