import type { Dictionary } from './types.js';
/** Options for {@link MicroEvents.subscribe} to control when and how long a handler stays subscribed */
export type SubscribeOptions<TEvents extends Dictionary, K extends keyof TEvents> = {
    /** Only invoke the handler when this returns true */
    when?: (data: TEvents[K]) => boolean;
    /** Automatically unsubscribe after the handler runs once (respects `when`, if given) */
    once?: boolean;
};
/**
 * A simple, environment-agnostic event bus. Instantiate once and use that single
 * instance to subscribe to and trigger typed events, without binding to any other source.
 *
 * @typeParam TEvents - A dictionary mapping event names to the type of data they carry
 *
 * @example
 *
 * ```ts
 * const events = new MicroEvents<{ greet: string }>();
 * const unsubscribe = events.subscribe('greet', (name) => console.log(`Hello, ${name}!`));
 *
 * events.trigger('greet', 'World'); // Logs: "Hello, World!"
 * unsubscribe();
 * ```
 */
export declare class MicroEvents<TEvents extends Dictionary> {
    #private;
    /**
     * Subscribe a handler to the given event
     *
     * @param eventName - The event to subscribe to
     * @param handler - Handler to call whenever the event is triggered
     * @param options - Options to control when and how long the handler stays subscribed
     * @typeParam K - The inferred event name
     * @returns A function that removes this subscription when called
     *
     * @example
     *
     * ```ts
     * const unsubscribe = events.subscribe('greet', (name) => console.log(name));
     *
     * events.subscribe('greet', (name) => console.log(name), { once: true });
     * events.subscribe('greet', (name) => console.log(name), { when: (name) => name !== '' });
     * ```
     */
    subscribe<K extends keyof TEvents>(eventName: K, handler: (data: TEvents[K]) => unknown, options?: SubscribeOptions<TEvents, K>): () => void;
    /**
     * Remove a specific handler previously subscribed to the given event
     *
     * @param eventName - The event to remove the handler from
     * @param handler - The handler to remove (the exact reference passed to, or returned by, `subscribe`)
     * @typeParam K - The inferred event name
     */
    unsubscribe<K extends keyof TEvents>(eventName: K, handler: (data: TEvents[K]) => unknown): void;
    /**
     * Remove every handler subscribed to the given event
     *
     * @param eventName - The event to clear all handlers from
     * @typeParam K - The inferred event name
     */
    unsubscribeAll<K extends keyof TEvents>(eventName: K): void;
    /**
     * Call every handler subscribed to the given event with the given data
     *
     * @param eventName - The event to trigger
     * @param data - The data to pass to each subscribed handler
     * @typeParam K - The inferred event name
     */
    trigger<K extends keyof TEvents>(eventName: K, data: TEvents[K]): void;
}