08-27-周三_17-09-29

node_modules/dagre-layout/lib/order/index.js

@@ -0,0 +1,78 @@
+import _ from 'lodash'
+import { Graph } from 'graphlibrary'
+
+import initOrder from './init-order'
+import crossCount from './cross-count'
+import sortSubgraph from './sort-subgraph'
+import buildLayerGraph from './build-layer-graph'
+import addSubgraphConstraints from './add-subgraph-constraints'
+import util from '../util'
+
+/*
+ * Applies heuristics to minimize edge crossings in the graph and sets the best
+ * order solution as an order attribute on each node.
+ *
+ * Pre-conditions:
+ *
+ *    1. Graph must be DAG
+ *    2. Graph nodes must be objects with a "rank" attribute
+ *    3. Graph edges must have the "weight" attribute
+ *
+ * Post-conditions:
+ *
+ *    1. Graph nodes will have an "order" attribute based on the results of the
+ *       algorithm.
+ */
+function order (g) {
+  const maxRank = util.maxRank(g)
+  const downLayerGraphs = buildLayerGraphs(g, _.range(1, maxRank + 1), 'inEdges')
+  const upLayerGraphs = buildLayerGraphs(g, _.range(maxRank - 1, -1, -1), 'outEdges')
+
+  let layering = initOrder(g)
+  assignOrder(g, layering)
+
+  let bestCC = Number.POSITIVE_INFINITY
+  let best
+
+  for (let i = 0, lastBest = 0; lastBest < 4; ++i, ++lastBest) {
+    sweepLayerGraphs(i % 2 ? downLayerGraphs : upLayerGraphs, i % 4 >= 2)
+
+    layering = util.buildLayerMatrix(g)
+    const cc = crossCount(g, layering)
+    if (cc < bestCC) {
+      lastBest = 0
+      best = _.cloneDeep(layering)
+      bestCC = cc
+    }
+  }
+
+  assignOrder(g, best)
+}
+
+function buildLayerGraphs (g, ranks, relationship) {
+  return _.map(ranks, function (rank) {
+    return buildLayerGraph(g, rank, relationship)
+  })
+}
+
+function sweepLayerGraphs (layerGraphs, biasRight) {
+  const cg = new Graph()
+  _.forEach(layerGraphs, function (lg) {
+    const root = lg.graph().root
+    const sorted = sortSubgraph(lg, root, cg, biasRight)
+    _.forEach(sorted.vs, function (v, i) {
+      lg.node(v).order = i
+    })
+    addSubgraphConstraints(lg, cg, sorted.vs)
+  })
+}
+
+function assignOrder (g, layering) {
+  _.forEach(layering, function (layer) {
+    _.forEach(layer, function (v, i) {
+      g.node(v).order = i
+    })
+  })
+}
+
+export default order