08-27-周三_17-09-29

node_modules/dagre-layout/lib/parent-dummy-chains.js

@@ -0,0 +1,86 @@
+import _ from 'lodash'
+
+function parentDummyChains (g) {
+  const postorderNums = postorder(g)
+
+  _.forEach(g.graph().dummyChains, function (v) {
+    let node = g.node(v)
+    const edgeObj = node.edgeObj
+    const pathData = findPath(g, postorderNums, edgeObj.v, edgeObj.w)
+    const path = pathData.path
+    const lca = pathData.lca
+    let pathIdx = 0
+    let pathV = path[pathIdx]
+    let ascending = true
+
+    while (v !== edgeObj.w) {
+      node = g.node(v)
+
+      if (ascending) {
+        while ((pathV = path[pathIdx]) !== lca &&
+               g.node(pathV).maxRank < node.rank) {
+          pathIdx++
+        }
+
+        if (pathV === lca) {
+          ascending = false
+        }
+      }
+
+      if (!ascending) {
+        while (pathIdx < path.length - 1 &&
+               g.node(pathV = path[pathIdx + 1]).minRank <= node.rank) {
+          pathIdx++
+        }
+        pathV = path[pathIdx]
+      }
+
+      g.setParent(v, pathV)
+      v = g.successors(v)[0]
+    }
+  })
+}
+
+// Find a path from v to w through the lowest common ancestor (LCA). Return the
+// full path and the LCA.
+function findPath (g, postorderNums, v, w) {
+  const vPath = []
+  const wPath = []
+  const low = Math.min(postorderNums[v].low, postorderNums[w].low)
+  const lim = Math.max(postorderNums[v].lim, postorderNums[w].lim)
+  let parent
+  let lca
+
+  // Traverse up from v to find the LCA
+  parent = v
+  do {
+    parent = g.parent(parent)
+    vPath.push(parent)
+  } while (parent &&
+           (postorderNums[parent].low > low || lim > postorderNums[parent].lim))
+  lca = parent
+
+  // Traverse from w to LCA
+  parent = w
+  while ((parent = g.parent(parent)) !== lca) {
+    wPath.push(parent)
+  }
+
+  return { path: vPath.concat(wPath.reverse()), lca: lca }
+}
+
+function postorder (g) {
+  const result = {}
+  let lim = 0
+
+  function dfs (v) {
+    const low = lim
+    _.forEach(g.children(v), dfs)
+    result[v] = { low: low, lim: lim++ }
+  }
+  _.forEach(g.children(), dfs)
+
+  return result
+}
+
+export default parentDummyChains