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    }