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: AbstractLValue.java 3521 2007-10-16 10:55:14Z tmorgner $
028     * ------------
029     * (C) Copyright 2006-2007, by Pentaho Corporation.
030     */
031    package org.jfree.formula.lvalues;
032    
033    import org.jfree.formula.FormulaContext;
034    import org.jfree.formula.EvaluationException;
035    import org.jfree.formula.typing.Type;
036    
037    /**
038     * Creation-Date: 01.11.2006, 18:19:00
039     *
040     * @author Thomas Morgner
041     */
042    public abstract class AbstractLValue implements LValue
043    {
044      private static final LValue[] EMPTY_CHILDS = new LValue[0];
045    
046      private transient FormulaContext context;
047    
048      protected AbstractLValue()
049      {
050      }
051    
052      public void initialize(final FormulaContext context) throws EvaluationException
053      {
054        this.context = context;
055      }
056    
057      public FormulaContext getContext()
058      {
059        if (context == null)
060        {
061          throw new NullPointerException();
062        }
063        return context;
064      }
065    
066      public Object clone() throws CloneNotSupportedException
067      {
068        return super.clone();
069      }
070    
071      /**
072       * Returns any dependent lvalues (parameters and operands, mostly).
073       *
074       * @return
075       */
076      public LValue[] getChildValues()
077      {
078        return EMPTY_CHILDS;
079      }
080    
081      /**
082       * Querying the value type is only valid *after* the value has been
083       * evaluated.
084       *
085       * @return
086       */
087      public Type getValueType()
088      {
089        return null;
090      }
091    }