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<QueryNode>();
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;
}
}