export default class EventBus<EventTypes> {
    private handlers;
    /**
     * Subscribe to an event
     */
    subscribe<E extends keyof EventTypes>(eventType: E, callback: (data: EventTypes[E]) => void): () => void;
    /**
     * Subscribe to an event once
     */
    once<E extends keyof EventTypes>(eventType: E, callback: (data: EventTypes[E]) => void): () => void;
    /**
     * Unsubscribe a specific callback from an event by reference
     * @returns true if the callback was found and removed, false otherwise
     */
    unsubscribe<E extends keyof EventTypes>(eventType: E, callback: (data: EventTypes[E]) => void): boolean;
    /**
     * Internal method to add an event handler
     */
    private addHandler;
    /**
     * Publish an event. Data is required unless EventTypes[E] extends void | undefined.
     * Zero-allocation hot path: uses index-based iteration with a snapshot length
     * so handlers added mid-publish are not called in the same publish cycle.
     */
    publish<E extends keyof EventTypes>(eventType: EventTypes[E] extends void | undefined ? E : never): void;
    publish<E extends keyof EventTypes>(eventType: E, data: EventTypes[E]): void;
    clear(): void;
    clearEvent<E extends keyof EventTypes>(eventType: E): void;
}