[LUCENE-522] SpanFuzzyQuery

• Type: New Feature
• Status: Closed
• Priority: Minor
• Resolution: Duplicate
• Affects Version/s: 1.9
• Fix Version/s: 3.1
• Component/s: core/search
• Assignee: Unassigned
• Reporter: Karl Wettin
• Created: 17/Mar/06 06:33
• Updated: 28/Aug/22 11:26
• Resolved: 25/Jan/11 13:20

Description

This is my SpanFuzzyQuery. It is released under the Apache licensence. Just paste it in.

package se.snigel.lucene;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.search.*;
import org.apache.lucene.search.spans.SpanOrQuery;
import org.apache.lucene.search.spans.SpanQuery;
import org.apache.lucene.search.spans.SpanTermQuery;
import org.apache.lucene.search.spans.Spans;

import java.io.IOException;
import java.util.Collection;
import java.util.LinkedList;

/**

• @author Karl Wettin <[e-mail]>
  */
  public class SpanFuzzyQuery extends SpanQuery {

public final static float defaultMinSimilarity = 0.7f;
public final static int defaultPrefixLength = 0;

private final Term term;
private final float minimumSimilarity;
private final int prefixLength;

private BooleanQuery rewrittenFuzzyQuery;

public SpanFuzzyQuery(Term term)

{ this(term, defaultMinSimilarity, defaultPrefixLength); }

public SpanFuzzyQuery(Term term, float minimumSimilarity, int prefixLength) {
this.term = term;
this.minimumSimilarity = minimumSimilarity;
this.prefixLength = prefixLength;

if (minimumSimilarity >= 1.0f)

{ throw new IllegalArgumentException("minimumSimilarity >= 1"); }

else if (minimumSimilarity < 0.0f)

{ throw new IllegalArgumentException("minimumSimilarity < 0"); }

if (prefixLength < 0)

{ throw new IllegalArgumentException("prefixLength < 0"); }

}

public Query rewrite(IndexReader reader) throws IOException {

FuzzyQuery fuzzyQuery = new FuzzyQuery(term, minimumSimilarity, prefixLength);

rewrittenFuzzyQuery = (BooleanQuery) fuzzyQuery.rewrite(reader);
BooleanClause[] clauses = rewrittenFuzzyQuery.getClauses();
SpanQuery[] spanQueries = new SpanQuery[clauses.length];
for (int i = 0; i < clauses.length; i++)

{ BooleanClause clause = clauses[i]; TermQuery termQuery = (TermQuery) clause.getQuery(); spanQueries[i] = new SpanTermQuery(termQuery.getTerm()); spanQueries[i].setBoost(termQuery.getBoost()); }

SpanOrQuery query = new SpanOrQuery(spanQueries);
query.setBoost(fuzzyQuery.getBoost());
return query;
}

/** Expert: Returns the matches for this query in an index. Used internally

• to search for spans. */
  public Spans getSpans(IndexReader reader) throws IOException { throw new UnsupportedOperationException("Query should have been rewritten"); }

/** Returns the name of the field matched by this query.*/
public String getField()

{ return term.field(); }

/** Returns a collection of all terms matched by this query.*/
public Collection getTerms() {
if (rewrittenFuzzyQuery == null)

{ throw new RuntimeException("Query must be rewritten prior to calling getTerms()!"); }

else {
LinkedList<Term> terms = new LinkedList<Term>();
BooleanClause[] clauses = rewrittenFuzzyQuery.getClauses();
for (int i = 0; i < clauses.length; i++)

{ BooleanClause clause = clauses[i]; TermQuery termQuery = (TermQuery) clause.getQuery(); terms.add(termQuery.getTerm()); }

return terms;
}
}

/** Prints a query to a string, with <code>field</code> as the default field

• for terms. <p>The representation used is one that is supposed to be readable
• by {@link org.apache.lucene.queryParser.QueryParser QueryParser}

  . However,

• there are the following limitations:
• <ul>
• <li>If the query was created by the parser, the printed
• representation may not be exactly what was parsed. For example,
• characters that need to be escaped will be represented without
• the required backslash.</li>
• <li>Some of the more complicated queries (e.g. span queries)
• don't have a representation that can be parsed by QueryParser.</li>
• </ul>
  */
  public String toString(String field) { return "spans(" + rewrittenFuzzyQuery.toString() + ")"; }

  }