rxact/es/stateStream/combineStateSteams.js

an observable application management for Javascript apps

var _extends = Object.assign || function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };

function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }

function _toConsumableArray(arr) { if (Array.isArray(arr)) { for (var i = 0, arr2 = Array(arr.length); i < arr.length; i++) { arr2[i] = arr[i]; } return arr2; } else { return Array.from(arr); } }

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


function combineStateStreams(state$, streamName, stateStreams) {
  var _this = this;

  if (!stateStreams || stateStreams.length === 0) {
    return state$;
  }

  var streamNames = {};
  var streams = [].concat(_toConsumableArray(stateStreams), [{ streamName: streamName, state$: state$ }]);

  streams.forEach(function (stream) {
    if (!(stream instanceof StateStream) && (!isObservable(stream.state$) || !stream.streamName)) {
      throw new Error('Expected the element of stateStreams to be instance of StateStream.');
    }

    streamNames[stream.streamName] = true;
  });

  if (Object.keys(streamNames).length !== streams.length) {
    throw new Error('StateStreams\' name should be unique.');
  }

  var combinedState$ = new this.Observable(function (observer) {
    var currentState = {};

    var subscriptions = streams.map(function (source) {
      return source.state$.subscribe(function (state) {
        var sourceName = source.streamName;

        var nextState = _extends({}, currentState, _defineProperty({}, sourceName, state));
        currentState = nextState;

        if (Object.keys(currentState).length === streams.length) {
          observer.next(currentState);
        }
      });
    });

    _this.subscriptions = _this.subscriptions.concat(subscriptions);

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

  return combinedState$;
}

export default combineStateStreams;