Bug 731779: Integrate the Add-on SDK loader and API libraries into Firefox (uplifting from addon-sdk a16bbd5772880b578a939eeb65102bca6560d494)

addon-sdk/source/lib/sdk/event/target.js

@@ -0,0 +1,80 @@
+/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et: */
+/* 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';
+
+module.metadata = {
+  "stability": "stable"
+};
+
+const { on, once, off } = require('./core');
+const { method } = require('../lang/functional');
+const { Class } = require('../core/heritage');
+
+const EVENT_TYPE_PATTERN = /^on([A-Z]\w+$)/;
+
+/**
+ * `EventTarget` is an exemplar for creating an objects that can be used to
+ * add / remove event listeners on them. Events on these objects may be emitted
+ * via `emit` function exported by 'event/core' module.
+ */
+const EventTarget = Class({
+  /**
+   * Method initializes `this` event source. It goes through properties of a
+   * given `options` and registers listeners for the ones that look like an
+   * event listeners.
+   */
+  initialize: function initialize(options) {
+    options = options || {};
+    // Go through each property and registers event listeners for those
+    // that have a name matching following pattern (`onEventType`).
+    Object.keys(options).forEach(function onEach(key) {
+      let match = EVENT_TYPE_PATTERN.exec(key);
+      let type = match && match[1].toLowerCase();
+      let listener = options[key];
+
+      if (type && typeof(listener) === 'function')
+        this.on(type, listener);
+    }, this);
+  },
+  /**
+   * Registers an event `listener` that is called every time events of
+   * specified `type` are emitted.
+   * @param {String} type
+   *    The type of event.
+   * @param {Function} listener
+   *    The listener function that processes the event.
+   * @example
+   *      worker.on('message', function (data) {
+   *        console.log('data received: ' + data)
+   *      })
+   */
+  on: method(on),
+  /**
+   * Registers an event `listener` that is called once the next time an event
+   * of the specified `type` is emitted.
+   * @param {String} type
+   *    The type of the event.
+   * @param {Function} listener
+   *    The listener function that processes the event.
+   */
+  once: method(once),
+  /**
+   * Removes an event `listener` for the given event `type`.
+   * @param {String} type
+   *    The type of event.
+   * @param {Function} listener
+   *    The listener function that processes the event.
+   */
+  removeListener: function removeListener(type, listener) {
+    // Note: We can't just wrap `off` in `method` as we do it for other methods
+    // cause skipping a second or third argument will behave very differently
+    // than intended. This way we make sure all arguments are passed and only
+    // one listener is removed at most.
+    off(this, type, listener);
+  }
+});
+exports.EventTarget = EventTarget;