1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/addon-sdk/source/lib/sdk/output/system.js Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,71 @@
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 } = require("chrome");
1.10 +const { Input, start, stop, receive, outputs } = require("../event/utils");
1.11 +const { id: addonID } = require("../self");
1.12 +const { setImmediate } = require("../timers");
1.13 +const { notifyObservers } = Cc['@mozilla.org/observer-service;1'].
1.14 + getService(Ci.nsIObserverService);
1.15 +
1.16 +const NOT_AN_INPUT = "OutputPort can be used only for sending messages";
1.17 +
1.18 +// `OutputPort` creates a port to which messages can be send. Those
1.19 +// messages are actually disptached as `subject`'s of the observer
1.20 +// notifications. This is handy for communicating between different
1.21 +// components of the SDK. By default messages are dispatched
1.22 +// asynchronously, although `options.sync` can be used to make them
1.23 +// synchronous. If `options.id` is given `topic` for observer
1.24 +// notifications is generated by namespacing it, to avoid spamming
1.25 +// other SDK add-ons. It's also possible to provide `options.topic`
1.26 +// to use excat `topic` without namespacing it.
1.27 +//
1.28 +// Note: Symmetric `new InputPort({ id: "x" })` instances can be used to
1.29 +// receive messages send to the instances of `new OutputPort({ id: "x" })`.
1.30 +const OutputPort = function({id, topic, sync}) {
1.31 + this.id = id || topic;
1.32 + this.sync = !!sync;
1.33 + this.topic = topic || "sdk:" + addonID + ":" + id;
1.34 +};
1.35 +// OutputPort extends base signal type to implement same message
1.36 +// receiving interface.
1.37 +OutputPort.prototype = new Input();
1.38 +OutputPort.constructor = OutputPort;
1.39 +
1.40 +// OutputPort can not be consumed there for starting or stopping it
1.41 +// is not supported.
1.42 +OutputPort.prototype[start] = _ => { throw TypeError(NOT_AN_INPUT); };
1.43 +OutputPort.prototype[stop] = _ => { throw TypeError(NOT_AN_INPUT); };
1.44 +
1.45 +// Port reecives message send to it, which will be dispatched via
1.46 +// observer notification service.
1.47 +OutputPort.receive = ({topic, sync}, message) => {
1.48 + const type = typeof(message);
1.49 + const supported = message === null ||
1.50 + type === "object" ||
1.51 + type === "function";
1.52 +
1.53 + // There is no sensible way to wrap JS primitives that would make sense
1.54 + // for general observer notification users. It's also probably not very
1.55 + // useful to dispatch JS primitives as subject of observer service, there
1.56 + // for we do not support those use cases.
1.57 + if (!supported)
1.58 + throw new TypeError("Unsupproted message type: `" + type + "`");
1.59 +
1.60 + // Normalize `message` to create a valid observer notification `subject`.
1.61 + // If `message` is `null`, implements `nsISupports` interface or already
1.62 + // represents wrapped JS object use it as is. Otherwise create a wrapped
1.63 + // object so that observers could receive it.
1.64 + const subject = message === null ? null :
1.65 + message instanceof Ci.nsISupports ? message :
1.66 + message.wrappedJSObject ? message :
1.67 + {wrappedJSObject: message};
1.68 + if (sync)
1.69 + notifyObservers(subject, topic, null);
1.70 + else
1.71 + setImmediate(notifyObservers, subject, topic, null);
1.72 +};
1.73 +OutputPort.prototype[receive] = OutputPort.receive;
1.74 +exports.OutputPort = OutputPort;
