Issue 4931 - add possibility to not send data depending on connection properties

include/AdblockPlus/FilterEngine.h

 /*
  * 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
@@ skipping 196 matching lines @@
      */
     typedef std::map<std::string, AdblockPlus::JsValuePtr> Prefs;
 
     /**
      * Callback type invoked when a new notification should be shown.
      * The parameter is the Notification object to be shown.
      */
     typedef std::function<void(const NotificationPtr&)> ShowNotificationCallback;
 
     /**
+     * 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
@@ skipping 196 matching lines @@
      * @param callback Callback to invoke.
      */
     void SetFilterChangeCallback(FilterChangeCallback callback);
 
     /**
      * Removes the callback invoked when the filters change.
      */
     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.
      * @param v2 Second version string.
      * @return
      *         - `0` if `v1` and `v2` are identical.
      *         - A negative number if `v1` is less than `v2`.
      *         - A positive number if `v1` is greater than `v2`.
      */
     int CompareVersions(const std::string& v1, const std::string& v2);
@@ skipping 33 matching lines @@
       const JsValueList& params);
     FilterPtr GetWhitelistingFilter(const std::string& url,
       ContentTypeMask contentTypeMask, const std::string& documentUrl) const;
     FilterPtr GetWhitelistingFilter(const std::string& url,
       ContentTypeMask contentTypeMask,
       const std::vector<std::string>& documentUrls) const;
   };
 }
 
 #endif