feat(ui): add type filter toggles

node_modules/dagre/lib/rank/feasible-tree.js

@@ -0,0 +1,89 @@
+"use strict";
+
+var _ = require("../lodash");
+var Graph = require("../graphlib").Graph;
+var slack = require("./util").slack;
+
+module.exports = feasibleTree;
+
+/*
+ * Constructs a spanning tree with tight edges and adjusted the input node's
+ * ranks to achieve this. A tight edge is one that is has a length that matches
+ * its "minlen" attribute.
+ *
+ * The basic structure for this function is derived from Gansner, et al., "A
+ * Technique for Drawing Directed Graphs."
+ *
+ * Pre-conditions:
+ *
+ *    1. Graph must be a DAG.
+ *    2. Graph must be connected.
+ *    3. Graph must have at least one node.
+ *    5. Graph nodes must have been previously assigned a "rank" property that
+ *       respects the "minlen" property of incident edges.
+ *    6. Graph edges must have a "minlen" property.
+ *
+ * Post-conditions:
+ *
+ *    - Graph nodes will have their rank adjusted to ensure that all edges are
+ *      tight.
+ *
+ * Returns a tree (undirected graph) that is constructed using only "tight"
+ * edges.
+ */
+function feasibleTree(g) {
+  var t = new Graph({ directed: false });
+
+  // Choose arbitrary node from which to start our tree
+  var start = g.nodes()[0];
+  var size = g.nodeCount();
+  t.setNode(start, {});
+
+  var edge, delta;
+  while (tightTree(t, g) < size) {
+    edge = findMinSlackEdge(t, g);
+    delta = t.hasNode(edge.v) ? slack(g, edge) : -slack(g, edge);
+    shiftRanks(t, g, delta);
+  }
+
+  return t;
+}
+
+/*
+ * Finds a maximal tree of tight edges and returns the number of nodes in the
+ * tree.
+ */
+function tightTree(t, g) {
+  function dfs(v) {
+    _.forEach(g.nodeEdges(v), function(e) {
+      var edgeV = e.v,
+        w = (v === edgeV) ? e.w : edgeV;
+      if (!t.hasNode(w) && !slack(g, e)) {
+        t.setNode(w, {});
+        t.setEdge(v, w, {});
+        dfs(w);
+      }
+    });
+  }
+
+  _.forEach(t.nodes(), dfs);
+  return t.nodeCount();
+}
+
+/*
+ * Finds the edge with the smallest slack that is incident on tree and returns
+ * it.
+ */
+function findMinSlackEdge(t, g) {
+  return _.minBy(g.edges(), function(e) {
+    if (t.hasNode(e.v) !== t.hasNode(e.w)) {
+      return slack(g, e);
+    }
+  });
+}
+
+function shiftRanks(t, g, delta) {
+  _.forEach(t.nodes(), function(v) {
+    g.node(v).rank += delta;
+  });
+}