versioning.h

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#ifndef REFLECTIVE_RAPIDJSON_VERSIONING
#define REFLECTIVE_RAPIDJSON_VERSIONING
 
#include <c++utilities/misc/traits.h>
 
namespace ReflectiveRapidJSON {
 
#ifdef REFLECTIVE_RAPIDJSON_GENERATOR
#define REFLECTIVE_RAPIDJSON_CAT_1(a, b) a##b
#define REFLECTIVE_RAPIDJSON_CAT_2(a, b) REFLECTIVE_RAPIDJSON_CAT_1(a, b)
#define REFLECTIVE_RAPIDJSON_AS_OF_VERSION(version)                                                                                                  \
    static constexpr std::size_t REFLECTIVE_RAPIDJSON_CAT_2(rrjAsOfVersion, __COUNTER__) = version;                                                  \
public
#define REFLECTIVE_RAPIDJSON_UNTIL_VERSION(version)                                                                                                  \
    static constexpr std::size_t REFLECTIVE_RAPIDJSON_CAT_2(rrjUntilVersion, __COUNTER__) = version;                                                 \
public
#else
#define REFLECTIVE_RAPIDJSON_AS_OF_VERSION(version) public
#define REFLECTIVE_RAPIDJSON_UNTIL_VERSION(version) public
#endif
 
#ifdef REFLECTIVE_RAPIDJSON_SHORT_MACROS
#define as_of_version(version) REFLECTIVE_RAPIDJSON_AS_OF_VERSION(version)
#define until_version(version) REFLECTIVE_RAPIDJSON_UNTIL_VERSION(version)
#endif
 
CPP_UTILITIES_TRAITS_DEFINE_TYPE_CHECK(IsVersioned, T::version);
 
template <typename VersionType> struct VersionNotSupported {
    VersionType presentVersion = 0, maxVersion = 0;
    const char *record = nullptr;
};
 
template <typename Type, bool Condition = IsVersioned<Type>::value> struct Versioning {
    static constexpr auto enabled = false;
};
 
template <typename Type> struct Versioning<Type, true> {
    static constexpr auto enabled = Type::version != 0;
    static constexpr auto serializationDefault = Type::version;
    static constexpr auto maxSupported = Type::version;
    static constexpr auto &applyDefault(std::remove_const_t<decltype(serializationDefault)> &version)
    {
        if (!version) {
            version = serializationDefault;
        }
        return version;
    }
    static constexpr auto applyDefaultValue(std::remove_const_t<decltype(serializationDefault)> version)
    {
        return applyDefault(version);
    }
    static constexpr auto isSupported(decltype(maxSupported) version)
    {
        return version <= maxSupported;
    }
    static constexpr auto assertVersion(decltype(maxSupported) version, const char *record = nullptr)
    {
        if (!isSupported(version)) {
            throw typename Type::VersionNotSupported({ .presentVersion = version, .maxVersion = maxSupported, .record = record });
        }
    }
};
 
} // namespace ReflectiveRapidJSON
 
#endif // REFLECTIVE_RAPIDJSON_TRAITS