Destroy view-models when destroying trees

backend/src/Model/Destroyable.ts

@@ -0,0 +1,3 @@
+export interface Destroyable {
+  destroy(): void
+}

backend/src/Model/Edge.ts

@@ -1,7 +1,8 @@
+import { Destroyable } from './Destroyable'
 import { Hashable, TreeNode } from './'
 const sha1 = require('sha1')
 
-export class Edge<ViewModel> implements Hashable {
+export class Edge<ViewModel extends Destroyable> implements Hashable {
   public name: string
 
   public target!: TreeNode<ViewModel>

backend/src/Model/Tree.ts

@@ -1,4 +1,5 @@
 import { ChangeBuffer } from './ChangeBuffer'
+import { Destroyable } from './Destroyable'
 import {
   EventBusInterface,
   EventDispatcher,
@@ -8,7 +9,7 @@ import {
 import { TreeNode } from './'
 import { TreeNodeFactory } from './TreeNodeFactory'
 
-export class Tree<ViewModel> extends TreeNode<ViewModel> {
+export class Tree<ViewModel extends Destroyable> extends TreeNode<ViewModel> {
   public connectionId?: string
   public updateSource?: EventBusInterface
   public nodeFilter?: (node: TreeNode<ViewModel>) => boolean

backend/src/Model/TreeNode.ts

@@ -1,7 +1,8 @@
+import { Destroyable } from './Destroyable'
 import { Edge, Message, RingBuffer } from './'
 import { EventDispatcher, MqttMessage } from '../../../events'
 
-export class TreeNode<ViewModel> {
+export class TreeNode<ViewModel extends Destroyable> {
   public sourceEdge?: Edge<ViewModel>
   public message?: Message
   public mqttMessage?: MqttMessage
@@ -103,6 +104,8 @@ export class TreeNode<ViewModel> {
     for (const edge of this.edgeArray) {
       edge.target.destroy()
     }
+    this.viewModel && this.viewModel.destroy()
+    this.viewModel = undefined
     this.edgeArray = []
     this.edges = {}
     this.cachedChildTopics = []

backend/src/Model/TreeNodeFactory.ts

@@ -1,9 +1,10 @@
 import { Base64Message } from './Base64Message'
+import { Destroyable } from './Destroyable'
 import { Edge, Tree, TreeNode } from './'
 
 export abstract class TreeNodeFactory {
   private static messageCounter = 0
-  public static insertNodeAtPosition<ViewModel>(edgeNames: Array<string>, node: TreeNode<ViewModel>) {
+  public static insertNodeAtPosition<ViewModel extends Destroyable>(edgeNames: Array<string>, node: TreeNode<ViewModel>) {
     let currentNode: TreeNode<ViewModel> = new Tree()
     let edge
     for (const edgeName of edgeNames) {
@@ -16,7 +17,7 @@ export abstract class TreeNodeFactory {
     node.sourceEdge!.target = node
   }
 
-  public static fromEdgesAndValue<ViewModel>(edgeNames: Array<string>, value?: Base64Message | null): TreeNode<ViewModel> {
+  public static fromEdgesAndValue<ViewModel extends Destroyable>(edgeNames: Array<string>, value?: Base64Message | null): TreeNode<ViewModel> {
     const node = new TreeNode<ViewModel>()
     node.setMessage({
       value: value || undefined,