com.healthmarketscience.jackcess.scsu
Class Compress

java.lang.Object
  com.healthmarketscience.jackcess.scsu.SCSU
      com.healthmarketscience.jackcess.scsu.Compress

public class Compress
extends SCSU

This class implements a simple compression algorithm

Constructor Summary

Compress()

Method Summary

int	bytesWritten() returns the number of bytes written
int	charsRead() returns the number of bytes written
byte[]	compress(java.lang.String inStr)
static boolean	isAsciiCrLfOrTab(int ch) returns true if the character is ASCII, but not a control other than CR, LF and TAB
int	outputSingleByteRun(char[] in, byte[] out) output a run of characters in single byte mode In single byte mode pass through characters in the ASCII range, but quote characters overlapping with compression command codes.
char	outputUnicodeRun(char[] in, byte[] out) output a run of characters in Unicode mode A run of Unicode mode consists of characters which are all in the range of non-compressible characters or isolated occurrence of any other characters.
void	reset() reset is only needed to bail out after an exception and restart with new input
int	simpleCompress(char[] in, int iStartIn, byte[] out, int iStartOut) compress a Unicode character array with some simplifying assumptions

Methods inherited from class com.healthmarketscience.jackcess.scsu.SCSU

getCurrentWindow, isCompressible, selectWindow

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Compress

public Compress()

Method Detail

isAsciiCrLfOrTab

public static boolean isAsciiCrLfOrTab(int ch)

returns true if the character is ASCII, but not a control other than CR, LF and TAB

outputSingleByteRun

public int outputSingleByteRun(char[] in,
                               byte[] out)
                        throws EndOfOutputException,
                               EndOfInputException,
                               IllegalInputException

output a run of characters in single byte mode In single byte mode pass through characters in the ASCII range, but quote characters overlapping with compression command codes. Runs of characters fitting the current window are output as runs of bytes in the range 0x80-0xFF. Checks for and validates Surrogate Pairs. Uses and updates the current input and output cursors store in the instance variables iIn and iOut.

Parameters:

in - - input character array

out - - output byte array

Returns:

the next chaacter to be processed. This may be an extended character.

Throws:

EndOfOutputException

EndOfInputException

IllegalInputException

outputUnicodeRun

public char outputUnicodeRun(char[] in,
                             byte[] out)
                      throws EndOfOutputException

output a run of characters in Unicode mode A run of Unicode mode consists of characters which are all in the range of non-compressible characters or isolated occurrence of any other characters. Characters in the range 0xE00-0xF2FF must be quoted to avoid overlap with the Unicode mode compression command codes. Uses and updates the current input and output cursors store in the instance variables iIn and iOut. NOTE: Characters from surrogate pairs are passed through and unlike single byte mode no checks are made for unpaired surrogate characters.

Parameters:

in - - input character array

out - - output byte array

Returns:

the next input character to be processed

Throws:

EndOfOutputException

simpleCompress

public int simpleCompress(char[] in,
                          int iStartIn,
                          byte[] out,
                          int iStartOut)
                   throws IllegalInputException,
                          EndOfInputException,
                          EndOfOutputException

compress a Unicode character array with some simplifying assumptions

Throws:

IllegalInputException

EndOfInputException

EndOfOutputException

compress

public byte[] compress(java.lang.String inStr)
                throws IllegalInputException,
                       EndOfInputException

Throws:

IllegalInputException

EndOfInputException

reset

public void reset()

reset is only needed to bail out after an exception and restart with new input

Overrides:

reset in class SCSU

bytesWritten

public int bytesWritten()

returns the number of bytes written

charsRead

public int charsRead()

returns the number of bytes written