/*
* Copyright 1998-2014 University Corporation for Atmospheric Research/Unidata
*
* Portions of this software were developed by the Unidata Program at the
* University Corporation for Atmospheric Research.
*
* Access and use of this software shall impose the following obligations
* and understandings on the user. The user is granted the right, without
* any fee or cost, to use, copy, modify, alter, enhance and distribute
* this software, and any derivative works thereof, and its supporting
* documentation for any purpose whatsoever, provided that this entire
* notice appears in all copies of the software, derivative works and
* supporting documentation. Further, UCAR requests that the user credit
* UCAR/Unidata in any publications that result from the use of this
* software or in any product that includes this software. The names UCAR
* and/or Unidata, however, may not be used in any advertising or publicity
* to endorse or promote any products or commercial entity unless specific
* written permission is obtained from UCAR/Unidata. The user also
* understands that UCAR/Unidata is not obligated to provide the user with
* any support, consulting, training or assistance of any kind with regard
* to the use, operation and performance of this software nor to provide
* the user with any updates, revisions, new versions or "bug fixes."
*
* THIS SOFTWARE IS PROVIDED BY UCAR/UNIDATA "AS IS" AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL UCAR/UNIDATA BE LIABLE FOR ANY SPECIAL,
* INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
* FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE ACCESS, USE OR PERFORMANCE OF THIS SOFTWARE.
*/
package ucar.unidata.io;
import net.jcip.annotations.Immutable;
/**
* Knuth-Morris-Pratt Algorithm for Pattern Matching.
* Immutable
*
* @author caron
* @see <a href="http://www.fmi.uni-sofia.bg/fmi/logic/vboutchkova/sources/KMPMatch_java.html">http://www.fmi.uni-sofia.bg/fmi/logic/vboutchkova/sources/KMPMatch_java.html</a>
* @since May 9, 2008
*/
@Immutable
public class KMPMatch {
private final byte[] match;
private final int[] failure;
/**
* Constructor
* @param match search for this byte pattern
*/
public KMPMatch(byte[] match) {
this.match = match;
failure = computeFailure(match);
}
public int getMatchLength() { return match.length; }
/**
* Finds the first occurrence of match in data.
* @param data search in this byte block
* @param start start at data[start]
* @param max end at data[start+max]
* @return index into data[] of first match, else -1 if not found.
*/
public int indexOf(byte[] data, int start, int max) {
int j = 0;
if (data.length == 0) return -1;
if (start + max > data.length)
System.out.println("HEY KMPMatch");
for (int i = start; i < start + max; i++) {
while (j > 0 && match[j] != data[i])
j = failure[j - 1];
if (match[j] == data[i])
j++;
if (j == match.length)
return i - match.length + 1;
}
return -1;
}
/*
* Finds the first occurrence of match in data.
* @param data search in this byte block
* @param start start at data[start]
* @param max end at data[start+max]
* @return index into block of first match, else -1 if not found.
*
public int scan(InputStream is, int start, int max) {
int j = 0;
if (data.length == 0) return -1;
for (int i = start; i < start + max; i++) {
while (j > 0 && match[j] != data[i])
j = failure[j - 1];
if (match[j] == data[i])
j++;
if (j == match.length)
return i - match.length + 1;
}
return -1;
} // */
private int[] computeFailure(byte[] match) {
int[] result = new int[match.length];
int j = 0;
for (int i = 1; i < match.length; i++) {
while (j > 0 && match[j] != match[i])
j = result[j - 1];
if (match[j] == match[i])
j++;
result[i] = j;
}
return result;
}
}