Issue 4948 - add possibility to not send data depending on connection properties

include/AdblockPlus/FilterEngine.h

Index: include/AdblockPlus/FilterEngine.h
diff --git a/include/AdblockPlus/FilterEngine.h b/include/AdblockPlus/FilterEngine.h
index 94b376eb8caadee35db2d4b96893ee5b0702b16d..11098d68d3a5c09c5e56db2298f35852a7da4697 100644
--- a/include/AdblockPlus/FilterEngine.h
+++ b/include/AdblockPlus/FilterEngine.h
@@ -1,6 +1,6 @@
 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
- * Copyright (C) 2006-2016 Eyeo GmbH
+ * 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
@@ -29,6 +29,7 @@
 namespace AdblockPlus
 {
   class FilterEngine;
+  typedef std::shared_ptr<FilterEngine> FilterEnginePtr;
 
   /**
    * Wrapper for an Adblock Plus filter object.
@@ -213,15 +214,52 @@ namespace AdblockPlus
     typedef std::function<void(const NotificationPtr&)> ShowNotificationCallback;
 
     /**
-     * Constructor.
+     * Callback function returning false when current connection is not
+     * allowedConnectionType, e.g. because it is a metered connection.
+     */
+    typedef std::function<bool(const std::string* allowedConnectionType)> IsConnectionAllowedCallback;
+
+    /**
+     * FilterEngine creation parameters.
+     */
+    struct CreationParameters
+    {
+      /**
+       * `AdblockPlus::FilterEngine::Prefs` name - value list of preconfigured
+       * prefs.
+       */
+      Prefs preconfiguredPrefs;
+      /**
+       * `AdblockPlus::FilterEngine::IsConnectionAllowedCallback` a callback
+       * checking whether the request from Adblock Plus should be blocked on
+       * the current connection.
+       */
+      IsConnectionAllowedCallback isConnectionAllowedCallback;
+    };
+
+    /**
+    * Callback type invoked when FilterEngine is created.
+    */
+    typedef std::function<void(const FilterEnginePtr&)> OnCreatedCallback;
+
+    /**
+     * Asynchronously constructs FilterEngine.
      * @param jsEngine `JsEngine` instance used to run JavaScript code
      *        internally.
-     * @param preconfiguredPrefs `AdblockPlus::FilterEngine::Prefs`
-     *        name-value list of preconfigured prefs.
+     * @param onCreated A callback which is called when FilterEngine is ready
+     *        for use.
+     * @param parameters optional creation parameters.
      */
-    explicit FilterEngine(JsEnginePtr jsEngine, 
-        const Prefs& preconfiguredPrefs = Prefs()
-      );
+    static void CreateAsync(const JsEnginePtr& jsEngine,
+      const OnCreatedCallback& onCreated,
+      const CreationParameters& parameters = CreationParameters());
+
+    /**
+     * Synchronous interface to construct FilterEngine. For details see
+     * asynchronous version CreateAsync.
+     */
+    static FilterEnginePtr Create(const JsEnginePtr& jsEngine,
+      const CreationParameters& params = CreationParameters());
 
     /**
      * Retrieves the `JsEngine` instance associated with this `FilterEngine`
@@ -399,7 +437,7 @@ namespace AdblockPlus
      *        available or not - to react to updates being available, use
      *        `FilterEngine::SetUpdateAvailableCallback()`.
      */
-    void ForceUpdateCheck(UpdateCheckDoneCallback callback);
+    void ForceUpdateCheck(const UpdateCheckDoneCallback& callback = UpdateCheckDoneCallback());
 
     /**
      * Sets the callback invoked when the filters change.
@@ -413,6 +451,20 @@ namespace AdblockPlus
     void RemoveFilterChangeCallback();
 
     /**
+     * Stores the value indicating what connection types are allowed, it is
+     * passed to CreateParameters::isConnectionAllowed callback.
+     * @param value Stored value. nullptr means removing of any previously
+     *        stored value.
+     */
+    void SetAllowedConnectionType(const std::string* value);
+
+    /**
+      * Retrieves previously stored allowed connection type.
+      * @return Preference value, or `nullptr` if it doesn't exist.
+      */
+    std::unique_ptr<std::string> GetAllowedConnectionType();
+
+    /**
      * Compares two version strings in
      * [Mozilla toolkit version format](https://developer.mozilla.org/en/docs/Toolkit_version_format).
      * @param v1 First version string.
@@ -442,12 +494,12 @@ namespace AdblockPlus
 
   private:
     JsEnginePtr jsEngine;
-    bool initialized;
     bool firstRun;
     int updateCheckId;
     static const std::map<ContentType, std::string> contentTypes;
 
-    void InitDone(JsValueList& params);
+    explicit FilterEngine(const JsEnginePtr& jsEngine);
+
     FilterPtr CheckFilterMatch(const std::string& url,
                                ContentTypeMask contentTypeMask,
                                const std::string& documentUrl) const;