update weakAction

utils/weak-action.ts

@@ -0,0 +1,30 @@
+/**
+ * Run a weak action (function that is called once with weak dependencies).
+ * If one of the weak dependencies is garbage collected, an optional deinit function is called.
+ * @param weakRefs
+ * @param action 
+ * @param deinit 
+ */
+export function weakAction<T extends Record<string, WeakKey>, R>(weakDependencies: T, action: (values: {[K in keyof T]: WeakRef<T[K]>}) => R, deinit?: (actionResult: R, collectedVariable: keyof T) => unknown) {
+	const weakRefs = Object.fromEntries(
+		Object.entries(weakDependencies)
+			.map(([k, v]) => [k, new WeakRef(v)])
+	) as {[K in keyof T]: WeakRef<T[K]>};
+
+	let result:R;
+
+	// optional deinit
+	if (deinit) {
+		const registry = new FinalizationRegistry((k: string) => {
+			console.log("deinitalized weak action (variable '" + k + "' was garbage collected)")
+			deinit(result, k);
+		});
+
+		for (const [k, v] of Object.entries(weakDependencies)) {
+			registry.register(v, k);
+		}
+	}
+
+	// call action once
+	result = action(weakRefs);
+}