libstdc++-v3/testsuite/27_io/basic_stringstream/str/char/2.cc

   1 // 2001-05-24 Benjamin Kosnik  <bkoz@redhat.com>
   2
   3 // Copyright (C) 2001-2021 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // You should have received a copy of the GNU General Public License along
  17 // with this library; see the file COPYING3.  If not see
  18 // <http://www.gnu.org/licenses/>.
  19
  20 // 27.7.6 member functions (stringstream_members)
  21
  22 #include <sstream>
  23 #include <testsuite_hooks.h>
  24
  25 void
  26 redirect_buffer(std::ios& stream, std::streambuf* new_buf)
  27 { stream.rdbuf(new_buf); }
  28
  29 std::streambuf*
  30 active_buffer(std::ios& stream)
  31 { return stream.rdbuf(); }
  32
  33 // libstdc++/2832
  34 void test02()
  35 {
  36   const char* strlit01 = "fuck war";
  37   const std::string str00;
  38   const std::string str01(strlit01);
  39   std::string str02;
  40   std::stringbuf sbuf(str01);
  41   std::streambuf* pbasebuf0 = &sbuf;
  42
  43   std::stringstream sstrm1;
  44   VERIFY( sstrm1.str() == str00 );
  45   // derived rdbuf() always returns original streambuf, even though
  46   // it's no longer associated with the stream.
  47   std::stringbuf* const buf1 = sstrm1.rdbuf();
  48   // base rdbuf() returns the currently associated streambuf
  49   std::streambuf* pbasebuf1 = active_buffer(sstrm1);
  50   redirect_buffer(sstrm1, &sbuf);
  51   std::stringbuf* const buf2 = sstrm1.rdbuf();
  52   std::streambuf* pbasebuf2 = active_buffer(sstrm1);
  53   VERIFY( buf1 == buf2 );
  54   VERIFY( pbasebuf1 != pbasebuf2 );
  55   VERIFY( pbasebuf2 == pbasebuf0 );
  56
  57   // derived rdbuf() returns the original buf, so str() doesn't change.
  58   VERIFY( sstrm1.str() != str01 );
  59   VERIFY( sstrm1.str() == str00 );
  60   // however, casting the active streambuf to a stringbuf shows what's up:
  61   std::stringbuf* psbuf = dynamic_cast<std::stringbuf*>(pbasebuf2);
  62   str02 = psbuf->str();
  63   VERIFY( str02 == str01 );
  64
  65   // How confusing and non-intuitive is this?
  66   // These semantics are a joke, a serious defect, and incredibly lame.
  67 }
  68
  69 int main()
  70 {
  71   test02();
  72   return 0;
  73 }