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1   /*
2   * E-nspire Gemini.
3   * A Java and AspectJ based framework that enables transparent 
4   * bidirectional relationships between Plain Old Java Objects.
5   * 
6   * Copyright (C) 2005 Dragan Djuric
7   * 
8   * This program is free software; you can redistribute it and/or
9   * modify it under the terms of the GNU General Public License
10  * as published by the Free Software Foundation; either version 2
11  * of the License, or (at your option) any later version.
12  * 
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16  * GNU General Public License for more details.
17  * 
18  * You should have received a copy of the GNU General Public License
19  * along with this program; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
21  * 
22  * Contact the author at dragand@dev.java.net
23  */
24  package com.enspire.gemini.commands;
25  
26  import java.util.Collection;
27  
28  import com.enspire.gemini.BidirectionalProperty;
29  
30  /***
31   * Executes the <code>remove()</code> operation on a <code>BidirectionalCollection</code>.
32   * @author Dragan Djuric <dragand@dev.java.net>
33   * @since 1.0
34   */
35  public class BidirectionalCollectionRemove extends
36          BidirectionalCollectionCommand {
37  
38      Object removeValue;
39      boolean hasChanged = false;
40      
41      /***
42       * Creates a command and sets its dependencies.
43       * @param bidirectional the bidirectional collection that this command is tied to
44       * @param collection the unidirectional collection that this command is tied to
45       * @param removeValue an object that should be removed from the collection
46       */
47      public BidirectionalCollectionRemove(BidirectionalProperty bidirectional,
48              Collection collection, Object removeValue) {
49          super(bidirectional, collection);
50          this.removeValue = removeValue;
51      }
52  
53      /***
54       * @see com.enspire.gemini.commands.Command#execute()
55       */
56      public void execute() {
57          hasChanged = getCollection().remove(removeValue);
58          if (hasChanged) {
59              try {
60                  getBidirectionalProperty().getRelationshipUpdater().
61                          unset(removeValue, 
62                          getBidirectionalProperty().getOppositeName(), 
63                          getBidirectionalProperty().getOwner());
64              } catch(RuntimeException e) {
65                  getCollection().add(removeValue);
66                  throw e;
67              }
68          }
69      }
70  
71      /***
72       * @see com.enspire.gemini.commands.Command#undo()
73       */
74      public void undo() {
75          if (!hasChanged) {
76              return;
77          }
78          getCollection().add(removeValue);
79          getBidirectionalProperty().getRelationshipUpdater().set(removeValue, 
80                  getBidirectionalProperty().getOppositeName(), 
81                  getBidirectionalProperty().getOwner());
82          }
83      }