DTensor.h

// Copyright 2024, UChicago Argonne, LLC
// All Rights Reserved
// Software Name: NEML2 -- the New Engineering material Model Library, version 2
// By: Argonne National Laboratory
// OPEN SOURCE LICENSE (MIT)
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#pragma once
 
#include "neml2/tensors/PrimitiveTensor.h"
#include "neml2/tensors/Tensor.h"
 
namespace neml2
{
// Helper to concatenate two integer sequences
template <class Seq1, class Seq2>
struct concat_seq;
template <Size... A, Size... B>
struct concat_seq<std::integer_sequence<Size, A...>, std::integer_sequence<Size, B...>>
{
  using type = std::integer_sequence<Size, A..., B...>;
};
template <class Seq1, class Seq2>
using concat_seq_t = typename concat_seq<Seq1, Seq2>::type;
 
// Turn integer_sequence<Size, ...> into a PrimitiveTensor<Tensor, ...>
template <class Derived, class Seq>
struct DTensorBase;
template <class Derived, Size... S>
struct DTensorBase<Derived, std::integer_sequence<Size, S...>>
{
  using type = PrimitiveTensor<Derived, S...>;
};
template <class Derived, class Seq>
using DTensorBase_t = typename DTensorBase<Derived, Seq>::type;
 
template <class T1, class T2, class TR>
class DTensor
  : public DTensorBase_t<
        TR,
        concat_seq_t<typename T1::base_sizes_sequence, typename T2::base_sizes_sequence>>
{
public:
  DTensor() = default;
 
  template <class Derived2>
  DTensor(const TensorBase<Derived2> & tensor);
};
 
template <class T1, class T2, class TR>
template <class Derived2>
DTensor<T1, T2, TR>::DTensor(const TensorBase<Derived2> & tensor)
  : DTensorBase_t<TR,
                  concat_seq_t<typename T1::base_sizes_sequence, typename T2::base_sizes_sequence>>(
        tensor)
{
}
} // namespace neml2