/*************************************************************************
 *
 *  OpenOffice.org - a multi-platform office productivity suite
 *
 *  $RCSfile: ReportExpression.java,v $
 *
 *  $Revision: 1.2 $
 *
 *  last change: $Author: rt $ $Date: 2007-07-09 11:56:03 $
 *
 *  The Contents of this file are made available subject to
 *  the terms of GNU Lesser General Public License Version 2.1.
 *
 *
 *    GNU Lesser General Public License Version 2.1
 *    =============================================
 *    Copyright 2007 by Sun Microsystems, Inc.
 *    901 San Antonio Road, Palo Alto, CA 94303, USA
 *    Copyright 2007 by Pentaho Corporation
 *
 *    This library is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU Lesser General Public
 *    License version 2.1, as published by the Free Software Foundation.
 *
 *    This library 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 this library; if not, write to the Free Software
 *    Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 *    MA  02111-1307  USA
 *
 ************************************************************************/


package com.sun.star.report;

/**
 * Expressions are simple computation components.
 *
 * Expressions are always assumed to be immutable. They are not allowed to
 * change their state and it is not guaranteed, in which order they get called.
 * If the expression has been called before, the last computed value will be
 * available from the datarow.
 *
 * This construct allows us to write expressions in the form
 * "Sum := Sum + Column".
 *
 * Multiple calls to getValue on the same expression instance must return the
 * same value (assuming that the datarow passed in is the same).
 */
public interface ReportExpression
{
  public void setParameters (Object[] parameters);
  public Object getParameters ();

  public Object getValue(DataRow row);
}
