narrow.hpp

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// SPDX-License-Identifier: BSD-2-Clause
 
#ifndef pRC_CORE_TENSOR_FUNCTIONS_NARROW_H
#define pRC_CORE_TENSOR_FUNCTIONS_NARROW_H
 
#include <prc/core/tensor/declarations.hpp>
 
namespace pRC
{
    template<Index... Ns, class F, class... Xs>
        requires(IsTensorish<RemoveReference<Xs>> && ...) &&
        (sizeof...(Xs) > 0) &&
        ((chip<Ns...>(typename TupleElement<0,
              Tuple<RemoveReference<Xs>...>>::Sizes()) ==
             chip<Ns...>(RemoveReference<Xs>::Sizes())) &&
            ...)
    static inline constexpr auto narrow(F &&f, Xs &&...args)
    {
        return expand(
            chip<Ns...>(makeSeries<Index,
                Common<typename RemoveReference<Xs>::Dimension...>{}>()),
            [&f, &args...](auto const... seq)
            {
                return exclude<seq...>(forward<F>(f), forward<Xs>(args)...);
            });
    }
 
    template<class F, Index... Ns, class... Xs>
        requires(IsTensorish<RemoveReference<Xs>> && ...) &&
        requires { narrow<Ns...>(declval<F>(), declval<Xs>()...); }
    static inline constexpr auto exclude(Xs &&...args)
    {
        return narrow<Ns...>(F(), forward<Xs>(args)...);
    }
}
#endif // pRC_CORE_TENSOR_FUNCTIONS_NARROW_H