import type { PartialObserver } from './types/inputs/Observer.js';
import type { Subscribable, SubscribableValue } from './types/inputs/Subscribable.js';
import type { MappingKey } from './types/mapping.js';
import type { ListenEventMap, StrictListenable } from './types/outputs/StrictListenable.js';
export type OnceCallback<in D = any> = (data: D) => void;
/**
 * Register a callback that will be called only once
 *
 * @since 1.0.0
 */
export declare function once$<O extends Subscribable>(observable: O, callback: OnceCallback<SubscribableValue<O>>): ReturnType<O['subscribe']>;
/**
 * Register an observer that completes right after the first call (either "next" or "error")
 *
 * @since 1.0.0
 */
export declare function once$<O extends Subscribable>(observable: O, observer: PartialObserver<SubscribableValue<O>>): ReturnType<O['subscribe']>;
/**
 Register a callback that will be called only once

 @since 1.0.0
 */
export declare function once$<L extends StrictListenable, K extends MappingKey<ListenEventMap<L>>>(listenable: L, key: K, callback: OnceCallback<ListenEventMap<L>[K]>): ReturnType<L['on']>;
/**
 * Register an observer to a given event, that completes right after the first call (either "next" or "error")
 *
 * @since 1.0.0
 */
export declare function once$<L extends StrictListenable, K extends MappingKey<ListenEventMap<L>>>(listenable: L, key: K, observer: PartialObserver<ListenEventMap<L>[K]>): ReturnType<L['on']>;