1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/addon-sdk/source/lib/sdk/input/system.js Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,109 @@
1.4 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.5 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.6 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.7 +"use strict";
1.8 +
1.9 +const { Cc, Ci, Cr, Cu } = require("chrome");
1.10 +const { Input, start, stop, end, receive, outputs } = require("../event/utils");
1.11 +const { once, off } = require("../event/core");
1.12 +const { id: addonID } = require("../self");
1.13 +
1.14 +const unloadMessage = require("@loader/unload");
1.15 +const { addObserver, removeObserver } = Cc['@mozilla.org/observer-service;1'].
1.16 + getService(Ci.nsIObserverService);
1.17 +
1.18 +const addonUnloadTopic = "sdk:loader:destroy";
1.19 +
1.20 +const isXrayWrapper = Cu.isXrayWrapper;
1.21 +// In the past SDK used to double-wrap notifications dispatched, which
1.22 +// made them awkward to use outside of SDK. At present they no longer
1.23 +// do that, although we still supported for legacy reasons.
1.24 +const isLegacyWrapper = x =>
1.25 + x && x.wrappedJSObject &&
1.26 + "observersModuleSubjectWrapper" in x.wrappedJSObject;
1.27 +
1.28 +const unwrapLegacy = x => x.wrappedJSObject.object;
1.29 +
1.30 +// `InputPort` provides a way to create a signal out of the observer
1.31 +// notification subject's for the given `topic`. If `options.initial`
1.32 +// is provided it is used as initial value otherwise `null` is used.
1.33 +// Constructor can be given `options.id` that will be used to create
1.34 +// a `topic` which is namespaced to an add-on (this avoids conflicts
1.35 +// when multiple add-on are used, although in a future host probably
1.36 +// should just be shared across add-ons). It is also possible to
1.37 +// specify a specific `topic` via `options.topic` which is used as
1.38 +// without namespacing. Created signal ends whenever add-on is
1.39 +// unloaded.
1.40 +const InputPort = function InputPort({id, topic, initial}) {
1.41 + this.id = id || topic;
1.42 + this.topic = topic || "sdk:" + addonID + ":" + id;
1.43 + this.value = initial === void(0) ? null : initial;
1.44 + this.observing = false;
1.45 + this[outputs] = [];
1.46 +};
1.47 +
1.48 +// InputPort type implements `Input` signal interface.
1.49 +InputPort.prototype = new Input();
1.50 +InputPort.prototype.constructor = InputPort;
1.51 +
1.52 +// When port is started (which is when it's subgraph get's
1.53 +// first subscriber) actual observer is registered.
1.54 +InputPort.start = input => {
1.55 + input.addListener(input);
1.56 + // Also register add-on unload observer to end this signal
1.57 + // when that happens.
1.58 + addObserver(input, addonUnloadTopic, false);
1.59 +};
1.60 +InputPort.prototype[start] = InputPort.start;
1.61 +
1.62 +InputPort.addListener = input => addObserver(input, input.topic, false);
1.63 +InputPort.prototype.addListener = InputPort.addListener;
1.64 +
1.65 +// When port is stopped (which is when it's subgraph has no
1.66 +// no subcribers left) an actual observer unregistered.
1.67 +// Note that port stopped once it ends as well (which is when
1.68 +// add-on is unloaded).
1.69 +InputPort.stop = input => {
1.70 + input.removeListener(input);
1.71 + removeObserver(input, addonUnloadTopic);
1.72 +};
1.73 +InputPort.prototype[stop] = InputPort.stop;
1.74 +
1.75 +InputPort.removeListener = input => removeObserver(input, input.topic);
1.76 +InputPort.prototype.removeListener = InputPort.removeListener;
1.77 +
1.78 +// `InputPort` also implements `nsIObserver` interface and
1.79 +// `nsISupportsWeakReference` interfaces as it's going to be used as such.
1.80 +InputPort.prototype.QueryInterface = function(iid) {
1.81 + if (!iid.equals(Ci.nsIObserver) && !iid.equals(Ci.nsISupportsWeakReference))
1.82 + throw Cr.NS_ERROR_NO_INTERFACE;
1.83 +
1.84 + return this;
1.85 +};
1.86 +
1.87 +// `InputPort` instances implement `observe` method, which is invoked when
1.88 +// observer notifications are dispatched. The `subject` of that notification
1.89 +// are received on this signal.
1.90 +InputPort.prototype.observe = function(subject, topic, data) {
1.91 + // Unwrap message from the subject. SDK used to have it's own version of
1.92 + // wrappedJSObjects which take precedence, if subject has `wrappedJSObject`
1.93 + // and it's not an XrayWrapper use it as message. Otherwise use subject as
1.94 + // is.
1.95 + const message = subject === null ? null :
1.96 + isLegacyWrapper(subject) ? unwrapLegacy(subject) :
1.97 + isXrayWrapper(subject) ? subject :
1.98 + subject.wrappedJSObject ? subject.wrappedJSObject :
1.99 + subject;
1.100 +
1.101 + // If observer topic matches topic of the input port receive a message.
1.102 + if (topic === this.topic) {
1.103 + receive(this, message);
1.104 + }
1.105 +
1.106 + // If observe topic is add-on unload topic we create an end message.
1.107 + if (topic === addonUnloadTopic && message === unloadMessage) {
1.108 + end(this);
1.109 + }
1.110 +};
1.111 +
1.112 +exports.InputPort = InputPort;
