Auto reload and bug fixes

public/js-source/src/utils/resolvable.ts

@@ -0,0 +1,78 @@
+enum ResolvableState {
+	WAITING,
+	PENDING,
+	ERROR,
+	DONE
+}
+
+class FetchOnce<T> {
+	protected data: T|undefined;
+	protected error: unknown|undefined;
+	protected state: ResolvableState = ResolvableState.WAITING;
+	protected pendings: [(res: Promise<T>|T) => void, (reason: unknown) => void][] = [];
+
+	constructor(protected fetchMethod?: () => Promise<T>) {  }
+
+	public resolve(): Promise<T> {
+		return new Promise((resolve, reject) => {
+			switch (this.state) {
+				case ResolvableState.WAITING:
+					this.state = ResolvableState.PENDING;
+					this.pendings.push([resolve, reject]);
+					if (this.fetchMethod) this.parsePromise(this.fetchMethod());
+					break;
+				case ResolvableState.PENDING:
+					this.pendings.push([resolve, reject]);
+					break;
+				case ResolvableState.DONE:
+					resolve(this.data);
+					break;
+				case ResolvableState.ERROR:
+					reject(this.error);
+					break;
+			}
+		});
+	}
+
+	protected isFinished(): boolean {
+		return this.state === ResolvableState.DONE || this.state === ResolvableState.ERROR;
+	}
+
+	protected parsePromise(promise: Promise<T>): void {
+		promise.then((data) => {
+			this.data = data;
+			this.state = ResolvableState.DONE;
+			this.pendings.forEach(pending => pending[0](data));
+		}).catch(err => {
+			this.error = err;
+			this.state = ResolvableState.ERROR;
+			this.pendings.forEach(pending => pending[1](err));
+		});
+	}
+}
+
+export class Resolvable<T> extends FetchOnce<T> {
+	constructor(fetchMethod: () => Promise<T>) {
+		super(fetchMethod);
+	}
+}
+
+export class WaitForSync<T> extends FetchOnce<T> {
+	protected state: ResolvableState = ResolvableState.PENDING;
+
+	constructor() {
+		super(undefined);
+	}
+
+	public setData(data: T): void {
+		if (!this.isFinished()) {
+			this.parsePromise((async () => data)());
+		}
+	}
+
+	public setError(error: unknown): void {
+		if (!this.isFinished()) {
+			this.parsePromise((async () => { throw error; })());
+		}
+	}
+}