01: /* Copyright (C) 2004 - 2007 db4objects Inc. http://www.db4o.com
02:
03: This file is part of the db4o open source object database.
04:
05: db4o is free software; you can redistribute it and/or modify it under
06: the terms of version 2 of the GNU General Public License as published
07: by the Free Software Foundation and as clarified by db4objects' GPL
08: interpretation policy, available at
09: http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
10: Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
11: Suite 350, San Mateo, CA 94403, USA.
12:
13: db4o is distributed in the hope that it will be useful, but WITHOUT ANY
14: WARRANTY; without even the implied warranty of MERCHANTABILITY or
15: FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16: for more details.
17:
18: You should have received a copy of the GNU General Public License along
19: with this program; if not, write to the Free Software Foundation, Inc.,
20: 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
21: package EDU.purdue.cs.bloat.util;
22:
23: import java.util.*;
24:
25: /**
26: * GraphNode represents a node in a Graph. Each node has a set of predacessors
27: * and successors associated with it as well as a pre-order and post-order
28: * traversal index. This information is maintained by the Graph in which the
29: * GraphNode resides.
30: *
31: * @see Graph
32: */
33: public abstract class GraphNode {
34: protected HashSet succs;
35:
36: protected HashSet preds;
37:
38: protected int preIndex;
39:
40: protected int postIndex;
41:
42: /**
43: * Constructor.
44: */
45: public GraphNode() {
46: succs = new HashSet();
47: preds = new HashSet();
48: preIndex = -1;
49: postIndex = -1;
50: }
51:
52: /**
53: * @return This node's index in a pre-order traversal of the Graph that
54: * contains it.
55: */
56: int preOrderIndex() {
57: return preIndex;
58: }
59:
60: /**
61: * @return This node's index in a post-order traversal of the Graph that
62: * contains it.
63: */
64: int postOrderIndex() {
65: return postIndex;
66: }
67:
68: void setPreOrderIndex(final int index) {
69: preIndex = index;
70: }
71:
72: void setPostOrderIndex(final int index) {
73: postIndex = index;
74: }
75:
76: /**
77: * Returns the successor (or children) nodes of this GraphNode.
78: */
79: protected Collection succs() {
80: return succs;
81: }
82:
83: /**
84: * Returns the predacessor (or parent) nodes of this GraphNode.
85: */
86: protected Collection preds() {
87: return preds;
88: }
89: }
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