boost::graph_traits< DGtal::Object< TDigitalTopology, TDigitalSet > >::adjacency_iterator Class Reference

#include <DGtal/graph/ObjectBoostGraphInterface.h>

Inheritance diagram for boost::graph_traits< DGtal::Object< TDigitalTopology, TDigitalSet > >::adjacency_iterator:

Public Member Functions
	adjacency_iterator ()
	Default, invalid, constructor.
	adjacency_iterator (typename AdjacentVertexContainer::const_iterator it, const DGtal::CountedPtr< AdjacentVertexContainer > &vertices)

Private Member Functions
const Vertex &	dereference () const
bool	equal (const adjacency_iterator &other) const
void	increment ()
void	decrement ()

Private Attributes
AdjacentVertexContainer::const_iterator	myIterator
	The iterator pointing in the container of adjacent vertices.
DGtal::CountedPtr< AdjacentVertexContainer >	myVertices

Friends
class	iterator_core_access
	Requirement for boost::iterator_facade.

Detailed Description

template<class TDigitalTopology, class TDigitalSet>
class boost::graph_traits< DGtal::Object< TDigitalTopology, TDigitalSet > >::adjacency_iterator

Iterator for visiting adjacent vertices. We use an iterator facade to create a STL-compliant iterator with as little effort as possible.

Note

The difficulty is that DGtal graphs do not provide iterators for visiting edges or adjacent vertices, but merely provide a method that outputs them. Therefore, this iterator shares the container of adjacent vertices (a std::vector) with other (potentially) iterators, through a DGtal::CountedPtr. When the last iterator pointing in this structure is deallocated, the container is automatically deallocated. This is for instance used by function adjacent_vertices, which returns a pair of adjacency_iterator, both points on the same container. Another problem is that the user may have called twice adjacent_vertices on the same vertex, and may wish to compare iterators obtained by two different calls.

typedef typename Object<...> G;
typedef typename graph_traits<G>::adjacency_iterator adjacency_iterator;
G g(...);
std::pair<adjacency_iterator,adjacency_iterator> vp1 = boost::adjacent_vertices( vertex, g );
std::pair<adjacency_iterator,adjacency_iterator> vp2 = boost::adjacent_vertices( vertex, g );

In this case, vp1 and vp2 are not pointing on the same structure, hence the address pointed by vp1 is different from the address pointed by vp2. They are then not comparable a priori. The adjacency_iterator is written so that vp1 (.first or .second) and vp2 (.first or .second) are comparable, using value comparison and out-of-range check.

Definition at line 165 of file ObjectBoostGraphInterface.h.

Constructor & Destructor Documentation

adjacency_iterator() [1/2]

template<class TDigitalTopology , class TDigitalSet >

boost::graph_traits< DGtal::Object< TDigitalTopology, TDigitalSet > >::adjacency_iterator::adjacency_iterator ( )

inline

Default, invalid, constructor.

Definition at line 174 of file ObjectBoostGraphInterface.h.

        : myIterator(), myVertices( 0 ) {}

adjacency_iterator() [2/2]

template<class TDigitalTopology , class TDigitalSet >

boost::graph_traits< DGtal::Object< TDigitalTopology, TDigitalSet > >::adjacency_iterator::adjacency_iterator ( typename AdjacentVertexContainer::const_iterator it, const DGtal::CountedPtr< AdjacentVertexContainer > & vertices )

inline

Valid constructor from instance of AdjacentVertexContainer. The iterator shares the container of adjacent vertices (a std::vector) with other (potentially) iterators, through a DGtal::CountedPtr.

Parameters

it	const_iterator of AdjacentVertexContainer.
vertices	CountedPtr of an AdjacentVertexContainer

Definition at line 187 of file ObjectBoostGraphInterface.h.

        : myIterator( it ), myVertices( vertices ) {}

References boost::vertices().

Member Function Documentation

decrement()

template<class TDigitalTopology , class TDigitalSet >

void boost::graph_traits< DGtal::Object< TDigitalTopology, TDigitalSet > >::adjacency_iterator::decrement ( )

inlineprivate

Decrement iterator. Required to implement Bidirectional Traversal Iterator Concept.

Definition at line 232 of file ObjectBoostGraphInterface.h.

{ --myIterator; }

dereference()

template<class TDigitalTopology , class TDigitalSet >

const Vertex & boost::graph_traits< DGtal::Object< TDigitalTopology, TDigitalSet > >::adjacency_iterator::dereference ( ) const

inlineprivate

Returns

const reference to the Vertex the iterator is pointing to. Required for Readable Iterator, Writable Iterator Concepts

Definition at line 197 of file ObjectBoostGraphInterface.h.

      {
        ASSERT( myIterator != myVertices->end() );
        return *myIterator;
      }

equal()

template<class TDigitalTopology , class TDigitalSet >

bool boost::graph_traits< DGtal::Object< TDigitalTopology, TDigitalSet > >::adjacency_iterator::equal ( const adjacency_iterator & other ) const

inlineprivate

Predicate to compare equal value of iterators. Required to implement Single Pass Iterator Concept.

Parameters

other

adjacency_iterator to compare with.

Returns

true iff other and this refer to the same Vertex.

Definition at line 212 of file ObjectBoostGraphInterface.h.

      {
        bool thisAtEnd = ( myIterator == myVertices->end() );
        bool otherAtEnd = ( other.myIterator == other.myVertices->end() );
        if ( thisAtEnd || otherAtEnd ) return thisAtEnd && otherAtEnd;
        else return *myIterator == *other.myIterator;
      }

References myIterator, and myVertices.

increment()

template<class TDigitalTopology , class TDigitalSet >

void boost::graph_traits< DGtal::Object< TDigitalTopology, TDigitalSet > >::adjacency_iterator::increment ( )

inlineprivate

Increment iterator. Required to implement Incrementable Iterator Concept.

Definition at line 225 of file ObjectBoostGraphInterface.h.

{ ++myIterator; }

Friends And Related Symbol Documentation

iterator_core_access

template<class TDigitalTopology , class TDigitalSet >

friend class iterator_core_access

friend

Requirement for boost::iterator_facade.

Definition at line 246 of file ObjectBoostGraphInterface.h.

Field Documentation

myIterator

template<class TDigitalTopology , class TDigitalSet >

AdjacentVertexContainer::const_iterator boost::graph_traits< DGtal::Object< TDigitalTopology, TDigitalSet > >::adjacency_iterator::myIterator

private

The iterator pointing in the container of adjacent vertices.

Definition at line 237 of file ObjectBoostGraphInterface.h.

Referenced by equal().

myVertices

template<class TDigitalTopology , class TDigitalSet >

DGtal::CountedPtr< AdjacentVertexContainer > boost::graph_traits< DGtal::Object< TDigitalTopology, TDigitalSet > >::adjacency_iterator::myVertices

private

A counted pointer to the dynamically allocated container of vertices. Will be automatically deallocated when there is no more iterators pointing on it.

Definition at line 243 of file ObjectBoostGraphInterface.h.

Referenced by equal().

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

• ObjectBoostGraphInterface.h