PMemoryFile Class Reference

This class is used to allow a block of memory to substitute for a disk file. More...

#include <memfile.h>

Inheritance diagram for PMemoryFile:

List of all members.

Public Member Functions
Construction
	PMemoryFile ()
	Create a new, empty, memory file.
	PMemoryFile (const PBYTEArray &data)
	Create a new memory file initialising to the specified content.
Overrides from class PObject
Comparison	Compare (const PObject &obj) const
	Determine the relative rank of the two objects.
Overrides from class PChannel
virtual PBoolean	Read (void *buf, PINDEX len)
	Low level read from the memory file channel.
virtual PBoolean	Write (const void *buf, PINDEX len)
	Low level write to the memory file channel.
Overrides from class PFile
off_t	GetLength () const
	Get the current size of the file.
PBoolean	SetLength (off_t len)
	Set the size of the file, padding with 0 bytes if it would require expanding the file, or truncating it if being made shorter.
PBoolean	SetPosition (off_t pos, FilePositionOrigin origin=Start)
	Set the current active position in the file for the next read or write operation.
off_t	GetPosition () const
	Get the current active position in the file for the next read or write operation.
Overrides from class PFile
const PBYTEArray &	GetData () const
	Get the memory data the file has operated with.
Protected Attributes
PBYTEArray	data
off_t	position

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Detailed Description

This class is used to allow a block of memory to substitute for a disk file.

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Constructor & Destructor Documentation

PMemoryFile::PMemoryFile

(

)

Create a new, empty, memory file.

PMemoryFile::PMemoryFile

(

const PBYTEArray &

data

)

Create a new memory file initialising to the specified content.

Parameters:

data	New content filr memory file.

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Member Function Documentation

Comparison PMemoryFile::Compare

(

const PObject &

obj

)

const [virtual]

Determine the relative rank of the two objects.

This is essentially the string comparison of the PFilePath names of the files.

Returns:

relative rank of the file paths.

Parameters:

obj	Other file to compare against.

Reimplemented from PFile.

const PBYTEArray& PMemoryFile::GetData

(

)

const [inline]

Get the memory data the file has operated with.

off_t PMemoryFile::GetLength

(

)

const [virtual]

Get the current size of the file.

The size of the file corresponds to the size of the data array.

Returns:

length of file in bytes.

Reimplemented from PFile.

off_t PMemoryFile::GetPosition

(

)

const [virtual]

Get the current active position in the file for the next read or write operation.

Returns:

current file position relative to start of file.

Reimplemented from PFile.

virtual PBoolean PMemoryFile::Read	(	void *	buf,
		PINDEX	len
	)			[virtual]

Low level read from the memory file channel.

The read timeout is ignored. The GetLastReadCount() function returns the actual number of bytes read.

The GetErrorCode() function should be consulted after Read() returns false to determine what caused the failure.

Returns:

true indicates that at least one character was read from the channel. false means no bytes were read due to timeout or some other I/O error.

Parameters:

buf	Pointer to a block of memory to receive the read bytes.
len	Maximum number of bytes to read into the buffer.

Reimplemented from PFile.

PBoolean PMemoryFile::SetLength

(

off_t

len

)

[virtual]

Set the size of the file, padding with 0 bytes if it would require expanding the file, or truncating it if being made shorter.

Returns:

true if the file size was changed to the length specified.

Parameters:

len	New length of file.

Reimplemented from PFile.

PBoolean PMemoryFile::SetPosition	(	off_t	pos,
		FilePositionOrigin	origin = Start
	)

Set the current active position in the file for the next read or write operation.

The pos variable is a signed number which is added to the specified origin. For origin == PFile::Start only positive values for pos are meaningful. For origin == PFile::End only negative values for pos are meaningful.

Returns:

true if the new file position was set.

Parameters:

pos	New position to set.
origin	Origin for position change.

virtual PBoolean PMemoryFile::Write	(	const void *	buf,
		PINDEX	len
	)			[virtual]

Low level write to the memory file channel.

The write timeout is ignored. The GetLastWriteCount() function returns the actual number of bytes written.

The GetErrorCode() function should be consulted after Write() returns false to determine what caused the failure.

Returns:

true if at least len bytes were written to the channel.

Parameters:

buf	Pointer to a block of memory to write.
len	Number of bytes to write.

Reimplemented from PFile.

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Member Data Documentation

PBYTEArray PMemoryFile::data [protected]

off_t PMemoryFile::position [protected]

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The documentation for this class was generated from the following file:

• memfile.h

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