001/**
002 *
003 * Licensed to the Apache Software Foundation (ASF) under one or more
004 * contributor license agreements.  See the NOTICE file distributed with
005 * this work for additional information regarding copyright ownership.
006 * The ASF licenses this file to You under the Apache License, Version 2.0
007 * (the "License"); you may not use this file except in compliance with
008 * the License.  You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.granite.gravity.selector;
019
020import javax.jms.JMSException;
021
022/**
023 * A filter performing a comparison of two objects
024 *
025 * @version $Revision: 1.2 $
026 */
027public abstract class LogicExpression extends BinaryExpression implements BooleanExpression {
028
029    public static BooleanExpression createOR(BooleanExpression lvalue, BooleanExpression rvalue) {
030        return new LogicExpression(lvalue, rvalue) {
031            @Override
032            public Object evaluate(MessageEvaluationContext message) throws JMSException {
033
034                Boolean lv = (Boolean) left.evaluate(message);
035                // Can we do an OR shortcut??
036                if (lv !=null && lv.booleanValue()) {
037                    return Boolean.TRUE;
038                }
039
040                Boolean rv = (Boolean) right.evaluate(message);
041                return rv==null ? null : rv;
042            }
043
044            @Override
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            @Override
054            public Object evaluate(MessageEvaluationContext 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            @Override
070            public String getExpressionSymbol() {
071                return "AND";
072            }
073        };
074    }
075
076    /**
077     * @param left
078     * @param right
079     */
080    public LogicExpression(BooleanExpression left, BooleanExpression right) {
081        super(left, right);
082    }
083
084    abstract public Object evaluate(MessageEvaluationContext message) throws JMSException;
085
086    public boolean matches(MessageEvaluationContext message) throws JMSException {
087        Object object = evaluate(message);
088        return object!=null && object==Boolean.TRUE;
089    }
090
091}