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

include/AdblockPlus/JsEngine.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 70 matching lines @@
     friend class JsValue;
     friend class JsContext;
 
   public:
     /**
      * Event callback function.
      */
     typedef std::function<void(JsValueList& params)> EventCallback;
 
     /**
+    * Callback function returning false when current connection is not allowed
+    * e.g. because it is a metered connection.
+    */
+    typedef std::function<bool()> IsConnectionAllowedCallback;
+
+    /**
      * Maps events to callback functions.
      */
     typedef std::map<std::string, EventCallback> EventMap;
 
     /**
      * Creates a new JavaScript engine instance.
      * @param appInfo Information about the app.
      * @param isolate v8::Isolate wrapper. This parameter should be considered
      *        as a temporary hack for tests, it will go away. Issue #3593.
      * @return New `JsEngine` instance.
@@ skipping 114 matching lines @@
 
     /**
      * Sets the `WebRequest` implementation used for XMLHttpRequests.
      * Setting this is optional, the engine will use a `DefaultWebRequest`
      * instance by default, which might be sufficient.
      * @param The `WebRequest` instance to use.
      */
     void SetWebRequest(WebRequestPtr val);
 
     /**
+    * Registers the callback function to check whether current connection is
+    * allowed for network requests.
+    * @param callback callback function.
+    */
+    void SetIsConnectionAllowedCallback(const IsConnectionAllowedCallback& callback);
+
+    /**
+     * Checks whether current connection is allowed. If
+     * IsConnectionAllowedCallback is not set then then it returns true.
+     */
+    bool IsConnectionAllowed();
+
+    /**
      * @see `SetLogSystem()`.
      */
     LogSystemPtr GetLogSystem();
 
     /**
      * Sets the `LogSystem` implementation used for logging (e.g. to handle
      * `console.log()` calls from JavaScript).
      * Setting this is optional, the engine will use a `DefaultLogSystem`
      * instance by default, which might be sufficient.
      * @param The `LogSystem` instance to use.
@@ skipping 22 matching lines @@
 
     /// Isolate must be disposed only after disposing of all objects which are
     /// using it.
     ScopedV8IsolatePtr isolate;
 
     FileSystemPtr fileSystem;
     WebRequestPtr webRequest;
     LogSystemPtr logSystem;
     std::unique_ptr<v8::Persistent<v8::Context>> context;
     EventMap eventCallbacks;
+    IsConnectionAllowedCallback isConnectionAllowed;
   };
 }
 
 #endif