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: ChooseFunction.java 2752 2007-04-10 14:10:41Z taqua $
028     * ------------
029     * (C) Copyright 2006-2007, by Pentaho Corporation.
030     */
031    
032    package org.jfree.formula.function.information;
033    
034    import org.jfree.formula.EvaluationException;
035    import org.jfree.formula.FormulaContext;
036    import org.jfree.formula.LibFormulaErrorValue;
037    import org.jfree.formula.function.Function;
038    import org.jfree.formula.function.ParameterCallback;
039    import org.jfree.formula.lvalues.TypeValuePair;
040    import org.jfree.formula.typing.Type;
041    
042    /**
043     * This function uses an index to return a value from a list of values.
044     * The first value index is 1, 2 for the second and so on.
045     *
046     * @author Cedric Pronzato
047     */
048    public class ChooseFunction implements Function
049    {
050      public ChooseFunction()
051      {
052      }
053    
054      public String getCanonicalName()
055      {
056        return "CHOOSE";
057      }
058    
059      public TypeValuePair evaluate(final FormulaContext context,
060                                    final ParameterCallback parameters)
061          throws EvaluationException
062      {
063    
064        if(parameters.getParameterCount() <= 2)
065        {
066          throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE);
067        }
068    
069        final Type indexType = parameters.getType(0);
070        final Object indexValue = parameters.getValue(0);
071    
072        final int index= context.getTypeRegistry().convertToNumber(indexType, indexValue).intValue();
073        if(index >= 1 && index < parameters.getParameterCount())
074        {
075          return new TypeValuePair(parameters.getType(index), parameters.getValue(index));
076        }
077        // else
078        throw new EvaluationException(LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE);
079      }
080    }