import { State } from "../state.js";

//#region src/field/get.d.ts
declare namespace get {
  type Callback<T = any> = (state: T, subject: State) => void | boolean | (() => void);
}
/**
 * Fetches upstream State from context with optional lifecycle callback.
 * Callback runs on mount and can return cleanup function for unmount.
 *
 * @param Type - Type of State to fetch.
 * @param callback - Optional lifecycle callback, receives (state, subject). Can return cleanup function.
 */
declare function get<T extends State>(Type: State.Extends<T>, callback?: get.Callback<T>): T;
/**
 * Fetches and assigns the controller which spawned this host.
 * When parent assigns an instance via `use()` directive, it
 * will be made available to child upon this request.
 *
 * @param Type - Type of controller compatible with this class.
 * @param required - If false, property may be undefined. Otherwise will throw.
 */
declare function get<T extends State>(Type: State.Extends<T>, required: false): T | undefined;
/**
 * Collects downstream States, accumulating all instances of specified type
 * for which this is an ancestor. Returns an array that updates as States
 * are added or removed. Callback runs on each registration and can return
 * cleanup or false to prevent registration.
 *
 * @param Type - Type of State to collect.
 * @param downstream - Must be true to enable downstream mode.
 * @param callback - Optional lifecycle callback, receives (state, subject). May return false to prevent registration.
 */
declare function get<T extends State>(Type: State.Extends<T>, downstream: true, callback?: get.Callback<T>): T[];
/**
 * Fetches a single downstream State of specified type.
 * Updates when a matching child appears or is removed.
 * Throws if not found.
 *
 * @param Type - Type of State to fetch.
 * @param downstream - Must be true to enable downstream mode.
 * @param required - Throw if no match found.
 */
declare function get<T extends State>(Type: State.Extends<T>, downstream: true, single: true): T;
/**
 * Fetches a single downstream State of specified type.
 * Updates when a matching child appears or is removed.
 * Returns undefined if not found.
 *
 * @param Type - Type of State to fetch.
 * @param downstream - Must be true to enable downstream mode.
 * @param required - If false, returns undefined if no match found.
 */
declare function get<T extends State>(Type: State.Extends<T>, downstream: true, required: false): T | undefined;
//#endregion
export { get };
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