test/std/input.output/file.streams/fstreams/fstream.assign/nonmember_swap.pass.cpp

   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 // template <class charT, class traits>
  16 //   void swap(basic_fstream<charT, traits>& x, basic_fstream<charT, traits>& y);
  17
  18 #include <fstream>
  19 #include <utility>
  20 #include <cassert>
  21 #include "platform_support.h"
  22
  23
  24 std::pair<std::string, std::string> get_temp_file_names() {
  25   std::pair<std::string, std::string> names;
  26   names.first = get_temp_file_name();
  27
  28   // Create the file so the next call to `get_temp_file_name()` doesn't
  29   // return the same file.
  30   std::FILE *fd1 = std::fopen(names.first.c_str(), "w");
  31
  32   names.second = get_temp_file_name();
  33   assert(names.first != names.second);
  34
  35   std::fclose(fd1);
  36   std::remove(names.first.c_str());
  37
  38   return names;
  39 }
  40
  41 int main()
  42 {
  43     std::pair<std::string, std::string> temp_files = get_temp_file_names();
  44     std::string& temp1 = temp_files.first;
  45     std::string& temp2 = temp_files.second;
  46     assert(temp1 != temp2);
  47     {
  48         std::fstream fs1(temp1.c_str(), std::ios_base::in | std::ios_base::out
  49                                                   | std::ios_base::trunc);
  50         std::fstream fs2(temp2.c_str(), std::ios_base::in | std::ios_base::out
  51                                                   | std::ios_base::trunc);
  52         fs1 << 1 << ' ' << 2;
  53         fs2 << 2 << ' ' << 1;
  54         fs1.seekg(0);
  55         swap(fs1, fs2);
  56         fs1.seekg(0);
  57         int i;
  58         fs1 >> i;
  59         assert(i == 2);
  60         fs1 >> i;
  61         assert(i == 1);
  62         i = 0;
  63         fs2 >> i;
  64         assert(i == 1);
  65         fs2 >> i;
  66         assert(i == 2);
  67     }
  68     std::remove(temp1.c_str());
  69     std::remove(temp2.c_str());
  70     {
  71         std::wfstream fs1(temp1.c_str(), std::ios_base::in | std::ios_base::out
  72                                                    | std::ios_base::trunc);
  73         std::wfstream fs2(temp2.c_str(), std::ios_base::in | std::ios_base::out
  74                                                    | std::ios_base::trunc);
  75         fs1 << 1 << ' ' << 2;
  76         fs2 << 2 << ' ' << 1;
  77         fs1.seekg(0);
  78         swap(fs1, fs2);
  79         fs1.seekg(0);
  80         int i;
  81         fs1 >> i;
  82         assert(i == 2);
  83         fs1 >> i;
  84         assert(i == 1);
  85         i = 0;
  86         fs2 >> i;
  87         assert(i == 1);
  88         fs2 >> i;
  89         assert(i == 2);
  90     }
  91     std::remove(temp1.c_str());
  92     std::remove(temp2.c_str());
  93 }