DuplicatingFilter.java

package org.apache.solr.analysis;

import java.io.IOException;

import org.apache.lucene.analysis.TokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.DuplicateTermAttribute;

/*
 * Purpose of this filter is just to make a copy of the currently processed token
 * (so that we can comapre the copy against the later version of the transformed
 * token)
 */
public final class DuplicatingFilter extends TokenFilter {
	
	
	private final DuplicateTermAttribute dupAttr = addAttribute(DuplicateTermAttribute.class);
	private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
	
	public DuplicatingFilter(TokenStream input) {
		super(input);
	}

	@Override
	public boolean incrementToken() throws IOException {
		
		if (input.incrementToken()) {
			dupAttr.setValue(termAtt.toString());
			return true;
		}
		else {
			return false;
		}
	}

}