Dune::EntityPointer< GridImp, IteratorImp > Class Template Reference

Wrapper class for pointers to entities. More...

#include <dune/grid/common/entitypointer.hh>

Public Types
enum
	codimension of entity pointer
enum	{ codim = IteratorImp::codimension }
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.
	EntityPointer (const Entity &entity)
	Templatized constructor from type of entity that this entity pointer points to. This constructor can be used to create an entity pointer from an entity in order to store an entity. The implementation of EntityPointer has to have a constructor taking a Dune::Entity.
	EntityPointer (const typename Entity::Implementation &entityImp)
	Constructor from type of entity implementation that this entity pointer points to. This constructor is only used in the EntityDefaultImplementation to implement the method seed() by default when the type of EntitySeed and EntityPointer coniside.
template<class ItImp >
EntityPointer &	operator= (const EntityPointer< GridImp, ItImp > &ep)
Dereferencing
Entity &	operator* () const
	Dereferencing operator.
Entity *	operator-> () const
	Pointer operator.
Compare methods
template<class ItImp >
bool	operator== (const EntityPointer< GridImp, ItImp > &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.
template<class ItImp >
bool	operator!= (const EntityPointer< GridImp, ItImp > &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. More...
template<class ItImp >
bool	equals (const EntityPointer< GridImp, ItImp > &rhs) const
	Forward equality check to realIterator.

Protected Member Functions
Implementation &	impl ()
	return reference to the real implementation
const Implementation &	impl () const
	return reference to the real implementation

Detailed Description

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

Wrapper class for pointers to entities.

Template parameters are:

• GridImp Type that is a model of Dune::Grid
• IteratorImp Class template that is a model of Dune::EntityPointer

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::EntityIterator as a Dune::EntityPointer. Therefore we need an inheritance hierarchy of the Iterator wrappers:

class Dune::EntityPointer< Grid, IteratorImp >;
 
class Dune::EntityIterator< codim, Grid, IteratorImp >
: public Dune::EntityPointer< Grid, IteratorImp >;

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

class SEntityPointer<...>;
 
class SLevelIterator<...> :
   public SEntityPointer <...>;
 
class SHierarchicIterator<...> :
   public SEntityPointer <...>;
 
...

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.

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.

Member Enumeration Documentation

anonymous enum

template<class GridImp , class IteratorImp >

anonymous enum

Enumerator
codim	The codimension of this EntityPointer.

Constructor & Destructor Documentation

EntityPointer()

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.

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

• dune/grid/common/entitypointer.hh