Interface IHuffProcessor

All Superinterfaces:

IHuffConstants

All Known Implementing Classes:

SimpleHuffProcessor

public interface IHuffProcessor
extends IHuffConstants

The interface for the model that can be attached to a HuffViewer. Most of the work done in huffing (and unhuffing) will be via a class that implements this interface. The interface may need to be extended depending on the design of the huffman program.

Field Summary

Fields inherited from interface IHuffConstants

ALPH_SIZE, BITS_PER_INT, BITS_PER_WORD, MAGIC_NUMBER, STORE_COUNTS, STORE_CUSTOM, STORE_TREE

Method Summary

Methods

Modifier and Type	Method and Description
int	compress(InputStream in, OutputStream out, boolean force) Compresses input to output, where the same InputStream has previously been pre-processed via preprocessCompress storing state used by this call.
int	preprocessCompress(InputStream in, int headerFormat) Preprocess data so that compression is possible --- count characters/create tree/store state so that a subsequent call to compress will work.
void	setViewer(IHuffViewer viewer) Make sure this model communicates with some view.
int	uncompress(InputStream in, OutputStream out) Uncompress a previously compressed stream in, writing the uncompressed bits/data to out.

Method Detail

setViewer

void setViewer(IHuffViewer viewer)

Make sure this model communicates with some view.

Parameters:

viewer - is the view for communicating.

preprocessCompress

int preprocessCompress(InputStream in,
                     int headerFormat)
                       throws IOException

Preprocess data so that compression is possible --- count characters/create tree/store state so that a subsequent call to compress will work. The InputStream is not a BitInputStream, so wrap it in one as needed.

Parameters:

in - is the stream which could be subsequently compressed

headerFormat - a constant from IHuffProcessor that determines what kind of header to use, standard count format, standard tree format, or possibly some format added in the future.

Returns:

number of bits saved by compression or some other measure Note, to determine the number of bits saved, the number of bits written includes ALL bits that will be written including the magic number, the header format number, the header to reproduce the tree, AND the actual data.

Throws:

IOException - if an error occurs while reading from the input file.

compress

int compress(InputStream in,
           OutputStream out,
           boolean force)
             throws IOException

Compresses input to output, where the same InputStream has previously been pre-processed via preprocessCompress storing state used by this call.
pre: preprocessCompress must be called before this method

Parameters:

in - is the stream being compressed (NOT a BitInputStream)

out - is bound to a file/stream to which bits are written for the compressed file (not a BitOutputStream)

force - if this is true create the output file even if it is larger than the input file. If this is false do not create the output file if it is larger than the input file.

Returns:

the number of bits written.

Throws:

IOException - if an error occurs while reading from the input file or writing to the output file.

uncompress

int uncompress(InputStream in,
             OutputStream out)
               throws IOException

Uncompress a previously compressed stream in, writing the uncompressed bits/data to out.

Parameters:

in - is the previously compressed data (not a BitInputStream)

out - is the uncompressed file/stream

Returns:

the number of bits written to the uncompressed file/stream

Throws:

IOException - if an error occurs while reading from the input file or writing to the output file.