import { Emitter } from './emitter';
import { Observable } from './observable';
/**
 * An event emitter class used to emit events and register listeners.
 */
export declare class Event<Args extends Array<any> = []> extends Emitter<Args> {
    hasListeners: Observable<boolean, never>;
    /**
     * Emit an event.
     *
     * @param a - The argument to pass to handler functions.
     */
    emit(...args: Args): void;
    /**
     * Clears all listeners from the event. If there are no listeners, it sets `this.hasListeners.value` to `true`.
     */
    clearListeners(): void;
    /**
     * Adds a listener to the event. After adding the listener, it sets `this.hasListeners.value` to `true`.
     *
     * @param f - The listener function to add.
     * @param priority - The priority of the listener. Higher priority listeners are called first.
     */
    addListener(f: (...args: Args) => void, priority?: number): void;
    /**
     * Removes a listener from the event. If there are no more listeners after the removal, it sets `this.hasListeners.value` to `false`.
     *
     * @param f - The listener function to remove.
     */
    removeListener(f: (...args: Args) => void): void;
}