Issue 3839 - Adapt for Prefs event changes

background.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 (function(global)
 {
+  function EventEmitter()
+  {
+    this._listeners = Object.create(null);
+  }
+  EventEmitter.prototype = {
+    on: function(name, listener)
+    {
+      if (name in this._listeners)
+        this._listeners[name].push(listener);
+      else
+        this._listeners[name] = [listener];
+    },
+    off: function(name, listener)
+    {
+      var listeners = this._listeners[name];
+      if (listeners)
+      {
+        var idx = listeners.indexOf(listener);
+        if (idx != -1)
+          listeners.splice(idx, 1);
+      }
+    },
+    emit: function(name)
+    {
+      var listeners = this._listeners[name];
+      if (listeners)
+      {
+        for (var i = 0; i < listeners.length; i++)
+          listeners[i].apply(null, Array.prototype.slice.call(arguments, 1));
+      }
+    }
+  };
+
   function Notifier()
   {
-    this._listeners = [];
+    this._eventEmitter = new EventEmitter();
   }
   Notifier.prototype = {
-    _listeners: null,
-
     addListener: function(listener)
     {
-      if (this._listeners.indexOf(listener) < 0)
-        this._listeners.push(listener);
-    },
-
+      var listeners = this._eventEmitter._listeners[""];
+      if (!listeners || listener.indexOf(listener) == -1)
+        this._eventEmitter.on("", listener);
+    },
     removeListener: function(listener)
     {
-      var index = this._listeners.indexOf(listener);
-      if (index >= 0)
-        this._listeners.splice(index, 1);
-    },
-
+      this._eventEmitter.off("", listener);
+    },
     triggerListeners: function()
     {
       var args = Array.prototype.slice.apply(arguments);
-      var listeners = this._listeners.slice();
-      for (var i = 0; i < listeners.length; i++)
-        listeners[i].apply(null, args);
+      args.unshift("");
+      this._eventEmitter.emit.apply(this._eventEmitter, args);
     }
   };
 
   function updateFromURL(data)
   {
     if (window.location.search)
     {
       var params = window.location.search.substr(1).split("&");
       for (var i = 0; i < params.length; i++)
       {
@@ skipping 28 matching lines @@
       {
         return "https://adblockplus.org/redirect?link=" + encodeURIComponent(link);
       },
       get appLocale()
       {
         return parent.ext.i18n.getMessage("@@ui_locale").replace(/_/g, "-");
       }
     }
   };
 
-  modules.prefs = {
-    Prefs: {
-      _listeners: Object.create(null),
-
-      on: function(preference, callback)

[Thomas Greiner, 2016/03/21 17:55:55]

What about extending `Notifier` instead so that `Notifier.addListener()` and
`Notifier.removeListener()` accept an optional name parameter at the first
position?

That way we could reuse it when we decide to migrate other APIs to the new
calling scheme. We'd also avoid duplicating some of the logic.

[Sebastian Noack, 2016/03/21 19:40:07]

Well, changing the calling convention of existing APIs across core and platform
is not the scope of this patch. However, we can move the this logic into a class
and use it under the hood to implement Notifier. Did that.

-      {
-        if (preference in this._listeners)
-          this._listeners[preference].push(callback);
-        else
-          this._listeners[preference] = [callback];
-      }
-    }
-  };
+  modules.prefs = {Prefs: new EventEmitter()};
   var prefs = {
     notifications_ignoredcategories: (params.showNotificationUI) ? ["*"] : [],
     notifications_showui: params.showNotificationUI,
     safari_contentblocker: false,
     shouldShowBlockElementMenu: true,
     show_devtools_panel: true,
     subscriptions_exceptionsurl: "https://easylist-downloads.adblockplus.org/exceptionrules.txt"
   };
   Object.keys(prefs).forEach(function(key)
   {
     Object.defineProperty(modules.prefs.Prefs, key, {
       get: function()
       {
         return prefs[key];
       },
       set: function(value)
       {
         prefs[key] = value;
-
-        var listeners = modules.prefs.Prefs._listeners[key];
-        if (listeners)
-          for (var i = 0; i < listeners.length; i++)
-            listeners[i]();
+        modules.prefs.Prefs.emit(key);
       }
     });
   });
 
   modules.notification = {
     Notification: {
       toggleIgnoreCategory: function(category)
       {
         var categories = prefs.notifications_ignoredcategories;
         var index = categories.indexOf(category);
@@ skipping 341 matching lines @@
 
   if (params.safariContentBlocker)
   {
     global.safari = {
       extension: {
         setContentBlocker: function() {}
       }
     };
   }
 })(this);