IODevice Class Reference

Endpoint for I/O operations. More...

#include <cxxtools/iodevice.h>

Inheritance diagram for IODevice:

List of all members.

Public Types
typedef std::char_traits< char > ::pos_type	pos_type
typedef std::char_traits< char > ::off_type	off_type
typedef std::ios_base::seekdir	SeekDir
typedef IOS_OpenMode	OpenMode
Public Member Functions
virtual	~IODevice ()
	Destructor.
void	beginRead (char *buffer, size_t n)
size_t	endRead ()
size_t	read (char *buffer, size_t n)
	Read data from I/O device.
void	beginWrite (const char *buffer, size_t n)
size_t	endWrite ()
size_t	write (const char *buffer, size_t n)
	Write data to I/O device.
bool	seekable () const
	Returns true if device is seekable.
pos_type	seek (off_type offset, std::ios::seekdir sd)
	Move the next read position to the given offset.
size_t	peek (char *buffer, size_t n)
	Read data from I/O device without consuming them.
void	sync ()
	Synchronize device.
pos_type	position ()
	Returns the current I/O position.
bool	eof () const
	Returns if the device has reached EOF.
bool	async () const
	Returns true if the device operates in asynchronous mode.
virtual IODeviceImpl &	ioimpl ()=0
bool	reading () const
bool	writing () const
char *	rbuf () const
size_t	rbuflen () const
const char *	wbuf () const
size_t	wbuflen () const
Public Attributes
Signal< IODevice & >	inputReady
	Notifies about availavle data.
Signal< IODevice & >	outputReady
	Notifies when data can be written.
Signal< IODevice & >	errorOccured
	Notifies when an error occured.
Static Public Attributes
static const OpenMode	Sync = IOS_Sync
static const OpenMode	Async = IOS_Async
static const OpenMode	Read = IOS_Read
static const OpenMode	Write = IOS_Write
static const OpenMode	AtEnd = IOS_AtEnd
static const OpenMode	Append = IOS_Append
static const OpenMode	Trunc = IOS_Trunc
Protected Member Functions
	IODevice ()
	Default Constructor.
virtual size_t	onBeginRead (char *buffer, size_t n, bool &eof)=0
virtual size_t	onEndRead (bool &eof)=0
virtual size_t	onRead (char *buffer, size_t count, bool &eof)=0
	Read bytes from device.
virtual size_t	onBeginWrite (const char *buffer, size_t n)=0
virtual size_t	onEndWrite ()=0
virtual size_t	onWrite (const char *buffer, size_t count)=0
	Write bytes to device.
virtual size_t	onPeek (char *, size_t)
	Read data from I/O device without consuming them.
virtual bool	onSeekable () const
	Returns true if device is seekable.
virtual pos_type	onSeek (off_type, std::ios::seekdir)
	Move the next read position to the given offset.
virtual void	onSync () const
	Synchronize device.
virtual size_t	onSize () const
	Returns the size of the device.
void	setEof (bool eof)
	Sets or unsets the device to eof.
void	setAsync (bool async)
	Sets or unsets the device to async.
Protected Attributes
char *	_rbuf
size_t	_rbuflen
size_t	_ravail
const char *	_wbuf
size_t	_wbuflen
size_t	_wavail
void *	_reserved

---

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 cxxtools 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. A Selector can be used to wait on activity on an IODevice, which will send the Singal inputReady or outputReady of the IODevice that is ready to perform I/O.

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Member Function Documentation

size_t read	(	char *	buffer,
		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

size_t write	(	const char *	buffer,
		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 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 containing the data to be written.
	n	number of bytes that should be written.

Returns:

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

Exceptions:

IOError

bool seekable

(

)

const

Tests if the device is seekable.

Returns:

true if the device is seekable, false otherwise.

pos_type seek	(	off_type	offset,
		std::ios::seekdir	sd
	)

Tries to move the current read position to the given offset. SeekMode determines the relative starting point of offset.

Parameters:

	offset	the offset the pointer should be moved by.
	mode	determines the relative starting offset.

Returns:

the new abosulte read positing.

Exceptions:

IOError

size_t peek	(	char *	buffer,
		size_t	n
	)

Tries to extract up to n bytes from this object without consuming them. The bytes are stored in buffer, and the number of bytes peeked is returned.

Parameters:

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

Returns:

number of bytes peek.

Exceptions:

IOError

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 BasicIODevice::seekable().

Exceptions:

IOError

bool eof

(

)

const

Test if the I/O device has reached eof.

Returns:

true if the I/O device is usable, false otherwise.

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Member Data Documentation

Signal<IODevice&> inputReady

This signal is send when the IODevice is monitored in a Selector or EventLoop and data becomes available.

Signal<IODevice&> outputReady

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

Signal<IODevice&> errorOccured

This signal is send when the device is monitored in a Selector or EventLoop and an error occured on the device.