import type { Observable } from '../../external/rxjs/index.js';
export type { Observable } from '../../external/rxjs/index.js';
export type ObserverCallback<T> = (value: T) => void;
export declare class UmbObserver<T> {
    #private;
    constructor(source: Observable<T>, callback?: ObserverCallback<T>);
    /**
     * provides a promise which is resolved ones the observer got a value that is not undefined.
     * Notice this promise will resolve immediately if the Observable holds an empty array or empty string.
     *
     */
    asPromise(): Promise<Exclude<T, undefined>>;
    hostConnected(): void;
    hostDisconnected(): void;
    destroy(): void;
}