lower_triangular.hpp

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// SPDX-License-Identifier: BSD-2-Clause
 
#ifndef pRC_CORE_TENSOR_OPERATOR_VIEWS_LOWER_TRIANGULAR_H
#define pRC_CORE_TENSOR_OPERATOR_VIEWS_LOWER_TRIANGULAR_H
 
#include <prc/core/basic/functions/zero.hpp>
#include <prc/core/tensor/declarations.hpp>
 
namespace pRC::TensorViews
{
    template<class T, class N, class V>
        requires IsTensorView<V> && (N::Dimension == 2)
    class LowerTriangular : public View<T, N, LowerTriangular<T, N, V>>
    {
    private:
        using Base = View<T, N, LowerTriangular>;
 
    public:
        template<class X>
            requires IsSame<V, RemoveReference<X>>
        LowerTriangular(X &&a)
            : mA(forward<X>(a))
        {
        }
 
        constexpr T operator()(Index const i, Index const j)
        {
            if(i >= j)
            {
                return mA(i, j);
            }
 
            return zero();
        }
 
        constexpr T operator()(Index const i, Index const j) const
        {
            if(i >= j)
            {
                return mA(i, j);
            }
 
            return zero();
        }
 
        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) = delete;
        constexpr decltype(auto) operator[](Index const index) const = delete;
 
    private:
        V mA;
    };
}
#endif // pRC_CORE_TENSOR_OPERATOR_VIEWS_LOWER_TRIANGULAR_H