Eigen/src/Core/NestByValue.h

// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2008 Gael Guennebaud <gael.guennebaud@inria.fr>
// Copyright (C) 2006-2008 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/.
// SPDX-License-Identifier: MPL-2.0

#ifndef EIGEN_NESTBYVALUE_H
#define EIGEN_NESTBYVALUE_H

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

namespace Eigen {

namespace internal {
template <typename ExpressionType>
struct traits<NestByValue<ExpressionType> > : public traits<ExpressionType> {
  enum { Flags = traits<ExpressionType>::Flags & ~NestByRefBit };
};
}  // namespace internal

/** \class NestByValue
 * \ingroup Core_Module
 *
 * \brief Expression which must be nested by value
 *
 * \tparam ExpressionType the type of the object of which we are requiring nesting-by-value
 *
 * This class is the return type of MatrixBase::nestByValue()
 * and most of the time this is the only way it is used.
 *
 * \sa MatrixBase::nestByValue()
 */
template <typename ExpressionType>
class NestByValue : public internal::dense_xpr_base<NestByValue<ExpressionType> >::type {
 public:
  using Base = typename internal::dense_xpr_base<NestByValue>::type;
  static constexpr bool HasDirectAccess = internal::has_direct_access<ExpressionType>::value;

  EIGEN_DENSE_PUBLIC_INTERFACE(NestByValue)

  EIGEN_DEVICE_FUNC constexpr explicit inline NestByValue(const ExpressionType& matrix) : m_expression(matrix) {}

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

  EIGEN_DEVICE_FUNC constexpr operator const ExpressionType&() const { return m_expression; }

  EIGEN_DEVICE_FUNC constexpr const ExpressionType& nestedExpression() const { return m_expression; }

  template <bool Enable = HasDirectAccess, std::enable_if_t<Enable, bool> = true>
  EIGEN_DEVICE_FUNC constexpr const Scalar* data() const {
    return m_expression.data();
  }

  template <bool Enable = HasDirectAccess, std::enable_if_t<Enable, bool> = true>
  EIGEN_DEVICE_FUNC constexpr Index innerStride() const {
    return m_expression.innerStride();
  }

  template <bool Enable = HasDirectAccess, std::enable_if_t<Enable, bool> = true>
  EIGEN_DEVICE_FUNC constexpr Index outerStride() const {
    return m_expression.outerStride();
  }

 protected:
  const ExpressionType m_expression;
};

/** \returns an expression of the temporary version of *this.
 */
template <typename Derived>
EIGEN_DEVICE_FUNC constexpr inline const NestByValue<Derived> DenseBase<Derived>::nestByValue() const {
  return NestByValue<Derived>(derived());
}

namespace internal {

// Evaluator of NestByValue<> -> forwards to the evaluator of the nested expression
template <typename ArgType>
struct evaluator<NestByValue<ArgType> > : public evaluator<ArgType> {
  using Base = evaluator<ArgType>;

  EIGEN_DEVICE_FUNC constexpr explicit evaluator(const NestByValue<ArgType>& xpr) : Base(xpr.nestedExpression()) {}
};
}  // namespace internal

}  // end namespace Eigen

#endif  // EIGEN_NESTBYVALUE_H