org.apache.axiom.attachments.utils
Class ByteSearch

java.lang.Object
  org.apache.axiom.attachments.utils.ByteSearch

public class ByteSearch
extends Object

ByteSearch Various byte array searching utilities. This includes a "skip search", which is a an optimized search for finding a byte pattern in a large byte array.

Constructor Summary

ByteSearch()

Method Summary

static short[]	getSkipArray(byte[] pattern, boolean direction) skipArray Builds a skip array for this pattern and direction.
static boolean	isEqual(byte[] pattern, byte[] buffer, int start, int end) isEqual
static int	search(byte[] search, byte[] bytes, int start, int end, boolean direction) search Look for the search bytes in the bytes array using a straight search.
static int	skipSearch(byte[] pattern, boolean direction, byte[] buffer, int start, int end, short[] skip) Search a byte sequence for a given pattern.

Methods inherited from class java.lang.Object

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

Constructor Detail

ByteSearch

public ByteSearch()

Method Detail

skipSearch

public static int skipSearch(byte[] pattern,
                             boolean direction,
                             byte[] buffer,
                             int start,
                             int end,
                             short[] skip)

Search a byte sequence for a given pattern. The method uses the skip search algorithm. The search can be performed in forward or backward direction, i.e. beginning from the start or end of the byte sequence.

Parameters:

pattern - byte[]

direction - true if forward, false if backward

buffer - byte[] to search

start - index to start search

end - index to end search (end index is not within the search)

skip - short[256] A skipArray generated from a call to generateSkipArray.

Returns:

index or -1 if not found

getSkipArray

public static short[] getSkipArray(byte[] pattern,
                                   boolean direction)

skipArray Builds a skip array for this pattern and direction. The skipArray is used in the optimized skipSearch

Parameters:

pattern -

direction -

Returns:

short[256]

isEqual

public static boolean isEqual(byte[] pattern,
                              byte[] buffer,
                              int start,
                              int end)

isEqual

Parameters:

pattern -

buffer -

start - index

end - index

Returns:

true if the bytes in buffer[start] equal pattern

search

public static int search(byte[] search,
                         byte[] bytes,
                         int start,
                         int end,
                         boolean direction)

search Look for the search bytes in the bytes array using a straight search. Use the skip search if the number of bytes to search is large or if this search is performed frequently.

Parameters:

search - byte[]

bytes - byte[] to search

start - starting index

end - end index (exclusive

direction - boolean (true indicates forward search, false is backwards search

Returns:

index or -1