248 lines
8.7 KiB
JavaScript
248 lines
8.7 KiB
JavaScript
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import isPlainObject from 'lodash-es/isPlainObject';
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import $$observable from 'symbol-observable';
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/**
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* These are private action types reserved by Redux.
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* For any unknown actions, you must return the current state.
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* If the current state is undefined, you must return the initial state.
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* Do not reference these action types directly in your code.
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*/
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export var ActionTypes = {
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INIT: '@@redux/INIT'
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/**
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* Creates a Redux store that holds the state tree.
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* The only way to change the data in the store is to call `dispatch()` on it.
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*
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* There should only be a single store in your app. To specify how different
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* parts of the state tree respond to actions, you may combine several reducers
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* into a single reducer function by using `combineReducers`.
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*
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* @param {Function} reducer A function that returns the next state tree, given
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* the current state tree and the action to handle.
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*
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* @param {any} [preloadedState] The initial state. You may optionally specify it
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* to hydrate the state from the server in universal apps, or to restore a
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* previously serialized user session.
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* If you use `combineReducers` to produce the root reducer function, this must be
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* an object with the same shape as `combineReducers` keys.
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*
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* @param {Function} [enhancer] The store enhancer. You may optionally specify it
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* to enhance the store with third-party capabilities such as middleware,
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* time travel, persistence, etc. The only store enhancer that ships with Redux
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* is `applyMiddleware()`.
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*
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* @returns {Store} A Redux store that lets you read the state, dispatch actions
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* and subscribe to changes.
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*/
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};export default function createStore(reducer, preloadedState, enhancer) {
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var _ref2;
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if (typeof preloadedState === 'function' && typeof enhancer === 'undefined') {
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enhancer = preloadedState;
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preloadedState = undefined;
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}
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if (typeof enhancer !== 'undefined') {
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if (typeof enhancer !== 'function') {
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throw new Error('Expected the enhancer to be a function.');
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}
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return enhancer(createStore)(reducer, preloadedState);
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}
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if (typeof reducer !== 'function') {
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throw new Error('Expected the reducer to be a function.');
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}
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var currentReducer = reducer;
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var currentState = preloadedState;
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var currentListeners = [];
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var nextListeners = currentListeners;
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var isDispatching = false;
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function ensureCanMutateNextListeners() {
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if (nextListeners === currentListeners) {
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nextListeners = currentListeners.slice();
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}
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}
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/**
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* Reads the state tree managed by the store.
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*
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* @returns {any} The current state tree of your application.
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*/
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function getState() {
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return currentState;
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}
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/**
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* Adds a change listener. It will be called any time an action is dispatched,
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* and some part of the state tree may potentially have changed. You may then
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* call `getState()` to read the current state tree inside the callback.
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*
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* You may call `dispatch()` from a change listener, with the following
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* caveats:
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*
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* 1. The subscriptions are snapshotted just before every `dispatch()` call.
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* If you subscribe or unsubscribe while the listeners are being invoked, this
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* will not have any effect on the `dispatch()` that is currently in progress.
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* However, the next `dispatch()` call, whether nested or not, will use a more
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* recent snapshot of the subscription list.
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*
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* 2. The listener should not expect to see all state changes, as the state
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* might have been updated multiple times during a nested `dispatch()` before
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* the listener is called. It is, however, guaranteed that all subscribers
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* registered before the `dispatch()` started will be called with the latest
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* state by the time it exits.
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*
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* @param {Function} listener A callback to be invoked on every dispatch.
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* @returns {Function} A function to remove this change listener.
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*/
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function subscribe(listener) {
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if (typeof listener !== 'function') {
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throw new Error('Expected listener to be a function.');
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}
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var isSubscribed = true;
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ensureCanMutateNextListeners();
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nextListeners.push(listener);
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return function unsubscribe() {
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if (!isSubscribed) {
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return;
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}
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isSubscribed = false;
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ensureCanMutateNextListeners();
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var index = nextListeners.indexOf(listener);
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nextListeners.splice(index, 1);
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};
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}
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/**
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* Dispatches an action. It is the only way to trigger a state change.
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*
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* The `reducer` function, used to create the store, will be called with the
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* current state tree and the given `action`. Its return value will
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* be considered the **next** state of the tree, and the change listeners
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* will be notified.
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*
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* The base implementation only supports plain object actions. If you want to
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* dispatch a Promise, an Observable, a thunk, or something else, you need to
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* wrap your store creating function into the corresponding middleware. For
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* example, see the documentation for the `redux-thunk` package. Even the
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* middleware will eventually dispatch plain object actions using this method.
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*
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* @param {Object} action A plain object representing “what changed”. It is
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* a good idea to keep actions serializable so you can record and replay user
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* sessions, or use the time travelling `redux-devtools`. An action must have
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* a `type` property which may not be `undefined`. It is a good idea to use
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* string constants for action types.
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*
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* @returns {Object} For convenience, the same action object you dispatched.
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*
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* Note that, if you use a custom middleware, it may wrap `dispatch()` to
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* return something else (for example, a Promise you can await).
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*/
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function dispatch(action) {
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if (!isPlainObject(action)) {
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throw new Error('Actions must be plain objects. ' + 'Use custom middleware for async actions.');
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}
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if (typeof action.type === 'undefined') {
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throw new Error('Actions may not have an undefined "type" property. ' + 'Have you misspelled a constant?');
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}
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if (isDispatching) {
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throw new Error('Reducers may not dispatch actions.');
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}
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try {
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isDispatching = true;
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currentState = currentReducer(currentState, action);
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} finally {
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isDispatching = false;
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}
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var listeners = currentListeners = nextListeners;
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for (var i = 0; i < listeners.length; i++) {
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var listener = listeners[i];
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listener();
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}
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return action;
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}
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/**
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* Replaces the reducer currently used by the store to calculate the state.
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*
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* You might need this if your app implements code splitting and you want to
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* load some of the reducers dynamically. You might also need this if you
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* implement a hot reloading mechanism for Redux.
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*
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* @param {Function} nextReducer The reducer for the store to use instead.
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* @returns {void}
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*/
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function replaceReducer(nextReducer) {
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if (typeof nextReducer !== 'function') {
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throw new Error('Expected the nextReducer to be a function.');
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}
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currentReducer = nextReducer;
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dispatch({ type: ActionTypes.INIT });
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}
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/**
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* Interoperability point for observable/reactive libraries.
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* @returns {observable} A minimal observable of state changes.
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* For more information, see the observable proposal:
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* https://github.com/tc39/proposal-observable
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*/
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function observable() {
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var _ref;
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var outerSubscribe = subscribe;
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return _ref = {
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/**
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* The minimal observable subscription method.
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* @param {Object} observer Any object that can be used as an observer.
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* The observer object should have a `next` method.
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* @returns {subscription} An object with an `unsubscribe` method that can
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* be used to unsubscribe the observable from the store, and prevent further
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* emission of values from the observable.
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*/
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subscribe: function subscribe(observer) {
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if (typeof observer !== 'object') {
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throw new TypeError('Expected the observer to be an object.');
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}
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function observeState() {
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if (observer.next) {
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observer.next(getState());
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}
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}
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observeState();
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var unsubscribe = outerSubscribe(observeState);
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return { unsubscribe: unsubscribe };
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}
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}, _ref[$$observable] = function () {
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return this;
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}, _ref;
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}
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// When a store is created, an "INIT" action is dispatched so that every
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// reducer returns their initial state. This effectively populates
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// the initial state tree.
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dispatch({ type: ActionTypes.INIT });
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return _ref2 = {
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dispatch: dispatch,
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subscribe: subscribe,
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getState: getState,
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replaceReducer: replaceReducer
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}, _ref2[$$observable] = observable, _ref2;
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}
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