Issue 5137 - [emscripten] Added basic filter storage implementation

compiled/storage/FilterStorage.h

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
- * Copyright (C) 2006-2017 eyeo GmbH
+ * Copyright (C) 2006-present 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/>.
  */
 
 #pragma once
 
 #include "../subscription/Subscription.h"
 #include "../bindings/runtime.h"
 
-namespace FilterStorage
+class FilterStorage
 {
-  BINDINGS_EXPORTED unsigned int GetSubscriptionCount();
-  BINDINGS_EXPORTED Subscription* SubscriptionAt(unsigned int index);
-  BINDINGS_EXPORTED int IndexOfSubscription(const Subscription* subscription);
-  BINDINGS_EXPORTED Subscription* GetSubscriptionForFilter(
-        const Filter* filter);
-  BINDINGS_EXPORTED bool AddSubscription(Subscription* subscription);
-  BINDINGS_EXPORTED bool RemoveSubscription(Subscription* subscription);
-  BINDINGS_EXPORTED bool MoveSubscription(Subscription* subscription,
+public:
+  typedef std::vector<SubscriptionPtr> Subscriptions;
+
+private:
+  Subscriptions mSubscriptions;
+  static FilterStorage* mInstance;
+
+public:
+  static FilterStorage* BINDINGS_EXPORTED GetInstance()
+  {
+    return mInstance;
+  }
+  Subscriptions::size_type BINDINGS_EXPORTED GetSubscriptionCount() const;
+  Subscription* BINDINGS_EXPORTED SubscriptionAt(
+      Subscriptions::size_type index) const;
+  int BINDINGS_EXPORTED IndexOfSubscription(
+      const Subscription* subscription) const;
+  Subscription* BINDINGS_EXPORTED GetSubscriptionForFilter(
+      const Filter* filter) const;
+  bool BINDINGS_EXPORTED AddSubscription(Subscription* subscription);
+  bool BINDINGS_EXPORTED RemoveSubscription(Subscription* subscription);
+  bool BINDINGS_EXPORTED MoveSubscription(Subscription* subscription,
       const Subscription* insertBefore);
-}
+};