Update model and add invalidated cycle

src/model/DataModel.ts

@@ -1,12 +1,39 @@
 import { RootNode } from "../nodes/RootNode"
 import { Path } from "./Path"
 
+export interface ModelListener {
+  invalidated(model: DataModel): void
+}
+
 export class DataModel {
   data: any
   schema: RootNode
+  listeners: ModelListener[]
 
   constructor(schema: RootNode) {
     this.schema = schema
     this.data = schema.default
+    this.listeners = []
+  }
+
+  addListener(listener: ModelListener) {
+    this.listeners.push(listener)
+  }
+
+  invalidate() {
+    this.listeners.forEach(listener => listener.invalidated(this))
+  }
+
+  set(path: Path, value: any) {
+    let node = this.data;
+    for (let index of path.pop()) {
+      if (node[index] === undefined) {
+        node[index] = {}
+      }
+      node = node[index]
+    }
+    node[path.last()] = value
+
+    this.invalidate()
   }
 }