add unsubscribe listener function to event hub

Author: jimmycallin

source/event_hub.js

@@ -246,6 +246,26 @@ export class EventHub {
  return subscriber.metadata.id;
  }
 
+ /**
+ * Unsubscribe from *subscription* events.
+ *
+ * @param {String} identifier Subscriber ID returned from subscribe method.
+ * @return {Boolean} True if a subscriber was removed, false otherwise
+ */
+ unsubscribe(identifier) {
+ let hasFoundSubscriberToRemove = false;
+ this._subscribers = this._subscribers.filter((subscriber) => {
+ if (subscriber.metadata.id === identifier) {
+ this._notifyServerAboutUnsubscribe(hasFoundSubscriberToRemove);
+ hasFoundSubscriberToRemove = true;
+ return false;
+ }
+ return true;
+ });
+
+ return hasFoundSubscriberToRemove;
+ }
+
  /**
  * Return topic from *subscription* expression.
  *
@@ -317,6 +337,13 @@ export class EventHub {
  this.publish(subscribeEvent);
  }
 
+ _notifyServerAboutUnsubscribe(subscriber) {
+ const unsubscribeEvent = new Event("ftrack.meta.unsubscribe", {
+ subscriber,
+ });
+ this.publish(unsubscribeEvent);
+ }
+
  /**
  * Return subscriber with matching *identifier*.
  *