| /* |
| * 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. |
| */ |
| package org.apache.lucene.queryparser.flexible.standard.processors; |
| |
| import java.util.LinkedList; |
| import java.util.List; |
| |
| import org.apache.lucene.queryparser.flexible.core.QueryNodeException; |
| import org.apache.lucene.queryparser.flexible.core.nodes.GroupQueryNode; |
| import org.apache.lucene.queryparser.flexible.core.nodes.MatchNoDocsQueryNode; |
| import org.apache.lucene.queryparser.flexible.core.nodes.ModifierQueryNode; |
| import org.apache.lucene.queryparser.flexible.core.nodes.QueryNode; |
| import org.apache.lucene.queryparser.flexible.core.processors.QueryNodeProcessorImpl; |
| |
| /** |
| * This processor removes every {@link QueryNode} that is not a leaf and has not |
| * children. If after processing the entire tree the root node is not a leaf and |
| * has no children, a {@link MatchNoDocsQueryNode} object is returned. |
| * <br> |
| * This processor is used at the end of a pipeline to avoid invalid query node |
| * tree structures like a {@link GroupQueryNode} or {@link ModifierQueryNode} |
| * with no children. |
| * |
| * @see QueryNode |
| * @see MatchNoDocsQueryNode |
| */ |
| public class RemoveEmptyNonLeafQueryNodeProcessor extends |
| QueryNodeProcessorImpl { |
| |
| private LinkedList<QueryNode> childrenBuffer = new LinkedList<>(); |
| |
| public RemoveEmptyNonLeafQueryNodeProcessor() { |
| // empty constructor |
| } |
| |
| @Override |
| public QueryNode process(QueryNode queryTree) throws QueryNodeException { |
| queryTree = super.process(queryTree); |
| |
| if (!queryTree.isLeaf()) { |
| |
| List<QueryNode> children = queryTree.getChildren(); |
| |
| if (children == null || children.size() == 0) { |
| return new MatchNoDocsQueryNode(); |
| } |
| |
| } |
| |
| return queryTree; |
| |
| } |
| |
| @Override |
| protected QueryNode postProcessNode(QueryNode node) throws QueryNodeException { |
| |
| return node; |
| |
| } |
| |
| @Override |
| protected QueryNode preProcessNode(QueryNode node) throws QueryNodeException { |
| |
| return node; |
| |
| } |
| |
| @Override |
| protected List<QueryNode> setChildrenOrder(List<QueryNode> children) |
| throws QueryNodeException { |
| |
| try { |
| |
| for (QueryNode child : children) { |
| |
| if (!child.isLeaf()) { |
| |
| List<QueryNode> grandChildren = child.getChildren(); |
| |
| if (grandChildren != null && grandChildren.size() > 0) { |
| this.childrenBuffer.add(child); |
| } |
| |
| } else { |
| this.childrenBuffer.add(child); |
| } |
| |
| } |
| |
| children.clear(); |
| children.addAll(this.childrenBuffer); |
| |
| } finally { |
| this.childrenBuffer.clear(); |
| } |
| |
| return children; |
| |
| } |
| |
| } |