michael@0: /* -*- Mode: Javascript; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* vim: set ft=javascript ts=2 et sw=2 tw=80: */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: const {Cc, Ci, Cu, Cr} = require("chrome");
michael@0: 
michael@0: Cu.import("resource://gre/modules/Services.jsm");
michael@0: Cu.import("resource://gre/modules/devtools/event-emitter.js");
michael@0: 
michael@0: exports.PREF_ORIG_SOURCES = "devtools.styleeditor.source-maps-enabled";
michael@0: 
michael@0: /**
michael@0:  * A PreferenceObserver observes a pref branch for pref changes.
michael@0:  * It emits an event for each preference change.
michael@0:  */
michael@0: function PrefObserver(branchName) {
michael@0:   this.branchName = branchName;
michael@0:   this.branch = Services.prefs.getBranch(branchName);
michael@0:   this.branch.addObserver("", this, false);
michael@0: 
michael@0:   EventEmitter.decorate(this);
michael@0: }
michael@0: 
michael@0: exports.PrefObserver = PrefObserver;
michael@0: 
michael@0: PrefObserver.prototype = {
michael@0:   observe: function(subject, topic, data) {
michael@0:     if (topic == "nsPref:changed") {
michael@0:       this.emit(this.branchName + data);
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   destroy: function() {
michael@0:     if (this.branch) {
michael@0:       this.branch.removeObserver('', this);
michael@0:     }
michael@0:   }
michael@0: };