The Tor Browser: addon-sdk/source/lib/sdk/system/events.js@6474c204b198 (annotated)

addon-sdk/source/lib/sdk/system/events.js@6474c204b198 (annotated)

addon-sdk/source/lib/sdk/system/events.js

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* 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': 'unstable'
 };
 const { Cc, Ci, Cu } = require('chrome');
 const { Unknown } = require('../platform/xpcom');
 const { Class } = require('../core/heritage');
 const { ns } = require('../core/namespace');
 const { addObserver, removeObserver, notifyObservers } =
   Cc['@mozilla.org/observer-service;1'].getService(Ci.nsIObserverService);
 const unloadSubject = require('@loader/unload');
 const Subject = Class({
   extends: Unknown,
   initialize: function initialize(object) {
     // Double-wrap the object and set a property identifying the
     // wrappedJSObject as one of our wrappers to distinguish between
     // subjects that are one of our wrappers (which we should unwrap
     // when notifying our observers) and those that are real JS XPCOM
     // components (which we should pass through unaltered).
     this.wrappedJSObject = {
       observersModuleSubjectWrapper: true,
       object: object
     };
   },
   getHelperForLanguage: function() {},
   getInterfaces: function() {}
 });
 function emit(type, event) {
   // From bug 910599
   // We must test to see if 'subject' or 'data' is a defined property
   // of the event object, but also allow primitives to be passed in,
   // which the `in` operator breaks, yet `null` is an object, hence
   // the long conditional
   let subject = event && typeof event === 'object' && 'subject' in event ?
     Subject(event.subject) :
     null;
   let data = event && typeof event === 'object' ?
     // An object either returns its `data` property or null
     ('data' in event ? event.data : null) :
     // All other types return themselves (and cast to strings/null
     // via observer service)
     event;
   notifyObservers(subject, type, data);
 }
 exports.emit = emit;
 const Observer = Class({
   extends: Unknown,
   initialize: function initialize(listener) {
     this.listener = listener;
   },
   interfaces: [ 'nsIObserver', 'nsISupportsWeakReference' ],
   observe: function(subject, topic, data) {
     // Extract the wrapped object for subjects that are one of our
     // wrappers around a JS object.  This way we support both wrapped
     // subjects created using this module and those that are real
     // XPCOM components.
     if (subject && typeof(subject) == 'object' &&
         ('wrappedJSObject' in subject) &&
         ('observersModuleSubjectWrapper' in subject.wrappedJSObject))
       subject = subject.wrappedJSObject.object;
     try {
       this.listener({
         type: topic,
         subject: subject,
         data: data
       });
     }
     catch (error) {
       console.exception(error);
     }
   }
 });
 const subscribers = ns();
 function on(type, listener, strong) {
   // Unless last optional argument is `true` we use a weak reference to a
   // listener.
   let weak = !strong;
   // Take list of observers associated with given `listener` function.
   let observers = subscribers(listener);
   // If `observer` for the given `type` is not registered yet, then
   // associate an `observer` and register it.
   if (!(type in observers)) {
     let observer = Observer(listener);
     observers[type] = observer;
     addObserver(observer, type, weak);
     // WeakRef gymnastics to remove all alive observers on unload
     let ref = Cu.getWeakReference(observer);
     weakRefs.set(observer, ref);
     stillAlive.set(ref, type);
   }
 }
 exports.on = on;
 function once(type, listener) {
   // Note: this code assumes order in which listeners are called, which is fine
   // as long as dispatch happens in same order as listener registration which
   // is the case now. That being said we should be aware that this may break
   // in a future if order will change.
   on(type, listener);
   on(type, function cleanup() {
     off(type, listener);
     off(type, cleanup);
   }, true);
 }
 exports.once = once;
 function off(type, listener) {
   // Take list of observers as with the given `listener`.
   let observers = subscribers(listener);
   // If `observer` for the given `type` is registered, then
   // remove it & unregister.
   if (type in observers) {
     let observer = observers[type];
     delete observers[type];
     removeObserver(observer, type);
     stillAlive.delete(weakRefs.get(observer));
   }
 }
 exports.off = off;
 // must use WeakMap to keep reference to all the WeakRefs (!), see bug 986115
 let weakRefs = new WeakMap();
 // and we're out of beta, we're releasing on time!
 let stillAlive = new Map();
 on('sdk:loader:destroy', function onunload({ subject, data: reason }) {
   // using logic from ./unload, to avoid a circular module reference
   if (subject.wrappedJSObject === unloadSubject) {
     off('sdk:loader:destroy', onunload);
     // don't bother
     if (reason === 'shutdown')
       return;
     stillAlive.forEach( (type, ref) => {
       let observer = ref.get();
       if (observer)
         removeObserver(observer, type);
     })
   }
   // a strong reference
 }, true);