Source for org.jfree.formula.function.math.MinFunction

   1: /**
   2:  * =========================================
   3:  * LibFormula : a free Java formula library
   4:  * =========================================
   5:  *
   6:  * Project Info:  http://reporting.pentaho.org/libformula/
   7:  *
   8:  * (C) Copyright 2006-2007, by Pentaho Corporation and Contributors.
   9:  *
  10:  * This library is free software; you can redistribute it and/or modify it under the terms
  11:  * of the GNU Lesser General Public License as published by the Free Software Foundation;
  12:  * either version 2.1 of the License, or (at your option) any later version.
  13:  *
  14:  * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
  15:  * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  16:  * See the GNU Lesser General Public License for more details.
  17:  *
  18:  * You should have received a copy of the GNU Lesser General Public License along with this
  19:  * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  20:  * Boston, MA 02111-1307, USA.
  21:  *
  22:  * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
  23:  * in the United States and other countries.]
  24:  *
  25:  *
  26:  * ------------
  27:  * $Id$
  28:  * ------------
  29:  * (C) Copyright 2006-2007, by Pentaho Corporation.
  30:  */
  31: package org.jfree.formula.function.math;
  32: 
  33: import java.math.BigDecimal;
  34: 
  35: import org.jfree.formula.EvaluationException;
  36: import org.jfree.formula.FormulaContext;
  37: import org.jfree.formula.LibFormulaErrorValue;
  38: import org.jfree.formula.util.NumberUtil;
  39: import org.jfree.formula.function.Function;
  40: import org.jfree.formula.function.ParameterCallback;
  41: import org.jfree.formula.lvalues.TypeValuePair;
  42: import org.jfree.formula.typing.Type;
  43: import org.jfree.formula.typing.sequence.NumberSequence;
  44: import org.jfree.formula.typing.coretypes.NumberType;
  45: 
  46: /**
  47:  * This function returns the minimum from a set of numbers.
  48:  *
  49:  * @author Cedric Pronzato
  50:  *
  51:  */
  52: public class MinFunction implements Function
  53: {
  54:   public static final BigDecimal ZERO = new BigDecimal(0);
  55: 
  56:   public MinFunction()
  57:   {
  58:   }
  59: 
  60:   public TypeValuePair evaluate(final FormulaContext context, final ParameterCallback parameters) throws EvaluationException
  61:   {
  62:     final int parameterCount = parameters.getParameterCount();
  63: 
  64:     if(parameterCount == 0)
  65:     {
  66:       return new TypeValuePair(NumberType.GENERIC_NUMBER, ZERO);
  67:     }
  68: 
  69:     BigDecimal last = null;
  70:     for (int paramIdx = 0; paramIdx < parameterCount; paramIdx++)
  71:     {
  72:       final Type type = parameters.getType(paramIdx);
  73:       final Object value = parameters.getValue(paramIdx);
  74:       final NumberSequence sequence = context.getTypeRegistry().convertToNumberSequence(type, value);
  75: 
  76:       while(sequence.hasNext())
  77:       {
  78:         final BigDecimal next = NumberUtil.getAsBigDecimal(sequence.nextNumber());
  79:         if(last == null)
  80:         {
  81:           last = next;
  82:         }
  83:         else
  84:         {
  85:           if(last.compareTo(next) == 1)
  86:           {
  87:             last = next;
  88:           }
  89:         }
  90:       }
  91:     }
  92:     if(last == null)
  93:     {
  94:       throw new EvaluationException(
  95:           LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE);
  96:     }
  97: 
  98:     return new TypeValuePair(NumberType.GENERIC_NUMBER, last);
  99:   }
 100: 
 101:   public String getCanonicalName()
 102:   {
 103:     return "MIN";
 104:   }
 105: