The Tor Browser / file comparison
comparison: addon-sdk/source/lib/sdk/core/observer.js
addon-sdk/source/lib/sdk/core/observer.js
- branch
- TOR_BUG_3246
- changeset 7
- 129ffea94266
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deleted
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| -1:000000000000 | 0:3786f6a89f01 |
|---|---|
| 1 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 2 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 4 | |
| 5 "use strict"; | |
| 6 | |
| 7 module.metadata = { | |
| 8 "stability": "experimental" | |
| 9 }; | |
| 10 | |
| 11 | |
| 12 const { Cc, Ci, Cr } = require("chrome"); | |
| 13 const { Class } = require("./heritage"); | |
| 14 const { isWeak } = require("./reference"); | |
| 15 const method = require("../../method/core"); | |
| 16 | |
| 17 const { addObserver, removeObserver } = Cc['@mozilla.org/observer-service;1']. | |
| 18 getService(Ci.nsIObserverService); | |
| 19 | |
| 20 | |
| 21 // This is a method that will be invoked when notification observer | |
| 22 // subscribed to occurs. | |
| 23 const observe = method("observer/observe"); | |
| 24 exports.observe = observe; | |
| 25 | |
| 26 // Method to subscribe to the observer notification. | |
| 27 const subscribe = method("observe/subscribe"); | |
| 28 exports.subscribe = subscribe; | |
| 29 | |
| 30 | |
| 31 // Method to unsubscribe from the observer notifications. | |
| 32 const unsubscribe = method("observer/unsubscribe"); | |
| 33 exports.unsubscribe = unsubscribe; | |
| 34 | |
| 35 | |
| 36 // This is wrapper class that takes a `delegate` and produces | |
| 37 // instance of `nsIObserver` which will delegate to a given | |
| 38 // object when observer notification occurs. | |
| 39 const ObserverDelegee = Class({ | |
| 40 initialize: function(delegate) { | |
| 41 this.delegate = delegate; | |
| 42 }, | |
| 43 QueryInterface: function(iid) { | |
| 44 const isObserver = iid.equals(Ci.nsIObserver); | |
| 45 const isWeakReference = iid.equals(Ci.nsISupportsWeakReference); | |
| 46 | |
| 47 if (!isObserver && !isWeakReference) | |
| 48 throw Cr.NS_ERROR_NO_INTERFACE; | |
| 49 | |
| 50 return this; | |
| 51 }, | |
| 52 observe: function(subject, topic, data) { | |
| 53 observe(this.delegate, subject, topic, data); | |
| 54 } | |
| 55 }); | |
| 56 | |
| 57 | |
| 58 // Class that can be either mixed in or inherited from in | |
| 59 // order to subscribe / unsubscribe for observer notifications. | |
| 60 const Observer = Class({}); | |
| 61 exports.Observer = Observer; | |
| 62 | |
| 63 // Weak maps that associates instance of `ObserverDelegee` with | |
| 64 // an actual observer. It ensures that `ObserverDelegee` instance | |
| 65 // won't be GC-ed until given `observer` is. | |
| 66 const subscribers = new WeakMap(); | |
| 67 | |
| 68 // Implementation of `subscribe` for `Observer` type just registers | |
| 69 // observer for an observer service. If `isWeak(observer)` is `true` | |
| 70 // observer service won't hold strong reference to a given `observer`. | |
| 71 subscribe.define(Observer, (observer, topic) => { | |
| 72 if (!subscribers.has(observer)) { | |
| 73 const delegee = new ObserverDelegee(observer); | |
| 74 subscribers.set(observer, delegee); | |
| 75 addObserver(delegee, topic, isWeak(observer)); | |
| 76 } | |
| 77 }); | |
| 78 | |
| 79 // Unsubscribes `observer` from observer notifications for the | |
| 80 // given `topic`. | |
| 81 unsubscribe.define(Observer, (observer, topic) => { | |
| 82 const delegee = subscribers.get(observer); | |
| 83 if (delegee) { | |
| 84 subscribers.delete(observer); | |
| 85 removeObserver(delegee, topic); | |
| 86 } | |
| 87 }); |
