Reactive Store

reactive-store.ts

import { ReplaySubject } from 'rxjs/ReplaySubject';
import { Observable } from 'rxjs/Observable';

export abstract class ReplayStore<T> {

  private _isInitialized = false;
  private _state: T;
  private _state$: ReplaySubject<T>;

  constructor() {
    this._state$ = new ReplaySubject<T>(1);
    this._state$
      .subscribe((state) => this._state = state);
  }

  get state(): T {
    return this._state;
  }

  get replaySubject(): Observable<T> {

    if (!this._isInitialized) {
      return this._lazyInit()
        .do((state) => this._setState(state));
    }

    return this._state$.asObservable();
  }

  protected abstract _lazyInit(): Observable<T>;

  protected _setIsInitialized() {
    this._isInitialized = true;
  }

  protected _setState(state: T) {
    this._state$.next(state);
  }

}