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annotate org.eclipse.draw2d/src/org/eclipse/draw2d/graph/GraphUtilities.d @ 12:bc29606a740c

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Added dwt-addons in original directory structure of eclipse.org
author Frank Benoit <benoit@tionex.de>
date Sat, 14 Mar 2009 18:23:29 +0100
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1 /*******************************************************************************
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2 * Copyright (c) 2003, 2005 IBM Corporation and others.
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3 * All rights reserved. This program and the accompanying materials
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4 * are made available under the terms of the Eclipse Public License v1.0
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5 * which accompanies this distribution, and is available at
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6 * http://www.eclipse.org/legal/epl-v10.html
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7 *
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8 * Contributors:
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9 * IBM Corporation - initial API and implementation
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10 * Port to the D programming language:
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11 * Frank Benoit <benoit@tionex.de>
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12 *******************************************************************************/
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13 module org.eclipse.draw2d.graph.GraphUtilities;
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14
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15 import java.lang.all;
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16 import org.eclipse.draw2d.graph.Subgraph;
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17 import org.eclipse.draw2d.graph.Node;
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18 import org.eclipse.draw2d.graph.NodeList;
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19 import org.eclipse.draw2d.graph.DirectedGraph;
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20 import org.eclipse.draw2d.graph.Rank;
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21 import org.eclipse.draw2d.graph.Edge;
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22 import org.eclipse.draw2d.graph.EdgeList;
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23
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24 /**
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25 * Some utility methods for graphs.
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26 * @author Eric Bordeau
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27 * @since 2.1.2
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28 */
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29 class GraphUtilities {
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30
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31 static Subgraph getCommonAncestor(Node left, Node right) {
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32 Subgraph parent;
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33 if (auto p = cast(Subgraph)right )
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34 parent = p;
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35 else
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36 parent = right.getParent();
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37 while (parent !is null) {
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38 if (parent.isNested(left))
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39 return parent;
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40 parent = parent.getParent();
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41 }
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42 return null;
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43 }
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44
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45 /**
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46 * Returns <code>true</code> if the given graph contains at least one cycle.
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47 * @param graph the graph to test
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48 * @return whether the graph is cyclic
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49 */
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50 public static bool isCyclic(DirectedGraph graph) {
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51 return isCyclic(new NodeList(graph.nodes));
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52 }
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53
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54 /**
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55 * Recursively removes leaf nodes from the list until there are no nodes remaining (acyclic)
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56 * or there are no leaf nodes but the list is not empty (cyclic), then returns the result.
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57 * @param nodes the list of nodes to test
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58 * @return whether the graph is cyclic
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59 */
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60 public static bool isCyclic(NodeList nodes) {
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61 if (nodes.isEmpty())
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62 return false;
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63 int size = nodes.size();
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64 // remove all the leaf nodes from the graph
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65 for (int i = 0; i < nodes.size(); i++) {
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66 Node node = nodes.getNode(i);
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67 if (node.outgoing is null || node.outgoing.isEmpty()) { // this is a leaf node
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68 nodes.remove(node);
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69 for (int j = 0; j < node.incoming.size(); j++) {
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70 Edge e = node.incoming.getEdge(j);
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71 e.source.outgoing.remove(e);
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72 }
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73 }
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74 }
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75 // if no nodes were removed, that means there are no leaf nodes and the graph is cyclic
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76 if (nodes.size() is size)
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77 return true;
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78 // leaf nodes were removed, so recursively call this method with the new list
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79 return isCyclic(nodes);
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80 }
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81
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82 /**
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83 * Counts the number of edge crossings in a DirectedGraph
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84 * @param graph the graph whose crossed edges are counted
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85 * @return the number of edge crossings in the graph
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86 */
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87 public static int numberOfCrossingsInGraph(DirectedGraph graph) {
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88 int crossings = 0;
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89 for (int i = 0; i < graph.ranks.size(); i++) {
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90 Rank rank = graph.ranks.getRank(i);
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91 crossings += numberOfCrossingsInRank(rank);
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92 }
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93 return crossings;
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94 }
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95
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96 /**
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97 * Counts the number of edge crossings in a Rank
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98 * @param rank the rank whose crossed edges are counted
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99 * @return the number of edge crossings in the rank
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100 */
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101 public static int numberOfCrossingsInRank(Rank rank) {
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102 int crossings = 0;
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103 for (int i = 0; i < rank.size() - 1; i++) {
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104 Node currentNode = rank.getNode(i);
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105 Node nextNode;
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106 for (int j = i + 1; j < rank.size(); j++) {
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107 nextNode = rank.getNode(j);
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108 EdgeList currentOutgoing = currentNode.outgoing;
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109 EdgeList nextOutgoing = nextNode.outgoing;
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110 for (int k = 0; k < currentOutgoing.size(); k++) {
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111 Edge currentEdge = currentOutgoing.getEdge(k);
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112 for (int l = 0; l < nextOutgoing.size(); l++) {
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113 if (nextOutgoing.getEdge(l).getIndexForRank(currentNode.rank + 1)
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114 < currentEdge.getIndexForRank(currentNode.rank + 1))
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115 crossings++;
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116 }
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117 }
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118 }
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119 }
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120 return crossings;
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121 }
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122
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123 private static NodeList search(Node node, NodeList list) {
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124 if (node.flag)
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125 return list;
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126 node.flag = true;
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127 list.add(node);
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128 for (int i = 0; i < node.outgoing.size(); i++)
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129 search(node.outgoing.getEdge(i).target, list);
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130 return list;
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131 }
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132
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133 /**
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134 * Returns <code>true</code> if adding an edge between the 2 given nodes will introduce a
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135 * cycle in the containing graph.
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136 * @param source the potential source node
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137 * @param target the potential target node
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138 * @return whether an edge between the 2 given nodes will introduce a cycle
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139 */
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140 public static bool willCauseCycle(Node source, Node target) {
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141 NodeList nodes = search(target, new NodeList());
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142 nodes.resetFlags();
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143 return nodes.contains(source);
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144 }
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145
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146 static bool isConstrained(Node left, Node right) {
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147 Subgraph common = left.getParent();
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148 while (common !is null && !common.isNested(right)) {
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149 left = left.getParent();
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150 common = left.getParent();
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151 }
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152 while (right.getParent() !is common)
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153 right = right.getParent();
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154 return (left.rowOrder !is -1 && right.rowOrder !is -1)
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155 && left.rowOrder !is right.rowOrder;
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156 }
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157
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158 }