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/*******************************************************************************
*
* Copyright (c) 2004-2011 Oracle Corporation
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Kohsuke Kawaguchi
*
*******************************************************************************/
package hudson.util;
import java.util.Collection;
import java.util.Arrays;
/**
* Computes the string edit distance.
*
*
* Refer to a computer science text book for the definition
* of the "string edit distance".
*
* @author
* Kohsuke Kawaguchi ([email protected])
*/
public class EditDistance {
/**
* Computes the edit distance between two strings.
*
*
* The complexity is O(nm) where n=a.length() and m=b.length().
*/
public static int editDistance( String a, String b ) {
return new EditDistance(a,b).calc();
}
/**
* Finds the string in the group closest to
* key and returns it.
*
* @return null if group.length==0.
*/
public static String findNearest( String key, String[] group ) {
return findNearest(key,Arrays.asList(group));
}
public static String findNearest( String key, Collection group ) {
int c = Integer.MAX_VALUE;
String r = null;
for (String g : group) {
int ed = editDistance(key, g);
if (c > ed) {
c = ed;
r = g;
}
}
return r;
}
/** cost vector. */
private int[] cost;
/** back buffer. */
private int[] back;
/** Two strings to be compared. */
private final String a,b;
private EditDistance( String a, String b ) {
this.a=a;
this.b=b;
cost = new int[a.length()+1];
back = new int[a.length()+1]; // back buffer
for( int i=0; i<=a.length(); i++ )
cost[i] = i;
}
/**
* Swaps two buffers.
*/
private void flip() {
int[] t = cost;
cost = back;
back = t;
}
private int min(int a,int b,int c) {
return Math.min(a,Math.min(b,c));
}
private int calc() {
for( int j=0; j