package org.apache.lucene.queryParser.core.processors;
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.util.List;
import org.apache.lucene.queryParser.core.QueryNodeException;
import org.apache.lucene.queryParser.core.nodes.BooleanQueryNode;
import org.apache.lucene.queryParser.core.nodes.BoostQueryNode;
import org.apache.lucene.queryParser.core.nodes.DeletedQueryNode;
import org.apache.lucene.queryParser.core.nodes.MatchNoDocsQueryNode;
import org.apache.lucene.queryParser.core.nodes.ModifierQueryNode;
import org.apache.lucene.queryParser.core.nodes.QueryNode;
import org.apache.lucene.queryParser.core.nodes.TokenizedPhraseQueryNode;
/**
* <p>
* A {@link NoChildOptimizationQueryNodeProcessor} removes every
* BooleanQueryNode, BoostQueryNode, TokenizedPhraseQueryNode or
* ModifierQueryNode that do not have a valid children.
* </p>
* <p>
* Example: When the children of these nodes are removed for any reason then the
* nodes may become invalid.
* </p>
*/
public class NoChildOptimizationQueryNodeProcessor extends
QueryNodeProcessorImpl {
public NoChildOptimizationQueryNodeProcessor() {
// empty constructor
}
@Override
protected QueryNode postProcessNode(QueryNode node) throws QueryNodeException {
if (node instanceof BooleanQueryNode || node instanceof BoostQueryNode
|| node instanceof TokenizedPhraseQueryNode
|| node instanceof ModifierQueryNode) {
List<QueryNode> children = node.getChildren();
if (children != null && children.size() > 0) {
for (QueryNode child : children) {
if (!(child instanceof DeletedQueryNode)) {
return node;
}
}
}
return new MatchNoDocsQueryNode();
}
return node;
}
@Override
protected QueryNode preProcessNode(QueryNode node) throws QueryNodeException {
return node;
}
@Override
protected List<QueryNode> setChildrenOrder(List<QueryNode> children)
throws QueryNodeException {
return children;
}
}