001 /**
002 * =========================================
003 * LibFormula : a free Java formula library
004 * =========================================
005 *
006 * Project Info: http://reporting.pentaho.org/libformula/
007 *
008 * (C) Copyright 2006-2007, by 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 * ------------
027 * $Id: HasChangedFunction.java 3521 2007-10-16 10:55:14Z tmorgner $
028 * ------------
029 * (C) Copyright 2006-2007, by Pentaho Corporation.
030 */
031
032 package org.jfree.formula.function.information;
033
034 import org.jfree.formula.function.Function;
035 import org.jfree.formula.function.ParameterCallback;
036 import org.jfree.formula.lvalues.TypeValuePair;
037 import org.jfree.formula.FormulaContext;
038 import org.jfree.formula.EvaluationException;
039 import org.jfree.formula.typing.coretypes.LogicalType;
040
041 /**
042 * Creation-Date: 24.11.2006, 13:02:41
043 *
044 * @author Thomas Morgner
045 */
046 public class HasChangedFunction implements Function
047 {
048 private static final TypeValuePair RETURN_FALSE = new TypeValuePair(LogicalType.TYPE, Boolean.FALSE);
049 private static final TypeValuePair RETURN_TRUE = new TypeValuePair(LogicalType.TYPE, Boolean.TRUE);
050
051 public HasChangedFunction()
052 {
053 }
054
055 public String getCanonicalName()
056 {
057 return "HASCHANGED";
058 }
059
060 public TypeValuePair evaluate(final FormulaContext context,
061 final ParameterCallback parameters)
062 throws EvaluationException
063 {
064 // we expect strings and will check, whether the reference for theses
065 // strings is dirty.
066
067 final int parCount = parameters.getParameterCount();
068 for (int i = 0; i < parCount; i++)
069 {
070 final Object value = parameters.getValue(i);
071 if (value == null)
072 {
073 continue;
074 }
075
076 if (context.isReferenceDirty(value))
077 {
078 return RETURN_TRUE;
079 }
080 }
081 return RETURN_FALSE;
082 }
083 }