Re: WildcardQuery and SpanQuery

[Mark Miller]

You could give this a shot (From my Qsol query parser):

package com.mhs.qsol.spans;

/**
* Copyright 2006 Mark Miller ([EMAIL PROTECTED])
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Set;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.search.BooleanClause;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.TermQuery;
import org.apache.lucene.search.WildcardQuery;
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;

/**
* @author mark miller
*
*/
public class SpanWildcardQuery extends SpanQuery {
   private Term term;

   private BooleanQuery rewrittenWildQuery;

   public SpanWildcardQuery(Term term) {
       this.term = term;
   }

   public Term getTerm() {
       return term;
   }

   public Query rewrite(IndexReader reader) throws IOException {
       WildcardQuery wildQuery = new WildcardQuery(term);

       rewrittenWildQuery = (BooleanQuery) wildQuery.rewrite(reader);

       BooleanQuery bq = (BooleanQuery) rewrittenWildQuery.rewrite(reader);

       BooleanClause[] clauses = bq.getClauses();
       SpanQuery[] sqs = new SpanQuery[clauses.length];

       for (int i = 0; i < clauses.length; i++) {
           BooleanClause clause = clauses[i];

           TermQuery tq = (TermQuery) clause.getQuery();

           sqs[i] = new SpanTermQuery(tq.getTerm());
           sqs[i].setBoost(tq.getBoost());
       }

       SpanOrQuery query = new SpanOrQuery(sqs);
       query.setBoost(wildQuery.getBoost());

       return query;
   }

   public Spans getSpans(IndexReader reader) throws IOException {
       throw new UnsupportedOperationException(
               "Query should have been rewritten");
   }

   public String getField() {
       return term.field();
   }

   /**
    * @deprecated use extractTerms instead
    * @see #extractTerms(Set);
    */
   public Collection getTerms() {
       Collection terms = new ArrayList();
       terms.add(term);

       return terms;
   }

   public void extractTerms(Set terms) {
       terms.add(term);
   }

   public String toString(String field) {
       StringBuffer buffer = new StringBuffer();
       buffer.append("spanWildcardQuery(");
       buffer.append(term);
       buffer.append(")");

       // buffer.append(ToStringUtils.boost(getBoost()));
       return buffer.toString();
   }
}


Cedric Ho wrote:

Hi everybody,

We recently need to support wildcard search terms "*", "?" together
with SpanQuery. It seems that there's no SpanWildcardQuery available.
After looking into the lucene source code for a while, I guess we can
either:

1. Use SpanRegexQuery, or

2. Write our own SpanWildcardQuery, and implements the
rewrite(IndexReader) method to rewrite the query into a SpanOrQuery
with some SpanTermQuery.

Of the two approaches, Option 1 seems to be easier. But I am rather
concerned about the performance of using regular expression. On the
other hand, I am not sure if there are any other concerns I am not
aware of for option 2 (i.e. is there a reason why there's no
SpanWildcardQuery in the first place?)

Any advices ?

Cedric

---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]

---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]