import Subscription, { Subscriber } from "./Subscription";
export interface IObserver<T> {
    next(x: T): any;
    complete(): any;
    error(x: Error): any;
}
export interface IObservable<T> extends IObserver<T> {
    closed(): boolean;
}
export declare type SimpleObserver<T> = (x: T) => any;
export declare type UnaryFn<T, R> = (source: T) => R;
export declare type OperatorFunction<T, R> = UnaryFn<Observable<T>, Observable<R>>;
export default class Observable<T = any> {
    protected subscriber: Subscriber<T>;
    static of<U>(...items: U[]): Observable<U>;
    static from<U = any>(items: U[]): Observable<U>;
    constructor(subscriber: Subscriber<T>);
    pipe<R>(...fns: Array<OperatorFunction<T, R>>): Observable<R>;
    subscribe(observer: IObserver<T> | SimpleObserver<T>, error?: (err: Error) => void, complete?: () => void): Subscription<T>;
    protected _subscribe(observer: IObserver<T>, subscriber: Subscriber<T>): Subscription<T>;
}