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

   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: IsBlankFunction.java,v 1.7 2007/05/07 23:00:37 mimil 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.EvaluationException;
  35: import org.jfree.formula.FormulaContext;
  36: import org.jfree.formula.LibFormulaErrorValue;
  37: import org.jfree.formula.function.Function;
  38: import org.jfree.formula.function.ParameterCallback;
  39: import org.jfree.formula.lvalues.ContextLookup;
  40: import org.jfree.formula.lvalues.LValue;
  41: import org.jfree.formula.lvalues.TypeValuePair;
  42: import org.jfree.formula.typing.coretypes.LogicalType;
  43: 
  44: /**
  45:  * Document me!
  46:  * 
  47:  * @author : Thomas Morgner
  48:  */
  49: public class IsBlankFunction implements Function
  50: {
  51:   private static final TypeValuePair RETURN_FALSE = new TypeValuePair(
  52:       LogicalType.TYPE, Boolean.FALSE);
  53: 
  54:   private static final TypeValuePair RETURN_TRUE = new TypeValuePair(
  55:       LogicalType.TYPE, Boolean.TRUE);
  56: 
  57:   public IsBlankFunction()
  58:   {
  59:   }
  60: 
  61:   public String getCanonicalName()
  62:   {
  63:     return "ISBLANK";
  64:   }
  65: 
  66:   public TypeValuePair evaluate(FormulaContext context,
  67:       ParameterCallback parameters) throws EvaluationException
  68:   {
  69:     final int parameterCount = parameters.getParameterCount();
  70:     if (parameterCount < 1)
  71:     {
  72:       throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE);
  73:     }
  74:     final Object value = parameters.getValue(0);
  75: 
  76:     final LValue raw = parameters.getRaw(0);
  77:     if (raw instanceof ContextLookup)
  78:     {
  79:       if (value == null)
  80:       {
  81:         return RETURN_TRUE;
  82:       }
  83:     }
  84: 
  85:     return RETURN_FALSE;
  86:   }
  87: }