eu.europeana.assets.service.ir.text.bm25f.query.BMBooleanQuery.java Source code

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/*
 *  Copyright 2011 Diego Ceccarelli
 *
 *  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.
 *
 */
package eu.europeana.assets.service.ir.text.bm25f.query;

import java.io.IOException;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.index.Term;
import org.apache.lucene.queryParser.ParseException;
import org.apache.lucene.queryParser.QueryParser;
import org.apache.lucene.search.BooleanClause;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.Searcher;
import org.apache.lucene.search.Weight;
import org.apache.lucene.util.Version;

import eu.europeana.assets.service.ir.text.bm25f.BMParameters;

/**
 * Models a BM25/BM25F Query (@see org.apache.lucene.search.Query)
 * 
 * @author Diego Ceccarelli <diego.ceccarelli@isti.cnr.it>
 * @since 14/dec/2011
 */

public abstract class BMBooleanQuery extends BooleanQuery {
    private static final long serialVersionUID = 1L;
    private int doc = -1;
    private Set<Term> terms = new HashSet<Term>();
    private BMParameters bmParams;

    /**
     * Builds a query that will use BM25/BM25F ranking function
     * 
     */
    public BMBooleanQuery(String query, Analyzer analyzer, BMParameters bmParams)
            throws ParseException, IOException {
        QueryParser qp = new QueryParser(Version.LUCENE_29, bmParams.getMainField(), analyzer);
        Query q = qp.parse(query);
        this.bmParams = bmParams;

        if (q instanceof BooleanQuery) {
            BooleanQuery bq = (BooleanQuery) q;
            List<BooleanClause> clauses = bq.clauses();
            for (BooleanClause cl : clauses) {
                cl.getQuery().extractTerms(terms);
            }
        } else {
            q.extractTerms(terms);
        }
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = super.hashCode();
        result = prime * result + ((bmParams == null) ? 0 : bmParams.hashCode());
        result = prime * result + ((terms == null) ? 0 : terms.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (!super.equals(obj))
            return false;
        if (getClass() != obj.getClass())
            return false;
        BMBooleanQuery other = (BMBooleanQuery) obj;
        if (bmParams == null) {
            if (other.bmParams != null)
                return false;
        } else if (!bmParams.equals(other.bmParams))
            return false;
        if (terms == null) {
            if (other.terms != null)
                return false;
        } else if (!terms.equals(other.terms))
            return false;
        return true;
    }

    public int doc() {
        return this.doc;
    }

    public Set<Term> getTerms() {
        return terms;
    }

    public void setTerms(Set<Term> terms) {
        this.terms = terms;
    }

    @SuppressWarnings("unchecked")
    public void extractTerms(Set queryterms) {
        queryterms.addAll(terms);
    }

    public abstract Weight weight(Searcher searcher) throws IOException;

}