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From "Dima May (JIRA)" <j...@apache.org>
Subject [jira] Created: (LUCENE-1723) KeywordTokenizer does not properly set the end offset
Date Tue, 30 Jun 2009 02:22:47 GMT
KeywordTokenizer does not properly set the end offset
-----------------------------------------------------

                 Key: LUCENE-1723
                 URL: https://issues.apache.org/jira/browse/LUCENE-1723
             Project: Lucene - Java
          Issue Type: Bug
          Components: Analysis
    Affects Versions: 2.4.1
            Reporter: Dima May
            Priority: Minor
         Attachments: AnalyzerBug.java

KeywordTokenizer sets the Token's term length attribute but appears to omit the end offset.
The issue was discovered while using a highlighter with the KeywordAnalyzer. KeywordAnalyzer
delegates to KeywordTokenizer propagating the bug. 

Below is a JUnit test that exercises various analyzers via a Highlighter instance. Every analyzer
but the KeywordAnazlyzer successfully wraps the text with the highlight tags, such as "<b>thetext</b>".
When using KeywordAnalyzer the tags appear before the text, for example: "<b></b>thetext".


Please note NewKeywordAnalyzer and NewKeywordTokenizer classes below. When using NewKeywordAnalyzer
the tags are properly placed around the text. The NewKeywordTokenizer overrides the next method
of the KeywordTokenizer setting the end offset for the returned Token. NewKeywordAnalyzer
utilizes KeywordTokenizer to produce proper token.

-----------------------------
package lucene;

import java.io.IOException;
import java.io.Reader;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.KeywordAnalyzer;
import org.apache.lucene.analysis.KeywordTokenizer;
import org.apache.lucene.analysis.SimpleAnalyzer;
import org.apache.lucene.analysis.StopAnalyzer;
import org.apache.lucene.analysis.Token;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.WhitespaceAnalyzer;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.search.highlight.Highlighter;
import org.apache.lucene.search.highlight.QueryScorer;
import org.apache.lucene.search.highlight.SimpleHTMLFormatter;
import org.apache.lucene.search.highlight.WeightedTerm;
import org.junit.Test;
import static org.junit.Assert.*;

public class AnalyzerBug {

	@Test
	public void testWithHighlighting() throws IOException {
		String text = "thetext";
		WeightedTerm[] terms = { new WeightedTerm(1.0f, text) };

		Highlighter highlighter = new Highlighter(new SimpleHTMLFormatter(
				"<b>", "</b>"), new QueryScorer(terms));

		Analyzer[] analazers = { new StandardAnalyzer(), new SimpleAnalyzer(),
				new StopAnalyzer(), new WhitespaceAnalyzer(),
				new NewKeywordAnalyzer(), new KeywordAnalyzer() };

		// Analyzers pass except KeywordAnalyzer
		for (Analyzer analazer : analazers) {
			String highighted = highlighter.getBestFragment(analazer,
					"CONTENT", text);
			assertEquals("Failed for " + analazer.getClass().getName(), "<b>"
					+ text + "</b>", highighted);
			System.out.println(analazer.getClass().getName()
					+ " passed, value highlighted: " + highighted);
		}
	}
}

class NewKeywordAnalyzer extends KeywordAnalyzer {

	@Override
	public TokenStream reusableTokenStream(String fieldName, Reader reader)
			throws IOException {
		Tokenizer tokenizer = (Tokenizer) getPreviousTokenStream();
		if (tokenizer == null) {
			tokenizer = new NewKeywordTokenizer(reader);
			setPreviousTokenStream(tokenizer);
		} else
			tokenizer.reset(reader);
		return tokenizer;
	}

	@Override
	public TokenStream tokenStream(String fieldName, Reader reader) {
		return new NewKeywordTokenizer(reader);
	}
}

class NewKeywordTokenizer extends KeywordTokenizer {
	public NewKeywordTokenizer(Reader input) {
		super(input);
	}

	@Override
	public Token next(Token t) throws IOException {
		Token result = super.next(t);
		if (result != null) {
			result.setEndOffset(result.termLength());
		}
		return result;
	}
}


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