barrier/lib/io/IStream.h

/*
 * synergy -- mouse and keyboard sharing utility
 * Copyright (C) 2004 Chris Schoeneman
 * 
 * This package is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * found in the file COPYING that should have accompanied this file.
 * 
 * This package 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.
 */

#ifndef ISTREAM_H
#define ISTREAM_H

#include "IInterface.h"
#include "CEvent.h"

class IEventJob;

//! Bidirectional stream interface
/*!
Defines the interface for all streams.
*/
class IStream : public IInterface {
public:
	//! @name manipulators
	//@{

	//! Close the stream
	/*!
	Closes the stream.  Pending input data and buffered output data
	are discarded.  Use \c flush() before \c close() to send buffered
	output data.  Attempts to \c read() after a close return 0,
	attempts to \c write() generate output error events, and attempts
	to \c flush() return immediately.
	*/
	virtual void		close() = 0;

	//! Read from stream
	/*!
	Read up to \p n bytes into \p buffer, returning the number read
	(zero if no data is available or input is shutdown).  \p buffer
	may be NULL in which case the data is discarded.
	*/
	virtual UInt32		read(void* buffer, UInt32 n) = 0;

	//! Write to stream
	/*!
	Write \c n bytes from \c buffer to the stream.  If this can't
	complete immediately it will block.  Data may be buffered in
	order to return more quickly.  A output error event is generated
	when writing fails.
	*/
	virtual void		write(const void* buffer, UInt32 n) = 0;

	//! Flush the stream
	/*!
	Waits until all buffered data has been written to the stream.
	*/
	virtual void		flush() = 0;

	//! Shutdown input
	/*!
	Shutdown the input side of the stream.  Any pending input data is
	discarded and further reads immediately return 0.
	*/
	virtual void		shutdownInput() = 0;

	//! Shutdown output
	/*!
	Shutdown the output side of the stream.  Any buffered output data
	is discarded and further writes generate output error events.  Use
	\c flush() before \c shutdownOutput() to send buffered output data.
	*/
	virtual void		shutdownOutput() = 0;

	//! Set the event filter
	/*!
	If not NULL, the \p filter is passed any event that would've been
	added to the queue.  The filter can discard the event, modify it
	and add it to the queue, and add other events.  The default filter
	is NULL.  The caller retains ownership of the filter.
	*/
	virtual void		setEventFilter(IEventJob* filter) = 0;

	//@}

	//@}
	//! @name accessors
	//@{

	//! Get event target
	/*!
	Returns the event target for events generated by this stream.
	*/
	virtual void*		getEventTarget() const = 0;

	//! Test if \c read() will succeed
	/*!
	Returns true iff an immediate \c read() will return data.  This
	may or may not be the same as \c getSize() > 0, depending on the
	stream type.
	*/
	virtual bool		isReady() const = 0;

	//! Get bytes available to read
	/*!
	Returns a conservative estimate of the available bytes to read
	(i.e. a number not greater than the actual number of bytes).
	Some streams may not be able to determine this and will always
	return zero.
	*/
	virtual UInt32		getSize() const = 0;

	//! Get the event filter
	/*!
	Returns the current event filter.
	*/
	virtual IEventJob*	getEventFilter() const = 0;

	//! Get input ready event type
	/*!
	Returns the input ready event type.  A stream sends this event
	when \c read() will return with data.
	*/
	static CEvent::Type	getInputReadyEvent();

	//! Get output flushed event type
	/*!
	Returns the output flushed event type.  A stream sends this event
	when the output buffer has been flushed.  If there have been no
	writes since the event was posted, calling \c shutdownOutput() or
	\c close() will not discard any data and \c flush() will return
	immediately.
	*/
	static CEvent::Type	getOutputFlushedEvent();

	//! Get output error event type
	/*!
	Returns the output error event type.  A stream sends this event
	when a write has failed.
	*/
	static CEvent::Type	getOutputErrorEvent();

	//! Get input shutdown event type
	/*!
	Returns the input shutdown event type.  This is sent when the
	input side of the stream has shutdown.  When the input has
	shutdown, no more data will ever be available to read.
	*/
	static CEvent::Type	getInputShutdownEvent();

	//! Get output shutdown event type
	/*!
	Returns the output shutdown event type.  This is sent when the
	output side of the stream has shutdown.  When the output has
	shutdown, no more data can ever be written to the stream.  Any
	attempt to do so will generate a output error event.
	*/
	static CEvent::Type	getOutputShutdownEvent();

	//@}

private:
	static CEvent::Type	s_inputReadyEvent;
	static CEvent::Type	s_outputFlushedEvent;
	static CEvent::Type	s_outputErrorEvent;
	static CEvent::Type	s_inputShutdownEvent;
	static CEvent::Type	s_outputShutdownEvent;
};

#endif