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

compiled/ElemHideBase.cpp

 #include "ElemHideBase.h"
 #include "CSSPropertyFilter.h"
 #include "StringScanner.h"
 
 namespace
 {
   void NormalizeWhitespace(DependentString& text, String::size_type& domainsEnd,
       String::size_type& selectorStart)
   {
     // For element hiding filters we only want to remove spaces preceding the
@@ skipping 82 matching lines @@
     {
       case u'{':
       case u'}':
         return Type::UNKNOWN;
     }
   }
 
   // We are done validating, now we can normalize whitespace and the domain part
   if (seenSpaces)
     NormalizeWhitespace(text, data.mDomainsEnd, data.mSelectorStart);
-  DependentString(text, 0, data.mDomainsEnd).tolower();
+  DependentString(text, 0, data.mDomainsEnd).toLower();
 
   if (exception)
     return Type::ELEMHIDEEXCEPTION;
 
   do
   {
     // Is this a CSS property rule maybe?
     DependentString searchString(u"[-abp-properties="_str);
     data.mPrefixEnd = text.find(searchString, data.mSelectorStart);
     if (data.mPrefixEnd == text.npos ||
         data.mPrefixEnd + searchString.length() + 1 >= text.length())
     {
       break;
     }
 
     data.mRegexpStart = data.mPrefixEnd + searchString.length() + 1;
     char16_t quotation = text[data.mRegexpStart - 1];
     if (quotation != u'\'' && quotation != u'"')
       break;
 
     data.mRegexpEnd = text.find(quotation, data.mRegexpStart);
     if (data.mRegexpEnd == text.npos || data.mRegexpEnd + 1 >= text.length() ||
       text[data.mRegexpEnd + 1] != u']')
     {
       break;

[sergei, 2017/01/10 15:57:38]

Should not we rather return Type::UNKNOWN if the filter is in a broken format,
like the end is absent?

[Wladimir Palant, 2017/03/13 17:41:58]

No, a CSS property filter is an element hiding filter containing
[-abp-properties="..."]. If it doesn't contain that or only part of it then it
is just a regular element hiding filter and we leave it up to the browser to
validate its selector.

     }
 
     data.mSuffixStart = data.mRegexpEnd + 2;
     return Type::CSSPROPERTY;

[sergei, 2017/01/10 15:57:40]

Just in case, do we plan to add any information about -abp-properties to
https://adblockplus.org/filters?

[Wladimir Palant, 2017/03/13 17:41:56]

We do, once we don't consider them experimental any more. Right now they come
with big warnings and we don't want to encourage their use.

   } while (false);
 
   return Type::ELEMHIDE;
 }
 
 OwnedString ElemHideBase::GetSelectorDomain() const
 {
   /* TODO this is inefficient */
   OwnedString result;
   if (mDomains)
   {
     for (auto it = mDomains->begin(); it != mDomains->end(); ++it)
     {
       if (it->second && !it->first.empty())
       {
         if (!result.empty())
           result.append(u',');
         result.append(it->first);
       }
     }
   }
   return result;
 }