rxact/es/stateStream/eventRunnerFactory.js

an observable application management for Javascript apps

import isObservable from '../utils/isObservable';


var defaultFactory = function defaultFactory(source) {
  return source;
};

var source$Creator = function source$Creator(inputSource$, Observable, getState) {
  if (inputSource$ === undefined) {
    return Observable.of(getState());
  }

  if (isObservable(inputSource$)) {
    return inputSource$;
  }

  return Observable.of(inputSource$);
};

var eventRunnerFactory = function eventRunnerFactory(Observable, getState) {
  var eventRunner = function eventRunner(factory, inputSource$) {
    var source$ = source$Creator(inputSource$, Observable, getState);

    if (factory === null || factory === undefined) {
      factory = defaultFactory;
    }

    if (typeof factory !== 'function') {
      throw new Error('Expected first parameter of eventRunner to be a function.');
    }

    var outputSource$ = factory(source$);

    if (!outputSource$ || !isObservable(outputSource$)) {
      throw new Error('Expected an Observable object returned by factory in eventRunner');
    }

    var output = void 0;
    var next = void 0;
    var subscription = void 0;

    var stream$ = new Observable(function (observer) {
      if (output !== undefined) {
        observer.next(output);
      }

      next = function next(value) {
        return observer.next(value);
      };

      return {
        unsubscribe: function unsubscribe() {
          subscription.unsubscribe();
        }
      };
    });

    subscription = outputSource$.subscribe(function (value) {
      if (typeof next === 'function') {
        next(value);
      }

      output = value;
    });

    return stream$;
  };

  return eventRunner;
};

export default eventRunnerFactory;