import { AnyActorSystem } from "../system.js"; import { ActorLogic, ActorRefFrom, AnyEventObject, EventObject, NonReducibleUnknown, Snapshot } from "../types.js"; export type CallbackSnapshot = Snapshot & { input: TInput; }; export type CallbackActorLogic = ActorLogic, TEvent, TInput, AnyActorSystem, EventObject>; export type CallbackActorRef = ActorRefFrom>; export type Receiver = (listener: { bivarianceHack(event: TEvent): void; }['bivarianceHack']) => void; export type InvokeCallback = ({ input, system, self, sendBack, receive }: { /** * Data that was provided to the callback actor * @see {@link https://stately.ai/docs/input | Input docs} */ input: TInput; /** * The actor system to which the callback actor belongs */ system: AnyActorSystem; /** * The parent actor of the callback actor */ self: CallbackActorRef; /** * A function that can send events back to the parent actor */ sendBack: (event: TSentEvent) => void; /** * A function that can be called with a listener function argument; * the listener is then called whenever events are received by the callback actor */ receive: Receiver; }) => (() => void) | void; /** * An actor logic creator which returns callback logic as defined by a callback function. * * @remarks * Useful for subscription-based or other free-form logic that can send events back to the parent actor. * * Actors created from callback logic (“callback actors”) can: * - Receive events via the `receive` function * - Send events to the parent actor via the `sendBack` function * * Callback actors are a bit different from other actors in that they: * - Do not work with `onDone` * - Do not produce a snapshot using `.getSnapshot()` * - Do not emit values when used with `.subscribe()` * - Can not be stopped with `.stop()` * * @param invokeCallback - The callback function used to describe the callback logic * The callback function is passed an object with the following properties: * - `receive` - A function that can send events back to the parent actor; the listener is then called whenever events are received by the callback actor * - `sendBack` - A function that can send events back to the parent actor * - `input` - Data that was provided to the callback actor * - `self` - The parent actor of the callback actor * - `system` - The actor system to which the callback actor belongs * The callback function can (optionally) return a cleanup function, which is called when the actor is stopped. * @see {@link InvokeCallback} for more information about the callback function and its object argument * @see {@link https://stately.ai/docs/input | Input docs} for more information about how input is passed * @returns Callback logic * * @example * ```typescript * const callbackLogic = fromCallback(({ sendBack, receive }) => { * let lockStatus = 'unlocked'; * * const handler = (event) => { * if (lockStatus === 'locked') { * return; * } * sendBack(event); * }; * * receive((event) => { * if (event.type === 'lock') { * lockStatus = 'locked'; * } else if (event.type === 'unlock') { * lockStatus = 'unlocked'; * } * }); * * document.body.addEventListener('click', handler); * * return () => { * document.body.removeEventListener('click', handler); * }; * }); * ``` */ export declare function fromCallback(invokeCallback: InvokeCallback): CallbackActorLogic;