feat: supports undefined parent as unsetting parent for setParent API (#8)

* feat: supports undefiend parent as unsetting parent for setParent API

* chore: upgrade version num

* docs: update changelog

* fix: judgement for undefined parent id

Author: Yanyan-Wang

README.md

@@ -21,6 +21,10 @@
 
 ## Change Log
 
+#### 2.0.2
+
+- feat: supports undefined parent as unsetting parent for setParent API;
+
 #### 2.0
 
 - 🎉 Release new version

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@antv/graphlib",
-  "version": "2.0.0",
+  "version": "2.0.2",
   "sideEffects": false,
   "scripts": {
     "clean": "rimraf lib esm dist",

src/graph.ts

@@ -1001,16 +1001,29 @@ export class Graph<
   /**
    * Set node parent. If this operation causes a circle, it fails with an error.
    * @param id - ID of the child node.
-   * @param parent - ID of the parent node.
+   * @param parent - ID of the parent node. If it is undefined, means unset parent for node with id.
    * @param treeKey - Which tree structure the relation is applied to.
    * @group TreeMethods
    */
-  public setParent(id: ID, parent: ID, treeKey?: string) {
+  public setParent(id: ID, parent?: ID, treeKey?: string) {
     this.checkTreeExistence(treeKey);
 
     const tree = this.treeIndices.get(treeKey)!;
     const node = this.getNode(id);
     const oldParent = tree.parentMap.get(id);
+
+    // Same parent id as old one, skip
+    if (oldParent?.id === parent) return;
+
+    // New parent is undefined, unset parent for the node
+    if (parent === undefined) {
+      if (oldParent) {
+        tree.childrenMap.get(oldParent.id)?.delete(node);
+      }
+      tree.parentMap.delete(id);
+      return;
+    }
+
     const newParent = this.getNode(parent);
 
     // Set parent