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: 
michael@0: // A couple of classes to simplify creating observers. 
michael@0: //
michael@0: // // Example1:
michael@0: //
michael@0: // function doSomething() { ... }
michael@0: // var observer = new G_ObserverWrapper(topic, doSomething);
michael@0: // someObj.addObserver(topic, observer);
michael@0: //
michael@0: // // Example2: 
michael@0: //
michael@0: // function doSomething() { ... }
michael@0: // new G_ObserverServiceObserver("profile-after-change", 
michael@0: //                               doSomething,
michael@0: //                               true /* run only once */);
michael@0: 
michael@0: 
michael@0: /**
michael@0:  * This class abstracts the admittedly simple boilerplate required of
michael@0:  * an nsIObserver. It saves you the trouble of implementing the
michael@0:  * indirection of your own observe() function.
michael@0:  *
michael@0:  * @param topic String containing the topic the observer will filter for
michael@0:  *
michael@0:  * @param observeFunction Reference to the function to call when the 
michael@0:  *                        observer fires
michael@0:  *
michael@0:  * @constructor
michael@0:  */
michael@0: function G_ObserverWrapper(topic, observeFunction) {
michael@0:   this.debugZone = "observer";
michael@0:   this.topic_ = topic;
michael@0:   this.observeFunction_ = observeFunction;
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * XPCOM
michael@0:  */
michael@0: G_ObserverWrapper.prototype.QueryInterface = function(iid) {
michael@0:   if (iid.equals(Ci.nsISupports) || iid.equals(Ci.nsIObserver))
michael@0:     return this;
michael@0:   throw Components.results.NS_ERROR_NO_INTERFACE;
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Invoked by the thingy being observed
michael@0:  */
michael@0: G_ObserverWrapper.prototype.observe = function(subject, topic, data) {
michael@0:   if (topic == this.topic_)
michael@0:     this.observeFunction_(subject, topic, data);
michael@0: }
michael@0: 
michael@0: 
michael@0: /**
michael@0:  * This class abstracts the admittedly simple boilerplate required of
michael@0:  * observing an observerservice topic. It implements the indirection
michael@0:  * required, and automatically registers to hear the topic.
michael@0:  *
michael@0:  * @param topic String containing the topic the observer will filter for
michael@0:  *
michael@0:  * @param observeFunction Reference to the function to call when the 
michael@0:  *                        observer fires
michael@0:  *
michael@0:  * @param opt_onlyOnce Boolean indicating if the observer should unregister
michael@0:  *                     after it has fired
michael@0:  *
michael@0:  * @constructor
michael@0:  */
michael@0: function G_ObserverServiceObserver(topic, observeFunction, opt_onlyOnce) {
michael@0:   this.debugZone = "observerserviceobserver";
michael@0:   this.topic_ = topic;
michael@0:   this.observeFunction_ = observeFunction;
michael@0:   this.onlyOnce_ = !!opt_onlyOnce;
michael@0:   
michael@0:   this.observer_ = new G_ObserverWrapper(this.topic_, 
michael@0:                                          BindToObject(this.observe_, this));
michael@0:   this.observerService_ = Cc["@mozilla.org/observer-service;1"]
michael@0:                           .getService(Ci.nsIObserverService);
michael@0:   this.observerService_.addObserver(this.observer_, this.topic_, false);
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Unregister the observer from the observerservice
michael@0:  */
michael@0: G_ObserverServiceObserver.prototype.unregister = function() {
michael@0:   this.observerService_.removeObserver(this.observer_, this.topic_);
michael@0:   this.observerService_ = null;
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Invoked by the observerservice
michael@0:  */
michael@0: G_ObserverServiceObserver.prototype.observe_ = function(subject, topic, data) {
michael@0:   this.observeFunction_(subject, topic, data);
michael@0:   if (this.onlyOnce_)
michael@0:     this.unregister();
michael@0: }
michael@0: 
michael@0: #ifdef DEBUG
michael@0: function TEST_G_Observer() {
michael@0:   if (G_GDEBUG) {
michael@0: 
michael@0:     var z = "observer UNITTEST";
michael@0:     G_debugService.enableZone(z);
michael@0: 
michael@0:     G_Debug(z, "Starting");
michael@0: 
michael@0:     var regularObserverRan = 0;
michael@0:     var observerServiceObserverRan = 0;
michael@0: 
michael@0:     function regularObserver() {
michael@0:       regularObserverRan++;
michael@0:     };
michael@0: 
michael@0:     function observerServiceObserver() {
michael@0:       observerServiceObserverRan++;
michael@0:     };
michael@0: 
michael@0:     var service = Cc["@mozilla.org/observer-service;1"]
michael@0:                   .getService(Ci.nsIObserverService);
michael@0:     var topic = "google-observer-test";
michael@0: 
michael@0:     var o1 = new G_ObserverWrapper(topic, regularObserver);
michael@0:     service.addObserver(o1, topic, false);
michael@0: 
michael@0:     new G_ObserverServiceObserver(topic, 
michael@0:                                   observerServiceObserver, true /* once */);
michael@0: 
michael@0:     // Notifications happen synchronously, so this is easy
michael@0:     service.notifyObservers(null, topic, null);
michael@0:     service.notifyObservers(null, topic, null);
michael@0: 
michael@0:     G_Assert(z, regularObserverRan == 2, "Regular observer broken");
michael@0:     G_Assert(z, observerServiceObserverRan == 1, "ObsServObs broken");
michael@0: 
michael@0:     service.removeObserver(o1, topic);
michael@0:     G_Debug(z, "PASSED");
michael@0:   }
michael@0: }
michael@0: #endif