Added bits_t member to BitFlags and is_bitflags_v helper constant.

source/mijin/util/bitflags.hpp

@@ -25,6 +25,8 @@ namespace mijin
 template<typename TBits>
 struct BitFlags
 {
+    using bits_t = TBits;
+
     constexpr TBits& operator |=(const BitFlags& other) {
         for (std::size_t idx = 0; idx < sizeof(TBits); ++idx) {
             *(std::bit_cast<std::byte*>(asBits()) + idx) |= *(std::bit_cast<const std::byte*>(other.asBits()) + idx);
@@ -83,6 +85,9 @@ private:
     constexpr const TBits* asBits() const { return static_cast<const TBits*>(this); }
 };
 
+template<typename T>
+constexpr bool is_bitflags_v = std::is_base_of_v<BitFlags<T>, T>;
+
 //
 // public functions
 //