/* Copyright (c) 2003 The Nutch Organization. All rights reserved. */
/* Use subject to the conditions in http://www.nutch.org/LICENSE.txt. */
package net.nutch.util;
import java.util.Collection;
import java.util.Iterator;
/**
* A class for efficiently matching <code>String</code>s against a set
* of suffixes. Zero-length <code>Strings</code> are ignored.
*/
public class SuffixStringMatcher extends TrieStringMatcher {
/**
* Creates a new <code>PrefixStringMatcher</code> which will match
* <code>String</code>s with any suffix in the supplied array.
*/
public SuffixStringMatcher(String[] suffixes) {
super();
for (int i= 0; i < suffixes.length; i++)
addPatternBackward(suffixes[i]);
}
/**
* Creates a new <code>PrefixStringMatcher</code> which will match
* <code>String</code>s with any suffix in the supplied
* <code>Collection</code>
*/
public SuffixStringMatcher(Collection suffixes) {
super();
Iterator iter= suffixes.iterator();
while (iter.hasNext())
addPatternBackward((String)iter.next());
}
/**
* Returns true if the given <code>String</code> is matched by a
* suffix in the trie
*/
public boolean matches(String input) {
TrieNode node= root;
for (int i= input.length() - 1; i >= 0; i--) {
node= node.getChild(input.charAt(i));
if (node == null)
return false;
if (node.isTerminal())
return true;
}
return false;
}
/**
* Returns the shortest suffix of <code>input<code> that is matched,
* or <code>null<code> if no match exists.
*/
public String shortestMatch(String input) {
TrieNode node= root;
for (int i= input.length() - 1; i >= 0; i--) {
node= node.getChild(input.charAt(i));
if (node == null)
return null;
if (node.isTerminal())
return input.substring(i);
}
return null;
}
/**
* Returns the longest suffix of <code>input<code> that is matched,
* or <code>null<code> if no match exists.
*/
public String longestMatch(String input) {
TrieNode node= root;
String result= null;
for (int i= input.length() - 1; i >= 0; i--) {
node= node.getChild(input.charAt(i));
if (node == null)
break;
if (node.isTerminal())
result= input.substring(i);
}
return result;
}
public static final void main(String[] argv) {
SuffixStringMatcher matcher=
new SuffixStringMatcher(
new String[]
{"a", "abcd", "bcd", "bcdefg", "defg", "aac", "baz", "foo", "foobar"} );
String[] tests= {"a", "ac", "abcd", "abcdefg", "apple", "aa", "aac",
"aaccca", "abaz", "baz", "bazooka", "fo", "foobar",
"kite", };
for (int i= 0; i < tests.length; i++) {
System.out.println("testing: " + tests[i]);
System.out.println(" matches: " + matcher.matches(tests[i]));
System.out.println(" shortest: " + matcher.shortestMatch(tests[i]));
System.out.println(" longest: " + matcher.longestMatch(tests[i]));
}
}
}