--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dwtx/draw2d/graph/CollapsedEdges.d	Sun Aug 03 00:52:14 2008 +0200
@@ -0,0 +1,79 @@
+/*******************************************************************************
+ * Copyright (c) 2005 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ * Port to the D programming language:
+ *     Frank Benoit <benoit@tionex.de>
+ *******************************************************************************/
+module dwtx.draw2d.graph.CollapsedEdges;
+
+import dwt.dwthelper.utils;
+import dwtx.draw2d.graph.Edge;
+
+/**
+ * Contains the information from all edges going from a given cluster to some other
+ * cluster.  An edge with minimal slack as chosen to maintain the link between clusters.
+ * The weight and any slack more than the minimal edge's slack is tracked for all other
+ * edges.
+ * @since 3.1
+ */
+class CollapsedEdges {
+
+    /**
+     * The total weight of the collapsed edges.
+     */
+    int collapsedWeight;
+    int collapsedCount;
+
+    /**
+     * The total amount of weighted difference in the collapsed edges slack and the
+     * tightest edge's slack.
+     */
+    int overage;
+    int unOverage;
+    Edge tightestEdge;
+
+    this(Edge edge) {
+        tightestEdge = edge;
+        collapsedWeight = edge.weight;
+        collapsedCount++;
+    }
+
+    public int getWeightedPull() {
+        return tightestEdge.getSlack() * collapsedWeight + overage;
+    }
+
+    public bool isTight() {
+        return tightestEdge.getSlack() is 0;
+    }
+
+    /**
+     * Compares the given edge to the current tightest edge.  If the given edge is tighter
+     * than the current, the current tightest is returned.  Otherwise, the edge itself is
+     * returned.  The returned edge would be the one to remove from the graph.
+     * @param candidate another edge
+     * @return the edge which is not the tightest edge
+     * @since 3.1
+     */
+    Edge processEdge(Edge candidate) {
+        collapsedCount++;
+        if (candidate.getSlack() < tightestEdge.getSlack()) {
+            overage += collapsedWeight * (tightestEdge.getSlack() - candidate.getSlack());
+            Edge temp = tightestEdge;
+            tightestEdge = candidate;
+            collapsedWeight += candidate.weight;
+            return temp;
+        } else {
+            int over = candidate.getSlack() - tightestEdge.getSlack();
+            unOverage += over;
+            overage += candidate.weight * over;
+            collapsedWeight += candidate.weight;
+            return candidate;
+        }
+    }
+}