// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2009-2010 Gael Guennebaud <gael.guennebaud@inria.fr>
//
// 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/.
// SPDX-License-Identifier: MPL-2.0

#ifndef EIGEN_CWISE_UNARY_VIEW_H
#define EIGEN_CWISE_UNARY_VIEW_H

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

namespace Eigen {

namespace internal {
template <typename ViewOp, typename MatrixType, typename StrideType>
struct traits<CwiseUnaryView<ViewOp, MatrixType, StrideType> > : traits<MatrixType> {
  using ScalarRef = typename result_of<ViewOp(typename traits<MatrixType>::Scalar&)>::type1;
  static_assert(std::is_reference<ScalarRef>::value, "Views must return a reference type.");
  using Scalar = remove_cvref_t<ScalarRef>;
  using MatrixTypeNested = typename MatrixType::Nested;
  using MatrixTypeNested_ = remove_all_t<MatrixTypeNested>;
  enum {
    FlagsLvalueBit = is_lvalue<MatrixType>::value ? LvalueBit : 0,
    Flags =
        traits<MatrixTypeNested_>::Flags &
        (RowMajorBit | FlagsLvalueBit | DirectAccessBit),  // FIXME DirectAccessBit should not be handled by expressions
    MatrixTypeInnerStride = inner_stride_at_compile_time<MatrixType>::value,
    // need to cast the sizeof's from size_t to int explicitly, otherwise:
    // "error: no integral type can represent all of the enumerator values
    InnerStrideAtCompileTime =
        StrideType::InnerStrideAtCompileTime == 0
            ? (MatrixTypeInnerStride == Dynamic
                   ? int(Dynamic)
                   : int(MatrixTypeInnerStride) * int(sizeof(typename traits<MatrixType>::Scalar) / sizeof(Scalar)))
            : int(StrideType::InnerStrideAtCompileTime),

    OuterStrideAtCompileTime = StrideType::OuterStrideAtCompileTime == 0
                                   ? (outer_stride_at_compile_time<MatrixType>::value == Dynamic
                                          ? int(Dynamic)
                                          : outer_stride_at_compile_time<MatrixType>::value *
                                                int(sizeof(typename traits<MatrixType>::Scalar) / sizeof(Scalar)))
                                   : int(StrideType::OuterStrideAtCompileTime)
  };
};

// Generic API dispatcher
template <typename ViewOp, typename XprType, typename StrideType, typename StorageKind,
          bool Mutable = !std::is_const<XprType>::value>
class CwiseUnaryViewImpl : public generic_xpr_base<CwiseUnaryView<ViewOp, XprType, StrideType> >::type {
 public:
  using Base = typename generic_xpr_base<CwiseUnaryView<ViewOp, XprType, StrideType>>::type;
};

template <typename ViewOp, typename MatrixType, typename StrideType>
class CwiseUnaryViewImpl<ViewOp, MatrixType, StrideType, Dense, false>
    : public dense_xpr_base<CwiseUnaryView<ViewOp, MatrixType, StrideType> >::type {
 public:
  using Derived = CwiseUnaryView<ViewOp, MatrixType, StrideType>;
  using Base = typename dense_xpr_base<CwiseUnaryView<ViewOp, MatrixType, StrideType>>::type;
  EIGEN_DENSE_PUBLIC_INTERFACE(Derived)
  EIGEN_INHERIT_ASSIGNMENT_OPERATORS(CwiseUnaryViewImpl)

  EIGEN_DEVICE_FUNC inline const Scalar* data() const { return &(this->coeffRef(0)); }

  EIGEN_DEVICE_FUNC constexpr Index innerStride() const {
    return StrideType::InnerStrideAtCompileTime != 0 ? int(StrideType::InnerStrideAtCompileTime)
                                                     : derived().nestedExpression().innerStride() *
                                                           sizeof(typename traits<MatrixType>::Scalar) / sizeof(Scalar);
  }

  EIGEN_DEVICE_FUNC constexpr Index outerStride() const {
    return StrideType::OuterStrideAtCompileTime != 0 ? int(StrideType::OuterStrideAtCompileTime)
                                                     : derived().nestedExpression().outerStride() *
                                                           sizeof(typename traits<MatrixType>::Scalar) / sizeof(Scalar);
  }

 protected:
  EIGEN_DEFAULT_EMPTY_CONSTRUCTOR_AND_DESTRUCTOR(CwiseUnaryViewImpl)

  // Allow const access to coeffRef for the case of direct access being enabled.
  EIGEN_DEVICE_FUNC inline const Scalar& coeffRef(Index index) const {
    return internal::evaluator<Derived>(derived()).coeffRef(index);
  }

  EIGEN_DEVICE_FUNC inline const Scalar& coeffRef(Index row, Index col) const {
    return internal::evaluator<Derived>(derived()).coeffRef(row, col);
  }
};

template <typename ViewOp, typename MatrixType, typename StrideType>
class CwiseUnaryViewImpl<ViewOp, MatrixType, StrideType, Dense, true>
    : public CwiseUnaryViewImpl<ViewOp, MatrixType, StrideType, Dense, false> {
 public:
  using Base = CwiseUnaryViewImpl<ViewOp, MatrixType, StrideType, Dense, false>;
  using Derived = CwiseUnaryView<ViewOp, MatrixType, StrideType>;
  EIGEN_DENSE_PUBLIC_INTERFACE(Derived)
  EIGEN_INHERIT_ASSIGNMENT_OPERATORS(CwiseUnaryViewImpl)

  using Base::coeffRef;
  using Base::data;
  EIGEN_DEVICE_FUNC inline Scalar* data() { return &(this->coeffRef(0)); }

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Scalar& coeffRef(Index row, Index col) {
    return internal::evaluator<Derived>(derived()).coeffRef(row, col);
  }

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Scalar& coeffRef(Index index) {
    return internal::evaluator<Derived>(derived()).coeffRef(index);
  }

 protected:
  EIGEN_DEFAULT_EMPTY_CONSTRUCTOR_AND_DESTRUCTOR(CwiseUnaryViewImpl)
};

}  // namespace internal

/** \class CwiseUnaryView
 * \ingroup Core_Module
 *
 * \brief Generic lvalue expression of a coefficient-wise unary operator of a matrix or a vector
 *
 * \tparam ViewOp template functor implementing the view
 * \tparam MatrixType the type of the matrix we are applying the unary operator
 *
 * This class represents a lvalue expression of a generic unary view operator of a matrix or a vector.
 * It is the return type of real() and imag(), and most of the time this is the only way it is used.
 *
 * \sa MatrixBase::unaryViewExpr(const CustomUnaryOp &) const, class CwiseUnaryOp
 */
template <typename ViewOp, typename MatrixType, typename StrideType>
class CwiseUnaryView : public internal::CwiseUnaryViewImpl<ViewOp, MatrixType, StrideType,
                                                           typename internal::traits<MatrixType>::StorageKind> {
 public:
  using Base = typename internal::CwiseUnaryViewImpl<ViewOp, MatrixType, StrideType,
                                                     typename internal::traits<MatrixType>::StorageKind>::Base;
  EIGEN_GENERIC_PUBLIC_INTERFACE(CwiseUnaryView)
  using MatrixTypeNested = typename internal::ref_selector<MatrixType>::non_const_type;
  using NestedExpression = internal::remove_all_t<MatrixType>;

  explicit EIGEN_DEVICE_FUNC constexpr inline CwiseUnaryView(MatrixType& mat, const ViewOp& func = ViewOp())
      : m_matrix(mat), m_functor(func) {}

  EIGEN_INHERIT_ASSIGNMENT_OPERATORS(CwiseUnaryView)

  EIGEN_DEVICE_FUNC constexpr Index rows() const noexcept { return m_matrix.rows(); }
  EIGEN_DEVICE_FUNC constexpr Index cols() const noexcept { return m_matrix.cols(); }

  /** \returns the functor representing unary operation */
  EIGEN_DEVICE_FUNC constexpr const ViewOp& functor() const { return m_functor; }

  /** \returns the nested expression */
  EIGEN_DEVICE_FUNC constexpr const internal::remove_all_t<MatrixTypeNested>& nestedExpression() const {
    return m_matrix;
  }

  /** \returns the nested expression */
  EIGEN_DEVICE_FUNC constexpr std::remove_reference_t<MatrixTypeNested>& nestedExpression() { return m_matrix; }

 protected:
  MatrixTypeNested m_matrix;
  ViewOp m_functor;
};

}  // namespace Eigen

#endif  // EIGEN_CWISE_UNARY_VIEW_H