// This file is part of Eigen, a lightweight C++ template library
// for linear algebra. Eigen itself is part of the KDE project.
//
// Copyright (C) 2006-2007 Benoit Jacob <jacob@math.jussieu.fr>
//
// Eigen is free software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the Free Software
// Foundation; either version 2 or (at your option) any later version.
//
// Eigen is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
// details.
//
// You should have received a copy of the GNU General Public License along
// with Eigen; if not, write to the Free Software Foundation, Inc., 51
// Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
//
// As a special exception, if other files instantiate templates or use macros
// or functions from this file, or you compile this file and link it
// with other works to produce a work based on this file, this file does not
// by itself cause the resulting work to be covered by the GNU General Public
// License. This exception does not invalidate any other reasons why a work
// based on this file might be covered by the GNU General Public License.

#ifndef EIGEN_ROW_H
#define EIGEN_ROW_H

/** \class Row
  *
  * \brief Expression of a row
  *
  * \param MatrixType the type of the object in which we are taking a row
  *
  * This class represents an expression of a row. It is the return
  * type of MatrixBase::row() and most of the time this is the only way it
  * is used.
  *
  * However, if you want to directly maniputate row expressions,
  * for instance if you want to write a function returning such an expression, you
  * will need to use this class.
  *
  * Here is an example illustrating this:
  * \include class_Row.cpp
  * Output: \verbinclude class_Row.out
  *
  * \sa MatrixBase::row()
  */
template<typename MatrixType> class Row
  : public MatrixBase<typename MatrixType::Scalar, Row<MatrixType> >
{
  public:
    typedef typename MatrixType::Scalar Scalar;
    typedef typename MatrixType::Ref MatRef;
    friend class MatrixBase<Scalar, Row<MatrixType> >;

    Row(const MatRef& matrix, int row)
      : m_matrix(matrix), m_row(row)
    {
      assert(row >= 0 && row < matrix.rows());
    }
    
    Row(const Row& other)
      : m_matrix(other.m_matrix), m_row(other.m_row) {}
    
    template<typename OtherDerived>
    Row& operator=(const MatrixBase<Scalar, OtherDerived>& other)
    {
      return MatrixBase<Scalar, Row<MatrixType> >::operator=(other);
    }
    
    EIGEN_INHERIT_ASSIGNMENT_OPERATORS(Row)
    
  private:
    static const int _RowsAtCompileTime = 1,
                     _ColsAtCompileTime = MatrixType::ColsAtCompileTime;

    const Row& _ref() const { return *this; }
    
    int _rows() const { return 1; }
    int _cols() const { return m_matrix.cols(); }
    
    Scalar& _coeffRef(int, int col)
    {
      return m_matrix.coeffRef(m_row, col);
    }
    
    Scalar _coeff(int, int col) const
    {
      return m_matrix.coeff(m_row, col);
    }
    
  protected:
    MatRef m_matrix;
    const int m_row;
};

/** \returns an expression of the \a i-th row of *this. Note that the numbering starts at 0.
  *
  * Example: \include MatrixBase_row.cpp
  * Output: \verbinclude MatrixBase_row.out
  *
  * \sa col(), class Row */
template<typename Scalar, typename Derived>
Row<Derived>
MatrixBase<Scalar, Derived>::row(int i)
{
  return Row<Derived>(ref(), i);
}

/** This is the const version of row(). */
template<typename Scalar, typename Derived>
const Row<Derived>
MatrixBase<Scalar, Derived>::row(int i) const
{
  return Row<Derived>(ref(), i);
}

#endif // EIGEN_ROW_H