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Posted to dev@lucene.apache.org by "Steve Rowe (JIRA)" <ji...@apache.org> on 2016/05/19 20:26:13 UTC
[jira] [Reopened] (LUCENE-7231) Problem with NGramAnalyzer,
PhraseQuery and Highlighter
[ https://issues.apache.org/jira/browse/LUCENE-7231?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Steve Rowe reopened LUCENE-7231:
--------------------------------
Reopening to backport to 6.0.1.
> Problem with NGramAnalyzer, PhraseQuery and Highlighter
> -------------------------------------------------------
>
> Key: LUCENE-7231
> URL: https://issues.apache.org/jira/browse/LUCENE-7231
> Project: Lucene - Core
> Issue Type: Bug
> Components: modules/highlighter
> Affects Versions: 5.4.1
> Reporter: Eva Popenda
> Assignee: Alan Woodward
> Fix For: 6.1
>
> Attachments: LUCENE-7231.patch
>
>
> Using the Highlighter with N-GramAnalyzer and PhraseQuery and searching for a substring with length = N yields the following exception:
> {noformat}
> java.lang.IllegalArgumentException: Less than 2 subSpans.size():1
> at org.apache.lucene.search.spans.ConjunctionSpans.<init>(ConjunctionSpans.java:40)
> at org.apache.lucene.search.spans.NearSpansOrdered.<init>(NearSpansOrdered.java:56)
> at org.apache.lucene.search.spans.SpanNearQuery$SpanNearWeight.getSpans(SpanNearQuery.java:232)
> at org.apache.lucene.search.highlight.WeightedSpanTermExtractor.extractWeightedSpanTerms(WeightedSpanTermExtractor.java:292)
> at org.apache.lucene.search.highlight.WeightedSpanTermExtractor.extract(WeightedSpanTermExtractor.java:137)
> at org.apache.lucene.search.highlight.WeightedSpanTermExtractor.getWeightedSpanTerms(WeightedSpanTermExtractor.java:506)
> at org.apache.lucene.search.highlight.QueryScorer.initExtractor(QueryScorer.java:219)
> at org.apache.lucene.search.highlight.QueryScorer.init(QueryScorer.java:187)
> at org.apache.lucene.search.highlight.Highlighter.getBestTextFragments(Highlighter.java:196)
> {noformat}
> Below is a JUnit-Test reproducing this behavior. In case of searching for a string with more than N characters or using NGramPhraseQuery this problem doesn't occur.
> Why is it that more than 1 subSpans are required?
> {code:java}
> public class HighlighterTest {
> @Rule
> public final ExpectedException exception = ExpectedException.none();
> @Test
> public void testHighlighterWithPhraseQueryThrowsException() throws IOException, InvalidTokenOffsetsException {
> final Analyzer analyzer = new NGramAnalyzer(4);
> final String fieldName = "substring";
> final List<BytesRef> list = new ArrayList<>();
> list.add(new BytesRef("uchu"));
> final PhraseQuery query = new PhraseQuery(fieldName, list.toArray(new BytesRef[list.size()]));
> final QueryScorer fragmentScorer = new QueryScorer(query, fieldName);
> final SimpleHTMLFormatter formatter = new SimpleHTMLFormatter("<b>", "</b>");
> exception.expect(IllegalArgumentException.class);
> exception.expectMessage("Less than 2 subSpans.size():1");
> final Highlighter highlighter = new Highlighter(formatter,TextEncoder.NONE.getEncoder(), fragmentScorer);
> highlighter.setTextFragmenter(new SimpleFragmenter(100));
> final String fragment = highlighter.getBestFragment(analyzer, fieldName, "Buchung");
> assertEquals("B<b>uchu</b>ng",fragment);
> }
> public final class NGramAnalyzer extends Analyzer {
> private final int minNGram;
> public NGramAnalyzer(final int minNGram) {
> super();
> this.minNGram = minNGram;
> }
> @Override
> protected TokenStreamComponents createComponents(final String fieldName) {
> final Tokenizer source = new NGramTokenizer(minNGram, minNGram);
> return new TokenStreamComponents(source);
> }
> }
> }
> {code}
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