import { ConcurrentCollection } from './ConcurrentCollection.js';
/**
 * A listener callback for a {@link Notifier}.
 *
 * @category Helper
 */
export type Listener<E> = (event: E) => void;
/**
 * A base class that can be listened to, and dispatch events.
 *
 * @category Helper
 */
export declare abstract class Notifier<E> {
    protected readonly listeners: ConcurrentCollection<Listener<E>>;
    /** Listen to events from this helper. Duplicate listeners allowed. */
    addEventListener(listener: Listener<E>): void;
    /**
     * Stop listening to events from this helper. If a duplicate listener is
     * removed, only one is removed.
     *
     * @returns True if a listener was removed, false otherwise.
     */
    removeEventListener(listener: Listener<E>): boolean;
    /**
     * Dispatch an event to a specific listener. Listener does not have to be
     * added
     */
    protected dispatchToListener(event: E, listener: Listener<E>): void;
    /** Dispatch an event to all listeners. */
    protected dispatchEvent(event: E): void;
}