Dune::EntityPointer< GridImp, IteratorImp > Class Template Reference
[EntityPointer and Iterators]

#include <entitypointer.hh>

List of all members.


Detailed Description

template<class GridImp, class IteratorImp>
class Dune::EntityPointer< GridImp, IteratorImp >

Wrapper class for pointers to entities.

Template parameters are:

Engine Concept

The EntityPointer class template wraps an object of type IteratorImp and forwards all member function calls to corresponding members of this class. In that sense EntityPointer defines the interface and IteratorImp supplies the implementation.

Relation of EntityPointer and Iterators

The EntityPointer can be used like a static iterator. It points to a Dune::Entity and can be dereferenced, compared and it knows the Entity's level.

You should be able to initialize and interpret every Dune::XxxIterator that iterates over entities as a Dune::EntityPointer. Therefore we need an inheritance hierarchy of the Iterator wrappers:

    class Dune::EntityPointer<...>;

    class Dune::LevelIterator<...> :
       public Dune::EntityPointer<...>;

    class Dune::HierarchicIterator<...> :
       public Dune::EntityPointer<...>;

    class Dune::LeafIterator<...> :
       public Dune::EntityPointer<...>;

This hierarchy must be mimicked in the implementation (i.e. SGrid):

    class SEntityPointer<...> :
       public Dune::EntityPointerDefault<..., SEntityPointer>;

    class SLevelIterator<...> :
       public SEntityPointer <...>,
       public Dune::LevelIteratorDefault <..., SLevelIterator>;

    class SHierarchicIterator<...> :
       public SEntityPointer <...>,
       public Dune::HierarchicIteratorDefault <..., SHierarchicIterator>;
       
    ...
Please note that dereference(...), equals(...) and level() are only implemented in SEntityPointer -- SLevelIterator inherits these methods. And it is not possible to specialize these, because EntityPointer always uses the base class.

This leads to a hierarchy where Dune::LevelIterator<..., SLevelIterator> inherits Dune::EntityPointer<..., SLevelIterator> and Dune::HierarchicIterator<..., SHierarchicIterator> inherits Dune::EntityPointer<..., SHierarchicIterator>. And virtualy all Dune::EntityPointer<..., SXxxIterator> are descendents of Dune::EntityPointer<..., SEntityPointer>.

Now you can compare Dune::LevelIterator with Dune::EntityPointer and Dune::LeafIterator with Dune::HierarchicIterator. And you can assign Dune::EntityPointer from any Dune::XxxIterator class. Even more, you can cast an Iterator refence to a reference pointing to Dune::EntityPointer.

The compiler takes care that you only assign/compare Iterators from the same Grid.

The downside (or advantage) of this inheritance is that you can not use different comparison operators and different dereference oprators for the different Iterators in one Grid. On the first sight it is a downside because one might consider it a good idea to have special treatment for different iterators. On the other hand it's very confusing for the user if different Iterators show different behavior in the same situation. So now they are forced to show the same behavior.


Public Types

enum  { codim = IteratorImp::codimension }
typedef IteratorImp ImplementationType
 type of real implementation
typedef
Dune::EnableIfInterOperable
< typename IteratorImp::base,
IteratorImp, typename
IteratorImp::base >::type 
base
 autocheck wether imp is convertable into imp::base
typedef IteratorImp::Entity Entity
 The Entity that this EntityPointer can point to.

Public Member Functions

Constructor & conversion
template<class ItImp>
 EntityPointer (const EntityPointer< GridImp, ItImp > &ep)
 Templatized copy constructor from arbitrary IteratorImp. This enables that an EntityPointer can be copy-constructed from LevelIterator, LeafIterator and HierarchicIterator (because these are derived from EntityPointer<...> with their corresponding implementation.
 operator EntityPointer< GridImp, base > & ()
 Cast to EntityPointer with base class of implementation as engine. This conversion ensures assignablity of LevelIterator, LeafIterator and HierarchicIterator to EntityPointer.
 operator const EntityPointer< GridImp, base > & () const
 Cast to EntityPointer with const base class of implementation as engine. This conversion ensures assignablity of LevelIterator, LeafIterator and HierarchicIterator to EntityPointer.
Dereferencing
Entityoperator* () const
 Dereferencing operator.
Entityoperator-> () const
 Pointer operator.
Dereferencing methods
bool operator== (const EntityPointer< GridImp, base > &rhs) const
 Checks for equality. Only works for EntityPointers and iterators on the same grid. Due to the conversion operators one can compare all kinds of iterators and EntityPointer.
bool operator!= (const EntityPointer< GridImp, base > &rhs) const
 Checks for inequality. Only works for EntityPointers and iterators on the same grid. Due to the conversion operators one can compare all kinds of iterators and EntityPointer.
Query methods
int level () const
 Ask for level of entity. This method is redundant and is only there for efficiency reasons. It allows an implementation to return the level without actually constructing the entity.
Implementor interface
 EntityPointer (const IteratorImp &i)
 Copy Constructor from an Iterator implementation.
bool equals (const EntityPointer &rhs) const
 Forward equality check to realIterator.

Protected Member Functions

ImplementationTypegetRealImp ()
 return reference to the real implementation
const ImplementationTypegetRealImp () const
 return reference to the real implementation

Member Enumeration Documentation

template<class GridImp, class IteratorImp>
anonymous enum

Enumerator:
codim  The codimension of this EntityPointer.


Constructor & Destructor Documentation

template<class GridImp, class IteratorImp>
Dune::EntityPointer< GridImp, IteratorImp >::EntityPointer ( const IteratorImp &  i  )  [inline]

Copy Constructor from an Iterator implementation.

You can supply LeafIterator, LevelIterator, HierarchicIterator or EntityPointer.


The documentation for this class was generated from the following file:

Generated on 6 Nov 2008 with Doxygen (ver 1.5.6) [logfile].