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: IfFunction.java 3521 2007-10-16 10:55:14Z tmorgner $
028     * ------------
029     * (C) Copyright 2006-2007, by Pentaho Corporation.
030     */
031    package org.jfree.formula.function.logical;
032    
033    import org.jfree.formula.EvaluationException;
034    import org.jfree.formula.FormulaContext;
035    import org.jfree.formula.LibFormulaErrorValue;
036    import org.jfree.formula.function.Function;
037    import org.jfree.formula.function.ParameterCallback;
038    import org.jfree.formula.lvalues.TypeValuePair;
039    import org.jfree.formula.typing.Type;
040    import org.jfree.formula.typing.coretypes.LogicalType;
041    
042    /**
043     * Creation-Date: 04.11.2006, 18:28:15
044     *
045     * @author Thomas Morgner
046     */
047    public class IfFunction implements Function
048    {
049      private static final TypeValuePair RETURN_FALSE = new TypeValuePair(LogicalType.TYPE, Boolean.FALSE);
050    
051      public IfFunction()
052      {
053      }
054    
055      public String getCanonicalName()
056      {
057        return "IF";
058      }
059    
060      public TypeValuePair evaluate(final FormulaContext context,
061                                    final ParameterCallback parameters)
062          throws EvaluationException
063      {
064        final int parameterCount = parameters.getParameterCount();
065        if (parameterCount < 2)
066        {
067          throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE);
068        }
069    
070        final Type conditionType = parameters.getType(0);
071        final Object conditionValue = parameters.getValue(0);
072        final Boolean condition = context.getTypeRegistry().convertToLogical(conditionType, conditionValue);
073        if(condition == null)
074        {
075          throw new EvaluationException(LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE);
076        }
077        if (Boolean.TRUE.equals(condition))
078        {
079          final Object value = parameters.getValue(1);
080          final Type type = parameters.getType(1);
081          return new TypeValuePair(type, value);
082        }
083        // if condition is false and no third parameter, return false
084        if(parameterCount == 2 || parameters.getValue(2) == null)
085        {
086          return RETURN_FALSE;
087        }
088        // else return third parameter
089        final Object value = parameters.getValue(2);
090        final Type type = parameters.getType(2);
091        return new TypeValuePair(type, value);
092      }
093    }