import { OpenPromise } from "./OpenPromise.js";
/**
 * A subscription is a promise that gets reresolved multiple times.
 *
 * Subscriptions implments the asynchronous iterable protocol (@see AsyncIterable).
 * This makes it easy to iterate on subscriptions.
 *
 * @example ```
 * async function demo() {
 *    let subscription = new Subscription<string>();
 *
 *     global.setTimeout(() => {
 *         subscription.setCurrent(new Date().toString());
 *     }, 1000)
 *
 *     for await (let item of subscription) {
 *         console.log(item, "Subscription has new data")
 *     }
 * }
 * ```
 */
export declare class Subscription<T> implements AsyncIterable<T> {
    _current: T | undefined;
    pending: OpenPromise<T>;
    [Symbol.asyncIterator](): AsyncIterator<T>;
    get current(): Promise<T>;
    setCurrent(value: T): void;
}
export declare class SubscribedResourceIterator<T> implements AsyncIterator<T> {
    source: Subscription<T>;
    hasDeliveredFirst: boolean;
    constructor(source: Subscription<T>);
    next(): Promise<IteratorResult<T, any>>;
}