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 /***
34 * This class implements an action to delete the previous character from the current insertion point.
35 *
36 * @author Mathieu Champlon
37 * @version $Revision$ $Date$
38 */
39 public final class CharacterDeletion extends AbstractAction
40 {
41 /***
42 * The selection.
43 */
44 private final ISelection selection_;
45 /***
46 * The total number of characters removed.
47 */
48 private int count_;
49
50 /***
51 * Create a delete action.
52 *
53 * @param selection the selection
54 */
55 public CharacterDeletion( final ISelection selection )
56 {
57 super( selection );
58 selection_ = selection;
59 count_ = 1;
60 }
61
62 /***
63 * {@inheritDoc}
64 */
65 protected void onPerform()
66 {
67 selection_.backward();
68 backupData();
69 selection_.delete();
70 }
71
72 /***
73 * {@inheritDoc}
74 */
75 protected boolean onUndo()
76 {
77 restoreData();
78 for( int i = 0; i < count_; ++i )
79 selection_.forward();
80 return false;
81 }
82
83 /***
84 * {@inheritDoc}
85 */
86 protected boolean onRedo()
87 {
88 for( int i = 0; i < count_; ++i )
89 selection_.backward();
90 selection_.delete();
91 return false;
92 }
93
94 /***
95 * {@inheritDoc}
96 */
97 public boolean merge( final IAction action )
98 {
99 if( !(action instanceof CharacterDeletion) )
100 return false;
101 final CharacterDeletion other = (CharacterDeletion)action;
102 prependData( other );
103 overwriteFinalState( other );
104 ++count_;
105 return true;
106 }
107 }