tensor_stream_reference.hpp

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// vim: set tabstop=2:softtabstop=2:shiftwidth=2:expandtab

#ifndef LIN_REFERENCES_TENSOR_STREAM_REFERENCE_HPP_
#define LIN_REFERENCES_TENSOR_STREAM_REFERENCE_HPP_

#include "../core.hpp"

namespace lin {
namespace internal {

template <class D, class E>
class TensorStreamReference : public Stream<D>, public Dimensions<D> {
 public:
  typedef traits<D> Traits;

 private:
  Stream<E> const &_stream;
  size_t const _i;
  size_t const _j;

 protected:
  using Stream<D>::derived;

  using Dimensions<D>::resize;

 public:
  using Stream<D>::size;
  using Stream<D>::eval;

  using Dimensions<D>::rows;
  using Dimensions<D>::cols;

  constexpr TensorStreamReference() = delete;
  constexpr TensorStreamReference(TensorStreamReference<D, E> const &) = default;
  constexpr TensorStreamReference(TensorStreamReference<D, E> &&) = default;
  constexpr TensorStreamReference<D, E> &operator=(TensorStreamReference<D, E> const &) = default;
  constexpr TensorStreamReference<D, E> &operator=(TensorStreamReference<D, E> &&) = default;

  constexpr TensorStreamReference(Stream<E> const &stream, size_t i, size_t j)
  : _stream(stream), _i(i), _j(j) {
    LIN_ASSERT((i >= 0) && (i + Traits::max_rows <= stream.rows()));
    LIN_ASSERT((j >= 0) && (j + Traits::max_cols <= stream.cols()));

    resize(Traits::max_rows, Traits::max_cols);
  }

  constexpr TensorStreamReference(Stream<E> const &stream, size_t i, size_t j, size_t r, size_t c)
  : _stream(stream), _i(i), _j(j) {
    LIN_ASSERT((i >= 0) && (i + r <= stream.rows()));
    LIN_ASSERT((j >= 0) && (j + c <= stream.cols()));

    resize(r, c);
  }

  constexpr typename Traits::elem_t operator()(size_t i, size_t j) const {
    LIN_ASSERT((i >= 0) && (i < rows()));
    LIN_ASSERT((j >= 0) && (j < cols()));

    return _stream(_i + i, _j + j);
  }

  constexpr typename Traits::elem_t operator()(size_t i) const {
    LIN_ASSERT((i >= 0) && (i < size()));

    return operator()(i / cols(), i % cols());
  }
};
}  // namespace internal
}  // namespace lin

#endif