bufferedstreambuf.h

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

//
// BufferedStreamBuf.h
//
// $Id: //poco/Main/Foundation/include/Foundation/BufferedStreamBuf.h#5 $
//
// Definition of template BasicBufferedStreamBuf and class BufferedStreamBuf.
//
// 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_BufferedStreamBuf_INCLUDED
#define Foundation_BufferedStreamBuf_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 BasicBufferedStreamBuf: public std::basic_streambuf<ch, tr>
	/// This is an implementation of a buffered 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:
	BasicBufferedStreamBuf(std::streamsize bufferSize, openmode mode)
	{
		_mode    = mode;
		_bufsize = bufferSize;
		_pBuffer = new char_type[_bufsize];
		this->setp(_pBuffer, _pBuffer + (_bufsize - 1));
		this->setg(_pBuffer + 4, _pBuffer + 4, _pBuffer + 4);
	}

	~BasicBufferedStreamBuf()
	{
		delete _pBuffer;
	}

	virtual int_type overflow(int_type c)
	{
		if (!(_mode & IOS::out)) return char_traits::eof();

		if (c != char_traits::eof()) 
		{
			*this->pptr() = char_traits::to_char_type(c);
			this->pbump(1);
		}
		if (flush_buffer() == std::streamsize(-1)) return char_traits::eof();

		return c;
	}

	virtual int_type underflow()
	{
		if (!(_mode & IOS::in)) return char_traits::eof();

		if (this->gptr() && (this->gptr() < this->egptr()))
			return char_traits::to_int_type(*this->gptr());

		int putback = int(this->gptr() - this->eback());
		if (putback > 4) putback = 4;

		char_traits::copy(_pBuffer + (4 - putback), this->gptr() - putback, putback);

		int n = readFromDevice(_pBuffer + 4, _bufsize - 4);
		if (n <= 0) return char_traits::eof();

		this->setg(_pBuffer + (4 - putback), _pBuffer + 4, _pBuffer + 4 + n);

		// return next character
		return char_traits::to_int_type(*this->gptr());    
	}

	virtual int sync()
	{
		if (this->pptr() && this->pptr() > this->pbase()) 
		{
			if (flush_buffer() == -1) return -1;
		}
		return 0;
	}

private:
	virtual int readFromDevice(char_type* buffer, std::streamsize length)
	{
		return 0;
	}

	virtual int writeToDevice(const char_type* buffer, std::streamsize length)
	{
		return 0;
	}

	int flush_buffer()
	{
		int n = int(this->pptr() - this->pbase());
		if (writeToDevice(this->pbase(), n) == n) 
		{
			this->pbump(-n);
			return n;
		}
		return -1;
	}

	std::streamsize _bufsize;
	char_type*      _pBuffer;
	openmode        _mode;
};


//
// We provide an instantiation for char
//
typedef BasicBufferedStreamBuf<char, std::char_traits<char> > BufferedStreamBuf;


Foundation_END


#endif // Foundation_BufferedStreamBuf_INCLUDED