J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2000 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any 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 | |
| 44 | /** The data associated with this node. */ |
| 45 | protected Object data; |
| 46 | |
| 47 | /** |
| 48 | * A <code>Set</code> of neighboring nodes pointed to by this |
| 49 | * node. |
| 50 | */ |
| 51 | protected Set outNodes = new HashSet(); |
| 52 | |
| 53 | /** The in-degree of the node. */ |
| 54 | protected int inDegree = 0; |
| 55 | |
| 56 | /** |
| 57 | * A <code>Set</code> of neighboring nodes that point to this |
| 58 | * node. |
| 59 | */ |
| 60 | private Set inNodes = new HashSet(); |
| 61 | |
| 62 | public DigraphNode(Object data) { |
| 63 | this.data = data; |
| 64 | } |
| 65 | |
| 66 | /** Returns the <code>Object</code> referenced by this node. */ |
| 67 | public Object getData() { |
| 68 | return data; |
| 69 | } |
| 70 | |
| 71 | /** |
| 72 | * Returns an <code>Iterator</code> containing the nodes pointed |
| 73 | * to by this node. |
| 74 | */ |
| 75 | public Iterator getOutNodes() { |
| 76 | return outNodes.iterator(); |
| 77 | } |
| 78 | |
| 79 | /** |
| 80 | * Adds a directed edge to the graph. The outNodes list of this |
| 81 | * node is updated and the in-degree of the other node is incremented. |
| 82 | * |
| 83 | * @param node a <code>DigraphNode</code>. |
| 84 | * |
| 85 | * @return <code>true</code> if the node was not previously the |
| 86 | * target of an edge. |
| 87 | */ |
| 88 | public boolean addEdge(DigraphNode node) { |
| 89 | if (outNodes.contains(node)) { |
| 90 | return false; |
| 91 | } |
| 92 | |
| 93 | outNodes.add(node); |
| 94 | node.inNodes.add(this); |
| 95 | node.incrementInDegree(); |
| 96 | return true; |
| 97 | } |
| 98 | |
| 99 | /** |
| 100 | * Returns <code>true</code> if an edge exists between this node |
| 101 | * and the given node. |
| 102 | * |
| 103 | * @param node a <code>DigraphNode</code>. |
| 104 | * |
| 105 | * @return <code>true</code> if the node is the target of an edge. |
| 106 | */ |
| 107 | public boolean hasEdge(DigraphNode node) { |
| 108 | return outNodes.contains(node); |
| 109 | } |
| 110 | |
| 111 | /** |
| 112 | * Removes a directed edge from the graph. The outNodes list of this |
| 113 | * node is updated and the in-degree of the other node is decremented. |
| 114 | * |
| 115 | * @return <code>true</code> if the node was previously the target |
| 116 | * of an edge. |
| 117 | */ |
| 118 | public boolean removeEdge(DigraphNode node) { |
| 119 | if (!outNodes.contains(node)) { |
| 120 | return false; |
| 121 | } |
| 122 | |
| 123 | outNodes.remove(node); |
| 124 | node.inNodes.remove(this); |
| 125 | node.decrementInDegree(); |
| 126 | return true; |
| 127 | } |
| 128 | |
| 129 | /** |
| 130 | * Removes this node from the graph, updating neighboring nodes |
| 131 | * appropriately. |
| 132 | */ |
| 133 | public void dispose() { |
| 134 | Object[] inNodesArray = inNodes.toArray(); |
| 135 | for(int i=0; i<inNodesArray.length; i++) { |
| 136 | DigraphNode node = (DigraphNode) inNodesArray[i]; |
| 137 | node.removeEdge(this); |
| 138 | } |
| 139 | |
| 140 | Object[] outNodesArray = outNodes.toArray(); |
| 141 | for(int i=0; i<outNodesArray.length; i++) { |
| 142 | DigraphNode node = (DigraphNode) outNodesArray[i]; |
| 143 | removeEdge(node); |
| 144 | } |
| 145 | } |
| 146 | |
| 147 | /** Returns the in-degree of this node. */ |
| 148 | public int getInDegree() { |
| 149 | return inDegree; |
| 150 | } |
| 151 | |
| 152 | /** Increments the in-degree of this node. */ |
| 153 | private void incrementInDegree() { |
| 154 | ++inDegree; |
| 155 | } |
| 156 | |
| 157 | /** Decrements the in-degree of this node. */ |
| 158 | private void decrementInDegree() { |
| 159 | --inDegree; |
| 160 | } |
| 161 | } |