Observable実装

observable.ts

// [実装して学ぶRxJS - undefined](http://blog.bokuweb.me/entry/min-rxjs)

interface IObserver<T> {
    next: (v: T) => any;
    complete: () => any;
}

interface Producer<T> {
    (observer: IObserver<T>): any;
}

class Observable<T> {
    subscribe: (observer: IObserver<T>) => any;

    constructor(producer: (observer: IObserver<T>) => any) {
        this.subscribe = producer;
    }

    map<R>(f: (v: T) => R) {
        const producer: Producer<R> = (observer) => {
            return this.subscribe({
                next: (v: T) => observer.next(f(v)),
                complete: () => observer.complete()
            });
        };
        return new Observable<R>(producer);
    }

    static of<T>(...values: T[]) {
        const producer = (observer: IObserver<T>) => {
            values.forEach(x => observer.next(x));
            observer.complete();
        };
        return new Observable<T>(producer);
    }
}

Observable.of(1, 2, 3).map((n => n.toString())).subscribe({
    next: (s) => console.log(s),
    complete: () => console.log('done')
});