Regina Calculation Engine
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regina::NBoundaryComponent Class Reference

Represents a component of the boundary of a triangulation. More...

#include <triangulation/nboundarycomponent.h>

Inheritance diagram for regina::NBoundaryComponent:
regina::ShareableObject regina::NMarkedElement regina::boost::noncopyable

List of all members.

Public Member Functions

virtual ~NBoundaryComponent ()
 Default destructor.
unsigned long getNumberOfFaces () const
 Returns the number of faces in this boundary component.
unsigned long getNumberOfEdges () const
 Returns the number of edges in this boundary component.
unsigned long getNumberOfVertices () const
 Returns the number of vertices in this boundary component.
NFacegetFace (unsigned long index) const
 Returns the requested face in this boundary component.
NEdgegetEdge (unsigned long index) const
 Returns the requested edge in this boundary component.
NVertexgetVertex (unsigned long index) const
 Returns the requested vertex in this boundary component.
long getEulerCharacteristic () const
 Returns the Euler characteristic of this boundary component.
bool isIdeal () const
 Determines if this boundary component is ideal.
bool isOrientable () const
 Determines if this boundary component is orientable.
void writeTextShort (std::ostream &out) const
 Writes this object in short text format to the given output stream.

Friends

class NTriangulation
 Allow access to private members.

Detailed Description

Represents a component of the boundary of a triangulation.

Note that an ideal vertex constitutes a boundary component of its own.

We can run into some interesting cases with invalid triangulations. Suppose some vertex link is a multiply punctured surface (which makes the vertex and hence the entire triangulation invalid). This means that different parts of the 3-manifold boundary are effectively "pinched" together. If this happens, the different parts of the boundary that are pinched might or might not be listed as part of the same boundary component; if not then the offending vertex will be included in all of these boundary components. Nevertheless, only one of these can be considered the "official" boundary component of the vertex as returned by NVertex::getBoundaryComponent(). This is all a bit of a mess, but then again the entire triangulation is invalid and so you almost certainly have bigger problems to deal with.

Boundary components are highly temporary; once a triangulation changes, all its boundary component objects will be deleted and new ones will be created.


Constructor & Destructor Documentation

Default destructor.


Member Function Documentation

NEdge * regina::NBoundaryComponent::getEdge ( unsigned long  index) const [inline]

Returns the requested edge in this boundary component.

For an ideal boundary component (which consists of a single vertex), there are no real edges in the boundary component and this routine cannot be used.

Parameters:
indexthe index of the requested edge in the boundary component. This should be between 0 and getNumberOfEdges()-1 inclusive. Note that the index of a edge in the boundary component need not be the index of the same edge in the entire triangulation.
Returns:
the requested edge.

Returns the Euler characteristic of this boundary component.

If this boundary component is ideal, the Euler characteristic of the link of the corresponding ideal vertex is returned.

Returns:
the Euler characteristic.
NFace * regina::NBoundaryComponent::getFace ( unsigned long  index) const [inline]

Returns the requested face in this boundary component.

For an ideal boundary component (which consists of a single vertex), there are no real faces in the boundary component and this routine cannot be used.

Parameters:
indexthe index of the requested face in the boundary component. This should be between 0 and getNumberOfFaces()-1 inclusive. Note that the index of a face in the boundary component need not be the index of the same face in the entire triangulation.
Returns:
the requested face.
unsigned long regina::NBoundaryComponent::getNumberOfEdges ( ) const [inline]

Returns the number of edges in this boundary component.

Returns:
the number of edges.
unsigned long regina::NBoundaryComponent::getNumberOfFaces ( ) const [inline]

Returns the number of faces in this boundary component.

Returns:
the number of faces.
unsigned long regina::NBoundaryComponent::getNumberOfVertices ( ) const [inline]

Returns the number of vertices in this boundary component.

Returns:
the number of vertices.
NVertex * regina::NBoundaryComponent::getVertex ( unsigned long  index) const [inline]

Returns the requested vertex in this boundary component.

Parameters:
indexthe index of the requested vertex in the boundary component. This should be between 0 and getNumberOfVertices()-1 inclusive. Note that the index of a vertex in the boundary component need not be the index of the same vertex in the entire triangulation.
Returns:
the requested vertex.
bool regina::NBoundaryComponent::isIdeal ( ) const [inline]

Determines if this boundary component is ideal.

This is the case if and only if it consists of a single (ideal) vertex and no faces.

Returns:
true if and only if this boundary component is ideal.

Determines if this boundary component is orientable.

If the boundary component is ideal, the orientability of the link of the corresponding ideal vertex is returned.

Returns:
true if and only if this boundary component is orientable.
void regina::NBoundaryComponent::writeTextShort ( std::ostream &  out) const [inline, virtual]

Writes this object in short text format to the given output stream.

The output should fit on a single line and no newline should be written.

Python:
The parameter out does not exist; standard output will be used.
Parameters:
outthe output stream to which to write.

Implements regina::ShareableObject.


Friends And Related Function Documentation

friend class NTriangulation [friend]

Allow access to private members.


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

Copyright © 1999-2011, The Regina development team
This software is released under the GNU General Public License.
For further information, or to submit a bug or other problem, please contact Ben Burton (bab@debian.org).