Need help understanding this c++ template/enum

Question

I am reading through the SafeInt.hpp code from Microsoft Docs (V 3.0.26) and stumbled upon the following code. I am not well versed in templates as used in an enum statement.

I am specifically bamboozled by "method = (....) ? xxxxx : "

Any help understanding it will be greatly appreciated. Thanks.

//core logic to determine casting behavior
enum CastMethod
{
    CastOK = 0,
    CastCheckLTZero,
    CastCheckGTMax,
    CastCheckSafeIntMinMaxUnsigned,
    CastCheckSafeIntMinMaxSigned,
    CastToFloat,
    CastFromFloat,
    CastToBool,
    CastFromBool,
    CastFromEnum
};

template < typename ToType, typename FromType >
class GetCastMethod
{
public:
    enum
    {
        method = ( safeint_internal::numeric_type<FromType>::isEnum )                     ? CastFromEnum :
                 ( safeint_internal::int_traits< FromType >::isBool &&
                     !safeint_internal::int_traits< ToType >::isBool )                    ? CastFromBool :

                 ( !safeint_internal::int_traits< FromType >::isBool &&
                     safeint_internal::int_traits< ToType >::isBool )                     ? CastToBool :

                 ( safeint_internal::type_compare< ToType, FromType >::isCastOK )      ? CastOK :

                 ( ( std::numeric_limits< ToType >::is_signed &&
                        !std::numeric_limits< FromType >::is_signed &&
                        sizeof( FromType ) >= sizeof( ToType ) ) ||
                   ( safeint_internal::type_compare< ToType, FromType >::isBothUnsigned &&
                        sizeof( FromType ) > sizeof( ToType ) ) )      ? CastCheckGTMax :

                 ( !std::numeric_limits< ToType >::is_signed &&
                     std::numeric_limits< FromType >::is_signed &&
                     sizeof( ToType ) >= sizeof( FromType ) )          ? CastCheckLTZero :

                 ( !std::numeric_limits< ToType >::is_signed )                    ? CastCheckSafeIntMinMaxUnsigned
                                                                       : CastCheckSafeIntMinMaxSigned
    };
};