001 /**
002 * ========================================
003 * JFreeReport : a free Java report library
004 * ========================================
005 *
006 * Project Info: http://reporting.pentaho.org/
007 *
008 * (C) Copyright 2000-2007, by Object Refinery Limited, Pentaho Corporation and Contributors.
009 *
010 * This library is free software; you can redistribute it and/or modify it under the terms
011 * of the GNU Lesser General Public License as published by the Free Software Foundation;
012 * either version 2.1 of the License, or (at your option) any later version.
013 *
014 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
015 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
016 * See the GNU Lesser General Public License for more details.
017 *
018 * You should have received a copy of the GNU Lesser General Public License along with this
019 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
020 * Boston, MA 02111-1307, USA.
021 *
022 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
023 * in the United States and other countries.]
024 *
025 * ------------
026 * $Id: PrecomputedValueRegistry.java,v 1.7 2007/04/01 18:49:24 taqua Exp $
027 * ------------
028 * (C) Copyright 2000-2005, by Object Refinery Limited.
029 * (C) Copyright 2005-2007, by Pentaho Corporation.
030 */
031
032 package org.jfree.report.data;
033
034 /**
035 * Expression precomputation processes the report in a parallel process to
036 * retrieve the final value of an function. The final value of an expression
037 * is the value the expression would return before it goes out of scope.
038 *
039 * Precomputation can be generally considered expensive, so it should be done
040 * only once. During the precomputation run, no output is generated at all.
041 * Only named data-row expressions can be precomputed.
042 *
043 * @author Thomas Morgner
044 */
045 public interface PrecomputedValueRegistry
046 {
047 public void startElement (PrecomputeNodeKey element);
048 public void finishElement (PrecomputeNodeKey element);
049 public PrecomputeNode currentNode ();
050
051 public void addFunction(final String name, final Object value);
052
053 public void startElementPrecomputation(final PrecomputeNodeKey element);
054
055 public void finishElementPrecomputation(final PrecomputeNodeKey element);
056 }