libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/putback.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // <istream>
  10
  11 // basic_istream<charT,traits>& putback(char_type c);
  12
  13 #include <istream>
  14 #include <cassert>
  15
  16 #include "test_macros.h"
  17
  18 template <class CharT>
  19 struct testbuf
  20     : public std::basic_streambuf<CharT>
  21 {
  22     typedef std::basic_string<CharT> string_type;
  23     typedef std::basic_streambuf<CharT> base;
  24 private:
  25     string_type str_;
  26 public:
  27
  28     testbuf() {}
  29     testbuf(const string_type& str)
  30         : str_(str)
  31     {
  32         base::setg(const_cast<CharT*>(str_.data()),
  33                    const_cast<CharT*>(str_.data()),
  34                    const_cast<CharT*>(str_.data()) + str_.size());
  35     }
  36
  37     CharT* eback() const {return base::eback();}
  38     CharT* gptr() const {return base::gptr();}
  39     CharT* egptr() const {return base::egptr();}
  40 };
  41
  42 int main(int, char**)
  43 {
  44     {
  45         testbuf<char> sb(" 123456789");
  46         std::istream is(&sb);
  47         is.get();
  48         is.get();
  49         is.get();
  50         is.putback('a');
  51         assert(is.bad());
  52         assert(is.gcount() == 0);
  53         is.clear();
  54         is.putback('2');
  55         assert(is.good());
  56         assert(is.gcount() == 0);
  57         is.putback('1');
  58         assert(is.good());
  59         assert(is.gcount() == 0);
  60         is.putback(' ');
  61         assert(is.good());
  62         assert(is.gcount() == 0);
  63         is.putback(' ');
  64         assert(is.bad());
  65         assert(is.gcount() == 0);
  66     }
  67 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  68     {
  69         testbuf<wchar_t> sb(L" 123456789");
  70         std::wistream is(&sb);
  71         is.get();
  72         is.get();
  73         is.get();
  74         is.putback(L'a');
  75         assert(is.bad());
  76         assert(is.gcount() == 0);
  77         is.clear();
  78         is.putback(L'2');
  79         assert(is.good());
  80         assert(is.gcount() == 0);
  81         is.putback(L'1');
  82         assert(is.good());
  83         assert(is.gcount() == 0);
  84         is.putback(L' ');
  85         assert(is.good());
  86         assert(is.gcount() == 0);
  87         is.putback(L' ');
  88         assert(is.bad());
  89         assert(is.gcount() == 0);
  90     }
  91 #endif
  92 #ifndef TEST_HAS_NO_EXCEPTIONS
  93     {
  94         testbuf<char> sb;
  95         std::basic_istream<char> is(&sb);
  96         is.exceptions(std::ios_base::badbit);
  97         bool threw = false;
  98         try {
  99             is.putback('x');
 100         } catch (std::ios_base::failure&) {
 101             threw = true;
 102         }
 103         assert(threw);
 104         assert( is.bad());
 105         assert(!is.eof());
 106         assert( is.fail());
 107     }
 108 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
 109     {
 110         testbuf<wchar_t> sb;
 111         std::basic_istream<wchar_t> is(&sb);
 112         is.exceptions(std::ios_base::badbit);
 113         bool threw = false;
 114         try {
 115             is.putback(L'x');
 116         } catch (std::ios_base::failure&) {
 117             threw = true;
 118         }
 119         assert(threw);
 120         assert( is.bad());
 121         assert(!is.eof());
 122         assert( is.fail());
 123     }
 124 #endif
 125 #endif // TEST_HAS_NO_EXCEPTIONS
 126
 127     return 0;
 128 }