libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/peek.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 // XFAIL: stdlib=apple-libc++ && target={{.+}}-apple-macosx10.{{9|10|11|12|13|14}}
  10
  11 // <istream>
  12
  13 // int_type peek();
  14
  15 #include <istream>
  16 #include <cassert>
  17 #include "test_macros.h"
  18
  19 template <class CharT>
  20 struct testbuf
  21     : public std::basic_streambuf<CharT>
  22 {
  23     typedef std::basic_string<CharT> string_type;
  24     typedef std::basic_streambuf<CharT> base;
  25 private:
  26     string_type str_;
  27 public:
  28
  29     testbuf() {}
  30     testbuf(const string_type& str)
  31         : str_(str)
  32     {
  33         base::setg(const_cast<CharT*>(str_.data()),
  34                    const_cast<CharT*>(str_.data()),
  35                    const_cast<CharT*>(str_.data()) + str_.size());
  36     }
  37
  38     CharT* eback() const {return base::eback();}
  39     CharT* gptr() const {return base::gptr();}
  40     CharT* egptr() const {return base::egptr();}
  41 };
  42
  43 int main(int, char**)
  44 {
  45     {
  46         testbuf<char> sb(" 1\n2345\n6");
  47         std::istream is(&sb);
  48         assert(is.peek() == ' ');
  49         assert(!is.eof());
  50         assert(!is.fail());
  51         assert(is.gcount() == 0);
  52         is.get();
  53         assert(is.peek() == '1');
  54         assert(!is.eof());
  55         assert(!is.fail());
  56         assert(is.gcount() == 0);
  57     }
  58 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  59     {
  60         testbuf<wchar_t> sb(L" 1\n2345\n6");
  61         std::wistream is(&sb);
  62         assert(is.peek() == L' ');
  63         assert(!is.eof());
  64         assert(!is.fail());
  65         assert(is.gcount() == 0);
  66         is.get();
  67         assert(is.peek() == L'1');
  68         assert(!is.eof());
  69         assert(!is.fail());
  70         assert(is.gcount() == 0);
  71     }
  72 #endif
  73 #ifndef TEST_HAS_NO_EXCEPTIONS
  74     {
  75         testbuf<char> sb;
  76         std::basic_istream<char> is(&sb);
  77         is.exceptions(std::ios_base::eofbit);
  78         bool threw = false;
  79         try {
  80             is.peek();
  81         } catch (std::ios_base::failure&) {
  82             threw = true;
  83         }
  84         assert(threw);
  85         assert(!is.bad());
  86         assert( is.eof());
  87         assert(!is.fail());
  88     }
  89 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  90     {
  91         testbuf<wchar_t> sb;
  92         std::basic_istream<wchar_t> is(&sb);
  93         is.exceptions(std::ios_base::eofbit);
  94         bool threw = false;
  95         try {
  96             is.peek();
  97         } catch (std::ios_base::failure&) {
  98             threw = true;
  99         }
 100         assert(threw);
 101         assert(!is.bad());
 102         assert( is.eof());
 103         assert(!is.fail());
 104     }
 105 #endif
 106 #endif // TEST_HAS_NO_EXCEPTIONS
 107
 108     return 0;
 109 }