source: trunk/synergy/lib/io/IStream.h@ 3294

/*
 * 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"

//! 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;

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

        //! Get event target
        /*!
        Returns the event target for events generated by this stream.  It
        should be the source stream in a chain of stream filters.
        */
        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 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