libstdc++-v3/include/bits/std_streambuf.h - gcc.git - Git at Google

 // Stream buffer classes -*- C++ -*-

 // Copyright (C) 1997, 1998, 1999, 2000, 2001 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 2, 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.

 // You should have received a copy of the GNU General Public License along
 // with this library; see the file COPYING.  If not, write to the Free
 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
 // USA.

 // As a special exception, you may use this file as part of a free software
 // library without restriction.  Specifically, if other files instantiate
 // templates or use macros or inline functions from this file, or you compile
 // this file and link it with other files to produce an executable, this
 // file does not by itself cause the resulting executable to be covered by
 // the GNU General Public License.  This exception does not however
 // invalidate any other reasons why the executable file might be covered by
 // the GNU General Public License.

 //
 // ISO C++ 14882: 27.5  Stream buffers
 //

 /** @file std_streambuf.h
  *  This is an internal header file, included by other library headers.
  *  You should not attempt to use it directly.
  */

 #ifndef _CPP_STREAMBUF
 #define _CPP_STREAMBUF	1

 #pragma GCC system_header

 #include <bits/c++config.h>
 #include <bits/std_iosfwd.h>
 #include <bits/std_cstdio.h> 	// For SEEK_SET, SEEK_CUR, SEEK_END
 #include <bits/localefwd.h>
 #include <bits/ios_base.h>

 namespace std
 {
   template<typename _CharT, typename _Traits>
     streamsize
     __copy_streambufs(basic_ios<_CharT, _Traits>& _ios,
 		      basic_streambuf<_CharT, _Traits>* __sbin,
 		      basic_streambuf<_CharT, _Traits>* __sbout);

   // 27.5.2 Template class basic_streambuf<_CharT, _Traits>
   template<typename _CharT, typename _Traits>
     class basic_streambuf
     {
     public:
       // Types:
       typedef _CharT 					char_type;
       typedef _Traits 					traits_type;
       typedef typename traits_type::int_type 		int_type;
       typedef typename traits_type::pos_type 		pos_type;
       typedef typename traits_type::off_type 		off_type;

       // Non-standard Types:
       typedef ctype<char_type>           		__ctype_type;
       typedef basic_streambuf<char_type, traits_type>  	__streambuf_type;

       friend class basic_ios<char_type, traits_type>;
       friend class basic_istream<char_type, traits_type>;
       friend class basic_ostream<char_type, traits_type>;
       friend class istreambuf_iterator<char_type, traits_type>;
       friend class ostreambuf_iterator<char_type, traits_type>;

       friend streamsize
       __copy_streambufs<>(basic_ios<char_type, traits_type>& __ios,
 			  __streambuf_type* __sbin,__streambuf_type* __sbout);

     protected:

       // Pointer to the beginning of internally-allocated
       // space. Filebuf manually allocates/deallocates this, whereas
       // stringstreams attempt to use the built-in intelligence of the
       // string class. If you are managing memory, set this. If not,
       // leave it NULL.
       char_type*		_M_buf;

       // Actual size of allocated internal buffer, in bytes.
       int_type			_M_buf_size;

       // Optimal or preferred size of internal buffer, in bytes.
       int_type			_M_buf_size_opt;

       // True iff _M_in_* and _M_out_* buffers should always point to
       // the same place.  True for fstreams, false for sstreams.
       bool 			_M_buf_unified;

       // This is based on _IO_FILE, just reordered to be more
       // consistent, and is intended to be the most minimal abstraction
       // for an internal buffer.
       // get == input == read
       // put == output == write
       char_type* 		_M_in_beg;  	// Start of get area.
       char_type* 		_M_in_cur;	// Current read area.
       char_type* 		_M_in_end;	// End of get area.
       char_type* 		_M_out_beg; 	// Start of put area.
       char_type* 		_M_out_cur;  	// Current put area.
       char_type* 		_M_out_end;  	// End of put area.

       // Place to stash in || out || in | out settings for current streambuf.
       ios_base::openmode 	_M_mode;

       // Current locale setting.
       locale 			_M_buf_locale;

       // True iff locale is initialized.
       bool 			_M_buf_locale_init;

       // Necessary bits for putback buffer management. Only used in
       // the basic_filebuf class, as necessary for the standard
       // requirements. The only basic_streambuf member function that
       // needs access to these data members is in_avail...
       // NB: pbacks of over one character are not currently supported.
       int_type    		_M_pback_size;
       char_type*		_M_pback;
       char_type*		_M_pback_cur_save;
       char_type*		_M_pback_end_save;
       bool			_M_pback_init;

       // Initializes pback buffers, and moves normal buffers to safety.
       // Assumptions:
       // _M_in_cur has already been moved back
       void
       _M_pback_create()
       {
 	if (!_M_pback_init)
 	  {
 	    int_type __dist = _M_in_end - _M_in_cur;
 	    int_type __len = min(_M_pback_size, __dist);
 	    traits_type::copy(_M_pback, _M_in_cur, __len);
 	    _M_pback_cur_save = _M_in_cur;
 	    _M_pback_end_save = _M_in_end;
 	    this->setg(_M_pback, _M_pback, _M_pback + __len);
 	    _M_pback_init = true;
 	  }
       }

       // Deactivates pback buffer contents, and restores normal buffer.
       // Assumptions:
       // The pback buffer has only moved forward.
       void
       _M_pback_destroy()
       {
 	if (_M_pback_init)
 	  {
 	    // Length _M_in_cur moved in the pback buffer.
 	    int_type __off_cur = _M_in_cur - _M_pback;

 	    // For in | out buffers, the end can be pushed back...
 	    int_type __off_end = 0;
 	    int_type __pback_len = _M_in_end - _M_pback;
 	    int_type __save_len = _M_pback_end_save - _M_buf;
 	    if (__pback_len > __save_len)
 	      __off_end = __pback_len - __save_len;

 	    this->setg(_M_buf, _M_pback_cur_save + __off_cur,
 		       _M_pback_end_save + __off_end);
 	    _M_pback_cur_save = NULL;
 	    _M_pback_end_save = NULL;
 	    _M_pback_init = false;
 	  }
       }

       // Correctly sets the _M_in_cur pointer, and bumps the
       // _M_out_cur pointer as well if necessary.
       void
       _M_in_cur_move(off_type __n) // argument needs to be +-
       {
 	bool __testout = _M_out_cur;
 	_M_in_cur += __n;
 	if (__testout && _M_buf_unified)
 	  _M_out_cur += __n;
       }

       // Correctly sets the _M_out_cur pointer, and bumps the
       // appropriate _M_*_end pointers as well. Necessary for the
       // un-tied stringbufs, in in|out mode.
       // Invariant:
       // __n + _M_out_[cur, end] <= _M_buf + _M_buf_size
       // Assuming all _M_*_[beg, cur, end] pointers are operating on
       // the same range:
       // _M_buf <= _M_*_ <= _M_buf + _M_buf_size
       void
       _M_out_cur_move(off_type __n) // argument needs to be +-
       {
 	bool __testin = _M_in_cur;

 	_M_out_cur += __n;
 	if (__testin && _M_buf_unified)
 	  _M_in_cur += __n;
 	if (_M_out_cur > _M_out_end)
 	  {
 	    _M_out_end = _M_out_cur;
 	    // NB: in | out buffers drag the _M_in_end pointer along...
 	    if (__testin)
 	      _M_in_end += __n;
 	  }
       }

       // Return the size of the output buffer.  This depends on the
       // buffer in use: allocated buffers have a stored size in
       // _M_buf_size and setbuf() buffers don't.
       off_type
       _M_out_buf_size()
       {
 	off_type __ret = 0;
 	if (_M_out_cur)
 	  {
 	    // Using allocated buffer.
 	    if (_M_out_beg == _M_buf)
 	      __ret = _M_out_beg + _M_buf_size - _M_out_cur;
 	    // Using non-allocated buffer.
 	    else
 	      __ret = _M_out_end - _M_out_cur;
 	  }
 	return __ret;
       }

       // These three functions are used to clarify internal buffer
       // maintenance. After an overflow, or after a seekoff call that
       // started at beg or end, or possibly when the stream becomes
       // unbuffered, and a myrid other obscure corner cases, the
       // internal buffer does not truly reflect the contents of the
       // external buffer. At this point, for whatever reason, it is in
       // an indeterminate state.
       void
       _M_set_indeterminate(void)
       {
 	if (_M_mode & ios_base::in)
 	  this->setg(_M_buf, _M_buf, _M_buf);
 	if (_M_mode & ios_base::out)
 	  this->setp(_M_buf, _M_buf);
       }

       void
       _M_set_determinate(off_type __off)
       {
 	bool __testin = _M_mode & ios_base::in;
 	bool __testout = _M_mode & ios_base::out;
 	if (__testin)
 	  this->setg(_M_buf, _M_buf, _M_buf + __off);
 	if (__testout)
 	  this->setp(_M_buf, _M_buf + __off);
       }

       bool
       _M_is_indeterminate(void)
       {
 	bool __ret = false;
 	// Don't return true if unbuffered.
 	if (_M_buf)
 	  {
 	    if (_M_mode & ios_base::in)
 	      __ret = _M_in_beg == _M_in_cur && _M_in_cur == _M_in_end;
 	    if (_M_mode & ios_base::out)
 	      __ret = _M_out_beg == _M_out_cur && _M_out_cur == _M_out_end;
 	  }
 	return __ret;
       }

   public:
       virtual
       ~basic_streambuf()
       {
 	_M_buf_unified = false;
 	_M_buf_size = 0;
 	_M_buf_size_opt = 0;
 	_M_mode = ios_base::openmode(0);
 	_M_buf_locale_init = false;
       }

       // Locales:
       locale
       pubimbue(const locale &__loc)
       {
 	locale __tmp(this->getloc());
 	this->imbue(__loc);
 	return __tmp;
       }

       locale
       getloc() const
       {
 	if (_M_buf_locale_init)
 	  return _M_buf_locale;
 	else
 	  return locale();
       }

       // Buffer and positioning:
       __streambuf_type*
       pubsetbuf(char_type* __s, streamsize __n)
       { return this->setbuf(__s, __n); }

       pos_type
       pubseekoff(off_type __off, ios_base::seekdir __way,
 		 ios_base::openmode __mode = ios_base::in | ios_base::out)
       { return this->seekoff(__off, __way, __mode); }

       pos_type
       pubseekpos(pos_type __sp,
 		 ios_base::openmode __mode = ios_base::in | ios_base::out)
       { return this->seekpos(__sp, __mode); }

       int
       pubsync() { return this->sync(); }

       // Get and put areas:
       // Get area:
       streamsize
       in_avail()
       {
 	streamsize __ret;
 	if (_M_in_cur && _M_in_cur < _M_in_end)
 	  {
 	    if (_M_pback_init)
 	      {
 		int_type __save_len =  _M_pback_end_save - _M_pback_cur_save;
 		int_type __pback_len = _M_in_cur - _M_pback;
 		__ret = __save_len - __pback_len;
 	      }
 	    else
 	      __ret = this->egptr() - this->gptr();
 	  }
 	else
 	  __ret = this->showmanyc();
 	return __ret;
       }

       int_type
       snextc()
       {
 	int_type __eof = traits_type::eof();
 	return (this->sbumpc() == __eof ? __eof : this->sgetc());
       }

       int_type
       sbumpc();

       int_type
       sgetc()
       {
 	int_type __ret;
 	if (_M_in_cur && _M_in_cur < _M_in_end)
 	  __ret = traits_type::to_int_type(*(this->gptr()));
 	else
 	  __ret = this->underflow();
 	return __ret;
       }

       streamsize
       sgetn(char_type* __s, streamsize __n)
       { return this->xsgetn(__s, __n); }

       // Putback:
       int_type
       sputbackc(char_type __c);

       int_type
       sungetc();

       // Put area:
       int_type
       sputc(char_type __c);

       streamsize
       sputn(const char_type* __s, streamsize __n)
       { return this->xsputn(__s, __n); }

     protected:
       basic_streambuf()
       : _M_buf(NULL), _M_buf_size(0),
       _M_buf_size_opt(static_cast<int_type>(BUFSIZ)), _M_buf_unified(false),
       _M_in_beg(0), _M_in_cur(0), _M_in_end(0), _M_out_beg(0), _M_out_cur(0),
       _M_out_end(0), _M_mode(ios_base::openmode(0)), _M_buf_locale(locale()),
       _M_buf_locale_init(false), _M_pback_size(1), _M_pback(NULL),
       _M_pback_cur_save(NULL), _M_pback_end_save(NULL), _M_pback_init(false)
       { }

       // Get area:
       char_type*
       eback() const { return _M_in_beg; }

       char_type*
       gptr()  const { return _M_in_cur;  }

       char_type*
       egptr() const { return _M_in_end; }

       void
       gbump(int __n) { _M_in_cur += __n; }

       void
       setg(char_type* __gbeg, char_type* __gnext, char_type* __gend)
       {
 	_M_in_beg = __gbeg;
 	_M_in_cur = __gnext;
 	_M_in_end = __gend;
 	if (!(_M_mode & ios_base::in) && __gbeg && __gnext && __gend)
 	  _M_mode = _M_mode | ios_base::in;
       }

       // Put area:
       char_type*
       pbase() const { return _M_out_beg; }

       char_type*
       pptr() const { return _M_out_cur; }

       char_type*
       epptr() const { return _M_out_end; }

       void
       pbump(int __n) { _M_out_cur += __n; }

       void
       setp(char_type* __pbeg, char_type* __pend)
       {
 	_M_out_beg = _M_out_cur = __pbeg;
 	_M_out_end = __pend;
 	if (!(_M_mode & ios_base::out) && __pbeg && __pend)
 	  _M_mode = _M_mode | ios_base::out;
       }

       // Virtual functions:
       // Locales:
       virtual void
       imbue(const locale& __loc)
       {
 	_M_buf_locale_init = true;
 	if (_M_buf_locale != __loc)
 	  _M_buf_locale = __loc;
       }

       // Buffer management and positioning:
       virtual basic_streambuf<char_type,_Traits>*
       setbuf(char_type*, streamsize)
       {	return this; }

       virtual pos_type
       seekoff(off_type, ios_base::seekdir,
 	      ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out)
       { return pos_type(off_type(-1)); }

       virtual pos_type
       seekpos(pos_type,
 	      ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out)
       { return pos_type(off_type(-1)); }

       virtual int
       sync() { return 0; }

       // Get area:
       virtual streamsize
       showmanyc() { return 0; }

       virtual streamsize
       xsgetn(char_type* __s, streamsize __n);

       virtual int_type
       underflow()
       { return traits_type::eof(); }

       virtual int_type
       uflow()
       {
 	int_type __ret = traits_type::eof();
 	bool __testeof = this->underflow() == __ret;
 	bool __testpending = _M_in_cur && _M_in_cur < _M_in_end;
 	if (!__testeof && __testpending)
 	  {
 	    __ret = traits_type::to_int_type(*_M_in_cur);
 	    ++_M_in_cur;
 	    if (_M_buf_unified && _M_mode & ios_base::out)
 	      ++_M_out_cur;
 	  }
 	return __ret;
       }

       // Putback:
       virtual int_type
       pbackfail(int_type /* __c */  = traits_type::eof())
       { return traits_type::eof(); }

       // Put area:
       virtual streamsize
       xsputn(const char_type* __s, streamsize __n);

       virtual int_type
       overflow(int_type /* __c */ = traits_type::eof())
       { return traits_type::eof(); }

 #ifdef _GLIBCPP_DEPRECATED
     public:
       void
       stossc()
       {
 	if (_M_in_cur < _M_in_end)
 	  ++_M_in_cur;
 	else
 	  this->uflow();
       }
 #endif

 #ifdef _GLIBCPP_RESOLVE_LIB_DEFECTS
     // Side effect of DR 50.
     private:
       basic_streambuf(const __streambuf_type&);

       __streambuf_type&
       operator=(const __streambuf_type&);
 #endif
     };

 } // namespace std

 #ifdef _GLIBCPP_NO_TEMPLATE_EXPORT
 # define export
 #ifdef  _GLIBCPP_FULLY_COMPLIANT_HEADERS
 #include <bits/streambuf.tcc>
 #endif
 #endif

 #endif	/* _CPP_STREAMBUF */
	// Stream buffer classes -- C++ --

	// Copyright (C) 1997, 1998, 1999, 2000, 2001 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 2, 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.

	// You should have received a copy of the GNU General Public License along
	// with this library; see the file COPYING. If not, write to the Free
	// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
	// USA.

	// As a special exception, you may use this file as part of a free software
	// library without restriction. Specifically, if other files instantiate
	// templates or use macros or inline functions from this file, or you compile
	// this file and link it with other files to produce an executable, this
	// file does not by itself cause the resulting executable to be covered by
	// the GNU General Public License. This exception does not however
	// invalidate any other reasons why the executable file might be covered by
	// the GNU General Public License.

	//
	// ISO C++ 14882: 27.5 Stream buffers
	//

	/** @file std_streambuf.h
	* This is an internal header file, included by other library headers.
	* You should not attempt to use it directly.
	*/

	#ifndef _CPP_STREAMBUF
	#define _CPP_STREAMBUF 1

	#pragma GCC system_header

	#include <bits/c++config.h>
	#include <bits/std_iosfwd.h>
	#include <bits/std_cstdio.h> // For SEEK_SET, SEEK_CUR, SEEK_END
	#include <bits/localefwd.h>
	#include <bits/ios_base.h>

	namespace std
	{
	template<typename _CharT, typename _Traits>
	streamsize
	__copy_streambufs(basic_ios<_CharT, _Traits>& _ios,
	basic_streambuf<_CharT, _Traits>* __sbin,
	basic_streambuf<_CharT, _Traits>* __sbout);

	// 27.5.2 Template class basic_streambuf<_CharT, _Traits>
	template<typename _CharT, typename _Traits>
	class basic_streambuf
	{
	public:
	// Types:
	typedef _CharT char_type;
	typedef _Traits traits_type;
	typedef typename traits_type::int_type int_type;
	typedef typename traits_type::pos_type pos_type;
	typedef typename traits_type::off_type off_type;

	// Non-standard Types:
	typedef ctype<char_type> __ctype_type;
	typedef basic_streambuf<char_type, traits_type> __streambuf_type;

	friend class basic_ios<char_type, traits_type>;
	friend class basic_istream<char_type, traits_type>;
	friend class basic_ostream<char_type, traits_type>;
	friend class istreambuf_iterator<char_type, traits_type>;
	friend class ostreambuf_iterator<char_type, traits_type>;

	friend streamsize
	__copy_streambufs<>(basic_ios<char_type, traits_type>& __ios,
	__streambuf_type* __sbin,__streambuf_type* __sbout);

	protected:

	// Pointer to the beginning of internally-allocated
	// space. Filebuf manually allocates/deallocates this, whereas
	// stringstreams attempt to use the built-in intelligence of the
	// string class. If you are managing memory, set this. If not,
	// leave it NULL.
	char_type* _M_buf;

	// Actual size of allocated internal buffer, in bytes.
	int_type _M_buf_size;

	// Optimal or preferred size of internal buffer, in bytes.
	int_type _M_buf_size_opt;

	// True iff _M_in_* and _M_out_* buffers should always point to
	// the same place. True for fstreams, false for sstreams.
	bool _M_buf_unified;

	// This is based on _IO_FILE, just reordered to be more
	// consistent, and is intended to be the most minimal abstraction
	// for an internal buffer.
	// get == input == read
	// put == output == write
	char_type* _M_in_beg; // Start of get area.
	char_type* _M_in_cur; // Current read area.
	char_type* _M_in_end; // End of get area.
	char_type* _M_out_beg; // Start of put area.
	char_type* _M_out_cur; // Current put area.
	char_type* _M_out_end; // End of put area.

	// Place to stash in \|\| out \|\| in \| out settings for current streambuf.
	ios_base::openmode _M_mode;

	// Current locale setting.
	locale _M_buf_locale;

	// True iff locale is initialized.
	bool _M_buf_locale_init;

	// Necessary bits for putback buffer management. Only used in
	// the basic_filebuf class, as necessary for the standard
	// requirements. The only basic_streambuf member function that
	// needs access to these data members is in_avail...
	// NB: pbacks of over one character are not currently supported.
	int_type _M_pback_size;
	char_type* _M_pback;
	char_type* _M_pback_cur_save;
	char_type* _M_pback_end_save;
	bool _M_pback_init;

	// Initializes pback buffers, and moves normal buffers to safety.
	// Assumptions:
	// _M_in_cur has already been moved back
	void
	_M_pback_create()
	{
	if (!_M_pback_init)
	{
	int_type __dist = _M_in_end - _M_in_cur;
	int_type __len = min(_M_pback_size, __dist);
	traits_type::copy(_M_pback, _M_in_cur, __len);
	_M_pback_cur_save = _M_in_cur;
	_M_pback_end_save = _M_in_end;
	this->setg(_M_pback, _M_pback, _M_pback + __len);
	_M_pback_init = true;
	}
	}

	// Deactivates pback buffer contents, and restores normal buffer.
	// Assumptions:
	// The pback buffer has only moved forward.
	void
	_M_pback_destroy()
	{
	if (_M_pback_init)
	{
	// Length _M_in_cur moved in the pback buffer.
	int_type __off_cur = _M_in_cur - _M_pback;

	// For in \| out buffers, the end can be pushed back...
	int_type __off_end = 0;
	int_type __pback_len = _M_in_end - _M_pback;
	int_type __save_len = _M_pback_end_save - _M_buf;
	if (__pback_len > __save_len)
	__off_end = __pback_len - __save_len;

	this->setg(_M_buf, _M_pback_cur_save + __off_cur,
	_M_pback_end_save + __off_end);
	_M_pback_cur_save = NULL;
	_M_pback_end_save = NULL;
	_M_pback_init = false;
	}
	}

	// Correctly sets the _M_in_cur pointer, and bumps the
	// _M_out_cur pointer as well if necessary.
	void
	_M_in_cur_move(off_type __n) // argument needs to be +-
	{
	bool __testout = _M_out_cur;
	_M_in_cur += __n;
	if (__testout && _M_buf_unified)
	_M_out_cur += __n;
	}

	// Correctly sets the _M_out_cur pointer, and bumps the
	// appropriate _M_*_end pointers as well. Necessary for the
	// un-tied stringbufs, in in\|out mode.
	// Invariant:
	// __n + _M_out_[cur, end] <= _M_buf + _M_buf_size
	// Assuming all _M_*_[beg, cur, end] pointers are operating on
	// the same range:
	// _M_buf <= _M_*_ <= _M_buf + _M_buf_size
	void
	_M_out_cur_move(off_type __n) // argument needs to be +-
	{
	bool __testin = _M_in_cur;

	_M_out_cur += __n;
	if (__testin && _M_buf_unified)
	_M_in_cur += __n;
	if (_M_out_cur > _M_out_end)
	{
	_M_out_end = _M_out_cur;
	// NB: in \| out buffers drag the _M_in_end pointer along...
	if (__testin)
	_M_in_end += __n;
	}
	}

	// Return the size of the output buffer. This depends on the
	// buffer in use: allocated buffers have a stored size in
	// _M_buf_size and setbuf() buffers don't.
	off_type
	_M_out_buf_size()
	{
	off_type __ret = 0;
	if (_M_out_cur)
	{
	// Using allocated buffer.
	if (_M_out_beg == _M_buf)
	__ret = _M_out_beg + _M_buf_size - _M_out_cur;
	// Using non-allocated buffer.
	else
	__ret = _M_out_end - _M_out_cur;
	}
	return __ret;
	}

	// These three functions are used to clarify internal buffer
	// maintenance. After an overflow, or after a seekoff call that
	// started at beg or end, or possibly when the stream becomes
	// unbuffered, and a myrid other obscure corner cases, the
	// internal buffer does not truly reflect the contents of the
	// external buffer. At this point, for whatever reason, it is in
	// an indeterminate state.
	void
	_M_set_indeterminate(void)
	{
	if (_M_mode & ios_base::in)
	this->setg(_M_buf, _M_buf, _M_buf);
	if (_M_mode & ios_base::out)
	this->setp(_M_buf, _M_buf);
	}

	void
	_M_set_determinate(off_type __off)
	{
	bool __testin = _M_mode & ios_base::in;
	bool __testout = _M_mode & ios_base::out;
	if (__testin)
	this->setg(_M_buf, _M_buf, _M_buf + __off);
	if (__testout)
	this->setp(_M_buf, _M_buf + __off);
	}

	bool
	_M_is_indeterminate(void)
	{
	bool __ret = false;
	// Don't return true if unbuffered.
	if (_M_buf)
	{
	if (_M_mode & ios_base::in)
	__ret = _M_in_beg == _M_in_cur && _M_in_cur == _M_in_end;
	if (_M_mode & ios_base::out)
	__ret = _M_out_beg == _M_out_cur && _M_out_cur == _M_out_end;
	}
	return __ret;
	}

	public:
	virtual
	~basic_streambuf()
	{
	_M_buf_unified = false;
	_M_buf_size = 0;
	_M_buf_size_opt = 0;
	_M_mode = ios_base::openmode(0);
	_M_buf_locale_init = false;
	}

	// Locales:
	locale
	pubimbue(const locale &__loc)
	{
	locale __tmp(this->getloc());
	this->imbue(__loc);
	return __tmp;
	}

	locale
	getloc() const
	{
	if (_M_buf_locale_init)
	return _M_buf_locale;
	else
	return locale();
	}

	// Buffer and positioning:
	__streambuf_type*
	pubsetbuf(char_type* __s, streamsize __n)
	{ return this->setbuf(__s, __n); }

	pos_type
	pubseekoff(off_type __off, ios_base::seekdir __way,
	ios_base::openmode __mode = ios_base::in \| ios_base::out)
	{ return this->seekoff(__off, __way, __mode); }

	pos_type
	pubseekpos(pos_type __sp,
	ios_base::openmode __mode = ios_base::in \| ios_base::out)
	{ return this->seekpos(__sp, __mode); }

	int
	pubsync() { return this->sync(); }

	// Get and put areas:
	// Get area:
	streamsize
	in_avail()
	{
	streamsize __ret;
	if (_M_in_cur && _M_in_cur < _M_in_end)
	{
	if (_M_pback_init)
	{
	int_type __save_len = _M_pback_end_save - _M_pback_cur_save;
	int_type __pback_len = _M_in_cur - _M_pback;
	__ret = __save_len - __pback_len;
	}
	else
	__ret = this->egptr() - this->gptr();
	}
	else
	__ret = this->showmanyc();
	return __ret;
	}

	int_type
	snextc()
	{
	int_type __eof = traits_type::eof();
	return (this->sbumpc() == __eof ? __eof : this->sgetc());
	}

	int_type
	sbumpc();

	int_type
	sgetc()
	{
	int_type __ret;
	if (_M_in_cur && _M_in_cur < _M_in_end)
	__ret = traits_type::to_int_type(*(this->gptr()));
	else
	__ret = this->underflow();
	return __ret;
	}

	streamsize
	sgetn(char_type* __s, streamsize __n)
	{ return this->xsgetn(__s, __n); }

	// Putback:
	int_type
	sputbackc(char_type __c);

	int_type
	sungetc();

	// Put area:
	int_type
	sputc(char_type __c);

	streamsize
	sputn(const char_type* __s, streamsize __n)
	{ return this->xsputn(__s, __n); }

	protected:
	basic_streambuf()
	: _M_buf(NULL), _M_buf_size(0),
	_M_buf_size_opt(static_cast<int_type>(BUFSIZ)), _M_buf_unified(false),
	_M_in_beg(0), _M_in_cur(0), _M_in_end(0), _M_out_beg(0), _M_out_cur(0),
	_M_out_end(0), _M_mode(ios_base::openmode(0)), _M_buf_locale(locale()),
	_M_buf_locale_init(false), _M_pback_size(1), _M_pback(NULL),
	_M_pback_cur_save(NULL), _M_pback_end_save(NULL), _M_pback_init(false)
	{ }

	// Get area:
	char_type*
	eback() const { return _M_in_beg; }

	char_type*
	gptr() const { return _M_in_cur; }

	char_type*
	egptr() const { return _M_in_end; }

	void
	gbump(int __n) { _M_in_cur += __n; }

	void
	setg(char_type* __gbeg, char_type* __gnext, char_type* __gend)
	{
	_M_in_beg = __gbeg;
	_M_in_cur = __gnext;
	_M_in_end = __gend;
	if (!(_M_mode & ios_base::in) && __gbeg && __gnext && __gend)
	_M_mode = _M_mode \| ios_base::in;
	}

	// Put area:
	char_type*
	pbase() const { return _M_out_beg; }

	char_type*
	pptr() const { return _M_out_cur; }

	char_type*
	epptr() const { return _M_out_end; }

	void
	pbump(int __n) { _M_out_cur += __n; }

	void
	setp(char_type* __pbeg, char_type* __pend)
	{
	_M_out_beg = _M_out_cur = __pbeg;
	_M_out_end = __pend;
	if (!(_M_mode & ios_base::out) && __pbeg && __pend)
	_M_mode = _M_mode \| ios_base::out;
	}

	// Virtual functions:
	// Locales:
	virtual void
	imbue(const locale& __loc)
	{
	_M_buf_locale_init = true;
	if (_M_buf_locale != __loc)
	_M_buf_locale = __loc;
	}

	// Buffer management and positioning:
	virtual basic_streambuf<char_type,_Traits>*
	setbuf(char_type*, streamsize)
	{ return this; }

	virtual pos_type
	seekoff(off_type, ios_base::seekdir,
	ios_base::openmode /__mode/ = ios_base::in \| ios_base::out)
	{ return pos_type(off_type(-1)); }

	virtual pos_type
	seekpos(pos_type,
	ios_base::openmode /__mode/ = ios_base::in \| ios_base::out)
	{ return pos_type(off_type(-1)); }

	virtual int
	sync() { return 0; }

	// Get area:
	virtual streamsize
	showmanyc() { return 0; }

	virtual streamsize
	xsgetn(char_type* __s, streamsize __n);

	virtual int_type
	underflow()
	{ return traits_type::eof(); }

	virtual int_type
	uflow()
	{
	int_type __ret = traits_type::eof();
	bool __testeof = this->underflow() == __ret;
	bool __testpending = _M_in_cur && _M_in_cur < _M_in_end;
	if (!__testeof && __testpending)
	{
	__ret = traits_type::to_int_type(*_M_in_cur);
	++_M_in_cur;
	if (_M_buf_unified && _M_mode & ios_base::out)
	++_M_out_cur;
	}
	return __ret;
	}

	// Putback:
	virtual int_type
	pbackfail(int_type /* __c */ = traits_type::eof())
	{ return traits_type::eof(); }

	// Put area:
	virtual streamsize
	xsputn(const char_type* __s, streamsize __n);

	virtual int_type
	overflow(int_type /* __c */ = traits_type::eof())
	{ return traits_type::eof(); }

	#ifdef _GLIBCPP_DEPRECATED
	public:
	void
	stossc()
	{
	if (_M_in_cur < _M_in_end)
	++_M_in_cur;
	else
	this->uflow();
	}
	#endif

	#ifdef _GLIBCPP_RESOLVE_LIB_DEFECTS
	// Side effect of DR 50.
	private:
	basic_streambuf(const __streambuf_type&);

	__streambuf_type&
	operator=(const __streambuf_type&);
	#endif
	};

	} // namespace std

	#ifdef _GLIBCPP_NO_TEMPLATE_EXPORT
	# define export
	#ifdef _GLIBCPP_FULLY_COMPLIANT_HEADERS
	#include <bits/streambuf.tcc>
	#endif
	#endif

	#endif /* _CPP_STREAMBUF */