common.hpp

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// SPDX-License-Identifier: BSD-2-Clause
 
#ifndef pRC_CORE_BASIC_COMMON_H
#define pRC_CORE_BASIC_COMMON_H
 
#include <prc/core/basic/type_traits.hpp>
 
namespace pRC
{
    template<class TA, class TB>
    struct DetectCommonType
    {
        template<class S>
        struct Success
        {
            using Type = S;
        };
 
        struct Failure
        {
        };
 
        template<class U1, class U2>
        static Success<RemoveConstReference<decltype(false ? declval<U1>()
                                                           : declval<U2>())>>
        test(int);
 
        template<class, class>
        static Failure test(...);
 
        using Type = decltype(test<TA, TB>(0));
    };
 
    template<class TA, class TB, class = If<>>
    struct CommonType : DetectCommonType<TA, TB>::Type
    {
    };
 
    template<class T, class... Ts>
    struct CommonTypes : CommonTypes<typename CommonTypes<T, Ts>::Type...>
    {
    };
 
    template<class TA, class TB>
    struct CommonTypes<TA, TB> : CommonType<TA, TB>
    {
    };
 
    template<class T>
    struct CommonTypes<T> : CommonTypes<T, T>
    {
    };
 
    template<class... Ts>
    using Common = typename CommonTypes<Ts...>::Type;
 
    template<class... Ts>
    using HasCommon = IsDetected<Common, Ts...>;
}
#endif // pRC_CORE_BASIC_COMMON_H