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

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 DirectAccessBit means exactly that the underlying data of coefficients can be directly accessed as a plain
  // strided array, which means exactly that the underlying data of coefficients does exist in memory, which means
  // exactly that the coefficients is const-referencable, which means exactly that we can have coeff() return a const
  // reference. For example, Map<const Matrix> have DirectAccessBit but not LvalueBit, so that Map<const Matrix>.coeff()
  // does points to a const Scalar& which exists in memory, while does not allow coeffRef() as it would not provide a
  // lvalue. Notice that DirectAccessBit and LvalueBit are mutually orthogonal.
  // - 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 | DirectAccessBit)), 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;
  }

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

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

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE 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);
  }

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE 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);
  }

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

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

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

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

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

  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);
  }

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

  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();
};

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;

  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));
  }

  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);
  }

  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);
  }

  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);
  }

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

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

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

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

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

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;

  EIGEN_DEVICE_FUNC constexpr Index innerStride() const { return derived().innerStride(); }

  EIGEN_DEVICE_FUNC constexpr Index outerStride() const { return derived().outerStride(); }

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

  EIGEN_DEVICE_FUNC constexpr Index rowStride() const { return Derived::IsRowMajor ? outerStride() : innerStride(); }

  EIGEN_DEVICE_FUNC constexpr Index colStride() const { return Derived::IsRowMajor ? innerStride() : outerStride(); }
};

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;

  EIGEN_DEVICE_FUNC constexpr Index innerStride() const noexcept { return derived().innerStride(); }

  EIGEN_DEVICE_FUNC constexpr Index outerStride() const noexcept { return derived().outerStride(); }

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

  EIGEN_DEVICE_FUNC constexpr Index rowStride() const noexcept {
    return Derived::IsRowMajor ? outerStride() : innerStride();
  }

  EIGEN_DEVICE_FUNC constexpr Index colStride() const noexcept {
    return Derived::IsRowMajor ? innerStride() : outerStride();
  }
};

namespace internal {

template <int Alignment, typename Derived, bool JustReturnZero>
struct first_aligned_impl {
  static constexpr Index run(const Derived&) 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()); }
};

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