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: MaxFunction.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.math;
032    
033    import java.math.BigDecimal;
034    
035    import org.jfree.formula.EvaluationException;
036    import org.jfree.formula.FormulaContext;
037    import org.jfree.formula.LibFormulaErrorValue;
038    import org.jfree.formula.util.NumberUtil;
039    import org.jfree.formula.function.Function;
040    import org.jfree.formula.function.ParameterCallback;
041    import org.jfree.formula.lvalues.TypeValuePair;
042    import org.jfree.formula.typing.Type;
043    import org.jfree.formula.typing.sequence.NumberSequence;
044    import org.jfree.formula.typing.coretypes.NumberType;
045    
046    /**
047     * This function returns the maximum from a set of numbers.
048     *
049     * @author Cedric Pronzato
050     *
051     */
052    public class MaxFunction implements Function
053    {
054      public static final BigDecimal ZERO = new BigDecimal(0);
055      
056      public MaxFunction()
057      {
058      }
059    
060      public TypeValuePair evaluate(final FormulaContext context, final ParameterCallback parameters) throws EvaluationException
061      {
062        final int parameterCount = parameters.getParameterCount();
063    
064        if(parameterCount == 0)
065        {
066          return new TypeValuePair(NumberType.GENERIC_NUMBER, ZERO);
067        }
068    
069        BigDecimal last = null;
070        for (int paramIdx = 0; paramIdx < parameterCount; paramIdx++)
071        {
072          final Type type = parameters.getType(paramIdx);
073          final Object value = parameters.getValue(paramIdx);
074          final NumberSequence sequence = context.getTypeRegistry().convertToNumberSequence(type, value);
075    
076          while(sequence.hasNext())
077          {
078            final BigDecimal next = NumberUtil.getAsBigDecimal(sequence.nextNumber());
079            if(last == null)
080            {
081              last = next;
082            }
083            else
084            {
085              if(last.compareTo(next) == -1)
086              {
087                last = next;
088              }
089            }
090          }
091        }
092        if(last == null)
093        {
094          throw new EvaluationException(
095              LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE);
096        }
097    
098        return new TypeValuePair(NumberType.GENERIC_NUMBER, last);
099      }
100    
101      public String getCanonicalName()
102      {
103        return "MAX";
104      }
105    
106    }