1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
|
/* ***** 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>
* Atul Varma <atul@mozilla.com>
*
* 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 ***** */
"use strict";
const {Cc,Ci} = require("chrome");
var xpcom = require("./xpcom");
/**
* A service for adding, removing and notifying observers of notifications.
* Wraps the nsIObserverService interface.
*
* @version 0.2
*/
var service = Cc["@mozilla.org/observer-service;1"].
getService(Ci.nsIObserverService);
/**
* A cache of observers that have been added.
*
* We use this to remove observers when a caller calls |Observers.remove|.
*/
var cache = [];
/**
* Topics specifically available to Jetpack-generated extensions.
*
* Using these predefined consts instead of the platform strings is good:
* - allows us to scope topics specifically for Jetpacks
* - addons aren't dependent on strings nor behavior of core platform topics
* - the core platform topics are not clearly named
*
*/
exports.topics = {
/**
* A topic indicating that the application is in a state usable
* by add-ons.
*/
get APPLICATION_READY() packaging.jetpackID + "_APPLICATION_READY"
};
/**
* Register the given callback as an observer of the given topic.
*
* @param topic {String}
* the topic to observe
*
* @param callback {Object}
* the callback; an Object that implements nsIObserver or a Function
* that gets called when the notification occurs
*
* @param thisObject {Object} [optional]
* the object to use as |this| when calling a Function callback
*
* @returns the observer
*/
var add = exports.add = function add(topic, callback, thisObject) {
var observer = new Observer(topic, callback, thisObject);
service.addObserver(observer, topic, true);
cache.push(observer);
return observer;
};
/**
* Unregister the given callback as an observer of the given topic.
*
* @param topic {String}
* the topic being observed
*
* @param callback {Object}
* the callback doing the observing
*
* @param thisObject {Object} [optional]
* the object being used as |this| when calling a Function callback
*/
var remove = exports.remove = function remove(topic, callback, thisObject) {
// This seems fairly inefficient, but I'm not sure how much better
// we can make it. We could index by topic, but we can't index by callback
// or thisObject, as far as I know, since the keys to JavaScript hashes
// (a.k.a. objects) can apparently only be primitive values.
let observers = cache.filter(function(v) {
return (v.topic == topic &&
v.callback == callback &&
v.thisObject == thisObject);
});
if (observers.length) {
service.removeObserver(observers[0], topic);
cache.splice(cache.indexOf(observers[0]), 1);
}
};
/**
* Notify observers about something.
*
* @param topic {String}
* the topic to notify observers about
*
* @param subject {Object} [optional]
* some information about the topic; can be any JS object or primitive
*
* @param data {String} [optional] [deprecated]
* some more information about the topic; deprecated as the subject
* is sufficient to pass all needed information to the JS observers
* that this module targets; if you have multiple values to pass to
* the observer, wrap them in an object and pass them via the subject
* parameter (i.e.: { foo: 1, bar: "some string", baz: myObject })
*/
var notify = exports.notify = function notify(topic, subject, data) {
subject = (typeof subject == "undefined") ? null : new Subject(subject);
data = (typeof data == "undefined") ? null : data;
service.notifyObservers(subject, topic, data);
};
function Observer(topic, callback, thisObject) {
memory.track(this);
this.topic = topic;
this.callback = callback;
this.thisObject = thisObject;
}
Observer.prototype = {
QueryInterface: xpcom.utils.generateQI([Ci.nsIObserver,
Ci.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 {
if (typeof this.callback == "function") {
if (this.thisObject)
this.callback.call(this.thisObject, subject, data);
else
this.callback(subject, data);
} else // typeof this.callback == "object" (nsIObserver)
this.callback.observe(subject, topic, data);
} catch (e) {
console.exception(e);
}
}
};
function Subject(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
};
}
Subject.prototype = {
QueryInterface: xpcom.utils.generateQI([]),
getHelperForLanguage: function() {},
getInterfaces: function() {}
};
require("./unload").when(
function removeAllObservers() {
// Make a copy of cache first, since cache will be changing as we
// iterate through it.
cache.slice().forEach(
function(observer) {
remove(observer.topic, observer.callback, observer.thisObject);
});
});
|
