Class sparse_matrix_block_impl

include/Eigen/Eigen/src/SparseCore/SparseBlock.h:98–284

template<typename SparseMatrixType, int BlockRows, int BlockCols>
class sparse_matrix_block_impl
  : public SparseCompressedBase<Block<SparseMatrixType,BlockRows,BlockCols,true> >
{
    typedef internal::remove_all_t<typename SparseMatrixType::Nested> MatrixTypeNested_;
    typedef Block<SparseMatrixType, BlockRows, BlockCols, true> BlockType;
    typedef SparseCompressedBase<Block<SparseMatrixType,BlockRows,BlockCols,true> > Base;
    using Base::convert_index;
public:
    enum { IsRowMajor = internal::traits<BlockType>::IsRowMajor };
    EIGEN_SPARSE_PUBLIC_INTERFACE(BlockType)
protected:
    typedef typename Base::IndexVector IndexVector;
    enum { OuterSize = IsRowMajor ? BlockRows : BlockCols };
public:

    inline sparse_matrix_block_impl(SparseMatrixType& xpr, Index i)
      : m_matrix(xpr), m_outerStart(convert_index(i)), m_outerSize(OuterSize)
    {}

    inline sparse_matrix_block_impl(SparseMatrixType& xpr, Index startRow, Index startCol, Index blockRows, Index blockCols)
      : m_matrix(xpr), m_outerStart(convert_index(IsRowMajor ? startRow : startCol)), m_outerSize(convert_index(IsRowMajor ? blockRows : blockCols))
    {}

    template<typename OtherDerived>
    inline BlockType& operator=(const SparseMatrixBase<OtherDerived>& other)
    {
      typedef internal::remove_all_t<typename SparseMatrixType::Nested> NestedMatrixType_;
      NestedMatrixType_& matrix = m_matrix;
      // This assignment is slow if this vector set is not empty
      // and/or it is not at the end of the nonzeros of the underlying matrix.

      // 1 - eval to a temporary to avoid transposition and/or aliasing issues
      Ref<const SparseMatrix<Scalar, IsRowMajor ? RowMajor : ColMajor, StorageIndex> > tmp(other.derived());
      eigen_internal_assert(tmp.outerSize()==m_outerSize.value());

      // 2 - let's check whether there is enough allocated memory
      Index nnz           = tmp.nonZeros();
      Index start         = m_outerStart==0 ? 0 : m_matrix.outerIndexPtr()[m_outerStart]; // starting position of the current block
      Index end           = m_matrix.outerIndexPtr()[m_outerStart+m_outerSize.value()]; // ending position of the current block
      Index block_size    = end - start;                                                // available room in the current block
      Index tail_size     = m_matrix.outerIndexPtr()[m_matrix.outerSize()] - end;

      Index free_size     = m_matrix.isCompressed()
                          ? Index(matrix.data().allocatedSize()) + block_size
                          : block_size;

      Index tmp_start = tmp.outerIndexPtr()[0];

      bool update_trailing_pointers = false;
      if(nnz>free_size)
      {
        // realloc manually to reduce copies
        typename SparseMatrixType::Storage newdata(m_matrix.data().allocatedSize() - block_size + nnz);

        internal::smart_copy(m_matrix.valuePtr(),       m_matrix.valuePtr() + start,      newdata.valuePtr());
        internal::smart_copy(m_matrix.innerIndexPtr(),  m_matrix.innerIndexPtr() + start, newdata.indexPtr());

        internal::smart_copy(tmp.valuePtr() + tmp_start,      tmp.valuePtr() + tmp_start + nnz,       newdata.valuePtr() + start);