1 /*
2 * Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package javax.imageio.spi;
27
28 import java.io.Serializable;
29 import java.util.HashSet;
30 import java.util.Iterator;
31 import java.util.Set;
32
33 /**
34 * A node in a directed graph. In addition to an arbitrary
35 * <code>Object</code> containing user data associated with the node,
36 * each node maintains a <code>Set</code>s of nodes which are pointed
37 * to by the current node (available from <code>getOutNodes</code>).
38 * The in-degree of the node (that is, number of nodes that point to
39 * the current node) may be queried.
40 *
41 */
42 class DigraphNode implements Cloneable, Serializable {
43 private static final long serialVersionUID = 5308261378582246841L;
44
45 /** The data associated with this node. */
46 protected Object data;
47
48 /**
49 * A <code>Set</code> of neighboring nodes pointed to by this
50 * node.
51 */
52 protected Set outNodes = new HashSet();
53
54 /** The in-degree of the node. */
55 protected int inDegree = 0;
56
57 /**
58 * A <code>Set</code> of neighboring nodes that point to this
59 * node.
60 */
61 private Set inNodes = new HashSet();
62
63 public DigraphNode(Object data) {
64 this.data = data;
65 }
66
67 /** Returns the <code>Object</code> referenced by this node. */
68 public Object getData() {
69 return data;
70 }
71
72 /**
73 * Returns an <code>Iterator</code> containing the nodes pointed
74 * to by this node.
75 */
76 public Iterator getOutNodes() {
77 return outNodes.iterator();
78 }
79
80 /**
81 * Adds a directed edge to the graph. The outNodes list of this
82 * node is updated and the in-degree of the other node is incremented.
83 *
84 * @param node a <code>DigraphNode</code>.
85 *
86 * @return <code>true</code> if the node was not previously the
87 * target of an edge.
88 */
89 public boolean addEdge(DigraphNode node) {
90 if (outNodes.contains(node)) {
91 return false;
92 }
93
94 outNodes.add(node);
95 node.inNodes.add(this);
96 node.incrementInDegree();
97 return true;
98 }
99
100 /**
101 * Returns <code>true</code> if an edge exists between this node
102 * and the given node.
103 *
104 * @param node a <code>DigraphNode</code>.
105 *
106 * @return <code>true</code> if the node is the target of an edge.
107 */
108 public boolean hasEdge(DigraphNode node) {
109 return outNodes.contains(node);
110 }
111
112 /**
113 * Removes a directed edge from the graph. The outNodes list of this
114 * node is updated and the in-degree of the other node is decremented.
115 *
116 * @return <code>true</code> if the node was previously the target
117 * of an edge.
118 */
119 public boolean removeEdge(DigraphNode node) {
120 if (!outNodes.contains(node)) {
121 return false;
122 }
123
124 outNodes.remove(node);
125 node.inNodes.remove(this);
126 node.decrementInDegree();
127 return true;
128 }
129
130 /**
131 * Removes this node from the graph, updating neighboring nodes
132 * appropriately.
133 */
134 public void dispose() {
135 Object[] inNodesArray = inNodes.toArray();
136 for(int i=0; i<inNodesArray.length; i++) {
137 DigraphNode node = (DigraphNode) inNodesArray[i];
138 node.removeEdge(this);
139 }
140
141 Object[] outNodesArray = outNodes.toArray();
142 for(int i=0; i<outNodesArray.length; i++) {
143 DigraphNode node = (DigraphNode) outNodesArray[i];
144 removeEdge(node);
145 }
146 }
147
148 /** Returns the in-degree of this node. */
149 public int getInDegree() {
150 return inDegree;
151 }
152
153 /** Increments the in-degree of this node. */
154 private void incrementInDegree() {
155 ++inDegree;
156 }
157
158 /** Decrements the in-degree of this node. */
159 private void decrementInDegree() {
160 --inDegree;
161 }
162 }