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- import { createNanoEvents, type DefaultEvents, type Emitter, type EventsMap, type Unsubscribe } from "nanoevents";
- export interface NanoEmitterOptions {
- /** If set to true, allows emitting events through the public method emit() */
- publicEmit: boolean;
- }
- /** Class that can be extended or instantiated by itself to create an event emitter with helper methods and a strongly typed event map */
- export class NanoEmitter<TEvtMap extends EventsMap = DefaultEvents> {
- protected readonly events: Emitter<TEvtMap> = createNanoEvents<TEvtMap>();
- protected eventUnsubscribes: Unsubscribe[] = [];
- protected emitterOptions: NanoEmitterOptions;
- constructor(options: Partial<NanoEmitterOptions> = {}) {
- this.emitterOptions = {
- publicEmit: false,
- ...options,
- };
- }
- /** Subscribes to an event - returns a function that unsubscribes the event listener */
- public on<TKey extends keyof TEvtMap>(event: TKey | "_", cb: TEvtMap[TKey]): () => void {
- // eslint-disable-next-line prefer-const
- let unsub: Unsubscribe | undefined;
- const unsubProxy = (): void => {
- if(!unsub)
- return;
- unsub();
- this.eventUnsubscribes = this.eventUnsubscribes.filter(u => u !== unsub);
- };
- unsub = this.events.on(event, cb);
- this.eventUnsubscribes.push(unsub);
- return unsubProxy;
- }
- /** Subscribes to an event and calls the callback or resolves the Promise only once */
- public once<TKey extends keyof TEvtMap>(event: TKey | "_", cb?: TEvtMap[TKey]): Promise<Parameters<TEvtMap[TKey]>> {
- return new Promise((resolve) => {
- // eslint-disable-next-line prefer-const
- let unsub: Unsubscribe | undefined;
- const onceProxy = ((...args: Parameters<TEvtMap[TKey]>) => {
- unsub!();
- cb?.(...args);
- resolve(args);
- }) as TEvtMap[TKey];
- unsub = this.on(event, onceProxy);
- });
- }
- /** Emits an event on this instance - Needs `publicEmit` to be set to true in the constructor! */
- public emit<TKey extends keyof TEvtMap>(event: TKey, ...args: Parameters<TEvtMap[TKey]>): boolean {
- if(this.emitterOptions.publicEmit) {
- this.events.emit(event, ...args);
- return true;
- }
- return false;
- }
- /** Unsubscribes all event listeners */
- public unsubscribeAll(): void {
- for(const unsub of this.eventUnsubscribes)
- unsub();
- this.eventUnsubscribes = [];
- }
- }
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