/
WatchEmitter.ts
48 lines (40 loc) · 1.24 KB
/
WatchEmitter.ts
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import { EventEmitter } from 'node:events';
type PromiseReturn<T extends (...args: any) => any> = (
...args: Parameters<T>
) => Promise<ReturnType<T>>;
export class WatchEmitter<
T extends { [event: string]: (...args: any) => any }
> extends EventEmitter {
private awaitedHandlers: {
[K in keyof T]?: PromiseReturn<T[K]>[];
} = Object.create(null);
constructor() {
super();
// Allows more than 10 bundles to be watched without
// showing the `MaxListenersExceededWarning` to the user.
this.setMaxListeners(Infinity);
}
// Will be overwritten by Rollup
async close(): Promise<void> {}
emitAndAwait<K extends keyof T>(
event: K,
...args: Parameters<T[K]>
): Promise<ReturnType<T[K]>[]> {
this.emit(event as string, ...(args as any[]));
return Promise.all(this.getHandlers(event).map(handler => handler(...args)));
}
onCurrentAwaited<K extends keyof T>(
event: K,
listener: (...args: Parameters<T[K]>) => Promise<ReturnType<T[K]>>
): this {
this.getHandlers(event).push(listener);
return this;
}
removeAwaited(): this {
this.awaitedHandlers = {};
return this;
}
private getHandlers<K extends keyof T>(event: K): PromiseReturn<T[K]>[] {
return this.awaitedHandlers[event] || (this.awaitedHandlers[event] = []);
}
}