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comparison dwtx/draw2d/graph/GraphUtilities.d @ 98:95307ad235d9

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Added Draw2d code, still work in progress
author Frank Benoit <benoit@tionex.de>
date Sun, 03 Aug 2008 00:52:14 +0200
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96:b492ba44e44d 98:95307ad235d9
1 /*******************************************************************************
2 * Copyright (c) 2003, 2005 IBM Corporation and others.
3 * All rights reserved. This program and the accompanying materials
4 * are made available under the terms of the Eclipse Public License v1.0
5 * which accompanies this distribution, and is available at
6 * http://www.eclipse.org/legal/epl-v10.html
7 *
8 * Contributors:
9 * IBM Corporation - initial API and implementation
10 * Port to the D programming language:
11 * Frank Benoit <benoit@tionex.de>
12 *******************************************************************************/
13 module dwtx.draw2d.graph.GraphUtilities;
14
15 import dwt.dwthelper.utils;
16 import dwtx.draw2d.graph.Subgraph;
17 import dwtx.draw2d.graph.Node;
18 import dwtx.draw2d.graph.NodeList;
19 import dwtx.draw2d.graph.DirectedGraph;
20 import dwtx.draw2d.graph.Rank;
21 import dwtx.draw2d.graph.Edge;
22 import dwtx.draw2d.graph.EdgeList;
23
24 /**
25 * Some utility methods for graphs.
26 * @author Eric Bordeau
27 * @since 2.1.2
28 */
29 class GraphUtilities {
30
31 static Subgraph getCommonAncestor(Node left, Node right) {
32 Subgraph parent;
33 if (auto p = cast(Subgraph)right )
34 parent = p;
35 else
36 parent = right.getParent();
37 while (parent !is null) {
38 if (parent.isNested(left))
39 return parent;
40 parent = parent.getParent();
41 }
42 return null;
43 }
44
45 /**
46 * Returns <code>true</code> if the given graph contains at least one cycle.
47 * @param graph the graph to test
48 * @return whether the graph is cyclic
49 */
50 public static bool isCyclic(DirectedGraph graph) {
51 return isCyclic(new NodeList(graph.nodes));
52 }
53
54 /**
55 * Recursively removes leaf nodes from the list until there are no nodes remaining (acyclic)
56 * or there are no leaf nodes but the list is not empty (cyclic), then returns the result.
57 * @param nodes the list of nodes to test
58 * @return whether the graph is cyclic
59 */
60 public static bool isCyclic(NodeList nodes) {
61 if (nodes.isEmpty())
62 return false;
63 int size = nodes.size();
64 // remove all the leaf nodes from the graph
65 for (int i = 0; i < nodes.size(); i++) {
66 Node node = nodes.getNode(i);
67 if (node.outgoing is null || node.outgoing.isEmpty()) { // this is a leaf node
68 nodes.remove(node);
69 for (int j = 0; j < node.incoming.size(); j++) {
70 Edge e = node.incoming.getEdge(j);
71 e.source.outgoing.remove(e);
72 }
73 }
74 }
75 // if no nodes were removed, that means there are no leaf nodes and the graph is cyclic
76 if (nodes.size() is size)
77 return true;
78 // leaf nodes were removed, so recursively call this method with the new list
79 return isCyclic(nodes);
80 }
81
82 /**
83 * Counts the number of edge crossings in a DirectedGraph
84 * @param graph the graph whose crossed edges are counted
85 * @return the number of edge crossings in the graph
86 */
87 public static int numberOfCrossingsInGraph(DirectedGraph graph) {
88 int crossings = 0;
89 for (int i = 0; i < graph.ranks.size(); i++) {
90 Rank rank = graph.ranks.getRank(i);
91 crossings += numberOfCrossingsInRank(rank);
92 }
93 return crossings;
94 }
95
96 /**
97 * Counts the number of edge crossings in a Rank
98 * @param rank the rank whose crossed edges are counted
99 * @return the number of edge crossings in the rank
100 */
101 public static int numberOfCrossingsInRank(Rank rank) {
102 int crossings = 0;
103 for (int i = 0; i < rank.size() - 1; i++) {
104 Node currentNode = rank.getNode(i);
105 Node nextNode;
106 for (int j = i + 1; j < rank.size(); j++) {
107 nextNode = rank.getNode(j);
108 EdgeList currentOutgoing = currentNode.outgoing;
109 EdgeList nextOutgoing = nextNode.outgoing;
110 for (int k = 0; k < currentOutgoing.size(); k++) {
111 Edge currentEdge = currentOutgoing.getEdge(k);
112 for (int l = 0; l < nextOutgoing.size(); l++) {
113 if (nextOutgoing.getEdge(l).getIndexForRank(currentNode.rank + 1)
114 < currentEdge.getIndexForRank(currentNode.rank + 1))
115 crossings++;
116 }
117 }
118 }
119 }
120 return crossings;
121 }
122
123 private static NodeList search(Node node, NodeList list) {
124 if (node.flag)
125 return list;
126 node.flag = true;
127 list.add(node);
128 for (int i = 0; i < node.outgoing.size(); i++)
129 search(node.outgoing.getEdge(i).target, list);
130 return list;
131 }
132
133 /**
134 * Returns <code>true</code> if adding an edge between the 2 given nodes will introduce a
135 * cycle in the containing graph.
136 * @param source the potential source node
137 * @param target the potential target node
138 * @return whether an edge between the 2 given nodes will introduce a cycle
139 */
140 public static bool willCauseCycle(Node source, Node target) {
141 NodeList nodes = search(target, new NodeList());
142 nodes.resetFlags();
143 return nodes.contains(source);
144 }
145
146 static bool isConstrained(Node left, Node right) {
147 Subgraph common = left.getParent();
148 while (common !is null && !common.isNested(right)) {
149 left = left.getParent();
150 common = left.getParent();
151 }
152 while (right.getParent() !is common)
153 right = right.getParent();
154 return (left.rowOrder !is -1 && right.rowOrder !is -1)
155 && left.rowOrder !is right.rowOrder;
156 }
157
158 }