snowl/modules/Observers.js

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JavaScript

/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Observers.
*
* The Initial Developer of the Original Code is Daniel Aquino.
* Portions created by the Initial Developer are Copyright (C) 2008
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Daniel Aquino <mr.danielaquino@gmail.com>
* Myk Melez <myk@mozilla.org>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
let EXPORTED_SYMBOLS = ["Observers"];
const Cc = Components.classes;
const Ci = Components.interfaces;
const Cr = Components.results;
const Cu = Components.utils;
Cu.import("resource://gre/modules/XPCOMUtils.jsm");
let Observers = {
add: function(callback, topic) {
let observer = new Observer(callback);
if (!(topic in Observers._observers))
Observers._observers[topic] = {};
Observers._observers[topic][callback] = observer;
Observers._service.addObserver(observer, topic, true);
return observer;
},
remove: function(callback, topic) {
let observer = Observers._observers[topic][callback];
if (observer) {
Observers._service.removeObserver(observer, topic);
delete this._observers[topic][callback];
}
},
notify: function(subject, topic, data) {
Observers._service.notifyObservers(new Subject(subject), topic, data);
},
_service: Cc["@mozilla.org/observer-service;1"].
getService(Ci.nsIObserverService),
// Observers indexed by callback. This lets us get the observer
// to remove when a caller calls |remove|, passing it a callback.
_observers: {}
};
function Observer(callback) {
this._callback = callback;
}
Observer.prototype = {
QueryInterface: XPCOMUtils.generateQI([Ci.nsIObserver, Ci.nsISupportsWeakReference]),
observe: function(subject, topic, data) {
// Pass the wrappedJSObject for subjects that have one. Otherwise pass
// the subject itself. This way we support both wrapped subjects created
// using this module and those that are real XPCOM components.
let unwrappedSubject = subject.wrappedJSObject || subject;
if (typeof this._callback == "function")
this._callback(unwrappedSubject, topic, data);
else
this._callback.observe(unwrappedSubject, topic, data);
}
}
function Subject(object) {
this.wrappedJSObject = object;
}
Subject.prototype = {
QueryInterface: XPCOMUtils.generateQI([]),
getHelperForLanguage: function() {},
getInterfaces: function() {}
};