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| 1 | /* | ||
| 2 | * Copyright (c) 2000, 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 | |||
| 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 | } | ||