1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/jaxws_classes/com/sun/xml/internal/bind/v2/util/EditDistance.java Wed Apr 27 01:27:09 2016 +0800
1.3 @@ -0,0 +1,143 @@
1.4 +/*
1.5 + * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation. Oracle designates this
1.11 + * particular file as subject to the "Classpath" exception as provided
1.12 + * by Oracle in the LICENSE file that accompanied this code.
1.13 + *
1.14 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.15 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.16 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.17 + * version 2 for more details (a copy is included in the LICENSE file that
1.18 + * accompanied this code).
1.19 + *
1.20 + * You should have received a copy of the GNU General Public License version
1.21 + * 2 along with this work; if not, write to the Free Software Foundation,
1.22 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.23 + *
1.24 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.25 + * or visit www.oracle.com if you need additional information or have any
1.26 + * questions.
1.27 + */
1.28 +
1.29 +package com.sun.xml.internal.bind.v2.util;
1.30 +
1.31 +import java.util.AbstractMap;
1.32 +import java.util.Arrays;
1.33 +import java.util.Collection;
1.34 +import java.util.WeakHashMap;
1.35 +
1.36 +/**
1.37 + * Computes the string edit distance.
1.38 + *
1.39 + * <p>
1.40 + * Refer to a computer science text book for the definition
1.41 + * of the "string edit distance".
1.42 + *
1.43 + * @author
1.44 + * Kohsuke Kawaguchi (kohsuke.kawaguchi@sun.com)
1.45 + */
1.46 +public class EditDistance {
1.47 +
1.48 + /**
1.49 + * Weak results cache to avoid additional computations.
1.50 + * Because of high complexity caching is required.
1.51 + */
1.52 + private static final WeakHashMap<AbstractMap.SimpleEntry<String,String>, Integer> CACHE = new WeakHashMap<AbstractMap.SimpleEntry<String, String>, Integer>();
1.53 +
1.54 + /**
1.55 + * Computes the edit distance between two strings.
1.56 + *
1.57 + * <p>
1.58 + * The complexity is O(nm) where n=a.length() and m=b.length().
1.59 + */
1.60 + public static int editDistance( String a, String b ) {
1.61 + // let's check cache
1.62 + AbstractMap.SimpleEntry<String,String> entry = new AbstractMap.SimpleEntry<String, String>(a, b); // using this class to avoid creation of my own which will handle PAIR of values
1.63 + Integer result = null;
1.64 + if (CACHE.containsKey(entry))
1.65 + result = CACHE.get(entry); // looks like we have it
1.66 +
1.67 + if (result == null) {
1.68 + result = new EditDistance(a, b).calc();
1.69 + CACHE.put(entry, result); // cache the result
1.70 + }
1.71 + return result;
1.72 + }
1.73 +
1.74 + /**
1.75 + * Finds the string in the <code>group</code> closest to
1.76 + * <code>key</code> and returns it.
1.77 + *
1.78 + * @return null if group.length==0.
1.79 + */
1.80 + public static String findNearest( String key, String[] group ) {
1.81 + return findNearest(key, Arrays.asList(group));
1.82 + }
1.83 +
1.84 + /**
1.85 + * Finds the string in the <code>group</code> closest to
1.86 + * <code>key</code> and returns it.
1.87 + *
1.88 + * @return null if group.length==0.
1.89 + */
1.90 + public static String findNearest( String key, Collection<String> group ) {
1.91 + int c = Integer.MAX_VALUE;
1.92 + String r = null;
1.93 +
1.94 + for (String s : group) {
1.95 + int ed = editDistance(key,s);
1.96 + if( c>ed ) {
1.97 + c = ed;
1.98 + r = s;
1.99 + }
1.100 + }
1.101 + return r;
1.102 + }
1.103 +
1.104 + /** cost vector. */
1.105 + private int[] cost;
1.106 + /** back buffer. */
1.107 + private int[] back;
1.108 +
1.109 + /** Two strings to be compared. */
1.110 + private final String a,b;
1.111 +
1.112 + private EditDistance( String a, String b ) {
1.113 + this.a=a;
1.114 + this.b=b;
1.115 + cost = new int[a.length()+1];
1.116 + back = new int[a.length()+1]; // back buffer
1.117 +
1.118 + for( int i=0; i<=a.length(); i++ )
1.119 + cost[i] = i;
1.120 + }
1.121 +
1.122 + /**
1.123 + * Swaps two buffers.
1.124 + */
1.125 + private void flip() {
1.126 + int[] t = cost;
1.127 + cost = back;
1.128 + back = t;
1.129 + }
1.130 +
1.131 + private int min(int a,int b,int c) {
1.132 + return Math.min(a,Math.min(b,c));
1.133 + }
1.134 +
1.135 + private int calc() {
1.136 + for( int j=0; j<b.length(); j++ ) {
1.137 + flip();
1.138 + cost[0] = j+1;
1.139 + for( int i=0; i<a.length(); i++ ) {
1.140 + int match = (a.charAt(i)==b.charAt(j))?0:1;
1.141 + cost[i+1] = min( back[i]+match, cost[i]+1, back[i+1]+1 );
1.142 + }
1.143 + }
1.144 + return cost[a.length()];
1.145 + }
1.146 +}
