type_id.hpp

// SPDX-License-Identifier: MIT
#ifndef LIBSBX_UTILITY_TYPE_ID_HPP_
#define LIBSBX_UTILITY_TYPE_ID_HPP_
 
#include <cstdint>
#include <type_traits>
 
namespace sbx::utility {
 
namespace detail {
 
template<typename Scope>
struct id_generator final {
  [[nodiscard]] static auto next() noexcept -> std::uint32_t {
    static auto id = std::uint32_t{};
    return id++;
  }
}; // struct id_generator
 
struct default_type_id_scope { };
 
} // namespace detail
 
template<typename Scope, typename Type>
struct scoped_type_id {
 
  using type = Type;
  using scope = Scope;
 
  [[nodiscard]] static auto value() noexcept -> std::uint32_t {
    static const auto value = detail::id_generator<Scope>::next();
 
    return value;
  }
 
  [[nodiscard]] constexpr operator std::uint32_t() const noexcept {
    return value();
  }
 
}; // struct type_id
 
template<typename Type>
using type_id = scoped_type_id<detail::default_type_id_scope, Type>;
 
} // namespace sbx::utility
 
#endif // LIBSBX_UTILITY_TYPE_ID_HPP_