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Java > Open Source Codes > DEOS > DoubleLinkListNode


1 //
2 // Copyright (C) 2005 United States Government as represented by the
3 // Administrator of the National Aeronautics and Space Administration
4 // (NASA). All Rights Reserved.
5 //
6 // This software is distributed under the NASA Open Source Agreement
7 // (NOSA), version 1.3. The NOSA has been approved by the Open Source
8 // Initiative. See the file NOSA-1.3-JPF at the top of the distribution
9 // directory tree for the complete NOSA document.
10 //
11 // THE SUBJECT SOFTWARE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY OF ANY
12 // KIND, EITHER EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT
13 // LIMITED TO, ANY WARRANTY THAT THE SUBJECT SOFTWARE WILL CONFORM TO
14 // SPECIFICATIONS, ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR
15 // A PARTICULAR PURPOSE, OR FREEDOM FROM INFRINGEMENT, ANY WARRANTY THAT
16 // THE SUBJECT SOFTWARE WILL BE ERROR FREE, OR ANY WARRANTY THAT
17 // DOCUMENTATION, IF PROVIDED, WILL CONFORM TO THE SUBJECT SOFTWARE.
18 //
19 package DEOS;
20
21 /**
22  * DOCUMENT ME!
23  */
24 class DoubleLinkListNode {
25   protected DoubleLinkListNode previous;
26   protected DoubleLinkListNode next;
27
28   protected DoubleLinkListNode () {
29     previous = null;
30     next = null;
31   }
32
33   public boolean isOnAList () {
34     /* $$A20 */
35     return next != null;
36
37     /* $$E20 */
38   }
39
40   public void addAfter (DoubleLinkListNode newNode) {
41     // For some reason, the Borland 4.52 compiler was losing track of this
42 // in previous versions of this inline code, but was able to handle it
43 // if the code was not inlined. This version seems to work OK.
44
45     /* $$A60 */
46     DoubleLinkListNode t = this;
47     DoubleLinkListNode n = t.next;
48     DoubleLinkListNode nn = newNode;
49     nn.next = n;
50     nn.previous = t;
51     t.next = nn;
52     n.previous = nn;
53
54     /* $$E60 */
55   }
56
57   public void ensureNotOnList () {
58     if (isOnAList()) {
59       removeFromList();
60     }
61   }
62
63   public DoubleLinkListNode nextNode () {
64     return next;
65   }
66
67   public DoubleLinkListNode previousNode () {
68     return previous;
69   }
70
71   public void removeFromList () {
72     /* $$A10 */
73
74     // Copy "this", previous and next to locals to help compiler realize they
75 // won't change during the execution. Eliminates redundant memory
76 // references and copying.
77 //System.out.println("DoubleLinkListNode.removeFromList");
78 DoubleLinkListNode t = this;
79     DoubleLinkListNode p = t.previous;
80     DoubleLinkListNode n = t.next;
81     n.previous = p;
82     p.next = n;
83
84     DoubleLinkListNode zero = null;
85     t.previous = zero;
86     t.next = zero;
87
88     /* $$E10 */
89   }
90 };
91
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