mqtt/src/lib/TypedEmitter.ts

A library for the MQTT protocol

import EventEmitter from 'events'
import { applyMixin } from './shared'

export type EventHandler =
	// Add more overloads as necessary
	| ((arg1: any, arg2: any, arg3: any, arg4: any) => void)
	| ((arg1: any, arg2: any, arg3: any) => void)
	| ((arg1: any, arg2: any) => void)
	| ((arg1: any) => void)
	| ((...args: any[]) => void)

export interface TypedEventEmitter<
	TEvents extends Record<keyof TEvents, EventHandler>,
> {
	on<TEvent extends keyof TEvents>(
		event: TEvent,
		callback: TEvents[TEvent],
	): this
	once<TEvent extends keyof TEvents>(
		event: TEvent,
		callback: TEvents[TEvent],
	): this
	prependListener<TEvent extends keyof TEvents>(
		event: TEvent,
		callback: TEvents[TEvent],
	): this
	prependOnceListener<TEvent extends keyof TEvents>(
		event: TEvent,
		callback: TEvents[TEvent],
	): this

	removeListener<TEvent extends keyof TEvents>(
		event: TEvent,
		callback: TEvents[TEvent],
	): this
	off<TEvent extends keyof TEvents>(
		event: TEvent,
		callback: TEvents[TEvent],
	): this

	removeAllListeners(event?: keyof TEvents): this

	emit<TEvent extends keyof TEvents>(
		event: TEvent,
		...args: Parameters<TEvents[TEvent]>
	): boolean

	setMaxListeners(n: number): this
	getMaxListeners(): number

	listeners<TEvent extends keyof TEvents>(
		eventName: TEvent,
	): TEvents[TEvent][]
	rawListeners<TEvent extends keyof TEvents>(
		eventName: TEvent,
	): TEvents[TEvent][]
	listenerCount<TEvent extends keyof TEvents>(
		event: TEvent,
		listener?: TEvents[TEvent],
	): number

	eventNames(): Array<keyof TEvents>
}

// eslint-disable-next-line @typescript-eslint/no-unsafe-declaration-merging
export class TypedEventEmitter<
	TEvents extends Record<keyof TEvents, EventHandler>,
> {}

// Make TypedEventEmitter inherit from EventEmitter without actually extending
applyMixin(TypedEventEmitter, EventEmitter)