View Javadoc

1   /***
2    * Redistribution  and use  in source  and binary  forms, with  or without
3    * modification, are permitted provided  that the following conditions are
4    * met :
5    *
6    * . Redistributions  of  source  code  must  retain  the  above copyright
7    *   notice, this list of conditions and the following disclaimer.
8    *
9    * . Redistributions in  binary form  must reproduce  the above  copyright
10   *   notice, this list of conditions  and the following disclaimer in  the
11   *   documentation and/or other materials provided with the distribution.
12   *
13   * . The name of the author may not be used to endorse or promote products
14   *   derived from this software without specific prior written permission.
15   *
16   * THIS SOFTWARE IS  PROVIDED BY THE  AUTHOR ``AS IS''  AND ANY EXPRESS  OR
17   * IMPLIED  WARRANTIES,  INCLUDING,  BUT   NOT  LIMITED  TO,  THE   IMPLIED
18   * WARRANTIES OF MERCHANTABILITY AND  FITNESS FOR A PARTICULAR  PURPOSE ARE
19   * DISCLAIMED.  IN NO  EVENT SHALL  THE AUTHOR  BE LIABLE  FOR ANY  DIRECT,
20   * INDIRECT,  INCIDENTAL,  SPECIAL,  EXEMPLARY,  OR  CONSEQUENTIAL  DAMAGES
21   * (INCLUDING,  BUT  NOT LIMITED  TO,  PROCUREMENT OF  SUBSTITUTE  GOODS OR
22   * SERVICES;  LOSS  OF USE,  DATA,  OR PROFITS;  OR  BUSINESS INTERRUPTION)
23   * HOWEVER CAUSED  AND ON  ANY THEORY  OF LIABILITY,  WHETHER IN  CONTRACT,
24   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
25   * ANY  WAY  OUT OF  THE  USE OF  THIS  SOFTWARE, EVEN  IF  ADVISED OF  THE
26   * POSSIBILITY OF SUCH DAMAGE.
27   *
28   * $Id$
29   */
30  
31  package palmed.edit.selection;
32  
33  import java.io.ByteArrayInputStream;
34  import java.io.ByteArrayOutputStream;
35  import java.io.IOException;
36  import palmed.util.ChainedException;
37  
38  /***
39   * This class factorizes behaviours common to all actions.
40   *
41   * @author Mathieu Champlon
42   * @version $Revision$ $Date$
43   */
44  public abstract class AbstractAction implements IAction
45  {
46      /***
47       * The selection.
48       */
49      private final ISelection selection_;
50      /***
51       * A backup of the initial selection state.
52       */
53      private byte[] initial_;
54      /***
55       * A backup of the final selection state.
56       */
57      private byte[] final_;
58      /***
59       * A backup of the removed data.
60       */
61      private byte[] data_;
62  
63      /***
64       * Create an abstract action.
65       *
66       * @param selection the selection
67       */
68      protected AbstractAction( final ISelection selection )
69      {
70          if( selection == null )
71              throw new IllegalArgumentException( "parameter 'selection' is null" );
72          selection_ = selection;
73      }
74  
75      /***
76       * {@inheritDoc}
77       */
78      public final void perform()
79      {
80          initial_ = backupState();
81          onPerform();
82          final_ = backupState();
83      }
84  
85      /***
86       * {@inheritDoc}
87       */
88      public final void undo()
89      {
90          restoreState( final_ );
91          if( onUndo() )
92              restoreState( initial_ );
93      }
94  
95      /***
96       * {@inheritDoc}
97       */
98      public final void redo()
99      {
100         restoreState( initial_ );
101         if( onRedo() )
102             restoreState( final_ );
103     }
104 
105     /***
106      * Perform the action.
107      */
108     protected abstract void onPerform();
109 
110     /***
111      * Undo the action.
112      *
113      * @return Whether the initial state must be restored or not
114      */
115     protected abstract boolean onUndo();
116 
117     /***
118      * Redo the action.
119      *
120      * @return Whether the final state must be restored or not
121      */
122     protected abstract boolean onRedo();
123 
124     /***
125      * Overwrite the current final state with the one of another action.
126      *
127      * @param action the action
128      */
129     protected final void overwriteFinalState( final AbstractAction action ) // FIXME dirty
130     {
131         final_ = action.final_;
132     }
133 
134     /***
135      * Prepend the current backup data with the data from another action.
136      *
137      * @param action the action
138      */
139     protected final void prependData( final AbstractAction action ) // FIXME dirty
140     {
141         final byte[] data = new byte[data_.length + action.data_.length];
142         System.arraycopy( action.data_, 0, data, 0, action.data_.length );
143         System.arraycopy( data_, 0, data, action.data_.length, data_.length );
144         data_ = data;
145     }
146 
147     private byte[] backupState()
148     {
149         final ByteArrayOutputStream stream = new ByteArrayOutputStream();
150         try
151         {
152             selection_.marshall( stream );
153         }
154         catch( IOException e )
155         {
156             throw new ChainedException( e ); // FIXME custom exception
157         }
158         return stream.toByteArray();
159     }
160 
161     private void restoreState( final byte[] state )
162     {
163         try
164         {
165             selection_.unmarshall( new ByteArrayInputStream( state ) );
166         }
167         catch( IOException e )
168         {
169             throw new ChainedException( e ); // FIXME custom exception
170         }
171     }
172 
173     /***
174      * Backup the selected text.
175      */
176     protected final void backupData()
177     {
178         final ByteArrayOutputStream stream = new ByteArrayOutputStream();
179         try
180         {
181             selection_.write( stream );
182         }
183         catch( IOException e )
184         {
185             throw new ChainedException( e ); // FIXME custom exception
186         }
187         data_ = stream.toByteArray();
188     }
189 
190     /***
191      * Remove the selected text and restore backup.
192      */
193     protected final void restoreData()
194     {
195         try
196         {
197             selection_.read( new ByteArrayInputStream( data_ ) );
198         }
199         catch( IOException e )
200         {
201             throw new ChainedException( e ); // FIXME custom exception
202         }
203     }
204 }