Refactor BZgraflow: extract graph structure building into a separate method and enhance cross-layer link detection

bzGraflow.js

@@ -207,19 +207,7 @@ class BZgraflow extends Buildoz{
             linksWithoutBackEdges = this.flow.links
         }
 
-        const parents = {}
+        const { parents, adj } = this.buildGraphStructures(this.flow.nodes, linksWithoutBackEdges)
-        const adj = {}
-        this.flow.nodes.forEach(n => {
-            parents[n.id] = []
-            adj[n.id] = []
-        })
-
-        linksWithoutBackEdges.forEach(link => {
-            const from = link.from[0]
-            const to   = link.to[0]            
-            parents[to].push(from)
-            adj[from].push(to)
-        })
 
         const layers = this.computeLayers(this.flow.nodes, parents)
         let maxHeight = 0; let maxWidth = 0
@@ -366,6 +354,24 @@ class BZgraflow extends Buildoz{
         return(this.flow.links.find(item => ((item.from[0]==nid1) && (item.to[0]==nid2))))
     }
 
+    buildGraphStructures(nodes, links) {
+        const parents = {}
+        const adj = {}
+        nodes.forEach(n => {
+            parents[n.id] = []
+            adj[n.id] = []
+        })
+
+        links.forEach(link => {
+            const from = link.from[0]
+            const to   = link.to[0]            
+            parents[to].push(from)
+            adj[from].push(to)
+        })
+
+        return { parents, adj }
+    }
+
     computeLayers(nodes, parents) {
         const layer = {}
         const dfs = (id) => {
@@ -453,6 +459,19 @@ class BZgraflow extends Buildoz{
         return backEdges
     }
 
+    findCrossLayerLinks(links) {
+        const { parents } = this.buildGraphStructures(this.flow.nodes, links)
+        const layers = this.computeLayers(this.flow.nodes, parents)
+        const crossLayerLinks = []
+        for(const link of links){
+            const from = link.from[0]
+            const to = link.to[0]
+            if(layers[from] !== layers[to]) {
+                crossLayerLinks.push(link)
+            }
+        }
+        return crossLayerLinks
+    }
 }
 Buildoz.define('graflow', BZgraflow)