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: IsErrorFunction.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.information;
032    
033    import org.jfree.formula.ErrorValue;
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    import org.jfree.formula.typing.coretypes.ErrorType;
042    import org.jfree.formula.typing.coretypes.LogicalType;
043    
044    /**
045     * This function returns true if the parameter is of error.
046     *
047     * @author Cedric Pronzato
048     *
049     */
050    public class IsErrorFunction implements Function
051    {
052      private static final TypeValuePair RETURN_TRUE = new TypeValuePair(LogicalType.TYPE, Boolean.TRUE);
053      private static final TypeValuePair RETURN_FALSE = new TypeValuePair(LogicalType.TYPE, Boolean.FALSE);
054    
055      public IsErrorFunction()
056      {
057      }
058    
059      public TypeValuePair evaluate(final FormulaContext context, final ParameterCallback parameters) throws EvaluationException
060      {
061        if(parameters.getParameterCount() != 1)
062        {
063          throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE);
064        }
065    
066        try
067        {
068          final Type type = parameters.getType(0);
069          final Object value = parameters.getValue(0);
070    
071          if(ErrorType.TYPE.equals(type) && value instanceof ErrorValue)
072          {
073            return RETURN_TRUE;
074          }
075        } catch (EvaluationException e)
076        {
077          return RETURN_TRUE;
078        }
079    
080        return RETURN_FALSE;
081      }
082    
083      public String getCanonicalName()
084      {
085        return "ISERROR";
086      }
087    
088    }