diff -r efd9c589177a -r c0b4a8b5a012 toolkit/javascript/d3/src/layout/bundle.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/src/layout/bundle.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,57 @@
+// Implements hierarchical edge bundling using Holten's algorithm. For each
+// input link, a path is computed that travels through the tree, up the parent
+// hierarchy to the least common ancestor, and then back down to the destination
+// node. Each path is simply an array of nodes.
+d3.layout.bundle = function() {
+  return function(links) {
+    var paths = [],
+        i = -1,
+        n = links.length;
+    while (++i < n) paths.push(d3_layout_bundlePath(links[i]));
+    return paths;
+  };
+};
+
+function d3_layout_bundlePath(link) {
+  var start = link.source,
+      end = link.target,
+      lca = d3_layout_bundleLeastCommonAncestor(start, end),
+      points = [start];
+  while (start !== lca) {
+    start = start.parent;
+    points.push(start);
+  }
+  var k = points.length;
+  while (end !== lca) {
+    points.splice(k, 0, end);
+    end = end.parent;
+  }
+  return points;
+}
+
+function d3_layout_bundleAncestors(node) {
+  var ancestors = [],
+      parent = node.parent;
+  while (parent != null) {
+    ancestors.push(node);
+    node = parent;
+    parent = parent.parent;
+  }
+  ancestors.push(node);
+  return ancestors;
+}
+
+function d3_layout_bundleLeastCommonAncestor(a, b) {
+  if (a === b) return a;
+  var aNodes = d3_layout_bundleAncestors(a),
+      bNodes = d3_layout_bundleAncestors(b),
+      aNode = aNodes.pop(),
+      bNode = bNodes.pop(),
+      sharedNode = null;
+  while (aNode === bNode) {
+    sharedNode = aNode;
+    aNode = aNodes.pop();
+    bNode = bNodes.pop();
+  }
+  return sharedNode;
+}