Source for org.jfree.formula.function.information.HasChangedFunction

   1: /**
   2:  * =========================================
   3:  * LibFormula : a free Java formula library
   4:  * =========================================
   5:  *
   6:  * Project Info:  http://reporting.pentaho.org/libformula/
   7:  *
   8:  * (C) Copyright 2006-2007, by Pentaho Corporation and Contributors.
   9:  *
  10:  * This library is free software; you can redistribute it and/or modify it under the terms
  11:  * of the GNU Lesser General Public License as published by the Free Software Foundation;
  12:  * either version 2.1 of the License, or (at your option) any later version.
  13:  *
  14:  * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
  15:  * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  16:  * See the GNU Lesser General Public License for more details.
  17:  *
  18:  * You should have received a copy of the GNU Lesser General Public License along with this
  19:  * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  20:  * Boston, MA 02111-1307, USA.
  21:  *
  22:  * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
  23:  * in the United States and other countries.]
  24:  *
  25:  *
  26:  * ------------
  27:  * $Id: HasChangedFunction.java,v 1.5 2007/04/01 13:51:52 taqua Exp $
  28:  * ------------
  29:  * (C) Copyright 2006-2007, by Pentaho Corporation.
  30:  */
  31: 
  32: package org.jfree.formula.function.information;
  33: 
  34: import org.jfree.formula.function.Function;
  35: import org.jfree.formula.function.ParameterCallback;
  36: import org.jfree.formula.lvalues.TypeValuePair;
  37: import org.jfree.formula.FormulaContext;
  38: import org.jfree.formula.EvaluationException;
  39: import org.jfree.formula.typing.coretypes.LogicalType;
  40: 
  41: /**
  42:  * Creation-Date: 24.11.2006, 13:02:41
  43:  *
  44:  * @author Thomas Morgner
  45:  */
  46: public class HasChangedFunction implements Function
  47: {
  48:   private static final TypeValuePair RETURN_FALSE = new TypeValuePair(LogicalType.TYPE, Boolean.FALSE);
  49:   private static final TypeValuePair RETURN_TRUE = new TypeValuePair(LogicalType.TYPE, Boolean.TRUE);
  50: 
  51:   public HasChangedFunction()
  52:   {
  53:   }
  54: 
  55:   public String getCanonicalName()
  56:   {
  57:     return "HASCHANGED";
  58:   }
  59: 
  60:   public TypeValuePair evaluate(FormulaContext context,
  61:                                 ParameterCallback parameters)
  62:       throws EvaluationException
  63:   {
  64:     // we expect strings and will check, whether the reference for theses
  65:     // strings is dirty.
  66: 
  67:     final int parCount = parameters.getParameterCount();
  68:     for (int i = 0; i < parCount; i++)
  69:     {
  70:       final Object value = parameters.getValue(i);
  71:       if (value == null)
  72:       {
  73:         continue;
  74:       }
  75: 
  76:       if (context.isReferenceDirty(value))
  77:       {
  78:         return RETURN_TRUE;
  79:       }
  80:     }
  81:     return RETURN_FALSE;
  82:   }
  83: }