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Lucene example source code file (NoChildOptimizationQueryNodeProcessor.java)

This example Lucene source code file (NoChildOptimizationQueryNodeProcessor.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

booleanquerynode, boostquerynode, deletedquerynode, list, modifierquerynode, nochildoptimizationquerynodeprocessor, nochildoptimizationquerynodeprocessor, override, override, querynode, querynode, querynodeexception, querynodeexception, tokenizedphrasequerynode, util

The Lucene NoChildOptimizationQueryNodeProcessor.java source code

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,
 * 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

  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;


  protected QueryNode preProcessNode(QueryNode node) throws QueryNodeException {

    return node;


  protected List<QueryNode> setChildrenOrder(List children)
      throws QueryNodeException {

    return children;



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