MyCallbackHandler.java

/*
 * This file or a portion of this file is licensed under the terms of
 * the Globus Toolkit Public License, found in file ../GTPL, or at
 * http://www.globus.org/toolkit/download/license.html. This notice must
 * appear in redistributions of this file, with or without modification.
 *
 * Redistributions of this Software, with or without modification, must
 * reproduce the GTPL in: (1) the Software, or (2) the Documentation or
 * some other similar material which is provided with the Software (if
 * any).
 *
 * Copyright 1999-2004 University of Chicago and The University of
 * Southern California. All rights reserved.
 */
package org.griphyn.vdl.dbschema;

import org.griphyn.vdl.parser.*;
import org.griphyn.vdl.util.Logging;
import org.griphyn.vdl.classes.*;

/**
 * This class adds a given Definition from the parser's callback into
 * the fresh in-memory storage. It is a streamlined version of the more
 * versatile {@link MemoryStorage} handler. End-users should not use 
 * this class.
 *
 * @author Jens-S. Vöckler
 * @author Yong Zhao
 * @version $Revision$
 */
class MyCallbackHandler implements FinalizerHandler
{
  /**
   * This is a reference to the already established in-memory storage.
   */
  private Definition m_memory;

  /**
   * The c'tor initializes the references to a single Definition.
   */
  public MyCallbackHandler()
  {
    this.m_memory = null;
  }

  /**
   * Returns the value stored by the XML reader's callback function.
   *
   * @return a single Definition that was read, or <code>null</code>.
   */
  public Definition getDefinition()
  {
    return this.m_memory;
  }

  /**
   * This method adds the given Definition to whatever storage is
   * implemented underneath.
   *
   * @param d is the Definition that is ready to be stored.
   * @return true, if new version was stored and database modified
   */
  public boolean store( VDL d )
  {
    if ( d instanceof Definition ) {
      this.m_memory = (Definition) d;
      Logging.instance().log( "chunk", 0, "found " + m_memory.shortID() );
      return true;
    } else {
      Logging.instance().log( "chunk", 0, "not a definition: " + d.toString() );
      return false;
    }
  }
}