1 files changed, 39 insertions, 0 deletions
diff --git a/toolkit/jetpack/sdk/remote/utils.js b/toolkit/jetpack/sdk/remote/utils.js
new file mode 100644
index 000000000..5a5e39198
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+++ b/toolkit/jetpack/sdk/remote/utils.js
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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+"use strict";
+
+const { Class } = require('../core/heritage');
+const { List, addListItem, removeListItem } = require('../util/list');
+const { emit } = require('../event/core');
+const { pipe } = require('../event/utils');
+
+// A helper class that maintains a list of EventTargets. Any events emitted
+// to an EventTarget are also emitted by the EventParent. Likewise for an
+// EventTarget's port property.
+const EventParent = Class({
+  implements: [ List ],
+
+  attachItem: function(item) {
+    addListItem(this, item);
+
+    pipe(item.port, this.port);
+    pipe(item, this);
+
+    item.once('detach', () => {
+      removeListItem(this, item);
+    })
+
+    emit(this, 'attach', item);
+  },
+
+  // Calls listener for every object already in the list and every object
+  // subsequently added to the list.
+  forEvery: function(listener) {
+    for (let item of this)
+      listener(item);
+
+    this.on('attach', listener);
+  }
+});
+exports.EventParent = EventParent;