NAME
zipios::BackBuffer - A BackBuffer instance is useful for reading the
last part of a file in an efficient manner, when it is not known
exactly how far back (towards the front!) to go, to find the start of
the desired data block.
SYNOPSIS
#include <backbuffer.h>
Inherits std::vector< unsigned char >.
Public Member Functions
BackBuffer (istream &is, VirtualSeeker vs=VirtualSeeker(), int
chunk_size=1024)
BackBuffer constructor.
int readChunk (int &read_pointer)
Reads another chunk and returns the size of the chunk that has been
read.
Detailed Description
A BackBuffer instance is useful for reading the last part of a file in
an efficient manner, when it is not known exactly how far back (towards
the front!) to go, to find the start of the desired data block.
BackBuffer is a vector< unsigned char > that fills itself with data
from a file by reading chunks from the end of the file progressing
towards the start. Upon construction the BackBuffer instance is
associated with a file and a chunksize can be specified. To read a
chunk of the file into the BackBuffer call readChunk().
Definition at line 32 of file backbuffer.h.
Constructor & Destructor Documentation
zipios::BackBuffer::BackBuffer (istream & is, VirtualSeeker vs =
VirtualSeeker(), int chunk_size = 1024) [inline, explicit]
BackBuffer constructor.
Parameters:
is The istream to read the data from. The stream must be seekable,
as BackBuffer will reposition the file position to read chunks from
the back of the file.
chunk_size specifies the size of the chunks to read the file into
the BackBuffer in.
Exceptions:
FCollException Thrown if the VirtualSeeker vs that has been
specified is invalid for the istream is.
Definition at line 61 of file backbuffer.h.
Member Function Documentation
int zipios::BackBuffer::readChunk (int & read_pointer) [inline]
Reads another chunk and returns the size of the chunk that has been
read.
Returns 0 on I/O failure.
Parameters:
read_pointer When a new chunk is read in the already stored bytes
change position in the BackBuffer. read_pointer is assumed by
readChunk() to be a pointer into a position in the BackBuffer, and
is updated to point to the same position in the file as it pointed
to before the new chunk was read.
Definition at line 75 of file backbuffer.h.
Author
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