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     */
018    package org.granite.gravity.selector;
019    
020    import javax.jms.JMSException;
021    
022    /**
023     * A filter performing a comparison of two objects
024     *
025     * @version $Revision: 1.2 $
026     */
027    public 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    }