Eigen/src/Core/DenseCoeffsBase.h

// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2006-2010 Benoit Jacob <jacob.benoit.1@gmail.com>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifndef EIGEN_DENSECOEFFSBASE_H
#define EIGEN_DENSECOEFFSBASE_H

// IWYU pragma: private
#include "./InternalHeaderCheck.h"

namespace Eigen {

namespace internal {
template <typename T>
struct add_const_on_value_type_if_arithmetic {
  typedef std::conditional_t<is_arithmetic<T>::value, T, add_const_on_value_type_t<T>> type;
};
}  // namespace internal

/** \brief Base class providing read-only coefficient access to matrices and arrays.
 * \ingroup Core_Module
 * \tparam Derived Type of the derived class
 *
 * \note #ReadOnlyAccessors Constant indicating read-only access
 *
 * This class defines the \c operator() \c const function and friends, which can be used to read specific
 * entries of a matrix or array.
 *
 * \sa DenseCoeffsBase<Derived, WriteAccessors>, DenseCoeffsBase<Derived, DirectAccessors>,
 *     \ref TopicClassHierarchy
 */
template <typename Derived>
class DenseCoeffsBase<Derived, ReadOnlyAccessors> : public EigenBase<Derived> {
 public:
  typedef typename internal::traits<Derived>::StorageKind StorageKind;
  typedef typename internal::traits<Derived>::Scalar Scalar;
  typedef typename internal::packet_traits<Scalar>::type PacketScalar;

  // Explanation for this CoeffReturnType typedef.
  // - This is the return type of the coeff() method.
  // - The LvalueBit means exactly that we can offer a coeffRef() method, which means exactly that we can get references
  // to coeffs, which means exactly that we can have coeff() return a const reference (as opposed to returning a value).
  // - The is_arithmetic check is required since "const int", "const double", etc. will cause warnings on some systems
  // while the declaration of "const T", where T is a non arithmetic type does not. Always returning "const Scalar&" is
  // not possible, since the underlying expressions might not offer a valid address the reference could be referring to.
  typedef std::conditional_t<bool(internal::traits<Derived>::Flags& LvalueBit), const Scalar&,
                             std::conditional_t<internal::is_arithmetic<Scalar>::value, Scalar, const Scalar>>
      CoeffReturnType;

  typedef typename internal::add_const_on_value_type_if_arithmetic<typename internal::packet_traits<Scalar>::type>::type
      PacketReturnType;

  typedef EigenBase<Derived> Base;
  using Base::cols;
  using Base::derived;
  using Base::rows;
  using Base::size;

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Index rowIndexByOuterInner(Index outer, Index inner) const {
    return int(Derived::RowsAtCompileTime) == 1   ? 0
           : int(Derived::ColsAtCompileTime) == 1 ? inner
           : int(Derived::Flags) & RowMajorBit    ? outer
                                                  : inner;
  }

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Index colIndexByOuterInner(Index outer, Index inner) const {
    return int(Derived::ColsAtCompileTime) == 1   ? 0
           : int(Derived::RowsAtCompileTime) == 1 ? inner
           : int(Derived::Flags) & RowMajorBit    ? inner
                                                  : outer;
  }

  /** Short version: don't use this function, use
   * \link operator()(Index,Index) const \endlink instead.
   *
   * Long version: this function is similar to
   * \link operator()(Index,Index) const \endlink, but without the assertion.
   * Use this for limiting the performance cost of debugging code when doing
   * repeated coefficient access. Only use this when it is guaranteed that the
   * parameters \a row and \a col are in range.
   *
   * If EIGEN_INTERNAL_DEBUGGING is defined, an assertion will be made, making this
   * function equivalent to \link operator()(Index,Index) const \endlink.
   *
   * \sa operator()(Index,Index) const, coeffRef(Index,Index), coeff(Index) const
   */
  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType coeff(Index row, Index col) const {
    eigen_internal_assert(row >= 0 && row < rows() && col >= 0 && col < cols());
    return internal::evaluator<Derived>(derived()).coeff(row, col);
  }

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType coeffByOuterInner(Index outer,
                                                                                          Index inner) const {
    return coeff(rowIndexByOuterInner(outer, inner), colIndexByOuterInner(outer, inner));
  }

  /** \returns the coefficient at given the given row and column.
   *
   * \sa operator()(Index,Index), operator[](Index)
   */
  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType operator()(Index row, Index col) const {
    eigen_assert(row >= 0 && row < rows() && col >= 0 && col < cols());
    return coeff(row, col);
  }

  /** Short version: don't use this function, use
   * \link operator[](Index) const \endlink instead.
   *
   * Long version: this function is similar to
   * \link operator[](Index) const \endlink, but without the assertion.
   * Use this for limiting the performance cost of debugging code when doing
   * repeated coefficient access. Only use this when it is guaranteed that the
   * parameter \a index is in range.
   *
   * If EIGEN_INTERNAL_DEBUGGING is defined, an assertion will be made, making this
   * function equivalent to \link operator[](Index) const \endlink.
   *
   * \sa operator[](Index) const, coeffRef(Index), coeff(Index,Index) const
   */

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType coeff(Index index) const {
    EIGEN_STATIC_ASSERT(internal::evaluator<Derived>::Flags & LinearAccessBit,
                        THIS_COEFFICIENT_ACCESSOR_TAKING_ONE_ACCESS_IS_ONLY_FOR_EXPRESSIONS_ALLOWING_LINEAR_ACCESS)
    eigen_internal_assert(index >= 0 && index < size());
    return internal::evaluator<Derived>(derived()).coeff(index);
  }

  /** \returns the coefficient at given index.
   *
   * This method is allowed only for vector expressions, and for matrix expressions having the LinearAccessBit.
   *
   * \sa operator[](Index), operator()(Index,Index) const, x() const, y() const,
   * z() const, w() const
   */

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType operator[](Index index) const {
    EIGEN_STATIC_ASSERT(Derived::IsVectorAtCompileTime,
                        THE_BRACKET_OPERATOR_IS_ONLY_FOR_VECTORS__USE_THE_PARENTHESIS_OPERATOR_INSTEAD)
    eigen_assert(index >= 0 && index < size());
    return coeff(index);
  }

  /** \returns the coefficient at given index.
   *
   * This is synonymous to operator[](Index) const.
   *
   * This method is allowed only for vector expressions, and for matrix expressions having the LinearAccessBit.
   *
   * \sa operator[](Index), operator()(Index,Index) const, x() const, y() const,
   * z() const, w() const
   */

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType operator()(Index index) const {
    eigen_assert(index >= 0 && index < size());
    return coeff(index);
  }

  /** equivalent to operator[](0).  */

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType x() const { return (*this)[0]; }

  /** equivalent to operator[](1).  */

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType y() const {
    EIGEN_STATIC_ASSERT(Derived::SizeAtCompileTime == -1 || Derived::SizeAtCompileTime >= 2, OUT_OF_RANGE_ACCESS);
    return (*this)[1];
  }

  /** equivalent to operator[](2).  */

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType z() const {
    EIGEN_STATIC_ASSERT(Derived::SizeAtCompileTime == -1 || Derived::SizeAtCompileTime >= 3, OUT_OF_RANGE_ACCESS);
    return (*this)[2];
  }

  /** equivalent to operator[](3).  */

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType w() const {
    EIGEN_STATIC_ASSERT(Derived::SizeAtCompileTime == -1 || Derived::SizeAtCompileTime >= 4, OUT_OF_RANGE_ACCESS);
    return (*this)[3];
  }

  /** \internal
   * \returns the packet of coefficients starting at the given row and column. It is your responsibility
   * to ensure that a packet really starts there. This method is only available on expressions having the
   * PacketAccessBit.
   *
   * The \a LoadMode parameter may have the value \a #Aligned or \a #Unaligned. Its effect is to select
   * the appropriate vectorization instruction. Aligned access is faster, but is only possible for packets
   * starting at an address which is a multiple of the packet size.
   */

  template <int LoadMode>
  EIGEN_STRONG_INLINE PacketReturnType packet(Index row, Index col) const {
    typedef typename internal::packet_traits<Scalar>::type DefaultPacketType;
    eigen_internal_assert(row >= 0 && row < rows() && col >= 0 && col < cols());
    return internal::evaluator<Derived>(derived()).template packet<LoadMode, DefaultPacketType>(row, col);
  }

  /** \internal */
  template <int LoadMode>
  EIGEN_STRONG_INLINE PacketReturnType packetByOuterInner(Index outer, Index inner) const {
    return packet<LoadMode>(rowIndexByOuterInner(outer, inner), colIndexByOuterInner(outer, inner));
  }

  /** \internal
   * \returns the packet of coefficients starting at the given index. It is your responsibility
   * to ensure that a packet really starts there. This method is only available on expressions having the
   * PacketAccessBit and the LinearAccessBit.
   *
   * The \a LoadMode parameter may have the value \a #Aligned or \a #Unaligned. Its effect is to select
   * the appropriate vectorization instruction. Aligned access is faster, but is only possible for packets
   * starting at an address which is a multiple of the packet size.
   */

  template <int LoadMode>
  EIGEN_STRONG_INLINE PacketReturnType packet(Index index) const {
    EIGEN_STATIC_ASSERT(internal::evaluator<Derived>::Flags & LinearAccessBit,
                        THIS_COEFFICIENT_ACCESSOR_TAKING_ONE_ACCESS_IS_ONLY_FOR_EXPRESSIONS_ALLOWING_LINEAR_ACCESS)
    typedef typename internal::packet_traits<Scalar>::type DefaultPacketType;
    eigen_internal_assert(index >= 0 && index < size());
    return internal::evaluator<Derived>(derived()).template packet<LoadMode, DefaultPacketType>(index);
  }

 protected:
  // explanation: DenseBase is doing "using ..." on the methods from DenseCoeffsBase.
  // But some methods are only available in the DirectAccess case.
  // So we add dummy methods here with these names, so that "using... " doesn't fail.
  // It's not private so that the child class DenseBase can access them, and it's not public
  // either since it's an implementation detail, so has to be protected.
  void coeffRef();
  void coeffRefByOuterInner();
  void writePacket();
  void writePacketByOuterInner();
  void copyCoeff();
  void copyCoeffByOuterInner();
  void copyPacket();
  void copyPacketByOuterInner();
  void stride();
  void innerStride();
  void outerStride();
  void rowStride();
  void colStride();
};

/** \brief Base class providing read/write coefficient access to matrices and arrays.
 * \ingroup Core_Module
 * \tparam Derived Type of the derived class
 *
 * \note #WriteAccessors Constant indicating read/write access
 *
 * This class defines the non-const \c operator() function and friends, which can be used to write specific
 * entries of a matrix or array. This class inherits DenseCoeffsBase<Derived, ReadOnlyAccessors> which
 * defines the const variant for reading specific entries.
 *
 * \sa DenseCoeffsBase<Derived, DirectAccessors>, \ref TopicClassHierarchy
 */
template <typename Derived>
class DenseCoeffsBase<Derived, WriteAccessors> : public DenseCoeffsBase<Derived, ReadOnlyAccessors> {
 public:
  typedef DenseCoeffsBase<Derived, ReadOnlyAccessors> Base;

  typedef typename internal::traits<Derived>::StorageKind StorageKind;
  typedef typename internal::traits<Derived>::Scalar Scalar;
  typedef typename internal::packet_traits<Scalar>::type PacketScalar;
  typedef typename NumTraits<Scalar>::Real RealScalar;

  using Base::coeff;
  using Base::colIndexByOuterInner;
  using Base::cols;
  using Base::derived;
  using Base::rowIndexByOuterInner;
  using Base::rows;
  using Base::size;
  using Base::operator[];
  using Base::operator();
  using Base::w;
  using Base::x;
  using Base::y;
  using Base::z;

  /** Short version: don't use this function, use
   * \link operator()(Index,Index) \endlink instead.
   *
   * Long version: this function is similar to
   * \link operator()(Index,Index) \endlink, but without the assertion.
   * Use this for limiting the performance cost of debugging code when doing
   * repeated coefficient access. Only use this when it is guaranteed that the
   * parameters \a row and \a col are in range.
   *
   * If EIGEN_INTERNAL_DEBUGGING is defined, an assertion will be made, making this
   * function equivalent to \link operator()(Index,Index) \endlink.
   *
   * \sa operator()(Index,Index), coeff(Index, Index) const, coeffRef(Index)
   */
  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Scalar& coeffRef(Index row, Index col) {
    eigen_internal_assert(row >= 0 && row < rows() && col >= 0 && col < cols());
    return internal::evaluator<Derived>(derived()).coeffRef(row, col);
  }

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Scalar& coeffRefByOuterInner(Index outer, Index inner) {
    return coeffRef(rowIndexByOuterInner(outer, inner), colIndexByOuterInner(outer, inner));
  }

  /** \returns a reference to the coefficient at given the given row and column.
   *
   * \sa operator[](Index)
   */

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Scalar& operator()(Index row, Index col) {
    eigen_assert(row >= 0 && row < rows() && col >= 0 && col < cols());
    return coeffRef(row, col);
  }

  /** Short version: don't use this function, use
   * \link operator[](Index) \endlink instead.
   *
   * Long version: this function is similar to
   * \link operator[](Index) \endlink, but without the assertion.
   * Use this for limiting the performance cost of debugging code when doing
   * repeated coefficient access. Only use this when it is guaranteed that the
   * parameters \a row and \a col are in range.
   *
   * If EIGEN_INTERNAL_DEBUGGING is defined, an assertion will be made, making this
   * function equivalent to \link operator[](Index) \endlink.
   *
   * \sa operator[](Index), coeff(Index) const, coeffRef(Index,Index)
   */

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Scalar& coeffRef(Index index) {
    EIGEN_STATIC_ASSERT(internal::evaluator<Derived>::Flags & LinearAccessBit,
                        THIS_COEFFICIENT_ACCESSOR_TAKING_ONE_ACCESS_IS_ONLY_FOR_EXPRESSIONS_ALLOWING_LINEAR_ACCESS)
    eigen_internal_assert(index >= 0 && index < size());
    return internal::evaluator<Derived>(derived()).coeffRef(index);
  }

  /** \returns a reference to the coefficient at given index.
   *
   * This method is allowed only for vector expressions, and for matrix expressions having the LinearAccessBit.
   *
   * \sa operator[](Index) const, operator()(Index,Index), x(), y(), z(), w()
   */

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Scalar& operator[](Index index) {
    EIGEN_STATIC_ASSERT(Derived::IsVectorAtCompileTime,
                        THE_BRACKET_OPERATOR_IS_ONLY_FOR_VECTORS__USE_THE_PARENTHESIS_OPERATOR_INSTEAD)
    eigen_assert(index >= 0 && index < size());
    return coeffRef(index);
  }

  /** \returns a reference to the coefficient at given index.
   *
   * This is synonymous to operator[](Index).
   *
   * This method is allowed only for vector expressions, and for matrix expressions having the LinearAccessBit.
   *
   * \sa operator[](Index) const, operator()(Index,Index), x(), y(), z(), w()
   */

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR Scalar& operator()(Index index) {
    eigen_assert(index >= 0 && index < size());
    return coeffRef(index);
  }

  /** equivalent to operator[](0).  */

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR Scalar& x() { return (*this)[0]; }

  /** equivalent to operator[](1).  */

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR Scalar& y() {
    EIGEN_STATIC_ASSERT(Derived::SizeAtCompileTime == -1 || Derived::SizeAtCompileTime >= 2, OUT_OF_RANGE_ACCESS);
    return (*this)[1];
  }

  /** equivalent to operator[](2).  */

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR Scalar& z() {
    EIGEN_STATIC_ASSERT(Derived::SizeAtCompileTime == -1 || Derived::SizeAtCompileTime >= 3, OUT_OF_RANGE_ACCESS);
    return (*this)[2];
  }

  /** equivalent to operator[](3).  */

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR Scalar& w() {
    EIGEN_STATIC_ASSERT(Derived::SizeAtCompileTime == -1 || Derived::SizeAtCompileTime >= 4, OUT_OF_RANGE_ACCESS);
    return (*this)[3];
  }
};

/** \brief Base class providing direct read-only coefficient access to matrices and arrays.
 * \ingroup Core_Module
 * \tparam Derived Type of the derived class
 *
 * \note #DirectAccessors Constant indicating direct access
 *
 * This class defines functions to work with strides which can be used to access entries directly. This class
 * inherits DenseCoeffsBase<Derived, ReadOnlyAccessors> which defines functions to access entries read-only using
 * \c operator() .
 *
 * \sa \blank \ref TopicClassHierarchy
 */
template <typename Derived>
class DenseCoeffsBase<Derived, DirectAccessors> : public DenseCoeffsBase<Derived, ReadOnlyAccessors> {
 public:
  typedef DenseCoeffsBase<Derived, ReadOnlyAccessors> Base;
  typedef typename internal::traits<Derived>::Scalar Scalar;
  typedef typename NumTraits<Scalar>::Real RealScalar;

  using Base::cols;
  using Base::derived;
  using Base::rows;
  using Base::size;

  /** \returns the pointer increment between two consecutive elements within a slice in the inner direction.
   *
   * \sa outerStride(), rowStride(), colStride()
   */
  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline Index innerStride() const { return derived().innerStride(); }

  /** \returns the pointer increment between two consecutive inner slices (for example, between two consecutive columns
   *          in a column-major matrix).
   *
   * \sa innerStride(), rowStride(), colStride()
   */
  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline Index outerStride() const { return derived().outerStride(); }

  // FIXME shall we remove it ?
  EIGEN_CONSTEXPR inline Index stride() const { return Derived::IsVectorAtCompileTime ? innerStride() : outerStride(); }

  /** \returns the pointer increment between two consecutive rows.
   *
   * \sa innerStride(), outerStride(), colStride()
   */
  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline Index rowStride() const {
    return Derived::IsRowMajor ? outerStride() : innerStride();
  }

  /** \returns the pointer increment between two consecutive columns.
   *
   * \sa innerStride(), outerStride(), rowStride()
   */
  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline Index colStride() const {
    return Derived::IsRowMajor ? innerStride() : outerStride();
  }
};

/** \brief Base class providing direct read/write coefficient access to matrices and arrays.
 * \ingroup Core_Module
 * \tparam Derived Type of the derived class
 *
 * \note #DirectWriteAccessors Constant indicating direct access
 *
 * This class defines functions to work with strides which can be used to access entries directly. This class
 * inherits DenseCoeffsBase<Derived, WriteAccessors> which defines functions to access entries read/write using
 * \c operator().
 *
 * \sa \blank \ref TopicClassHierarchy
 */
template <typename Derived>
class DenseCoeffsBase<Derived, DirectWriteAccessors> : public DenseCoeffsBase<Derived, WriteAccessors> {
 public:
  typedef DenseCoeffsBase<Derived, WriteAccessors> Base;
  typedef typename internal::traits<Derived>::Scalar Scalar;
  typedef typename NumTraits<Scalar>::Real RealScalar;

  using Base::cols;
  using Base::derived;
  using Base::rows;
  using Base::size;

  /** \returns the pointer increment between two consecutive elements within a slice in the inner direction.
   *
   * \sa outerStride(), rowStride(), colStride()
   */
  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline Index innerStride() const EIGEN_NOEXCEPT { return derived().innerStride(); }

  /** \returns the pointer increment between two consecutive inner slices (for example, between two consecutive columns
   *          in a column-major matrix).
   *
   * \sa innerStride(), rowStride(), colStride()
   */
  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline Index outerStride() const EIGEN_NOEXCEPT { return derived().outerStride(); }

  // FIXME shall we remove it ?
  EIGEN_CONSTEXPR inline Index stride() const EIGEN_NOEXCEPT {
    return Derived::IsVectorAtCompileTime ? innerStride() : outerStride();
  }

  /** \returns the pointer increment between two consecutive rows.
   *
   * \sa innerStride(), outerStride(), colStride()
   */
  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline Index rowStride() const EIGEN_NOEXCEPT {
    return Derived::IsRowMajor ? outerStride() : innerStride();
  }

  /** \returns the pointer increment between two consecutive columns.
   *
   * \sa innerStride(), outerStride(), rowStride()
   */
  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline Index colStride() const EIGEN_NOEXCEPT {
    return Derived::IsRowMajor ? innerStride() : outerStride();
  }
};

namespace internal {

template <int Alignment, typename Derived, bool JustReturnZero>
struct first_aligned_impl {
  static EIGEN_CONSTEXPR inline Index run(const Derived&) EIGEN_NOEXCEPT { return 0; }
};

template <int Alignment, typename Derived>
struct first_aligned_impl<Alignment, Derived, false> {
  static inline Index run(const Derived& m) { return internal::first_aligned<Alignment>(m.data(), m.size()); }
};

/** \internal \returns the index of the first element of the array stored by \a m that is properly aligned with respect
 * to \a Alignment for vectorization.
 *
 * \tparam Alignment requested alignment in Bytes.
 *
 * There is also the variant first_aligned(const Scalar*, Integer) defined in Memory.h. See it for more
 * documentation.
 */
template <int Alignment, typename Derived>
static inline Index first_aligned(const DenseBase<Derived>& m) {
  enum { ReturnZero = (int(evaluator<Derived>::Alignment) >= Alignment) || !(Derived::Flags & DirectAccessBit) };
  return first_aligned_impl<Alignment, Derived, ReturnZero>::run(m.derived());
}

template <typename Derived>
static inline Index first_default_aligned(const DenseBase<Derived>& m) {
  typedef typename Derived::Scalar Scalar;
  typedef typename packet_traits<Scalar>::type DefaultPacketType;
  return internal::first_aligned<int(unpacket_traits<DefaultPacketType>::alignment), Derived>(m);
}

template <typename Derived, bool HasDirectAccess = has_direct_access<Derived>::ret>
struct inner_stride_at_compile_time {
  enum { ret = traits<Derived>::InnerStrideAtCompileTime };
};

template <typename Derived>
struct inner_stride_at_compile_time<Derived, false> {
  enum { ret = 0 };
};

template <typename Derived, bool HasDirectAccess = has_direct_access<Derived>::ret>
struct outer_stride_at_compile_time {
  enum { ret = traits<Derived>::OuterStrideAtCompileTime };
};

template <typename Derived>
struct outer_stride_at_compile_time<Derived, false> {
  enum { ret = 0 };
};

}  // end namespace internal

}  // end namespace Eigen

#endif  // EIGEN_DENSECOEFFSBASE_H