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Added And operation for template metaprogramming

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Vraiment 2017-07-30 12:43:49 -07:00
parent 8489103f6a
commit 315d032b3b
1 changed files with 29 additions and 0 deletions
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29
SDL2pp/Private/Utility.hh
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@ -64,6 +64,35 @@ namespace Private {
template <typename T, typename... Tx>
using Or = typename OrOperation<T, Tx...>::type;
#endif
/*
* Templated class to perform an "AND" operation on any amount of types.
*
* Usage is as follows:
* template <typename T,
* typename = typename And<HasFeatureOne<T>, HasFeatureTwo<T>>
* void UseFeatureOneAndFeatureTwo(T t) {
* // The code will be only compiled if both
* // HasFeatureOne<T> and HasFeatureTwo<T> are type_true
* }
*/
#if __cplusplus >= 201703L
// Use the standard definitions if they are available
template <typename T, typename... Tx>
using And = typename std::conjunction<T, Tx...>::type;
#else
template <typename...>
struct AndOperation : std::true_type { };
template <typename T>
struct AndOperation<T> : T { };
template <typename T, typename... Tx>
struct AndOperation<T, Tx...> : std::conditional<bool(T::value), AndOperation<Tx...>, T> { };
template <typename T, typename... Tx>
using And = typename AndOperation<T, Tx...>::type;
#endif
}
}