it.unibz.instasearch.indexing.querying.VisitableQuery.java Source code

Introduction

Here is the source code for it.unibz.instasearch.indexing.querying.VisitableQuery.java

Source

/*
 * Copyright (c) 2009 Andrejs Jermakovics.
 * 
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Andrejs Jermakovics - initial implementation
 */
package it.unibz.instasearch.indexing.querying;

import it.unibz.instasearch.indexing.Field;

import org.apache.lucene.search.BooleanClause;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.FilteredQuery;
import org.apache.lucene.search.PhraseQuery;
import org.apache.lucene.search.PrefixQuery;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.TermQuery;
import org.apache.lucene.search.WildcardQuery;

/**
 * A query that can accepts visitors for its clauses
 * The visitors can modify the query
 */
public class VisitableQuery {

    private Query query;

    public VisitableQuery(Query q) {
        this.query = q;
    }

    /**
     * Accept a query visitor
     * @param queryVisitor
     */
    public void accept(QueryVisitor queryVisitor) {
        queryVisitor.init(query);
        query = accept(query, queryVisitor);
        query = queryVisitor.endVisit(query);
    }

    /**
     * Recursively go through all the clauses of the query and call the visitor
     * 
     * @param query
     * @param queryVisitor
     * @return
     */
    private Query accept(Query query, QueryVisitor queryVisitor) {

        Query returnQuery = query;

        if (query instanceof TermQuery) {
            TermQuery termQuery = (TermQuery) query;
            Field field = Field.getByName(termQuery.getTerm().field());

            Query newQuery = queryVisitor.visit(termQuery, field);

            newQuery.setBoost(query.getBoost());
            returnQuery = newQuery;

        } else if (query instanceof BooleanQuery) {
            BooleanQuery boolQuery = (BooleanQuery) query;
            BooleanQuery newBoolQuery = queryVisitor.visit(boolQuery);

            for (BooleanClause boolClause : boolQuery.getClauses()) {
                if (!queryVisitor.visit(boolClause))
                    continue;
                Query newQuery = accept(boolClause.getQuery(), queryVisitor);
                boolClause.setQuery(newQuery);
            }

            newBoolQuery.setBoost(boolQuery.getBoost());
            newBoolQuery.setMinimumNumberShouldMatch(boolQuery.getMinimumNumberShouldMatch());

            returnQuery = newBoolQuery;
        } else if (query instanceof FilteredQuery) {
            FilteredQuery fq = (FilteredQuery) query;
            Query newQuery = accept(fq.getQuery(), queryVisitor);

            if (newQuery != fq.getQuery()) {
                FilteredQuery newFq = new FilteredQuery(fq.getQuery(), fq.getFilter());
                newFq.setBoost(fq.getBoost());

                returnQuery = newFq;
            }
        } else if (query instanceof PhraseQuery) {
            PhraseQuery phraseQuery = (PhraseQuery) query;

            returnQuery = queryVisitor.visit(phraseQuery);

        } else if (query instanceof WildcardQuery) {
            WildcardQuery wildcardQuery = (WildcardQuery) query;
            Field field = Field.getByName(wildcardQuery.getTerm().field());

            Query newQuery = queryVisitor.visit(wildcardQuery, field);

            newQuery.setBoost(query.getBoost());
            returnQuery = newQuery;

        } else if (query instanceof PrefixQuery) {
            PrefixQuery prefixQuery = (PrefixQuery) query;
            Field field = Field.getByName(prefixQuery.getPrefix().field());

            Query newQuery = queryVisitor.visit(prefixQuery, field);

            newQuery.setBoost(query.getBoost());
            returnQuery = newQuery;
        } else {
            returnQuery = queryVisitor.visitQuery(query);
        }

        return returnQuery;
    }

    /**
     * @return the resulting query after all visitors have changed it
     */
    public Query getQuery() {
        return query;
    }

}