TypeInfo.hpp

#pragma once
 
#include <cstddef>
#include <mutex>
#include <typeindex>
#include <unordered_map>
 
namespace PixelBullet
{
    using TypeID = std::size_t;
 
    template <typename Base>
    class TypeInfo
    {
    public:
        TypeInfo() = delete;
 
        template <typename K>
        static TypeID Get() noexcept
        {
            static_assert(std::is_convertible_v<K*, Base*>, "K must be derived from Base");
            const std::type_index key(typeid(K));
            {
                std::scoped_lock lock(s_Mutex);
                auto it = s_Map.find(key);
                if (it != s_Map.end())
                {
                    return it->second;
                }
                const TypeID id = s_NextID++;
                s_Map.emplace(key, id);
                return id;
            }
        }
 
    private:
        static inline std::mutex s_Mutex;
        static inline std::unordered_map<std::type_index, TypeID> s_Map;
        static inline TypeID s_NextID = 0;
    };
} // namespace PixelBullet