Issue 4125 - [emscripten] Convert filter classes to C++

compiled/ActiveFilter.h

 #pragma once
 
 #include <emscripten.h>
 
 #include "Filter.h"
 #include "StringMap.h"
 
 #define FILTER_PROPERTY(type, name, getter, setter) \
     private:\
       type name;\
     public:\
       type EMSCRIPTEN_KEEPALIVE getter() const\
       {\
         return name;\
       }\
       void EMSCRIPTEN_KEEPALIVE setter(type value)\
       {\
         if (name != value)\
         {\
           type oldvalue = name;\
           name = value;\
-          String action(u"filter."_str #name);\
+          DependentString action(u"filter."_str #name);\
           EM_ASM_ARGS({\
             var filter = new (exports[Filter_mapping[$2]])($1);\
-            FilterNotifier.triggerListeners(getStringData($0), filter, $3, $4);\

[sergei, 2016/02/17 12:54:31]

Why do we need to instantiate a new `filter` and cannot use `this`?

[Wladimir Palant, 2016/02/18 16:06:38]

What is `this`? That's JavaScript code, all it got is a pointer to the C++
filter instance - there is no JavaScript wrapper for it, so we create one.

[sergei, 2016/02/22 12:45:33]

Acknowledged, sorry, overlooked it.

-          }, &action, this, GetType(), value, oldvalue);\
+            FilterNotifier.triggerListeners(readString($0), filter, $3, $4);\
+          }, &action, this, mType, value, oldvalue);\
         }\
       }
 
 class ActiveFilter : public Filter
 {
 protected:
   typedef StringMap<bool> DomainMap;
   typedef StringSet SitekeySet;
-  void ParseDomains(const String& domains, char16_t separator) const;

[sergei, 2016/02/17 12:54:29]

`String::value_type` instead of `char16_t` would be better, even more it's
`value_type` in cpp file.

[Wladimir Palant, 2016/02/18 16:06:31]

Done.

+  void ParseDomains(const String& domains, String::value_type separator) const;
   void AddSitekey(const String& sitekey) const;

[sergei, 2016/02/17 12:54:30]

I have removed const on the methods above, `mutable`, added constant operator[]
into StringMap, and slightly hacky constant getters `GetDomains` and
`GetSitekeys`, it seems working. It just looks confusing that such methods are
constant, their names say that they should not be constant.

[Wladimir Palant, 2016/02/18 16:06:32]

I'm not really sure how you've done that. If AddSitekey() isn't const then it
cannot be called from GetDomains(). Of course we can call it via GetDomains()
via const_cast but I'm not sure it's actually less of a hack. Did I miss some
other option?

[sergei, 2016/02/22 12:45:35]

Yeah, I did it using const_cast, it's difficult to say what is better. Let's
leave it as is.

[sergei, 2016/06/16 21:16:08]

Actually there is another option with only one mutable member and better looking
const-correctness but I'm not sure it is worth it now. I would say, let's keep
it in mind for present.

The option is to have some auxiliary ActiveFilter::Data structure and derived
from it RegExpFilter::Data structure (RegExpFilterData is a good canditate). It
should be possible to inject ActiveFilter::Data* using protected constructor.
Only the pointer to m_data should be mutable. In this case we can call such
non-const methods of Data from const methods of ActiveFilter and any Data will
be const-correct without mutable. It also removes inheritance from
RegExpFilterData and can have a positive effect if we make
ActiveFilter::GetDomains and ActiveFilter::GetSitekeys non virtual but make
Data::GetDomains and Data::GetSitekeys virtual. Of course in derived classes
like RegExpFilter to get access to members of RegExpFilter::Data we firstly have
to make static_cast to it but it has no overhead in runtime.

   virtual DomainMap* GetDomains() const;
   virtual SitekeySet* GetSitekeys() const;
   mutable std::unique_ptr<DomainMap> mDomains;
   mutable std::unique_ptr<SitekeySet> mSitekeys;
 private:
   bool mIgnoreTrailingDot;
 public:
-  ActiveFilter(const String& text, bool ignoreTrailingDot);
+  explicit ActiveFilter(Type type, const String& text, bool ignoreTrailingDot);
   FILTER_PROPERTY(bool, mDisabled, GetDisabled, SetDisabled);
   FILTER_PROPERTY(unsigned int, mHitCount, GetHitCount, SetHitCount);
   FILTER_PROPERTY(unsigned int, mLastHit, GetLastHit, SetLastHit);
-  static void ToLower(String& str, String::size_type start,
-      String::size_type end);
   bool EMSCRIPTEN_KEEPALIVE IsActiveOnDomain(DependentString& docDomain,
       const String& sitekey) const;
   bool EMSCRIPTEN_KEEPALIVE IsActiveOnlyOnDomain(DependentString& docDomain) const;
   bool EMSCRIPTEN_KEEPALIVE IsGeneric() const;
   OwnedString EMSCRIPTEN_KEEPALIVE Serialize() const;
 };