/*************************************************************************
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * Copyright 2008 by Sun Microsystems, Inc.
 *
 * OpenOffice.org - a multi-platform office productivity suite
 *
 * $RCSfile: ReportFunction.java,v $
 * $Revision: 1.4 $
 *
 * This file is part of OpenOffice.org.
 *
 * OpenOffice.org is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License version 3
 * only, as published by the Free Software Foundation.
 *
 * OpenOffice.org 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 version 3 for more details
 * (a copy is included in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU Lesser General Public License
 * version 3 along with OpenOffice.org.  If not, see
 * <http://www.openoffice.org/license.html>
 * for a copy of the LGPLv3 License.
 *
 ************************************************************************/
package com.sun.star.report;

/**
 * Functions are statefull computation components.
 *
 * Functions are allowed to have a state, but are considered
 * immutable (the same is true for expressions). Functions are
 * allowed to update their state on every call to 'advance', which
 * signals, that the cursor has been moved.
 *
 * Functions have no way to 'reset' their state, if a reset is needed,
 * the report engine is urged to query a new instance from the ReportAddin.
 */
public interface ReportFunction extends ReportExpression
{

    public ReportFunction advance(DataRow row);
}