/*
* Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
package javax.imageio.spi;
import java.io.Serializable;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
/**
* A node in a directed graph. In addition to an arbitrary
* Object
containing user data associated with the node,
* each node maintains a Set
s of nodes which are pointed
* to by the current node (available from getOutNodes
).
* The in-degree of the node (that is, number of nodes that point to
* the current node) may be queried.
*
*/
class DigraphNode implements Cloneable, Serializable {
private static final long serialVersionUID = 5308261378582246841L;
/** The data associated with this node. */
protected E data;
/**
* A Set
of neighboring nodes pointed to by this
* node.
*/
protected Set> outNodes = new HashSet<>();
/** The in-degree of the node. */
protected int inDegree = 0;
/**
* A Set
of neighboring nodes that point to this
* node.
*/
private Set> inNodes = new HashSet<>();
public DigraphNode(E data) {
this.data = data;
}
/** Returns the Object
referenced by this node. */
public E getData() {
return data;
}
/**
* Returns an Iterator
containing the nodes pointed
* to by this node.
*/
public Iterator> getOutNodes() {
return outNodes.iterator();
}
/**
* Adds a directed edge to the graph. The outNodes list of this
* node is updated and the in-degree of the other node is incremented.
*
* @param node a DigraphNode
.
*
* @return true
if the node was not previously the
* target of an edge.
*/
public boolean addEdge(DigraphNode node) {
if (outNodes.contains(node)) {
return false;
}
outNodes.add(node);
node.inNodes.add(this);
node.incrementInDegree();
return true;
}
/**
* Returns true
if an edge exists between this node
* and the given node.
*
* @param node a DigraphNode
.
*
* @return true
if the node is the target of an edge.
*/
public boolean hasEdge(DigraphNode node) {
return outNodes.contains(node);
}
/**
* Removes a directed edge from the graph. The outNodes list of this
* node is updated and the in-degree of the other node is decremented.
*
* @return true
if the node was previously the target
* of an edge.
*/
public boolean removeEdge(DigraphNode node) {
if (!outNodes.contains(node)) {
return false;
}
outNodes.remove(node);
node.inNodes.remove(this);
node.decrementInDegree();
return true;
}
/**
* Removes this node from the graph, updating neighboring nodes
* appropriately.
*/
public void dispose() {
@SuppressWarnings("unchecked")
DigraphNode[] inNodesArray = (DigraphNode[])inNodes.toArray();
for(int i=0; i node = inNodesArray[i];
node.removeEdge(this);
}
@SuppressWarnings("unchecked")
DigraphNode[] outNodesArray = (DigraphNode[])outNodes.toArray();
for(int i=0; i node = outNodesArray[i];
removeEdge(node);
}
}
/** Returns the in-degree of this node. */
public int getInDegree() {
return inDegree;
}
/** Increments the in-degree of this node. */
private void incrementInDegree() {
++inDegree;
}
/** Decrements the in-degree of this node. */
private void decrementInDegree() {
--inDegree;
}
}