The Tor Browser: toolkit/components/url-classifier/content/moz/preferences.js@925c144e1f1f (annotated)

toolkit/components/url-classifier/content/moz/preferences.js@925c144e1f1f (annotated)

toolkit/components/url-classifier/content/moz/preferences.js

Fri, 16 Jan 2015 18:13:44 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Fri, 16 Jan 2015 18:13:44 +0100
branch: TOR_BUG_9701
changeset 14: 925c144e1f1f
permissions: -rw-r--r--

Integrate suggestion from review to improve consistency with existing code.

 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 // Class for manipulating preferences. Aside from wrapping the pref
 // service, useful functionality includes:
 //
 // - abstracting prefobserving so that you can observe preferences
 //   without implementing nsIObserver
 //
 // - getters that return a default value when the pref doesn't exist
 //   (instead of throwing)
 //
 // - get-and-set getters
 //
 // Example:
 //
 // var p = new PROT_Preferences();
 // dump(p.getPref("some-true-pref"));     // shows true
 // dump(p.getPref("no-such-pref", true)); // shows true
 // dump(p.getPref("no-such-pref", null)); // shows null
 //
 // function observe(prefThatChanged) {
 //   dump("Pref changed: " + prefThatChanged);
 // };
 //
 // p.addObserver("somepref", observe);
 // p.setPref("somepref", true);            // dumps
 // p.removeObserver("somepref", observe);
 //
 // TODO: should probably have the prefobserver pass in the new and old
 //       values
 // TODO(tc): Maybe remove this class and just call natively since we're no
 //           longer an extension.
 /**
  * A class that wraps the preferences service.
  *
  * @param opt_startPoint        A starting point on the prefs tree to resolve
  *                              names passed to setPref and getPref.
  *
  * @param opt_useDefaultPranch  Set to true to work against the default
  *                              preferences tree instead of the profile one.
  *
  * @constructor
  */
 function G_Preferences(opt_startPoint, opt_getDefaultBranch) {
   this.debugZone = "prefs";
   this.observers_ = {};
   this.getDefaultBranch_ = !!opt_getDefaultBranch;
   this.startPoint_ = opt_startPoint || null;
 }
 G_Preferences.setterMap_ = { "string": "setCharPref",
                              "boolean": "setBoolPref",
                              "number": "setIntPref" };
 G_Preferences.getterMap_ = {};
 G_Preferences.getterMap_[Ci.nsIPrefBranch.PREF_STRING] = "getCharPref";
 G_Preferences.getterMap_[Ci.nsIPrefBranch.PREF_BOOL] = "getBoolPref";
 G_Preferences.getterMap_[Ci.nsIPrefBranch.PREF_INT] = "getIntPref";
 G_Preferences.prototype.__defineGetter__('prefs_', function() {
   var prefs;
   var prefSvc = Cc["@mozilla.org/preferences-service;1"]
                   .getService(Ci.nsIPrefService);
   if (this.getDefaultBranch_) {
     prefs = prefSvc.getDefaultBranch(this.startPoint_);
   } else {
     prefs = prefSvc.getBranch(this.startPoint_);
   }
   // QI to prefs in case we want to add observers
   prefs.QueryInterface(Ci.nsIPrefBranchInternal);
   return prefs;
 });
 /**
  * Stores a key/value in a user preference. Valid types for val are string,
  * boolean, and number. Complex values are not yet supported (but feel free to
  * add them!).
  */
 G_Preferences.prototype.setPref = function(key, val) {
   var datatype = typeof(val);
   if (datatype == "number" && (val % 1 != 0)) {
     throw new Error("Cannot store non-integer numbers in preferences.");
   }
   var meth = G_Preferences.setterMap_[datatype];
   if (!meth) {
     throw new Error("Pref datatype {" + datatype + "} not supported.");
   }
   return this.prefs_[meth](key, val);
 }
 /**
  * Retrieves a user preference. Valid types for the value are the same as for
  * setPref. If the preference is not found, opt_default will be returned
  * instead.
  */
 G_Preferences.prototype.getPref = function(key, opt_default) {
   var type = this.prefs_.getPrefType(key);
   // zero means that the specified pref didn't exist
   if (type == Ci.nsIPrefBranch.PREF_INVALID) {
     return opt_default;
   }
   var meth = G_Preferences.getterMap_[type];
   if (!meth) {
     throw new Error("Pref datatype {" + type + "} not supported.");
   }
   // If a pref has been cleared, it will have a valid type but won't
   // be gettable, so this will throw.
   try {
     return this.prefs_[meth](key);
   } catch(e) {
     return opt_default;
   }
 }
 /**
  * Delete a preference.
  *
  * @param which Name of preference to obliterate
  */
 G_Preferences.prototype.clearPref = function(which) {
   try {
     // This throws if the pref doesn't exist, which is fine because a
     // nonexistent pref is cleared
     this.prefs_.clearUserPref(which);
   } catch(e) {}
 }
 /**
  * Add an observer for a given pref.
  *
  * @param which String containing the pref to listen to
  * @param callback Function to be called when the pref changes. This
  *                 function will receive a single argument, a string
  *                 holding the preference name that changed
  */
 G_Preferences.prototype.addObserver = function(which, callback) {
   // Need to store the observer we create so we can eventually unregister it
   if (!this.observers_[which])
     this.observers_[which] = { callbacks: [], observers: [] };
   /* only add an observer if the callback hasn't been registered yet */
   if (this.observers_[which].callbacks.indexOf(callback) == -1) {
     var observer = new G_PreferenceObserver(callback);
     this.observers_[which].callbacks.push(callback);
     this.observers_[which].observers.push(observer);
     this.prefs_.addObserver(which, observer, false /* strong reference */);
   }
 }
 /**
  * Remove an observer for a given pref.
  *
  * @param which String containing the pref to stop listening to
  * @param callback Function to remove as an observer
  */
 G_Preferences.prototype.removeObserver = function(which, callback) {
   var ix = this.observers_[which].callbacks.indexOf(callback);
   G_Assert(this, ix != -1, "Tried to unregister a nonexistent observer");
   this.observers_[which].callbacks.splice(ix, 1);
   var observer = this.observers_[which].observers.splice(ix, 1)[0];
   this.prefs_.removeObserver(which, observer);
 }
 /**
  * Remove all preference observers registered through this object.
  */
 G_Preferences.prototype.removeAllObservers = function() {
   for (var which in this.observers_) {
     for each (var observer in this.observers_[which].observers) {
       this.prefs_.removeObserver(which, observer);
     }
   }
   this.observers_ = {};
 }
 /**
  * Helper class that knows how to observe preference changes and
  * invoke a callback when they do
  *
  * @constructor
  * @param callback Function to call when the preference changes
  */
 function G_PreferenceObserver(callback) {
   this.debugZone = "prefobserver";
   this.callback_ = callback;
 }
 /**
  * Invoked by the pref system when a preference changes. Passes the
  * message along to the callback.
  *
  * @param subject The nsIPrefBranch that changed
  * @param topic String "nsPref:changed" (aka
  *              NS_PREFBRANCH_PREFCHANGE_OBSERVER_ID -- but where does it
  *              live???)
  * @param data Name of the pref that changed
  */
 G_PreferenceObserver.prototype.observe = function(subject, topic, data) {
   G_Debug(this, "Observed pref change: " + data);
   this.callback_(data);
 }
 /**
  * XPCOM cruft
  *
  * @param iid Interface id of the interface the caller wants
  */
 G_PreferenceObserver.prototype.QueryInterface = function(iid) {
   if (iid.equals(Ci.nsISupports) ||
       iid.equals(Ci.nsIObserver) ||
       iid.equals(Ci.nsISupportsWeakReference))
     return this;
   throw Components.results.NS_ERROR_NO_INTERFACE;
 }
 #ifdef DEBUG
 // UNITTESTS
 function TEST_G_Preferences() {
   if (G_GDEBUG) {
     var z = "preferences UNITTEST";
     G_debugService.enableZone(z);
     G_Debug(z, "Starting");
     var p = new G_Preferences();
     var testPref = "test-preferences-unittest";
     var noSuchPref = "test-preferences-unittest-aypabtu";
     // Used to test observing
     var observeCount = 0;
     function observe(prefChanged) {
       G_Assert(z, prefChanged == testPref, "observer broken");
       observeCount++;
     };
     // Test setting, getting, and observing
     p.addObserver(testPref, observe);
     p.setPref(testPref, true);
     G_Assert(z, p.getPref(testPref), "get or set broken");
     G_Assert(z, observeCount == 1, "observer adding not working");
     p.removeObserver(testPref, observe);
     p.setPref(testPref, false);
     G_Assert(z, observeCount == 1, "observer removal not working");
     G_Assert(z, !p.getPref(testPref), "get broken");
     // Remember to clean up the prefs we've set, and test removing prefs
     // while we're at it
     p.clearPref(noSuchPref);
     G_Assert(z, !p.getPref(noSuchPref, false), "clear broken");
     p.clearPref(testPref);
     G_Debug(z, "PASSED");
   }
 }
 #endif