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

   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: ChooseFunction.java,v 1.5 2007/04/10 14:10:41 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.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.TypeValuePair;
  40: import org.jfree.formula.typing.Type;
  41: 
  42: /**
  43:  * This function uses an index to return a value from a list of values.
  44:  * The first value index is 1, 2 for the second and so on.
  45:  *
  46:  * @author Cedric Pronzato
  47:  */
  48: public class ChooseFunction implements Function
  49: {
  50:   public ChooseFunction()
  51:   {
  52:   }
  53: 
  54:   public String getCanonicalName()
  55:   {
  56:     return "CHOOSE";
  57:   }
  58: 
  59:   public TypeValuePair evaluate(final FormulaContext context,
  60:                                 final ParameterCallback parameters)
  61:       throws EvaluationException
  62:   {
  63: 
  64:     if(parameters.getParameterCount() <= 2)
  65:     {
  66:       throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE);
  67:     }
  68: 
  69:     final Type indexType = parameters.getType(0);
  70:     final Object indexValue = parameters.getValue(0);
  71: 
  72:     final int index= context.getTypeRegistry().convertToNumber(indexType, indexValue).intValue();
  73:     if(index >= 1 && index < parameters.getParameterCount())
  74:     {
  75:       return new TypeValuePair(parameters.getType(index), parameters.getValue(index));
  76:     }
  77:     // else
  78:     throw new EvaluationException(LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE);
  79:   }
  80: }