Issue 6477 - separate done and error callbacks in IFileSystem::Read

include/AdblockPlus/JsEngine.h

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * 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
@@ skipping 200 matching lines @@
     JsWeakValuesID StoreJsValues(const JsValueList& values);
 
     /**
      * Extracts and removes from `JsEngine` earlier stored `JsValue`s.
      * The method is thread-safe.
      * @param id `JsWeakValuesID` of values.
      * @return `JsValueList` of stored values.
      */
     JsValueList TakeJsValues(const JsWeakValuesID& id);
 
+    /**
+     * Extracts earlier stored `JsValue`s from `JsEgnine` but does not remove
+     * them, one still must call `TakeJsValues`.
+     * @param id `JsWeakValuesID` of values.
+     * @return `JsValueList` of stored values.
+     */
+    JsValueList GetJsValues(const JsWeakValuesID& id);
+
     /*
      * Private functionality required to implement timers.
      * @param arguments `v8::FunctionCallbackInfo` is the arguments received in C++
      * callback associated for global setTimeout method.
      */
     static void ScheduleTimer(const v8::FunctionCallbackInfo<v8::Value>& arguments);
 
     /*
      * Private functionality required to implement web requests.
      * @param arguments `v8::FunctionCallbackInfo` is the arguments received in C++
@@ skipping 51 matching lines @@
 
     std::unique_ptr<v8::Global<v8::Context>> context;
     EventMap eventCallbacks;
     std::mutex eventCallbacksMutex;
     JsWeakValuesLists jsWeakValuesLists;
     std::mutex jsWeakValuesListsMutex;
   };
 }
 
 #endif