Eigen/src/Core/Select.h

// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2008-2010 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/.

#ifndef EIGEN_SELECT_H
#define EIGEN_SELECT_H

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

namespace Eigen {

/** \class Select
 * \ingroup Core_Module
 *
 * \brief Expression of a coefficient wise version of the C++ ternary operator ?:
 *
 * \tparam ConditionMatrixType the type of the \em condition expression which must be a boolean matrix
 * \tparam ThenMatrixType the type of the \em then expression
 * \tparam ElseMatrixType the type of the \em else expression
 *
 * This class represents an expression of a coefficient wise version of the C++ ternary operator ?:.
 * It is the return type of DenseBase::select() and most of the time this is the only way it is used.
 *
 * \sa DenseBase::select(const DenseBase<ThenDerived>&, const DenseBase<ElseDerived>&) const
 */

namespace internal {
template <typename ConditionMatrixType, typename ThenMatrixType, typename ElseMatrixType>
struct traits<Select<ConditionMatrixType, ThenMatrixType, ElseMatrixType> > : traits<ThenMatrixType> {
  typedef typename traits<ThenMatrixType>::Scalar Scalar;
  typedef Dense StorageKind;
  typedef typename traits<ThenMatrixType>::XprKind XprKind;
  typedef typename ConditionMatrixType::Nested ConditionMatrixNested;
  typedef typename ThenMatrixType::Nested ThenMatrixNested;
  typedef typename ElseMatrixType::Nested ElseMatrixNested;
  enum {
    RowsAtCompileTime = ConditionMatrixType::RowsAtCompileTime,
    ColsAtCompileTime = ConditionMatrixType::ColsAtCompileTime,
    MaxRowsAtCompileTime = ConditionMatrixType::MaxRowsAtCompileTime,
    MaxColsAtCompileTime = ConditionMatrixType::MaxColsAtCompileTime,
    Flags = (unsigned int)ThenMatrixType::Flags & ElseMatrixType::Flags & RowMajorBit
  };
};
}  // namespace internal

template <typename ConditionMatrixType, typename ThenMatrixType, typename ElseMatrixType>
class Select : public internal::dense_xpr_base<Select<ConditionMatrixType, ThenMatrixType, ElseMatrixType> >::type,
               internal::no_assignment_operator {
 public:
  typedef typename internal::dense_xpr_base<Select>::type Base;
  EIGEN_DENSE_PUBLIC_INTERFACE(Select)

  inline EIGEN_DEVICE_FUNC Select(const ConditionMatrixType& a_conditionMatrix, const ThenMatrixType& a_thenMatrix,
                                  const ElseMatrixType& a_elseMatrix)
      : m_condition(a_conditionMatrix), m_then(a_thenMatrix), m_else(a_elseMatrix) {
    eigen_assert(m_condition.rows() == m_then.rows() && m_condition.rows() == m_else.rows());
    eigen_assert(m_condition.cols() == m_then.cols() && m_condition.cols() == m_else.cols());
  }

  inline EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR Index rows() const EIGEN_NOEXCEPT { return m_condition.rows(); }
  inline EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR Index cols() const EIGEN_NOEXCEPT { return m_condition.cols(); }

  inline EIGEN_DEVICE_FUNC const Scalar coeff(Index i, Index j) const {
    if (m_condition.coeff(i, j))
      return m_then.coeff(i, j);
    else
      return m_else.coeff(i, j);
  }

  inline EIGEN_DEVICE_FUNC const Scalar coeff(Index i) const {
    if (m_condition.coeff(i))
      return m_then.coeff(i);
    else
      return m_else.coeff(i);
  }

  inline EIGEN_DEVICE_FUNC const ConditionMatrixType& conditionMatrix() const { return m_condition; }

  inline EIGEN_DEVICE_FUNC const ThenMatrixType& thenMatrix() const { return m_then; }

  inline EIGEN_DEVICE_FUNC const ElseMatrixType& elseMatrix() const { return m_else; }

 protected:
  typename ConditionMatrixType::Nested m_condition;
  typename ThenMatrixType::Nested m_then;
  typename ElseMatrixType::Nested m_else;
};

/** \returns a matrix where each coefficient (i,j) is equal to \a thenMatrix(i,j)
 * if \c *this(i,j) != Scalar(0), and \a elseMatrix(i,j) otherwise.
 *
 * Example: \include MatrixBase_select.cpp
 * Output: \verbinclude MatrixBase_select.out
 *
 * \sa DenseBase::bitwiseSelect(const DenseBase<ThenDerived>&, const DenseBase<ElseDerived>&)
 */
template <typename Derived>
template <typename ThenDerived, typename ElseDerived>
inline EIGEN_DEVICE_FUNC CwiseTernaryOp<
    internal::scalar_boolean_select_op<typename DenseBase<ThenDerived>::Scalar, typename DenseBase<ElseDerived>::Scalar,
                                       typename DenseBase<Derived>::Scalar>,
    ThenDerived, ElseDerived, Derived>
DenseBase<Derived>::select(const DenseBase<ThenDerived>& thenMatrix, const DenseBase<ElseDerived>& elseMatrix) const {
  using Op = internal::scalar_boolean_select_op<typename DenseBase<ThenDerived>::Scalar,
                                                typename DenseBase<ElseDerived>::Scalar, Scalar>;
  return CwiseTernaryOp<Op, ThenDerived, ElseDerived, Derived>(thenMatrix.derived(), elseMatrix.derived(), derived(),
                                                               Op());
}
/** Version of DenseBase::select(const DenseBase&, const DenseBase&) with
 * the \em else expression being a scalar value.
 *
 * \sa DenseBase::booleanSelect(const DenseBase<ThenDerived>&, const DenseBase<ElseDerived>&) const, class Select
 */
template <typename Derived>
template <typename ThenDerived>
inline EIGEN_DEVICE_FUNC CwiseTernaryOp<
    internal::scalar_boolean_select_op<typename DenseBase<ThenDerived>::Scalar, typename DenseBase<ThenDerived>::Scalar,
                                       typename DenseBase<Derived>::Scalar>,
    ThenDerived, typename DenseBase<ThenDerived>::ConstantReturnType, Derived>
DenseBase<Derived>::select(const DenseBase<ThenDerived>& thenMatrix,
                           const typename DenseBase<ThenDerived>::Scalar& elseScalar) const {
  using ElseConstantType = typename DenseBase<ThenDerived>::ConstantReturnType;
  using Op = internal::scalar_boolean_select_op<typename DenseBase<ThenDerived>::Scalar,
                                                typename DenseBase<ThenDerived>::Scalar, Scalar>;
  return CwiseTernaryOp<Op, ThenDerived, ElseConstantType, Derived>(
      thenMatrix.derived(), ElseConstantType(rows(), cols(), elseScalar), derived(), Op());
}
/** Version of DenseBase::select(const DenseBase&, const DenseBase&) with
 * the \em then expression being a scalar value.
 *
 * \sa DenseBase::booleanSelect(const DenseBase<ThenDerived>&, const DenseBase<ElseDerived>&) const, class Select
 */
template <typename Derived>
template <typename ElseDerived>
inline EIGEN_DEVICE_FUNC CwiseTernaryOp<
    internal::scalar_boolean_select_op<typename DenseBase<ElseDerived>::Scalar, typename DenseBase<ElseDerived>::Scalar,
                                       typename DenseBase<Derived>::Scalar>,
    typename DenseBase<ElseDerived>::ConstantReturnType, ElseDerived, Derived>
DenseBase<Derived>::select(const typename DenseBase<ElseDerived>::Scalar& thenScalar,
                           const DenseBase<ElseDerived>& elseMatrix) const {
  using ThenConstantType = typename DenseBase<ElseDerived>::ConstantReturnType;
  using Op = internal::scalar_boolean_select_op<typename DenseBase<ElseDerived>::Scalar,
                                                typename DenseBase<ElseDerived>::Scalar, Scalar>;
  return CwiseTernaryOp<Op, ThenConstantType, ElseDerived, Derived>(ThenConstantType(rows(), cols(), thenScalar),
                                                                    elseMatrix.derived(), derived(), Op());
}

}  // end namespace Eigen

#endif  // EIGEN_SELECT_H