Issue 5175 - Reject element hiding filter with empty domain names

compiled/filter/ActiveFilter.h

Index: compiled/filter/ActiveFilter.h
===================================================================
--- a/compiled/filter/ActiveFilter.h
+++ b/compiled/filter/ActiveFilter.h
@@ -37,24 +37,45 @@
           name = value;\
           if (FilterNotifier::Topic::topic != FilterNotifier::Topic::NONE)\
           {\
             FilterNotifier::FilterChange(FilterNotifier::Topic::topic, *this);\
           }\
         }\
       }
 
+struct ParsedDomains
+{
+  struct Domain {
+    String::size_type pos;
+    String::size_type len;
+    bool reverse;
+  };
+  bool hasIncludes;
+  bool hasEmpty;
+  std::vector<Domain> domains;
+
+  ParsedDomains()
+    : hasIncludes(false), hasEmpty(false)
+  {
+  }
+};
+
 class ActiveFilter : public Filter
 {
 public:
   typedef StringMap<bool> DomainMap;
   virtual DomainMap* GetDomains() const;
 protected:
   typedef StringSet SitekeySet;
-  void ParseDomains(const String& domains, String::value_type separator) const;
+  static ParsedDomains ParseDomainsInternal(const String& domains,
+      String::value_type separator, bool ignoreTrailingDot);
+  void FillDomains(const String& domains, const ParsedDomains& parsed) const;
+  void ParseDomains(const String& domains,
+      String::value_type separator, bool ignoreTrailingDot) const;
   void AddSitekey(const String& sitekey) const;
   virtual SitekeySet* GetSitekeys() const;
   mutable std::unique_ptr<DomainMap> mDomains;
   mutable std::unique_ptr<SitekeySet> mSitekeys;
 private:
   bool mIgnoreTrailingDot;
 public:
   static constexpr Type classType = Type::ACTIVE;