eigen/Eigen/src/SparseCore/SparseAssign.h

// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2008-2014 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_SPARSEASSIGN_H
#define EIGEN_SPARSEASSIGN_H

namespace Eigen { 

template<typename Derived>    
template<typename OtherDerived>
Derived& SparseMatrixBase<Derived>::operator=(const EigenBase<OtherDerived> &other)
{
  // TODO use the evaluator mechanism
  other.derived().evalTo(derived());
  return derived();
}

template<typename Derived>
template<typename OtherDerived>
Derived& SparseMatrixBase<Derived>::operator=(const ReturnByValue<OtherDerived>& other)
{
  // TODO use the evaluator mechanism
  other.evalTo(derived());
  return derived();
}

template<typename Derived>
template<typename OtherDerived>
inline Derived& SparseMatrixBase<Derived>::operator=(const SparseMatrixBase<OtherDerived>& other)
{
  // FIXME, by default sparse evaluation do not alias, so we should be able to bypass the generic call_assignment
  internal::call_assignment/*_no_alias*/(derived(), other.derived());
  return derived();
}

template<typename Derived>
inline Derived& SparseMatrixBase<Derived>::operator=(const Derived& other)
{
  internal::call_assignment_no_alias(derived(), other.derived());
  return derived();
}

namespace internal {

template<>
struct storage_kind_to_evaluator_kind<Sparse> {
  typedef IteratorBased Kind;
};

template<>
struct storage_kind_to_shape<Sparse> {
  typedef SparseShape Shape;
};

struct Sparse2Sparse {};
struct Sparse2Dense  {};

template<> struct AssignmentKind<SparseShape, SparseShape>           { typedef Sparse2Sparse Kind; };
template<> struct AssignmentKind<SparseShape, SparseTriangularShape> { typedef Sparse2Sparse Kind; };
template<> struct AssignmentKind<DenseShape,  SparseShape>           { typedef Sparse2Dense  Kind; };


template<typename DstXprType, typename SrcXprType>
void assign_sparse_to_sparse(DstXprType &dst, const SrcXprType &src)
{
  eigen_assert(dst.rows() == src.rows() && dst.cols() == src.cols());
  
  typedef typename DstXprType::Scalar Scalar;
  typedef typename internal::evaluator<DstXprType>::type DstEvaluatorType;
  typedef typename internal::evaluator<SrcXprType>::type SrcEvaluatorType;

  SrcEvaluatorType srcEvaluator(src);

  const bool transpose = (DstEvaluatorType::Flags & RowMajorBit) != (SrcEvaluatorType::Flags & RowMajorBit);
  const Index outerEvaluationSize = (SrcEvaluatorType::Flags&RowMajorBit) ? src.rows() : src.cols();
  if ((!transpose) && src.isRValue())
  {
    // eval without temporary
    dst.resize(src.rows(), src.cols());
    dst.setZero();
    dst.reserve((std::max)(src.rows(),src.cols())*2);
    for (Index j=0; j<outerEvaluationSize; ++j)
    {
      dst.startVec(j);
      for (typename SrcEvaluatorType::InnerIterator it(srcEvaluator, j); it; ++it)
      {
        Scalar v = it.value();
        dst.insertBackByOuterInner(j,it.index()) = v;
      }
    }
    dst.finalize();
  }
  else
  {
    // eval through a temporary
    eigen_assert(( ((internal::traits<DstXprType>::SupportedAccessPatterns & OuterRandomAccessPattern)==OuterRandomAccessPattern) ||
              (!((DstEvaluatorType::Flags & RowMajorBit) != (SrcEvaluatorType::Flags & RowMajorBit)))) &&
              "the transpose operation is supposed to be handled in SparseMatrix::operator=");

    enum { Flip = (DstEvaluatorType::Flags & RowMajorBit) != (SrcEvaluatorType::Flags & RowMajorBit) };

    
    DstXprType temp(src.rows(), src.cols());

    temp.reserve((std::max)(src.rows(),src.cols())*2);
    for (Index j=0; j<outerEvaluationSize; ++j)
    {
      temp.startVec(j);
      for (typename SrcEvaluatorType::InnerIterator it(srcEvaluator, j); it; ++it)
      {
        Scalar v = it.value();
        temp.insertBackByOuterInner(Flip?it.index():j,Flip?j:it.index()) = v;
      }
    }
    temp.finalize();

    dst = temp.markAsRValue();
  }
}

// Generic Sparse to Sparse assignment
template< typename DstXprType, typename SrcXprType, typename Functor, typename Scalar>
struct Assignment<DstXprType, SrcXprType, Functor, Sparse2Sparse, Scalar>
{
  static void run(DstXprType &dst, const SrcXprType &src, const internal::assign_op<typename DstXprType::Scalar> &/*func*/)
  {
    eigen_assert(dst.rows() == src.rows() && dst.cols() == src.cols());
    
    assign_sparse_to_sparse(dst.derived(), src.derived());
  }
};

// Sparse to Dense assignment
template< typename DstXprType, typename SrcXprType, typename Functor, typename Scalar>
struct Assignment<DstXprType, SrcXprType, Functor, Sparse2Dense, Scalar>
{
  static void run(DstXprType &dst, const SrcXprType &src, const Functor &func)
  {
    eigen_assert(dst.rows() == src.rows() && dst.cols() == src.cols());
    
    typename internal::evaluator<SrcXprType>::type srcEval(src);
    typename internal::evaluator<DstXprType>::type dstEval(dst);
    const Index outerEvaluationSize = (internal::evaluator<SrcXprType>::Flags&RowMajorBit) ? src.rows() : src.cols();
    for (Index j=0; j<outerEvaluationSize; ++j)
      for (typename internal::evaluator<SrcXprType>::InnerIterator i(srcEval,j); i; ++i)
        func.assignCoeff(dstEval.coeffRef(i.row(),i.col()), i.value());
  }
};

template< typename DstXprType, typename SrcXprType, typename Scalar>
struct Assignment<DstXprType, SrcXprType, internal::assign_op<typename DstXprType::Scalar>, Sparse2Dense, Scalar>
{
  static void run(DstXprType &dst, const SrcXprType &src, const internal::assign_op<typename DstXprType::Scalar> &)
  {
    eigen_assert(dst.rows() == src.rows() && dst.cols() == src.cols());
    
    dst.setZero();
    typename internal::evaluator<SrcXprType>::type srcEval(src);
    typename internal::evaluator<DstXprType>::type dstEval(dst);
    const Index outerEvaluationSize = (internal::evaluator<SrcXprType>::Flags&RowMajorBit) ? src.rows() : src.cols();
    for (Index j=0; j<outerEvaluationSize; ++j)
      for (typename internal::evaluator<SrcXprType>::InnerIterator i(srcEval,j); i; ++i)
        dstEval.coeffRef(i.row(),i.col()) = i.value();
  }
};

// Specialization for "dst = dec.solve(rhs)"
// NOTE we need to specialize it for Sparse2Sparse to avoid ambiguous specialization error
template<typename DstXprType, typename DecType, typename RhsType, typename Scalar>
struct Assignment<DstXprType, Solve<DecType,RhsType>, internal::assign_op<Scalar>, Sparse2Sparse, Scalar>
{
  typedef Solve<DecType,RhsType> SrcXprType;
  static void run(DstXprType &dst, const SrcXprType &src, const internal::assign_op<Scalar> &)
  {
    src.dec()._solve_impl(src.rhs(), dst);
  }
};

} // end namespace internal

} // end namespace Eigen

#endif // EIGEN_SPARSEASSIGN_H