/**
* Copyright 2014 National University of Ireland, Galway.
*
* This file is part of the SIREn project. Project and contact information:
*
* https://github.com/rdelbru/SIREn
*
* 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 org.sindice.siren.qparser.keyword.builders;
import org.apache.lucene.queryparser.flexible.core.QueryNodeException;
import org.apache.lucene.queryparser.flexible.core.builders.QueryTreeBuilder;
import org.apache.lucene.queryparser.flexible.core.nodes.QueryNode;
import org.apache.lucene.search.BooleanClause;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.Query;
import org.sindice.siren.qparser.keyword.config.KeywordQueryConfigHandler.KeywordConfigurationKeys;
import org.sindice.siren.qparser.keyword.nodes.TopLevelQueryNode;
import org.sindice.siren.qparser.keyword.processors.TopLevelQueryNodeProcessor;
import org.sindice.siren.search.node.LuceneProxyNodeQuery;
import org.sindice.siren.search.node.NodeQuery;
/**
* Visits each node in a {@link TopLevelQueryNode} and wraps each
* {@link NodeQuery} object tagged with
* {@link QueryTreeBuilder#QUERY_TREE_BUILDER_TAGID} into a
* {@link LuceneProxyNodeQuery}.
*
* <p>
*
* This builder is called at the last step of the query building. If the key
* {@link KeywordConfigurationKeys#ALLOW_TWIG} is <code>false</code>, this
* builder will not be called because it is removed from the {@link QueryNode}
* tree (see {@link TopLevelQueryNodeProcessor}).
*/
public class TopLevelQueryNodeBuilder
implements KeywordQueryBuilder {
@Override
public Query build(final QueryNode queryNode)
throws QueryNodeException {
final TopLevelQueryNode top = (TopLevelQueryNode) queryNode;
final Query q = (Query) top.getChildren().get(0)
.getTag(QueryTreeBuilder.QUERY_TREE_BUILDER_TAGID);
return this.wrap(q);
}
/**
* Wraps a {@link NodeQuery} into a {@link LuceneProxyNodeQuery}.
* This method is applied on each clause of a {@link BooleanQuery}.
*/
private Query wrap(final Query q)
throws QueryNodeException {
if (q instanceof BooleanQuery) {
for (final BooleanClause clause: ((BooleanQuery) q).clauses()) {
final Query cq = clause.getQuery();
clause.setQuery(this.wrap(cq));
}
return q;
} else if (q instanceof NodeQuery) {
return new LuceneProxyNodeQuery((NodeQuery) q);
} else {
throw new QueryNodeException(new Error("Expected a BooleanQuery or a NodeQuery: got '" +
q.getClass().getCanonicalName() + "'"));
}
}
}