libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/tellg.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 // pos_type tellg();
  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 protected:
  41     typename base::pos_type seekoff(typename base::off_type off,
  42                                     std::ios_base::seekdir way,
  43                                     std::ios_base::openmode which)
  44     {
  45         assert(off == 0);
  46         assert(way == std::ios_base::cur);
  47         assert(which == std::ios_base::in);
  48         return 5;
  49     }
  50 };
  51
  52 int main(int, char**)
  53 {
  54     {
  55         testbuf<char> sb(" 123456789");
  56         std::istream is(&sb);
  57         assert(is.tellg() == 5);
  58     }
  59 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  60     {
  61         testbuf<wchar_t> sb(L" 123456789");
  62         std::wistream is(&sb);
  63         assert(is.tellg() == 5);
  64     }
  65 #endif
  66
  67   return 0;
  68 }