Issue 5013 - Use const JsValue and pass reference where applicable

src/FilterEngine.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2017 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
@@ skipping 183 matching lines @@
 
   // Lock the JS engine while we are loading scripts, no timeouts should fire
   // until we are done.
   const JsContext context(jsEngine);
 
   // Set the preconfigured prefs
   JsValuePtr preconfiguredPrefsObject = jsEngine->NewObject();
   for (FilterEngine::Prefs::const_iterator it = params.preconfiguredPrefs.begin();
     it != params.preconfiguredPrefs.end(); it++)
   {
-    preconfiguredPrefsObject->SetProperty(it->first, *it->second);
-  }
-  jsEngine->SetGlobalProperty("_preconfiguredPrefs", *preconfiguredPrefsObject);
+    preconfiguredPrefsObject->SetProperty(it->first, it->second);
+  }
+  jsEngine->SetGlobalProperty("_preconfiguredPrefs", preconfiguredPrefsObject);
   // Load adblockplus scripts
   for (int i = 0; !jsSources[i].empty(); i += 2)
     jsEngine->Evaluate(jsSources[i + 1], jsSources[i]);
 }
 
 FilterEnginePtr FilterEngine::Create(const JsEnginePtr& jsEngine,
   const FilterEngine::CreationParameters& params)
 {
   FilterEnginePtr retValue;
   Sync sync;
@@ skipping 309 matching lines @@
 void FilterEngine::ShowNotification(const ShowNotificationCallback& callback,
                                          const JsConstValueList& params) const
 {
   if (params.size() < 1)
     return;
 
   if (!params[0]->IsObject())
   {
     return;
   }
   callback(NotificationPtr(new Notification(params[0]->Clone())));

[hub, 2017/04/12 15:28:20]

This is the tricky part. Before that patch we receive a list of values and we
want to move it to the Notification instance.

Because params is now const, we can't move (IMHO this is better), and I had to
implement clone as I couldn't figure out a better way to have a copy of the
JsValue. If you prefer an actual copy constructor, I'm fine with that.

 }
 
 
 int FilterEngine::CompareVersions(const std::string& v1, const std::string& v2) const
 {
   JsConstValueList params;
   params.push_back(jsEngine->NewValue(v1));
   params.push_back(jsEngine->NewValue(v2));
   JsValuePtr func = jsEngine->Evaluate("API.compareVersions");
   return func->Call(params).AsInt();
@@ skipping 27 matching lines @@
     FilterPtr filter = GetWhitelistingFilter(currentUrl, contentTypeMask, parentUrl);
     if (filter)
     {
       return filter;
     }
     currentUrl = parentUrl;
   }
   while (urlIterator != documentUrls.end());
   return FilterPtr();
 }