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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>add()</code> operation on a <code>BidirectionalCollection</code>.
32   * @author Dragan Djuric <dragand@dev.java.net>
33   * @since 1.0
34   */
35  public class BidirectionalCollectionAdd extends
36          BidirectionalCollectionCommand {
37  
38      Object oldOwner;
39      Object addValue;
40      boolean hasChanged = false;
41      
42      /***
43       * Creates a command and sets its dependencies.
44       * @param bidirectional the bidirectional collection that this command is tied to
45       * @param collection the unidirectional collection that this command is tied to
46       * @param addValue an object that should be added to the collection
47       */
48      public BidirectionalCollectionAdd(BidirectionalProperty bidirectional,
49              Collection collection, Object addValue) {
50          super(bidirectional, collection);
51          this.addValue = addValue;
52      }
53  
54      /***
55       * @see com.enspire.gemini.commands.Command#execute()
56       */
57      public void execute() {
58          hasChanged = getCollection().add(addValue);
59          if (hasChanged) {
60              try {
61                  oldOwner = getBidirectionalProperty().getRelationshipUpdater().
62                          set(addValue, 
63                          getBidirectionalProperty().getOppositeName(), 
64                          getBidirectionalProperty().getOwner());
65              } catch(RuntimeException e) {
66                  getCollection().remove(addValue);
67                  throw e;
68              }
69          }
70      }
71  
72      /***
73       * @see com.enspire.gemini.commands.Command#undo()
74       */
75      public void undo() {
76          if (!hasChanged) {
77              return;
78          }
79          getCollection().remove(addValue);
80          getBidirectionalProperty().getRelationshipUpdater().unset(addValue, 
81                  getBidirectionalProperty().getOppositeName(), 
82                  getBidirectionalProperty().getOwner());
83          if(oldOwner != null) {
84              getBidirectionalProperty().getRelationshipUpdater().set(addValue, 
85                      getBidirectionalProperty().getOppositeName(), oldOwner);
86          }
87      }
88  
89  }