/*
* Copyright 2009 Ralf Joachim, Ahmad Hassan
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.castor.cpa.persistence.sql.query.condition;
import org.castor.cpa.persistence.sql.query.expression.Expression;
/**
* Abstract base class for all predicates.
*
* @author <a href="mailto:ahmad DOT hassan AT gmail DOT com">Ahmad Hassan</a>
* @author <a href="mailto:ralf DOT joachim AT syscon DOT eu">Ralf Joachim</a>
* @version $Revision$ $Date: 2006-04-25 15:08:23 -0600 (Tue, 25 Apr 2006) $
*/
public abstract class Predicate extends Condition {
//-----------------------------------------------------------------------------------
/** Expression to apply the predicate to. */
private final Expression _expression;
/** What is the expected result of the evaluation? */
private boolean _evaluateTo;
//-----------------------------------------------------------------------------------
/**
* Construct a predicate with given expression.
*
* @param expression Expression to apply the predicate to.
* @param evaluateTo What is the expected result of the evaluation?
*/
protected Predicate(final Expression expression, final boolean evaluateTo) {
if (expression == null) { throw new NullPointerException(); }
_expression = expression;
_evaluateTo = evaluateTo;
}
//-----------------------------------------------------------------------------------
/**
* Expression to apply the predicate to.
*
* @return Expression to apply the predicate to.
*/
public final Expression expression() {
return _expression;
}
/**
* Returns if the predicate should evaluate to <code>true</code> or <code>false</code>.
*
* @return <code>true</code> if the predicate should evaluate to <code>true</code>,
* <code>false</code> otherwise.
*/
public final boolean evaluateTo() {
return _evaluateTo;
}
//-----------------------------------------------------------------------------------
@Override
public final Condition not() {
_evaluateTo = !_evaluateTo;
return this;
}
//-----------------------------------------------------------------------------------
}