libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/seekp.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 // <ostream>
  10
  11 // template <class charT, class traits = char_traits<charT> >
  12 //   class basic_ostream;
  13
  14 // basic_ostream<charT,traits>& seekp(pos_type pos);
  15
  16 #include <ostream>
  17 #include <cassert>
  18
  19 #include "test_macros.h"
  20
  21 int seekpos_called = 0;
  22
  23 template <class CharT>
  24 struct testbuf
  25     : public std::basic_streambuf<CharT>
  26 {
  27     typedef std::basic_streambuf<CharT> base;
  28     testbuf() {}
  29
  30 protected:
  31
  32     typename base::pos_type
  33     seekpos(typename base::pos_type sp, std::ios_base::openmode which)
  34     {
  35         ++seekpos_called;
  36         assert(which == std::ios_base::out);
  37         return sp;
  38     }
  39 };
  40
  41 int main(int, char**)
  42 {
  43     {
  44         seekpos_called = 0;
  45         std::ostream os((std::streambuf*)0);
  46         assert(&os.seekp(5) == &os);
  47         assert(seekpos_called == 0);
  48     }
  49     {
  50         seekpos_called = 0;
  51         testbuf<char> sb;
  52         std::ostream os(&sb);
  53         assert(&os.seekp(10) == &os);
  54         assert(seekpos_called == 1);
  55         assert(os.good());
  56         assert(&os.seekp(-1) == &os);
  57         assert(seekpos_called == 2);
  58         assert(os.fail());
  59     }
  60     { // See https://llvm.org/PR21361
  61         seekpos_called = 0;
  62         testbuf<char> sb;
  63         std::ostream os(&sb);
  64         os.setstate(std::ios_base::eofbit);
  65         assert(&os.seekp(10) == &os);
  66         assert(seekpos_called == 1);
  67         assert(os.rdstate() == std::ios_base::eofbit);
  68     }
  69
  70   return 0;
  71 }