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node_modules/react-redux/lib/utils/Subscription.js

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+"use strict";
+
+exports.__esModule = true;
+
+function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
+
+// encapsulates the subscription logic for connecting a component to the redux store, as
+// well as nesting subscriptions of descendant components, so that we can ensure the
+// ancestor components re-render before descendants
+
+var CLEARED = null;
+var nullListeners = {
+  notify: function notify() {}
+};
+
+function createListenerCollection() {
+  // the current/next pattern is copied from redux's createStore code.
+  // TODO: refactor+expose that code to be reusable here?
+  var current = [];
+  var next = [];
+
+  return {
+    clear: function clear() {
+      next = CLEARED;
+      current = CLEARED;
+    },
+    notify: function notify() {
+      var listeners = current = next;
+      for (var i = 0; i < listeners.length; i++) {
+        listeners[i]();
+      }
+    },
+    get: function get() {
+      return next;
+    },
+    subscribe: function subscribe(listener) {
+      var isSubscribed = true;
+      if (next === current) next = current.slice();
+      next.push(listener);
+
+      return function unsubscribe() {
+        if (!isSubscribed || current === CLEARED) return;
+        isSubscribed = false;
+
+        if (next === current) next = current.slice();
+        next.splice(next.indexOf(listener), 1);
+      };
+    }
+  };
+}
+
+var Subscription = function () {
+  function Subscription(store, parentSub, onStateChange) {
+    _classCallCheck(this, Subscription);
+
+    this.store = store;
+    this.parentSub = parentSub;
+    this.onStateChange = onStateChange;
+    this.unsubscribe = null;
+    this.listeners = nullListeners;
+  }
+
+  Subscription.prototype.addNestedSub = function addNestedSub(listener) {
+    this.trySubscribe();
+    return this.listeners.subscribe(listener);
+  };
+
+  Subscription.prototype.notifyNestedSubs = function notifyNestedSubs() {
+    this.listeners.notify();
+  };
+
+  Subscription.prototype.isSubscribed = function isSubscribed() {
+    return Boolean(this.unsubscribe);
+  };
+
+  Subscription.prototype.trySubscribe = function trySubscribe() {
+    if (!this.unsubscribe) {
+      this.unsubscribe = this.parentSub ? this.parentSub.addNestedSub(this.onStateChange) : this.store.subscribe(this.onStateChange);
+
+      this.listeners = createListenerCollection();
+    }
+  };
+
+  Subscription.prototype.tryUnsubscribe = function tryUnsubscribe() {
+    if (this.unsubscribe) {
+      this.unsubscribe();
+      this.unsubscribe = null;
+      this.listeners.clear();
+      this.listeners = nullListeners;
+    }
+  };
+
+  return Subscription;
+}();
+
+exports.default = Subscription;