template<int structdim, int dim, int spacedim = dim>
class TriaAccessorBase< structdim, dim, spacedim >
A base class for the accessor classes used by TriaRawIterator and derived classes.
This class offers only the basic functionality required by the iterators (stores the necessary data members, offers comparison operators and the like), but has no functionality to actually dereference data. This is done in the derived classes.
In the implementation, the behavior of this class differs between the cases where structdim==dim
(cells of a mesh) and structdim<dim
(faces and edges). For the latter, present_level is always equal to zero and the constructors may not receive a positive value there. For cells, any level is possible, but only those within the range of the levels of the Triangulation are reasonable. Furthermore, the function objects() returns either the container with all cells on the same level or the container with all objects of this dimension (structdim<dim
).
Some internals of this class are discussed in Iterator and accessor internals.
 Author
 Wolfgang Bangerth, Guido Kanschat, 1998, 2010
Definition at line 291 of file tria_accessor.h.
template<int structdim, int dim, int spacedim = dim>
Copy operator. These operators are usually used in a context like iterator a,b; *a=*b;
. Presumably, the intent here is to copy the object pointed to by b
to the object pointed to by a
. However, the result of dereferencing an iterator is not an object but an accessor; consequently, this operation is not useful for iterators on triangulations. Consequently, this operator is declared as deleted and can not be used.
template<int structdim, int dim, int spacedim = dim>
Copy operator. Since this is only called from iterators, do not return anything, since the iterator will return itself.
This method is protected, since it is only to be called from the iterator class.
template<int structdim, int dim, int spacedim = dim>
Comparison operator for accessors. This operator is used when comparing iterators into objects of a triangulation, for example when putting them into a std::map
.
If structure_dimension is less than dimension, we simply compare the index of such an object because faces and edges do not have levels. If structure_dimension equals dimension, we compare the level first, and the index only if levels are equal.
template<int structdim, int dim, int spacedim = dim>
This operator advances the iterator to the next element.
For dim=1
only: The next element is next on this level if there are more. If the present element is the last on this level, the first on the next level is accessed.
template<int structdim, int dim, int spacedim = dim>
This operator moves the iterator to the previous element.
For dim=1
only: The previous element is previous on this level if index>0
. If the present element is the first on this level, the last on the previous level is accessed.
template<int structdim, int dim, int spacedim = dim>
Return the index of the element presently pointed to on the present level.
Within a Triangulation object, cells are uniquely identified by a pair (level, index)
where the former is the cell's refinement level and the latter is the index of the cell within this refinement level (the latter being what this function returns). Consequently, there may be multiple cells on different refinement levels but with the same index within their level. Contrary to this, if the current object corresponds to a face or edge, then the object is uniquely identified solely by its index as faces and edges do not have a refinement level.
 Note
 The indices objects returned by this function are not a contiguous set of numbers on each level: going from cell to cell, some of the indices in a level may be unused.

If the triangulation is actually of type parallel::distributed::Triangulation then the indices are relatively only to that part of the distributed triangulation that is stored on the current processor. In other words, cells living in the partitions of the triangulation stored on different processors may have the same index even if they refer to the same cell, and the may have different indices even if they do refer to the same cell (e.g., if a cell is owned by one processor but is a ghost cell on another).
template<int structdim, int dim, int spacedim = dim>
const unsigned int TriaAccessorBase< structdim, dim, spacedim >::space_dimension = spacedim 

static 
Dimension of the space the object represented by this accessor lives in. For example, if this accessor represents a quad that is part of a two dimensional surface in fourdimensional space, then this value is four.
Definition at line 299 of file tria_accessor.h.
template<int structdim, int dim, int spacedim = dim>
const unsigned int TriaAccessorBase< structdim, dim, spacedim >::dimension = dim 

static 
Dimensionality of the object that the thing represented by this accessor is part of. For example, if this accessor represents a line that is part of a hexahedron, then this value will be three.
Definition at line 306 of file tria_accessor.h.
template<int structdim, int dim, int spacedim = dim>
const unsigned int TriaAccessorBase< structdim, dim, spacedim >::structure_dimension = structdim 

static 
Dimensionality of the current object represented by this accessor. For example, if it is line (irrespective of whether it is part of a quad or hex, and what dimension we are in), then this value equals 1.
Definition at line 313 of file tria_accessor.h.