libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/seekg_off.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}}
  10
  11 // <istream>
  12
  13 // basic_istream<charT,traits>& seekg(off_type off, ios_base::seekdir dir);
  14
  15 #include <istream>
  16 #include <cassert>
  17
  18 #include "test_macros.h"
  19
  20 int seekoff_called = 0;
  21
  22 template <class CharT>
  23 struct testbuf
  24     : public std::basic_streambuf<CharT>
  25 {
  26     typedef std::basic_string<CharT> string_type;
  27     typedef std::basic_streambuf<CharT> base;
  28 private:
  29     string_type str_;
  30 public:
  31
  32     testbuf() {}
  33     testbuf(const string_type& str)
  34         : str_(str)
  35     {
  36         base::setg(const_cast<CharT*>(str_.data()),
  37                    const_cast<CharT*>(str_.data()),
  38                    const_cast<CharT*>(str_.data()) + str_.size());
  39     }
  40
  41     CharT* eback() const {return base::eback();}
  42     CharT* gptr() const {return base::gptr();}
  43     CharT* egptr() const {return base::egptr();}
  44 protected:
  45     typename base::pos_type seekoff(typename base::off_type off,
  46                                     std::ios_base::seekdir,
  47                                     std::ios_base::openmode which)
  48     {
  49         assert(which == std::ios_base::in);
  50         ++seekoff_called;
  51         return off;
  52     }
  53 };
  54
  55 int main(int, char**)
  56 {
  57     {
  58         testbuf<char> sb(" 123456789");
  59         std::istream is(&sb);
  60         is.seekg(5, std::ios_base::cur);
  61         assert(is.good());
  62         assert(seekoff_called == 1);
  63         is.seekg(-1, std::ios_base::beg);
  64         assert(is.fail());
  65         assert(seekoff_called == 2);
  66     }
  67 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  68     {
  69         testbuf<wchar_t> sb(L" 123456789");
  70         std::wistream is(&sb);
  71         is.seekg(5, std::ios_base::cur);
  72         assert(is.good());
  73         assert(seekoff_called == 3);
  74         is.seekg(-1, std::ios_base::beg);
  75         assert(is.fail());
  76         assert(seekoff_called == 4);
  77     }
  78 #endif
  79     {
  80         testbuf<char> sb(" 123456789");
  81         std::istream is(&sb);
  82         is.setstate(std::ios_base::eofbit);
  83         assert(is.eof());
  84         is.seekg(5, std::ios_base::beg);
  85         assert(is.good());
  86         assert(!is.eof());
  87     }
  88
  89   return 0;
  90 }