permute.hpp

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// SPDX-License-Identifier: BSD-2-Clause
 
#ifndef pRC_CORE_TENSOR_VIEWS_PERMUTE_H
#define pRC_CORE_TENSOR_VIEWS_PERMUTE_H
 
#include <prc/core/basic/sequence.hpp>
#include <prc/core/functors/subscript.hpp>
#include <prc/core/tensor/declarations.hpp>
 
namespace pRC::TensorViews
{
    template<class T, class N, class P, class V>
    class Permute;
 
    template<class T, class N, Index... Ps, class V>
        requires IsTensorView<V>
    class Permute<T, N, Sequence<Index, Ps...>, V>
        : public Conditional<IsAssignable<V>,
              Assignable<T, N, Permute<T, N, Sequence<Index, Ps...>, V>>,
              View<T, N, Permute<T, N, Sequence<Index, Ps...>, V>>>
    {
    private:
        using Base = Conditional<IsAssignable<V>, Assignable<T, N, Permute>,
            View<T, N, Permute>>;
 
    public:
        template<class X>
            requires IsSame<V, RemoveReference<X>>
        Permute(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 this->call(indices...);
        }
 
        template<IsConvertible<Index>... Is>
            requires(sizeof...(Is) == Base::Dimension)
        constexpr decltype(auto) operator()(Is const... indices) const
        {
            return this->call(indices...);
        }
 
        constexpr decltype(auto) operator()(
            typename Base::Subscripts const &subscripts)
        {
            return expand(getPermutation(Sequence<Index, Ps...>()),
                [this, &subscripts](auto const... seq) -> decltype(auto)
                {
                    return mA(subscripts[seq]...);
                });
        }
 
        constexpr decltype(auto) operator()(
            typename Base::Subscripts const &subscripts) const
        {
            return expand(getPermutation(Sequence<Index, Ps...>()),
                [this, &subscripts](auto const... seq) -> decltype(auto)
                {
                    return mA(subscripts[seq]...);
                });
        }
 
        constexpr decltype(auto) operator[](Index const index)
            requires IsSubscriptable<V> &&
            (Sequence<Index, Ps...>() == makeSeriesFor<Index, Ps...>())
        {
            return mA[index];
        }
 
        constexpr decltype(auto) operator[](Index const index) const
            requires IsSubscriptable<V> &&
            (Sequence<Index, Ps...>() == makeSeriesFor<Index, Ps...>())
        {
            return mA[index];
        }
 
    private:
        V mA;
    };
}
#endif // pRC_CORE_TENSOR_VIEWS_PERMUTE_H