001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  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 */
017package org.apache.activemq.filter;
018
019import javax.jms.JMSException;
020
021/**
022 * A filter performing a comparison of two objects
023 * 
024 * 
025 */
026public abstract class LogicExpression extends BinaryExpression implements BooleanExpression {
027
028    /**
029     * @param left
030     * @param right
031     */
032    public LogicExpression(BooleanExpression left, BooleanExpression right) {
033        super(left, right);
034    }
035
036    public static BooleanExpression createOR(BooleanExpression lvalue, BooleanExpression rvalue) {
037        return new LogicExpression(lvalue, rvalue) {
038
039            public Object evaluate(MessageEvaluationContext message) throws JMSException {
040
041                Boolean lv = (Boolean)left.evaluate(message);
042                // Can we do an OR shortcut??
043                if (lv != null && lv.booleanValue()) {
044                    return Boolean.TRUE;
045                }
046
047                Boolean rv = (Boolean)right.evaluate(message);
048                return rv == null ? null : rv;
049            }
050
051            public String getExpressionSymbol() {
052                return "OR";
053            }
054        };
055    }
056
057    public static BooleanExpression createAND(BooleanExpression lvalue, BooleanExpression rvalue) {
058        return new LogicExpression(lvalue, rvalue) {
059
060            public Object evaluate(MessageEvaluationContext message) throws JMSException {
061
062                Boolean lv = (Boolean)left.evaluate(message);
063
064                // Can we do an AND shortcut??
065                if (lv == null) {
066                    return null;
067                }
068                if (!lv.booleanValue()) {
069                    return Boolean.FALSE;
070                }
071
072                Boolean rv = (Boolean)right.evaluate(message);
073                return rv == null ? null : rv;
074            }
075
076            public String getExpressionSymbol() {
077                return "AND";
078            }
079        };
080    }
081
082    public abstract Object evaluate(MessageEvaluationContext message) throws JMSException;
083
084    public boolean matches(MessageEvaluationContext message) throws JMSException {
085        Object object = evaluate(message);
086        return object != null && object == Boolean.TRUE;
087    }
088
089}