reverse.hpp

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// SPDX-License-Identifier: BSD-2-Clause
 
#ifndef pRC_CORE_TENSOR_VIEWS_REVERSE_H
#define pRC_CORE_TENSOR_VIEWS_REVERSE_H
 
#include <prc/core/functors/subscript.hpp>
#include <prc/core/tensor/declarations.hpp>
 
namespace pRC::TensorViews
{
    template<class T, class N, class R, class V>
    class Reverse;
 
    template<class T, Size... Ns, Bool... Rs, class V>
        requires IsTensorView<V>
    class Reverse<T, Sizes<Ns...>, Sequence<Bool, Rs...>, V>
        : public Conditional<IsAssignable<V>,
              Assignable<T, Sizes<Ns...>,
                  Reverse<T, Sizes<Ns...>, Sequence<Bool, Rs...>, V>>,
              View<T, Sizes<Ns...>,
                  Reverse<T, Sizes<Ns...>, Sequence<Bool, Rs...>, V>>>
    {
    private:
        using Base =
            Conditional<IsAssignable<V>, Assignable<T, Sizes<Ns...>, Reverse>,
                View<T, Sizes<Ns...>, Reverse>>;
 
    public:
        template<class X>
            requires IsSame<V, RemoveReference<X>>
        Reverse(X &&a)
            : mA(forward<X>(a))
        {
        }
 
        using Base::operator=;
 
        template<IsConvertible<Index>... Is>
            requires(sizeof...(Is) == Base::Dimension)
        constexpr decltype(auto) operator()(Is const... indices)
        {
            return mA((Rs ? Ns - indices - 1 : indices)...);
        }
 
        template<IsConvertible<Index>... Is>
            requires(sizeof...(Is) == Base::Dimension)
        constexpr decltype(auto) operator()(Is const... indices) const
        {
            return mA((Rs ? Ns - indices - 1 : indices)...);
        }
 
        constexpr decltype(auto) operator()(
            typename Base::Subscripts const &subscripts)
        {
            return this->call(subscripts);
        }
 
        constexpr decltype(auto) operator()(
            typename Base::Subscripts const &subscripts) const
        {
            return this->call(subscripts);
        }
 
        constexpr decltype(auto) operator[](Index const index)
            requires IsSubscriptable<V> &&
            (((Rs == false) && ...) || (Rs && ...))
        {
            if constexpr((Rs && ...))
            {
                return mA[Base::size() - 1 - index];
            }
            else
            {
                return mA[index];
            }
        }
 
        constexpr decltype(auto) operator[](Index const index) const
            requires IsSubscriptable<V> &&
            (((Rs == false) && ...) || (Rs && ...))
        {
            if constexpr((Rs && ...))
            {
                return mA[Base::size() - 1 - index];
            }
            else
            {
                return mA[index];
            }
        }
 
    private:
        V mA;
    };
}
#endif // pRC_CORE_TENSOR_VIEWS_REVERSE_H