001/**
002 *   GRANITE DATA SERVICES
003 *   Copyright (C) 2006-2013 GRANITE DATA SERVICES S.A.S.
004 *
005 *   This file is part of the Granite Data Services Platform.
006 *
007 *   Granite Data Services is free software; you can redistribute it and/or
008 *   modify it under the terms of the GNU Lesser General Public
009 *   License as published by the Free Software Foundation; either
010 *   version 2.1 of the License, or (at your option) any later version.
011 *
012 *   Granite Data Services is distributed in the hope that it will be useful,
013 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
014 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
015 *   General Public License for more details.
016 *
017 *   You should have received a copy of the GNU Lesser General Public
018 *   License along with this library; if not, write to the Free Software
019 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
020 *   USA, or see <http://www.gnu.org/licenses/>.
021 */
022package org.granite.gravity.selector;
023
024import javax.jms.JMSException;
025
026/**
027 * A filter performing a comparison of two objects
028 *
029 * @version $Revision: 1.2 $
030 */
031public abstract class LogicExpression extends BinaryExpression implements BooleanExpression {
032
033    public static BooleanExpression createOR(BooleanExpression lvalue, BooleanExpression rvalue) {
034        return new LogicExpression(lvalue, rvalue) {
035            @Override
036            public Object evaluate(MessageEvaluationContext message) throws JMSException {
037
038                Boolean lv = (Boolean) left.evaluate(message);
039                // Can we do an OR shortcut??
040                if (lv !=null && lv.booleanValue()) {
041                    return Boolean.TRUE;
042                }
043
044                Boolean rv = (Boolean) right.evaluate(message);
045                return rv==null ? null : rv;
046            }
047
048            @Override
049            public String getExpressionSymbol() {
050                return "OR";
051            }
052        };
053    }
054
055    public static BooleanExpression createAND(BooleanExpression lvalue, BooleanExpression rvalue) {
056        return new LogicExpression(lvalue, rvalue) {
057            @Override
058            public Object evaluate(MessageEvaluationContext message) throws JMSException {
059
060                Boolean lv = (Boolean) left.evaluate(message);
061
062                // Can we do an AND shortcut??
063                if (lv == null)
064                    return null;
065                if (!lv.booleanValue()) {
066                    return Boolean.FALSE;
067                }
068
069                Boolean rv = (Boolean) right.evaluate(message);
070                return rv == null ? null : rv;
071            }
072
073            @Override
074            public String getExpressionSymbol() {
075                return "AND";
076            }
077        };
078    }
079
080    /**
081     * @param left
082     * @param right
083     */
084    public LogicExpression(BooleanExpression left, BooleanExpression right) {
085        super(left, right);
086    }
087
088    abstract public Object evaluate(MessageEvaluationContext message) throws JMSException;
089
090    public boolean matches(MessageEvaluationContext message) throws JMSException {
091        Object object = evaluate(message);
092        return object!=null && object==Boolean.TRUE;
093    }
094
095}