Image.h

// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2009 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_MISC_IMAGE_H
#define EIGEN_MISC_IMAGE_H

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

namespace Eigen {

namespace internal {

/** \class image_retval_base
 *
 */
template <typename DecompositionType>
struct traits<image_retval_base<DecompositionType> > {
  typedef typename DecompositionType::MatrixType MatrixType;
  typedef Matrix<typename MatrixType::Scalar,
                 MatrixType::RowsAtCompileTime,  // the image is a subspace of the destination space, whose
                                                 // dimension is the number of rows of the original matrix
                 Dynamic,                        // we don't know at compile time the dimension of the image (the rank)
                 traits<MatrixType>::Options,
                 MatrixType::MaxRowsAtCompileTime,  // the image matrix will consist of columns from the original
                                                    // matrix,
                 MatrixType::MaxColsAtCompileTime   // so it has the same number of rows and at most as many columns.
                 >
      ReturnType;
};

template <typename DecompositionType_>
struct image_retval_base : public ReturnByValue<image_retval_base<DecompositionType_> > {
  typedef DecompositionType_ DecompositionType;
  typedef typename DecompositionType::MatrixType MatrixType;
  typedef ReturnByValue<image_retval_base> Base;

  image_retval_base(const DecompositionType& dec, const MatrixType& originalMatrix)
      : m_dec(dec), m_rank(dec.rank()), m_cols(m_rank == 0 ? 1 : m_rank), m_originalMatrix(originalMatrix) {}

  inline Index rows() const { return m_dec.rows(); }
  inline Index cols() const { return m_cols; }
  inline Index rank() const { return m_rank; }
  inline const DecompositionType& dec() const { return m_dec; }
  inline const MatrixType& originalMatrix() const { return m_originalMatrix; }

  template <typename Dest>
  inline void evalTo(Dest& dst) const {
    static_cast<const image_retval<DecompositionType>*>(this)->evalTo(dst);
  }

 protected:
  const DecompositionType& m_dec;
  Index m_rank, m_cols;
  const MatrixType& m_originalMatrix;
};

}  // end namespace internal

#define EIGEN_MAKE_IMAGE_HELPERS(DecompositionType)                   \
  typedef typename DecompositionType::MatrixType MatrixType;          \
  typedef typename MatrixType::Scalar Scalar;                         \
  typedef typename MatrixType::RealScalar RealScalar;                 \
  typedef Eigen::internal::image_retval_base<DecompositionType> Base; \
  using Base::dec;                                                    \
  using Base::originalMatrix;                                         \
  using Base::rank;                                                   \
  using Base::rows;                                                   \
  using Base::cols;                                                   \
  image_retval(const DecompositionType& dec, const MatrixType& originalMatrix) : Base(dec, originalMatrix) {}

}  // end namespace Eigen

#endif  // EIGEN_MISC_IMAGE_H