iosfwd

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// <iosfwd> Forward declarations -*- C++ -*-
 
// Copyright (C) 1997-2026 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
 
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
 
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
 
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.
 
/** @file include/iosfwd
 *  This is a Standard C++ Library header.
 */
 
//
// ISO C++ 14882: 27.2  Forward declarations
//
 
#ifndef _GLIBCXX_IOSFWD
#define _GLIBCXX_IOSFWD 1
 
#ifdef _GLIBCXX_SYSHDR
#pragma GCC system_header
#endif
 
#include <bits/requires_hosted.h> // iostreams
 
#include <bits/c++config.h>
#include <bits/stringfwd.h>     // For string forward declarations.
#include <bits/postypes.h>
 
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
 
  /**
   *  @defgroup io I/O
   *
   *  Nearly all of the I/O classes are parameterized on the type of
   *  characters they read and write.  (The major exception is ios_base at
   *  the top of the hierarchy.)  This is a change from pre-Standard
   *  streams, which were not templates.
   *
   *  For ease of use and compatibility, all of the basic_* I/O-related
   *  classes are given typedef names for both of the builtin character
   *  widths (wide and narrow).  The typedefs are the same as the
   *  pre-Standard names, for example:
   *
   *  @code
   *     typedef basic_ifstream<char>  ifstream;
   *  @endcode
   *
   *  Because properly forward-declaring these classes can be difficult, you
   *  should not do it yourself.  Instead, include the &lt;iosfwd&gt;
   *  header, which contains only declarations of all the I/O classes as
   *  well as the typedefs.  Trying to forward-declare the typedefs
   *  themselves (e.g., <code>class ostream;</code>) is not valid ISO C++.
   *
   *  For more specific declarations, see
   *  https://gcc.gnu.org/onlinedocs/libstdc++/manual/io.html#std.io.objects
   *
   *  @{
  */
  class ios_base;
 
  template<typename _CharT, typename _Traits = char_traits<_CharT> >
    class basic_ios;
 
  template<typename _CharT, typename _Traits = char_traits<_CharT> >
    class basic_streambuf;
 
  template<typename _CharT, typename _Traits = char_traits<_CharT> >
    class basic_istream;
 
  template<typename _CharT, typename _Traits = char_traits<_CharT> >
    class basic_ostream;
 
  template<typename _CharT, typename _Traits = char_traits<_CharT> >
    class basic_iostream;
 
 
_GLIBCXX_BEGIN_NAMESPACE_CXX11
 
  template<typename _CharT, typename _Traits = char_traits<_CharT>,
            typename _Alloc = allocator<_CharT> >
    class basic_stringbuf;
 
  template<typename _CharT, typename _Traits = char_traits<_CharT>,
           typename _Alloc = allocator<_CharT> >
    class basic_istringstream;
 
  template<typename _CharT, typename _Traits = char_traits<_CharT>,
           typename _Alloc = allocator<_CharT> >
    class basic_ostringstream;
 
  template<typename _CharT, typename _Traits = char_traits<_CharT>,
           typename _Alloc = allocator<_CharT> >
    class basic_stringstream;
 
_GLIBCXX_END_NAMESPACE_CXX11
 
  template<typename _CharT, typename _Traits = char_traits<_CharT> >
    class basic_filebuf;
 
  template<typename _CharT, typename _Traits = char_traits<_CharT> >
    class basic_ifstream;
 
  template<typename _CharT, typename _Traits = char_traits<_CharT> >
    class basic_ofstream;
 
  template<typename _CharT, typename _Traits = char_traits<_CharT> >
    class basic_fstream;
 
  template<typename _CharT, typename _Traits = char_traits<_CharT> >
    class istreambuf_iterator;
 
  template<typename _CharT, typename _Traits = char_traits<_CharT> >
    class ostreambuf_iterator;
 
 
  /// Base class for @c char streams.
  typedef basic_ios<char>               ios;
 
  /// Base class for @c char buffers.
  typedef basic_streambuf<char>         streambuf;
 
  /// Base class for @c char input streams.
  typedef basic_istream<char>           istream;
 
  /// Base class for @c char output streams.
  typedef basic_ostream<char>           ostream;
 
  /// Base class for @c char mixed input and output streams.
  typedef basic_iostream<char>          iostream;
 
  /// Class for @c char memory buffers.
  typedef basic_stringbuf<char>         stringbuf;
 
  /// Class for @c char input memory streams.
  typedef basic_istringstream<char>     istringstream;
 
  /// Class for @c char output memory streams.
  typedef basic_ostringstream<char>     ostringstream;
 
  /// Class for @c char mixed input and output memory streams.
  typedef basic_stringstream<char>      stringstream;
 
  /// Class for @c char file buffers.
  typedef basic_filebuf<char>           filebuf;
 
  /// Class for @c char input file streams.
  typedef basic_ifstream<char>          ifstream;
 
  /// Class for @c char output file streams.
  typedef basic_ofstream<char>          ofstream;
 
  /// Class for @c char mixed input and output file streams.
  typedef basic_fstream<char>           fstream;
 
#ifdef _GLIBCXX_USE_WCHAR_T
  /// Base class for @c wchar_t streams.
  typedef basic_ios<wchar_t>            wios;
 
  /// Base class for @c wchar_t buffers.
  typedef basic_streambuf<wchar_t>      wstreambuf;
 
  /// Base class for @c wchar_t input streams.
  typedef basic_istream<wchar_t>        wistream;
 
  /// Base class for @c wchar_t output streams.
  typedef basic_ostream<wchar_t>        wostream;
 
  /// Base class for @c wchar_t mixed input and output streams.
  typedef basic_iostream<wchar_t>       wiostream;
 
  /// Class for @c wchar_t memory buffers.
  typedef basic_stringbuf<wchar_t>      wstringbuf;
 
  /// Class for @c wchar_t input memory streams.
  typedef basic_istringstream<wchar_t>  wistringstream;
 
  /// Class for @c wchar_t output memory streams.
  typedef basic_ostringstream<wchar_t>  wostringstream;
 
  /// Class for @c wchar_t mixed input and output memory streams.
  typedef basic_stringstream<wchar_t>   wstringstream;
 
  /// Class for @c wchar_t file buffers.
  typedef basic_filebuf<wchar_t>        wfilebuf;
 
  /// Class for @c wchar_t input file streams.
  typedef basic_ifstream<wchar_t>       wifstream;
 
  /// Class for @c wchar_t output file streams.
  typedef basic_ofstream<wchar_t>       wofstream;
 
  /// Class for @c wchar_t mixed input and output file streams.
  typedef basic_fstream<wchar_t>        wfstream;
#endif
 
#if __cplusplus >= 202002L && _GLIBCXX_USE_CXX11_ABI
  template<typename _CharT, typename _Traits = char_traits<_CharT>,
           typename _Allocator = allocator<_CharT>>
    class basic_syncbuf;
  template<typename _CharT, typename _Traits = char_traits<_CharT>,
           typename _Allocator = allocator<_CharT>>
    class basic_osyncstream;
 
  using syncbuf = basic_syncbuf<char>;
  using osyncstream = basic_osyncstream<char>;
 
#ifdef _GLIBCXX_USE_WCHAR_T
  using wsyncbuf = basic_syncbuf<wchar_t>;
  using wosyncstream = basic_osyncstream<wchar_t>;
#endif
#endif // C++20 && CXX11_ABI
 
#if __cplusplus > 202002L
  template<typename _CharT, typename _Traits = char_traits<_CharT>>
    class basic_spanbuf;
  template<typename _CharT, typename _Traits = char_traits<_CharT>>
    class basic_ispanstream;
  template<typename _CharT, typename _Traits = char_traits<_CharT>>
    class basic_ospanstream;
  template<typename _CharT, typename _Traits = char_traits<_CharT>>
    class basic_spanstream;
 
  using spanbuf     = basic_spanbuf<char>;
  using ispanstream = basic_ispanstream<char>;
  using ospanstream = basic_ospanstream<char>;
  using spanstream  = basic_spanstream<char>;
 
#ifdef _GLIBCXX_USE_WCHAR_T
  using wspanbuf     = basic_spanbuf<wchar_t>;
  using wispanstream = basic_ispanstream<wchar_t>;
  using wospanstream = basic_ospanstream<wchar_t>;
  using wspanstream  = basic_spanstream<wchar_t>;
#endif
#endif // C++23
 
  /** @}  */
 
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
 
#endif /* _GLIBCXX_IOSFWD */