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/*******************************************************************************
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* Copyright (c) 2003, 2010 IBM Corporation and others.
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* All rights reserved. This program and the accompanying materials
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* are made available under the terms of the Eclipse Public License v1.0
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* which accompanies this distribution, and is available at
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* http://www.eclipse.org/legal/epl-v10.html
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*
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* Contributors:
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* IBM Corporation - initial API and implementation
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*******************************************************************************/
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package org.eclipse.draw2d.graph;
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/**
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* A base class for visitors which operate on the graphs spanning tree used to
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* induce rank assignments.
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*
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* @author Randy Hudson
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* @since 2.1.2
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*/
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abstract class SpanningTreeVisitor extends GraphVisitor {
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Edge getParentEdge(Node node) {
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return (Edge) node.workingData[1];
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}
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EdgeList getSpanningTreeChildren(Node node) {
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return (EdgeList) node.workingData[0];
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}
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protected Node getTreeHead(Edge edge) {
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if (getParentEdge(edge.source) == edge)
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return edge.target;
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return edge.source;
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}
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Node getTreeParent(Node node) {
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Edge e = getParentEdge(node);
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if (e == null)
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return null;
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return e.opposite(node);
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}
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protected Node getTreeTail(Edge edge) {
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if (getParentEdge(edge.source) == edge)
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return edge.source;
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return edge.target;
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}
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void setParentEdge(Node node, Edge edge) {
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node.workingData[1] = edge;
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}
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}
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