SpanFuzzyQuery
--------------
Key: LUCENE-522
URL: http://issues.apache.org/jira/browse/LUCENE-522
Project: Lucene - Java
Type: New Feature
Components: Search
Versions: 1.9
Reporter: karl wetttin
Priority: Minor
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 <[EMAIL PROTECTED]>
*/
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 [EMAIL PROTECTED] 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() + ")";
}
}
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