/**
 * @class
 * @description Gives event emitting/listening functionalities to its extenders.
 * @exports Emitter
 * @abstract
 */
export default abstract class Emitter {
    private _listeners;
    /**
     * Sets a listener to a given event. Use {@link emit} to trigger those events.
     * @param {string} eventName Name of the event.
     * @param {callback} callback Callback of the event. Receives event and data.
     * @return {this} Polymorphic with the type of the child class.
     * @public
     */
    on(eventName: string, callback: callback): this;
    /**
     * Removes given callback from the listeners of this object.
     * @param {string} eventName Name of the event.
     * @param {callback} callback Callback of the event.
     * @return {this} Polymorphic with the type of the child class.
     * @public
     */
    off(eventName: string, callback: callback): this;
    /**
     * Emits given event, triggering all the associated callbacks.
     * @param {string} eventName Name of the event.
     * @param {object} data Custom data to be sent to the callbacks.
     * @return {this} Polymorphic with the type of the child class
     * @protected
     */
    protected emit(eventName: string, data?: unknown): this;
}