unbufferedstreambuf.h

This software aims to create an applet and panel tools to manage a wireless interface card, such as

//
// UnufferedStreamBuf.h
//
// $Id: //poco/Main/Foundation/include/Foundation/UnbufferedStreamBuf.h#5 $
//
// Definition of template BasicUnbufferedStreamBuf and class UnbufferedStreamBuf.
//
// Copyright (c) 2004, Guenter Obiltschnig/Applied Informatics.
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
// 
// 3. Redistributions in any form must be accompanied by information on
//    how to obtain complete source code for this software and any
//    accompanying software that uses this software.  The source code
//    must either be included in the distribution or be available for no
//    more than the cost of distribution plus a nominal fee, and must be
//    freely redistributable under reasonable conditions.  For an
//    executable file, complete source code means the source code for all
//    modules it contains.  It does not include source code for modules or
//    files that typically accompany the major components of the operating
//    system on which the executable file runs.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//


#ifndef Foundation_UnbufferedStreamBuf_INCLUDED
#define Foundation_UnbufferedStreamBuf_INCLUDED


#ifndef Foundation_Foundation_INCLUDED
#include "Foundation/Foundation.h"
#endif
#ifndef STD_STREAMBUF_INCLUDED
#include <streambuf>
#define STD_STREAMBUF_INCLUDED
#endif
#ifndef STD_IOSFWD_INCLUDED
#include <iosfwd>
#define STD_IOSFWD_INCLUDED
#endif
#ifndef STD_IOS_INCLUDED
#include <ios>
#define STD_IOS_INCLUDED
#endif


Foundation_BEGIN


template<typename ch, typename tr> 
class BasicUnbufferedStreamBuf: public std::basic_streambuf<ch, tr>
	/// This is an implementation of an unbuffered streambuf
	/// that greatly simplifies the implementation of
	/// custom streambufs of various kinds.
	/// Derived classes only have to override the methods
	/// readFromDevice() or writeToDevice().
{
	typedef std::basic_streambuf<ch, tr> Base;
	typedef std::basic_ios<ch, tr> IOS;
	typedef ch char_type;
	typedef tr char_traits;
	typedef typename Base::int_type int_type;
	typedef typename Base::pos_type pos_type;
	typedef typename Base::off_type off_type;
	typedef typename IOS::openmode openmode;

public:
	BasicUnbufferedStreamBuf()
	{
		_pb     = char_traits::eof();
		_ispb   = false;
		this->setp(0, 0);
		this->setg(0, 0, 0);
	}

	~BasicUnbufferedStreamBuf()
	{
	}

	virtual int_type overflow(int_type c)
	{
		if (c != char_traits::eof()) 
			return writeToDevice(char_traits::to_char_type(c));
		else
			return c;
	}

	virtual int_type underflow()
	{
		if (_ispb)
		{
    		return _pb;
		}
		else
		{
    		int_type c = readFromDevice();
    		if (c != char_traits::eof())
    		{
    			_ispb = true;
    			_pb   = c;
    		}
    		return c;
		}
	}

	virtual int_type uflow()
	{
		if (_ispb)
		{
			_ispb = false;
			return _pb;
		}
		else
		{
    		int_type c = readFromDevice();
    		if (c != char_traits::eof())
    		{
    			_pb = c;
    		}
    		return c;
		}
	}

	virtual int_type pbackfail(int_type c)
	{
		if (_ispb)
		{
    		return char_traits::eof();
		}
		else
		{
    		_ispb = true;
    		_pb   = c;
    		return c;
		}
	}
	
	virtual std::streamsize xsgetn(char_type* p, std::streamsize count)
		/// Some platforms (for example, Compaq C++) have buggy implementations of 
		/// xsgetn that handle null buffers incorrectly.
		/// Anyway, it does not hurt to provide an optimized implementation
		/// of xsgetn for this streambuf implementation.
	{
		if (count == 0) return 0;
		std::streamsize copied = 0;
		int_type c = uflow();
		while (count > 0 && c != char_traits::eof())
		{
			*p++ = char_traits::to_char_type(c);
			++copied;
			--count;
			c = uflow();
		}
		return copied;
	}

private:
	virtual int_type readFromDevice()
	{
		return char_traits::eof();
	}
	
	virtual int_type writeToDevice(char_type c)
	{
		return char_traits::eof();
	}

	int_type _pb;
	bool     _ispb;
};


//
// We provide an instantiation for char
//
typedef BasicUnbufferedStreamBuf<char, std::char_traits<char> > UnbufferedStreamBuf;


Foundation_END


#endif // Foundation_UnbufferedStreamBuf_INCLUDED