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: SubtractOperator.java 2752 2007-04-10 14:10:41Z taqua $
028     * ------------
029     * (C) Copyright 2006-2007, by Pentaho Corporation.
030     */
031    package org.jfree.formula.operators;
032    
033    import java.math.BigDecimal;
034    
035    import org.jfree.formula.EvaluationException;
036    
037    /**
038     * Creation-Date: 31.10.2006, 16:34:11
039     *
040     * @author Thomas Morgner
041     */
042    public class SubtractOperator extends AbstractNumericOperator
043    {
044      public SubtractOperator()
045      {
046      }
047    
048      protected Number evaluate(final Number number1, final Number number2) throws EvaluationException
049      {
050        if ((number1 instanceof Integer || number1 instanceof Short) &&
051            (number2 instanceof Integer || number2 instanceof Short))
052        {
053          return new BigDecimal (number1.longValue() - number2.longValue());
054        }
055    
056        final BigDecimal bd1 = new BigDecimal(number1.toString());
057        final BigDecimal bd2 = new BigDecimal(number2.toString());
058        return bd1.subtract(bd2);
059      }
060    
061      public int getLevel()
062      {
063        return 200;
064      }
065    
066      public String toString()
067      {
068        return "-";
069      }
070    
071      public boolean isLeftOperation()
072      {
073        return true;
074      }
075    
076      /**
077       * Defines, whether the operation is associative. For associative operations,
078       * the evaluation order does not matter, if the operation appears more than
079       * once in an expression, and therefore we can optimize them a lot better than
080       * non-associative operations (ie. merge constant parts and precompute them
081       * once).
082       *
083       * @return true, if the operation is associative, false otherwise
084       */
085      public boolean isAssociative()
086      {
087        return false;
088      }
089    
090    }