feat: ReadonlyState is now only an interfac

MKRhere · MKRhere · commit b2982d4b84f2 · 2023-11-12T23:46:00.000+05:30
diff --git a/hyper/node.ts b/hyper/node.ts
@@ -2,7 +2,7 @@ import { Tag } from "./lib/tags.ts";
 import { EmptyElements } from "./lib/emptyElements.ts";
 import { Attr } from "./lib/attributes.ts";
 import { Falsy, isFalsy } from "./util.ts";
-import { State, ReadonlyState } from "./state.ts";
+import { State, type ReadonlyState } from "./state.ts";
 
 export type NonEmptyElement = Exclude<Tag, EmptyElements>;
 
@@ -46,7 +46,6 @@ export type HyperNodeish<T extends Tag = Tag> =
 	| HyperTextNode
 	| HyperHTMLStringNode
 	| Falsy
-	| State<HyperNode<T> | HyperTextNode | HyperHTMLStringNode | Falsy>
 	| ReadonlyState<HyperNode<T> | HyperTextNode | HyperHTMLStringNode | Falsy>;
 
 // deno-lint-ignore no-explicit-any
diff --git a/hyper/render/dom.ts b/hyper/render/dom.ts
@@ -1,6 +1,6 @@
 import { guessEnv } from "../guessEnv.ts";
 import { Falsy, isFalsy } from "../util.ts";
-import { State, ReadonlyState } from "../state.ts";
+import { State, type ReadonlyState } from "../state.ts";
 import { Document, HTMLElement, Node, Text } from "../lib/dom.ts";
 import { HyperHTMLStringNode, HyperNodeish } from "../node.ts";
 
diff --git a/hyper/state.ts b/hyper/state.ts
@@ -4,11 +4,22 @@ type MergedStateValue<Obj extends Record<string, State>> = {
 	[key in keyof Obj]: [key: key, value: Obj[key]["value"]];
 }[keyof Obj];
 
-export class ReadonlyState<T = any> {
-	protected subscribers: Subscriber<T>[] = [];
+export interface ReadonlyState<T = any> {
+	value: T;
+	listen(listener: Subscriber<T>): void;
+	map<U>(mapper: (t: T) => U): ReadonlyState<U>;
+	into(state: State<T>): void;
+}
+
+const StateSymbol = Symbol("@hyperactive/state");
+
+export class State<T = any> implements ReadonlyState<T> {
+	#subscribers: Subscriber<T>[] = [];
 	#state: { value: T };
+	[StateSymbol] = true;
 
-	constructor(state: { value: T }) {
+	constructor(value: T) {
+		const state = { value };
 		this.#state = state;
 	}
 
@@ -17,33 +28,7 @@ export class ReadonlyState<T = any> {
 	}
 
 	static isState<X>(x: X): x is Extract<X, State | ReadonlyState> {
-		return x instanceof ReadonlyState;
-	}
-
-	listen(listener: Subscriber<T>) {
-		this.subscribers.push(listener);
-	}
-
-	map<U>(mapper: (t: T) => U) {
-		const s = new State(mapper(this.value));
-		// publish mapped changes when value changes
-		this.listen(value => s.publish(mapper(value)));
-		// return readonly so mapped state can't be published into
-		return s.readonly();
-	}
-
-	into(state: State<T>) {
-		this.listen(value => state.publish(value));
-	}
-}
-
-export class State<T = any> extends ReadonlyState<T> {
-	#state: { value: T };
-
-	constructor(value: T) {
-		const state = { value };
-		super(state);
-		this.#state = state;
+		return x && typeof x === "object" && StateSymbol in x;
 	}
 
 	/**
@@ -55,31 +40,55 @@ export class State<T = any> extends ReadonlyState<T> {
 
 	static merge<T, RefMap extends { [k: string]: State }>(
 		...states: [State<T> | RefMap, ...State<T>[]]
-	): State<T> | State<[number, T]> | State<MergedStateValue<RefMap>> {
+	): ReadonlyState<[number, T]> | ReadonlyState<MergedStateValue<RefMap>> {
 		if (State.isState(states[0])) {
 			const merged = new State<[number, T]>([0, states[0].value]);
 			for (let index = 0; index < states.length; index++) {
 				const state = states[index] as State<T>;
 				state.listen(updated => merged.publish([index, updated]));
 			}
-			return merged;
+			return merged.readonly();
 		} else {
 			const obj = states[0];
 			type MergedValue = MergedStateValue<RefMap>;
 			const merged = new State<MergedValue>(Object.values(obj)[0]?.value);
 			for (const key in obj) obj[key].listen(updated => merged.publish([key, updated]));
-			return merged;
+			return merged.readonly();
 		}
 	}
 
 	publish(next: T | Promise<T>) {
 		return Promise.resolve(next).then(val => {
 			this.#state.value = val;
-			this.subscribers.forEach(subscriber => subscriber(val));
+			this.#subscribers.forEach(subscriber => subscriber(val));
 		});
 	}
 
+	listen(listener: Subscriber<T>) {
+		this.#subscribers.push(listener);
+	}
+
+	map<U>(mapper: (t: T) => U): ReadonlyState<U> {
+		const s = new State(mapper(this.value));
+		// publish mapped changes when value changes
+		this.listen(value => s.publish(mapper(value)));
+		// return readonly so mapped state can't be published into
+		return s.readonly();
+	}
+
+	into(state: State<T>) {
+		this.listen(value => state.publish(value));
+	}
+
 	readonly() {
-		return new ReadonlyState(this.#state);
+		return {
+			get value(): T {
+				return this.value;
+			},
+			listen: this.listen.bind(this),
+			map: this.map.bind(this),
+			into: this.into.bind(this),
+			[StateSymbol]: true,
+		};
 	}
 }
