001    /**
002     * ========================================
003     * JFreeReport : a free Java report library
004     * ========================================
005     *
006     * Project Info:  http://reporting.pentaho.org/
007     *
008     * (C) Copyright 2000-2007, by Object Refinery Limited, 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     * $Id: IsEmptyExpression.java 3525 2007-10-16 11:43:48Z tmorgner $
027     * ------------
028     * (C) Copyright 2000-2005, by Object Refinery Limited.
029     * (C) Copyright 2005-2007, by Pentaho Corporation.
030     */
031    package org.jfree.report.expressions.sys;
032    
033    import org.jfree.report.DataSourceException;
034    import org.jfree.report.expressions.AbstractExpression;
035    
036    /**
037     * Creation-Date: 27.01.2006, 20:42:19
038     *
039     * @author Thomas Morgner
040     */
041    public class IsEmptyExpression extends AbstractExpression
042    {
043      private Object value;
044    
045      public IsEmptyExpression()
046      {
047      }
048    
049      public Object getValue()
050      {
051        return value;
052      }
053    
054      public void setValue(final Object value)
055      {
056        this.value = value;
057      }
058    
059      /**
060       * Return the current expression value. <P> The value depends (obviously) on
061       * the expression implementation.
062       *
063       * @return the value of the function.
064       */
065      public Object computeValue() throws DataSourceException
066      {
067        if (value == null)
068        {
069          return Boolean.TRUE;
070        }
071        if (value instanceof String)
072        {
073          final String s = (String) value;
074          if (s.trim().length() == 0)
075          {
076            return Boolean.TRUE;
077          }
078          return Boolean.FALSE;
079        }
080        if (value instanceof Number)
081        {
082          final Number n = (Number) value;
083          if (n.intValue() == 0)
084          {
085            return Boolean.TRUE;
086          }
087          return Boolean.FALSE;
088        }
089        return Boolean.FALSE;
090      }
091    }