001 /**
002 *
003 * Copyright 2004 Hiram Chirino
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 *
017 **/
018 package org.activemq.filter;
019
020 import javax.jms.JMSException;
021 import javax.jms.Message;
022
023 /**
024 * A filter performing a comparison of two objects
025 *
026 * @version $Revision: 1.1.1.1 $
027 */
028 public abstract class LogicExpression extends BinaryExpression implements BooleanExpression {
029
030 public static BooleanExpression createOR(BooleanExpression lvalue, BooleanExpression rvalue) {
031 return new LogicExpression(lvalue, rvalue) {
032
033 public Object evaluate(Message message) throws JMSException {
034
035 Boolean lv = (Boolean) left.evaluate(message);
036 // Can we do an OR shortcut??
037 if (lv !=null && lv.booleanValue()) {
038 return Boolean.TRUE;
039 }
040
041 Boolean rv = (Boolean) right.evaluate(message);
042 return rv==null ? null : rv;
043 }
044
045 public String getExpressionSymbol() {
046 return "OR";
047 }
048 };
049 }
050
051 public static BooleanExpression createAND(BooleanExpression lvalue, BooleanExpression rvalue) {
052 return new LogicExpression(lvalue, rvalue) {
053
054 public Object evaluate(Message message) throws JMSException {
055
056 Boolean lv = (Boolean) left.evaluate(message);
057
058 // Can we do an AND shortcut??
059 if( lv==null )
060 return null;
061 if (!lv.booleanValue()) {
062 return Boolean.FALSE;
063 }
064
065 Boolean rv = (Boolean) right.evaluate(message);
066 return rv==null ? null : rv;
067 }
068
069 public String getExpressionSymbol() {
070 return "AND";
071 }
072 };
073 }
074
075 /**
076 * @param left
077 * @param right
078 */
079 public LogicExpression(BooleanExpression left, BooleanExpression right) {
080 super(left, right);
081 }
082
083 abstract public Object evaluate(Message message) throws JMSException;
084
085
086 }