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

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

addon-sdk/source/lib/sdk/input/system.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";
 const { Cc, Ci, Cr, Cu } = require("chrome");
 const { Input, start, stop, end, receive, outputs } = require("../event/utils");
 const { once, off } = require("../event/core");
 const { id: addonID } = require("../self");
 const unloadMessage = require("@loader/unload");
 const { addObserver, removeObserver } = Cc['@mozilla.org/observer-service;1'].
                                           getService(Ci.nsIObserverService);
 const addonUnloadTopic = "sdk:loader:destroy";
 const isXrayWrapper = Cu.isXrayWrapper;
 // In the past SDK used to double-wrap notifications dispatched, which
 // made them awkward to use outside of SDK. At present they no longer
 // do that, although we still supported for legacy reasons.
 const isLegacyWrapper = x =>
     x && x.wrappedJSObject &&
     "observersModuleSubjectWrapper" in x.wrappedJSObject;
 const unwrapLegacy = x => x.wrappedJSObject.object;
 // `InputPort` provides a way to create a signal out of the observer
 // notification subject's for the given `topic`. If `options.initial`
 // is provided it is used as initial value otherwise `null` is used.
 // Constructor can be given `options.id` that will be used to create
 // a `topic` which is namespaced to an add-on (this avoids conflicts
 // when multiple add-on are used, although in a future host probably
 // should just be shared across add-ons). It is also possible to
 // specify a specific `topic` via `options.topic` which is used as
 // without namespacing. Created signal ends whenever add-on is
 // unloaded.
 const InputPort = function InputPort({id, topic, initial}) {
   this.id = id || topic;
   this.topic = topic || "sdk:" + addonID + ":" + id;
   this.value = initial === void(0) ? null : initial;
   this.observing = false;
   this[outputs] = [];
 };
 // InputPort type implements `Input` signal interface.
 InputPort.prototype = new Input();
 InputPort.prototype.constructor = InputPort;
 // When port is started (which is when it's subgraph get's
 // first subscriber) actual observer is registered.
 InputPort.start = input => {
   input.addListener(input);
   // Also register add-on unload observer to end this signal
   // when that happens.
   addObserver(input, addonUnloadTopic, false);
 };
 InputPort.prototype[start] = InputPort.start;
 InputPort.addListener = input => addObserver(input, input.topic, false);
 InputPort.prototype.addListener = InputPort.addListener;
 // When port is stopped (which is when it's subgraph has no
 // no subcribers left) an actual observer unregistered.
 // Note that port stopped once it ends as well (which is when
 // add-on is unloaded).
 InputPort.stop = input => {
   input.removeListener(input);
   removeObserver(input, addonUnloadTopic);
 };
 InputPort.prototype[stop] = InputPort.stop;
 InputPort.removeListener = input => removeObserver(input, input.topic);
 InputPort.prototype.removeListener = InputPort.removeListener;
 // `InputPort` also implements `nsIObserver` interface and
 // `nsISupportsWeakReference` interfaces as it's going to be used as such.
 InputPort.prototype.QueryInterface = function(iid) {
   if (!iid.equals(Ci.nsIObserver) && !iid.equals(Ci.nsISupportsWeakReference))
     throw Cr.NS_ERROR_NO_INTERFACE;
   return this;
 };
 // `InputPort` instances implement `observe` method, which is invoked when
 // observer notifications are dispatched. The `subject` of that notification
 // are received on this signal.
 InputPort.prototype.observe = function(subject, topic, data) {
   // Unwrap message from the subject. SDK used to have it's own version of
   // wrappedJSObjects which take precedence, if subject has `wrappedJSObject`
   // and it's not an XrayWrapper use it as message. Otherwise use subject as
   // is.
   const message = subject === null ? null :
         isLegacyWrapper(subject) ? unwrapLegacy(subject) :
         isXrayWrapper(subject) ? subject :
         subject.wrappedJSObject ? subject.wrappedJSObject :
         subject;
   // If observer topic matches topic of the input port receive a message.
   if (topic === this.topic) {
     receive(this, message);
   }
   // If observe topic is add-on unload topic we create an end message.
   if (topic === addonUnloadTopic && message === unloadMessage) {
     end(this);
   }
 };
 exports.InputPort = InputPort;