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:

PFile PChannel PObject 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.
 ~PMemoryFile ()
 Destroy the memory file.
Overrides from class PObject
Comparison Compare (const PObject &obj) const
 Determine the relative rank of the two objects.
Overrides from class PChannel
virtual PBoolean Open (OpenMode mode=ReadWrite, int opts=ModeDefault)
 Open the current file in the specified mode and with the specified options.
virtual PBoolean Open (const PFilePath &name, OpenMode mode=ReadWrite, int opts=ModeDefault)
 Open the specified file name in the specified mode and with the specified options.
virtual PBoolean Close ()
 Close the channel, shutting down the link to the data source.
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
virtual off_t GetLength () const
 Get the current size of the file.
virtual 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.
virtual PBoolean SetPosition (off_t pos, FilePositionOrigin origin=Start)
 Set the current active position in the file for the next read or write operation.
virtual off_t GetPosition () const
 Get the current active position in the file for the next read or write operation.
Overrides from class PFile
const PBYTEArrayGetData () const
 Get the memory data the file has operated with.

Protected Attributes

PBYTEArray m_data
off_t m_position

Detailed Description

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


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.

PMemoryFile::~PMemoryFile (  ) 

Destroy the memory file.


Member Function Documentation

virtual PBoolean PMemoryFile::Close (  )  [virtual]

Close the channel, shutting down the link to the data source.

Returns:
true if the channel successfully closed.

Reimplemented from PFile.

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.

virtual 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.

virtual 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::Open ( const PFilePath name,
OpenMode  mode = ReadWrite,
int  opts = ModeDefault 
) [virtual]

Open the specified file name in the specified mode and with the specified options.

If the file object already has an open file then it is closed.

Note: if mode is StandardInput, StandardOutput or StandardError, then the name parameter is ignored.

Returns:
true if the file was successfully opened.

virtual PBoolean PMemoryFile::Open ( OpenMode  mode = ReadWrite,
int  opts = ModeDefault 
) [virtual]

Open the current file in the specified mode and with the specified options.

If the file object already has an open file then it is closed.

If there has not been a filename attached to the file object (via SetFilePath(), the name parameter or a previous open) then a new unique temporary filename is generated.

Returns:
true if the file was successfully opened.

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.

virtual 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.

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

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.


Member Data Documentation

PBYTEArray PMemoryFile::m_data [protected]

off_t PMemoryFile::m_position [protected]


The documentation for this class was generated from the following file:
Generated on Fri Feb 15 20:58:34 2013 for PTLib by  doxygen 1.4.7