Issue 5258 - Implement Filter::As<>() method to make working with filters easier from C++ code

compiled/subscription/UserDefinedSubscription.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present 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 12 matching lines @@
 namespace
 {
   enum FilterCategory
   {
     NONE = 0,
     WHITELIST = 1,
     BLOCKING = 2,
     ELEMHIDE = 4,
   };
 
-  const FilterCategory filterTypeToCategory[] = {
-    FilterCategory::BLOCKING,   // UNKNOWN
-    FilterCategory::NONE,       // INVALID
-    FilterCategory::NONE,       // COMMENT
-    FilterCategory::BLOCKING,   // BLOCKING
-    FilterCategory::WHITELIST,  // WHITELIST
-    FilterCategory::ELEMHIDE,   // ELEMHIDE
-    FilterCategory::ELEMHIDE,   // ELEMHIDEEXCEPTION
-    FilterCategory::ELEMHIDE,   // ELEMHIDEEMULATION
-  };
+  FilterCategory filterTypeToCategory(Filter::Type type)
+  {
+    if (type == Filter::Type::BLOCKING)
+      return FilterCategory::BLOCKING;
+    if (type == Filter::Type::WHITELIST)
+      return FilterCategory::WHITELIST;
+    if ((type & Filter::Type::ELEMHIDEBASE) == Filter::Type::ELEMHIDEBASE)
+      return FilterCategory::ELEMHIDE;
 
-  static_assert(
-    sizeof(filterTypeToCategory) / sizeof(filterTypeToCategory[0]) == Filter::Type::VALUE_COUNT,
-    "Unexpected number of filter types, was a new type added?"
-  );
+    return FilterCategory::NONE;
+  }
 }
 
 UserDefinedSubscription::UserDefinedSubscription(const String& id)
     : Subscription(Type::USERDEFINED, id), mDefaults(0)
 {
 }
 
 bool UserDefinedSubscription::IsDefaultFor(const Filter& filter) const
 {
-  if (filter.mType >= Filter::Type::VALUE_COUNT)
-  {
-    assert2(false, "Filter type exceeds valid range");
-    abort();
-  }
-  return mDefaults & filterTypeToCategory[filter.mType];
+  return mDefaults & filterTypeToCategory(filter.mType);
 }
 
 void UserDefinedSubscription::MakeDefaultFor(const Filter& filter)
 {
-  if (filter.mType >= Filter::Type::VALUE_COUNT)
-  {
-    assert2(false, "Filter type exceeds valid range");
-    abort();
-  }
-  mDefaults |= filterTypeToCategory[filter.mType];
+  mDefaults |= filterTypeToCategory(filter.mType);
 }
 
 void UserDefinedSubscription::InsertFilterAt(Filter& filter, unsigned pos)
 {
   if (pos >= mFilters.size())
     pos = mFilters.size();
   mFilters.emplace(mFilters.begin() + pos, &filter);
 
   if (GetListed())
   {
@@ skipping 26 matching lines @@
     if (mDefaults & FilterCategory::BLOCKING)
       result.append(u" blocking"_str);
     if (mDefaults & FilterCategory::WHITELIST)
       result.append(u" whitelist"_str);
     if (mDefaults & FilterCategory::ELEMHIDE)
       result.append(u" elemhide"_str);
     result.append(u'\n');
   }
   return result;
 }