IODevice Class Reference

#include <Pt/System/IODevice.h>

Endpoint for I/O operations. More...

Inherits Selectable.

Inherited by TcpSocket, UdpSocket, FileDevice, and SerialDevice.

Public Member Functions
virtual	~IODevice ()
	Destructor.
void	beginRead (char *buffer, std::size_t n)
	Begins to read data.
void	beginWrite (const char *buffer, std::size_t n)
	Begins to write data.
void	cancel ()
	Cancels all operations.
void	close ()
	Closes the device.
void	detach ()
	Remove from event loop and cancels outstanding operations.
std::size_t	endRead ()
	Ends reading data.
std::size_t	endWrite ()
	Ends writing data.
Signal< IODevice & > &	inputReady ()
	Notifies about available data. More...
bool	isEof () const
	Returns if the device has reached EOF.
bool	isReading () const
	Returns true if the device is reading.
bool	isWriting () const
	Returns true if the device is writing.
EventLoop *	loop () const
	Returns the used event loop.
Signal< IODevice & > &	outputReady ()
	Notifies when data can be written. More...
std::size_t	peek (char *buffer, std::size_t n)
	Peek data from I/O device without consuming them. More...
pos_type	position ()
	Returns the current I/O position. More...
std::size_t	read (char *buffer, std::size_t n)
	Read data from I/O device. More...
bool	run ()
	Run operation if it is ready.
pos_type	seek (off_type offset, seekdir sd)
	Moves the read position to the given offset. More...
bool	seekable () const
	Returns true if device is seekable.
void	setActive (EventLoop &parent)
	Sets the parent loop, so that operations can be run.
void	setTimeout (std::size_t timeout)
	Sets the timeout for blocking I/O in milliseconds.
void	sync ()
	Synchronize device. More...
std::size_t	write (const char *buffer, std::size_t n)
	Write data to I/O device. More...

Protected Member Functions
	IODevice ()
	Default Constructor.
virtual void	onAttach (EventLoop &loop)
	Attached to loop.
virtual void	onCancel ()
	Blocks until operation has cancelled.
virtual void	onDetach (EventLoop &loop)
	Detached from loop.
virtual bool	onRun ()=0
	Check if ready and run.

Detailed Description

This class serves as the base class for all kinds of I/O devices. The interface supports synchronous and asynchronous I/O operations, peeking and seeking. I/O buffers and I/O streams within the Pt framework use IODevices as endpoints and therefore fully feaured standard C++ compliant IOStreams can be constructed at runtime. Examples of IODevices are the SerialDevice, the endpoints of a Pipe or the FileDevice. An EventLoop can be used to wait on activity on an IODevice. The signals inputReady or outputReady of the IODevice indicate that an I/O operation has finished.

Member Function Documentation

std::size_t read	(	char *	buffer,
		std::size_t	n
	)

Reads up to n bytes and stores them in buffer. Returns the number of bytes read, which may be less than requested and even 0 if the device operates in asynchronous (non-blocking) mode. In case of EOF the IODevice is set to eof.

Parameters

buffer	buffer where to place the data to be read.
n	number of bytes to read

Returns

number of bytes read, which may be less than requested.

Exceptions

IOError

std::size_t write	(	const char *	buffer,
		std::size_t	n
	)

Writes n bytes from buffer to this I/O device. Returns the number of bytes written, which may be less than requested. In case of EOF the IODevice is set to eof.

Exceptions

IOError

pos_type seek	(	off_type	offset,
		seekdir	sd
	)

Exceptions

IOError

std::size_t peek	(	char *	buffer,
		std::size_t	n
	)

void sync

(

)

Commits written data to physical device.

Exceptions

IOError

pos_type position

(

)

The current I/O position is returned or an IOError is thrown if the device is not seekable. Seekability can be tested with seekable().

Exceptions

IOError

Signal<IODevice&>& inputReady

(

)

This signal is send when the IODevice is monitored in an EventLoop and data becomes available.

Signal<IODevice&>& outputReady

(

)

This signal is send when the IODevice is monitored in an EventLoop and the device is ready to write data.