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: XorFunction.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 XorFunction implements Function
048    {
049      private static final TypeValuePair RETURN_FALSE = new TypeValuePair(LogicalType.TYPE, Boolean.FALSE);
050      private static final TypeValuePair RETURN_TRUE = new TypeValuePair(LogicalType.TYPE, Boolean.TRUE);
051    
052    
053      public XorFunction()
054      {
055      }
056    
057      public String getCanonicalName()
058      {
059        return "XOR";
060      }
061    
062    
063      public TypeValuePair evaluate(final FormulaContext context,
064                                    final ParameterCallback parameters)
065          throws EvaluationException
066      {
067        if(parameters.getParameterCount() < 1)
068        {
069          throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE);
070        }
071        int count = 0;
072        final int parameterCount = parameters.getParameterCount();
073        for (int i = 0; i < parameterCount; i++)
074        {
075          final Type conditionType = parameters.getType(i);
076          final Object conditionValue = parameters.getValue(i);
077          final Boolean condition = context.getTypeRegistry().convertToLogical(conditionType, conditionValue);
078          if(condition == null)
079          {
080            throw new EvaluationException(LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE);
081          }
082          if (Boolean.TRUE.equals(condition))
083          {
084            count += 1;
085          }
086        }
087        if (count == 1)
088        {
089          return RETURN_TRUE;
090        }
091        else
092        {
093          return RETURN_FALSE;
094        }
095    
096      }
097    }