Issue 5013 - Improve some const-correctness

include/AdblockPlus/FilterEngine.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 34 matching lines @@
      * Filter types, see https://adblockplus.org/en/filters.
      */
     enum Type {TYPE_BLOCKING, TYPE_EXCEPTION,
                TYPE_ELEMHIDE, TYPE_ELEMHIDE_EXCEPTION,
                TYPE_COMMENT, TYPE_INVALID};
 
     /**
      * Retrieves the type of this filter.
      * @return Type of this filter.
      */
-    Type GetType();
+    Type GetType() const;

[sergei, 2017/03/23 10:49:56]

Do you mind to put it into another commit? I think it would be better to mark
all necessary methods of Filter and Subscription in one commit.

 
     /**
      * Checks whether this filter has been added to the list of custom filters.
      * @return `true` if this filter has been added.
      */
     bool IsListed();
 
     /**
      * Adds this filter to the list of custom filters.
      */
@@ skipping 445 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