Issue 5013 - Make parameter const ref when applicable.

include/AdblockPlus/JsEngine.h

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * 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
  * 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 75 matching lines @@
    */
   class JsEngine : public std::enable_shared_from_this<JsEngine>
   {
     friend class JsValue;
     friend class JsContext;
 
   public:
     /**
      * Event callback function.
      */
-    typedef std::function<void(JsValueList& params)> EventCallback;
+    typedef std::function<void(const 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.
      */
@@ skipping 10 matching lines @@
     static JsEnginePtr New(const AppInfo& appInfo = AppInfo(),
       TimerPtr timer = CreateDefaultTimer(),
       const ScopedV8IsolatePtr& isolate = ScopedV8IsolatePtr(new ScopedV8Isolate()));
 
     /**
      * Registers the callback function for an event.
      * @param eventName Event name. Note that this can be any string - it's a
      *        general purpose event handling mechanism.
      * @param callback Event callback function.
      */
-    void SetEventCallback(const std::string& eventName, EventCallback callback);
+    void SetEventCallback(const std::string& eventName, const EventCallback& callback);
 
     /**
      * Removes the callback function for an event.
      * @param eventName Event name.
      */
     void RemoveEventCallback(const std::string& eventName);
 
     /**
      * Triggers an event.
      * @param eventName Event name.
      * @param params Event parameters.
      */
-    void TriggerEvent(const std::string& eventName, JsValueList& params);
+    void TriggerEvent(const std::string& eventName, const JsValueList& params);
 
     /**
      * Evaluates a JavaScript expression.
      * @param source JavaScript expression to evaluate.
      * @param filename Optional file name for the expression, used in error
      *        messages.
      * @return Result of the evaluated expression.
      */
     JsValuePtr Evaluate(const std::string& source,
         const std::string& filename = "");
@@ skipping 34 matching lines @@
      */
     JsValuePtr NewObject();
 
     /**
      * Creates a JavaScript function that invokes a C++ callback.
      * @param callback C++ callback to invoke. The callback receives a
      *        `v8::Arguments` object and can use `FromArguments()` to retrieve
      *        the current `JsEngine`.
      * @return New `JsValue` instance.
      */
-    JsValuePtr NewCallback(v8::InvocationCallback callback);
+    JsValuePtr NewCallback(const v8::InvocationCallback& callback);
 
     /**
      * Returns a `JsEngine` instance contained in a `v8::Arguments` object.
      * Use this in callbacks created via `NewCallback()` to retrieve the current
      * `JsEngine`.
      * @param arguments `v8::Arguments` object containing the `JsEngine`
      *        instance.
      * @return `JsEngine` instance from `v8::Arguments`.
      */
     static JsEnginePtr FromArguments(const v8::Arguments& arguments);
@@ skipping 17 matching lines @@
      * @see `SetFileSystem()`.
      */
     FileSystemPtr GetFileSystem() const;
 
     /**
      * Sets the `FileSystem` implementation used for all file I/O.
      * Setting this is optional, the engine will use a `DefaultFileSystem`
      * instance by default, which might be sufficient.
      * @param The `FileSystem` instance to use.
      */
-    void SetFileSystem(FileSystemPtr val);
+    void SetFileSystem(const FileSystemPtr& val);
 
     /**
      * @see `SetWebRequest()`.
      */
     WebRequestPtr GetWebRequest() const;
 
     /**
      * 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);
+    void SetWebRequest(const 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() const;
 
     /**
      * @see `SetLogSystem()`.
      */
     LogSystemPtr GetLogSystem() const;
 
     /**
      * 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.
      */
-    void SetLogSystem(LogSystemPtr val);
+    void SetLogSystem(const LogSystemPtr& val);
 
     /**
      * Sets a global property that can be accessed by all the scripts.
      * @param name Name of the property to set.
      * @param value Value of the property to set.
      */
-    void SetGlobalProperty(const std::string& name, AdblockPlus::JsValuePtr value);
+    void SetGlobalProperty(const std::string& name, const AdblockPlus::JsValuePtr& value);
 
     /**
      * Returns a pointer to associated v8::Isolate.
      */
     v8::Isolate* GetIsolate()
     {
       return isolate->Get();
     }
 
   private:
     struct TimerTask
     {
       ~TimerTask();
       std::vector<std::unique_ptr<v8::Persistent<v8::Value>>> arguments;
     };
     typedef std::list<TimerTask> TimerTasks;
-    void CallTimerTask(TimerTasks::const_iterator timerTaskIterator);
+    void CallTimerTask(const TimerTasks::const_iterator& timerTaskIterator);

[sergei, 2017/04/12 13:34:30]

I'm not sure that passing of const_iterator of std::list by reference makes
sense.

[hub, 2017/04/12 15:06:14]

still more than a plain copy since it is not a PoD.

 
     explicit JsEngine(const ScopedV8IsolatePtr& isolate, TimerPtr timer);
 
     JsValuePtr GetGlobalObject();
 
     /// 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;
     std::mutex eventCallbacksMutex;
     mutable std::mutex isConnectionAllowedMutex;
     IsConnectionAllowedCallback isConnectionAllowed;
     TimerTasks timerTasks;
     TimerPtr timer;
   };
 }
 
 #endif