/*
* JasperReports - Free Java Reporting Library.
* Copyright (C) 2001 - 2009 Jaspersoft Corporation. All rights reserved.
* http://www.jaspersoft.com
*
* Unless you have purchased a commercial license agreement from Jaspersoft,
* the following license terms apply:
*
* This program is part of JasperReports.
*
* JasperReports is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* JasperReports is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with JasperReports. If not, see <http://www.gnu.org/licenses/>.
*/
package net.sf.jasperreports.engine.fill;
import net.sf.jasperreports.engine.JRException;
/**
* Extended incrementer interface.
* <p>
* The {@link net.sf.jasperreports.engine.fill.JRIncrementer JRIncrementer} has been
* kept for backward compatibility.
* <p>
* The crosstab calculation engine requires extended incrementers. An incrementer implementing
* {@link net.sf.jasperreports.engine.fill.JRIncrementer JRIncrementer} can be used for report
* variables only.
*
* @author Lucian Chirita (lucianc@users.sourceforge.net)
* @version $Id: JRExtendedIncrementer.java 3034 2009-08-27 11:58:04Z teodord $
*/
public interface JRExtendedIncrementer extends JRIncrementer
{
/**
* Increments a calculable object with a value.
*
* @param calculable the calculable
* @param expressionValue the value
* @param valueProvider value provider
* @return the incremented value
* @throws JRException
*/
public Object increment(
JRCalculable calculable,
Object expressionValue,
AbstractValueProvider valueProvider
) throws JRException;
/**
* Returns the initial value for this calculation.
* <p>
* This method should return a neutral value for this calculation
* (e.g. 0 for sum, 1 for product, etc) or a default value if no neutral value exists.
*
* @return the initial value for this calculation
*/
public Object initialValue();
/**
* Combines two calculated values into one.
*
* @param calculable the first calculated value
* @param calculableValue the second calculated value
* @param valueProvider the value provider used for the helper variables
* @return the combined value
* @throws JRException
*/
public Object combine(
JRCalculable calculable,
JRCalculable calculableValue,
AbstractValueProvider valueProvider
) throws JRException;
/**
* Specifies whether <code>null</code> values are ignored by this incrementer.
*
* If <code>null</code> values are ignored, the caller can chose to skip
* incrementing a calculation with a <code>null</code> value.
*
* @return whether <code>null</code> values are ignored by this incrementer
*/
public boolean ignoresNullValues();
}