package org.apache.ojb.broker.util.collections;

 /* Copyright 2003-2005 The Apache Software Foundation

  *

  * Licensed under the Apache License, Version 2.0 (the "License");

  * you may not use this file except in compliance with the License.

  * You may obtain a copy of the License at

  *

  *     http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 import java.util.Iterator;

 import java.util.Vector;

 import org.apache.ojb.broker.PersistenceBroker;

 import org.apache.ojb.broker.PersistenceBrokerException;

 /**

  * This is a set implementation that tracks removal and addition of elements.

  * This tracking allow the PersistenceBroker to delete elements from

  * the database that have been removed from the collection before a

  * PB.store() orperation occurs.

  * This will allow to use the PB api in way pretty close to ODMG persistent

  * collections!

  * 

  * @author Thomas Dudziak

  * @version $Id: RemovalAwareSet.java,v 1.1 2007-08-24 22:17:39 ewestfal Exp $

  */

 public class RemovalAwareSet extends ManageableHashSet implements IRemovalAwareCollection

 {

     private Vector allObjectsToBeRemoved = new Vector();

     /**

      * @see org.apache.ojb.broker.ManageableCollection#afterStore(PersistenceBroker broker)

      */

     public void afterStore(PersistenceBroker broker) throws PersistenceBrokerException

     {

         // make sure allObjectsToBeRemoved does not contain

         // any instances that got re-added to the list

         allObjectsToBeRemoved.removeAll(this);

         Iterator iter = allObjectsToBeRemoved.iterator();

         while (iter.hasNext())

         {

             broker.delete(iter.next());

         }

         allObjectsToBeRemoved.clear();

     }

     protected void registerForDeletion(Object toBeRemoved)

     {

         //only add objects once to avoid double deletions

         if (!allObjectsToBeRemoved.contains(toBeRemoved))

         {

             this.allObjectsToBeRemoved.add(toBeRemoved);

         }

     }

     /**

      * @see java.util.Collection#remove(Object)

      */

     public boolean remove(Object o)

     {

         boolean result = super.remove(o);

         registerForDeletion(o);

         return result;

     }

     /**

      * @see java.util.Vector#removeAllElements()

      */

     public synchronized void removeAllElements()

     {

         for (Iterator it = iterator(); it.hasNext();)

         {

             registerForDeletion(it.next());

         }

         super.clear();

     }

     public synchronized void clear()

     {

       removeAllElements();

     }

     public void resetDeleted()

     {

       this.allObjectsToBeRemoved.clear();

     }

 }