strong_typedef_fwd.hpp

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#pragma once
 
/// @file userver/utils/strong_typedef_fwd.hpp
/// @brief Forward declarations and options for StrongTypedef.
/// @ingroup userver_universal
 
#include <type_traits>
 
USERVER_NAMESPACE_BEGIN
 
namespace utils {
 
enum class StrongTypedefOps {
    kNoCompare = 0,  /// Forbid all comparisons for StrongTypedef
 
    kCompareStrong = 1,           /// Allow comparing two StrongTypedef<Tag, T>
    kCompareTransparentOnly = 2,  /// Allow comparing StrongTypedef<Tag, T> and T
    kCompareTransparent = 3,      /// Allow both of the above
 
    kNonLoggable = 4,  /// Forbid logging and serializing for StrongTypedef
};
 
template <class Tag, class T, StrongTypedefOps Ops = StrongTypedefOps::kCompareStrong>
class StrongTypedef;
 
// Helpers
namespace impl::strong_typedef {
 
struct StrongTypedefTag {};
 
template <typename T>
concept IsStrongTypedef = std::is_base_of_v<StrongTypedefTag, T> && std::is_convertible_v<T&, StrongTypedefTag&>;
 
}  // namespace impl::strong_typedef
 
template <typename T>
using IsStrongTypedef = std::bool_constant<impl::strong_typedef::IsStrongTypedef<T>>;
 
}  // namespace utils
 
USERVER_NAMESPACE_END