Lucene example source code file (QueryNodeOperation.java)

This example Lucene source code file (QueryNodeOperation.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

andoperation, andquerynode, andquerynode, arraylist, both, both, clonenotsupportedexception, none, none, q1, q2, querynode, querynode, querynodeoperation, util

The Lucene QueryNodeOperation.java source code

package org.apache.lucene.queryParser.core.util;

/**
 * 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.ArrayList;
import java.util.List;

import org.apache.lucene.queryParser.core.QueryNodeError;
import org.apache.lucene.queryParser.core.nodes.AndQueryNode;
import org.apache.lucene.queryParser.core.nodes.QueryNode;

/**
 * Allow joining 2 QueryNode Trees, into one.
 */
public final class QueryNodeOperation {
  private QueryNodeOperation() {
    // Exists only to defeat instantiation.
  }

  private enum ANDOperation {
    BOTH, Q1, Q2, NONE
  }

  /**
   * perform a logical and of 2 QueryNode trees. if q1 and q2 are ANDQueryNode
   * nodes it uses head Node from q1 and adds the children of q2 to q1 if q1 is
   * a AND node and q2 is not, add q2 as a child of the head node of q1 if q2 is
   * a AND node and q1 is not, add q1 as a child of the head node of q2 if q1
   * and q2 are not ANDQueryNode nodes, create a AND node and make q1 and q2
   * children of that node if q1 or q2 is null it returns the not null node if
   * q1 = q2 = null it returns null
   */
  public final static QueryNode logicalAnd(QueryNode q1, QueryNode q2) {
    if (q1 == null)
      return q2;
    if (q2 == null)
      return q1;

    ANDOperation op = null;
    if (q1 instanceof AndQueryNode && q2 instanceof AndQueryNode)
      op = ANDOperation.BOTH;
    else if (q1 instanceof AndQueryNode)
      op = ANDOperation.Q1;
    else if (q1 instanceof AndQueryNode)
      op = ANDOperation.Q2;
    else
      op = ANDOperation.NONE;

    try {
      QueryNode result = null;
      switch (op) {
      case NONE:
        List<QueryNode> children = new ArrayList();
        children.add(q1.cloneTree());
        children.add(q2.cloneTree());
        result = new AndQueryNode(children);
        return result;
      case Q1:
        result = q1.cloneTree();
        result.add(q2.cloneTree());
        return result;
      case Q2:
        result = q2.cloneTree();
        result.add(q1.cloneTree());
        return result;
      case BOTH:
        result = q1.cloneTree();
        result.add(q2.cloneTree().getChildren());
        return result;
      }
    } catch (CloneNotSupportedException e) {
      throw new QueryNodeError(e);
    }

    return null;

  }

}