CGAL 6.1.2 - 2D Triangulation Data Structure: TriangulationDSVertexBase_2 Concept Reference

CGAL 6.1.2 - 2D Triangulation Data Structure

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TriangulationDSVertexBase_2 Concept Reference
Reference Manual » Concepts

## Definition

Refines
  `TriangulationDataStructure_2::Vertex`

The concept `TriangulationDSVertexBase_2` describes the requirements for the vertex base class of a `CGAL::Triangulation_data_structure_2<Vb,Fb>`.

Note that if the `CGAL::Triangulation_data_structure_2` is plugged into a triangulation class, the vertex base class may have additional geometric requirements depending on the triangulation class.

At the base level, provides access to one of its incident faces through a `Face_handle`.

Since the `CGAL::Triangulation_data_structure_2` is the class which defines the handle types, the vertex base class has to be somehow parameterized by the triangulation data structure. But since the `CGAL::Triangulation_data_structure_2` itself is parameterized by the face and vertex base classes, there is a cycle in the definition of these classes. In order to break the cycle, the base classes for faces and vertices which are plugged in to instantiate a `Triangulation_data_structure_2` use `void` as triangulation data structure parameter. Then, the `CGAL::Triangulation_data_structure_2` uses a rebind mechanism (similar to the one specified in `std::allocator`) in order to plug itself as parameter in the face and vertex base classes. This mechanism requires that the base class provides a templated nested class `Rebind_TDS` that itself provides the subtype `Rebind_TDS::Other` which is the rebound version of the base class. This rebound base class is the class that the `CGAL::Triangulation_data_structure_2` actually uses as a base class for the class of `CGAL::Triangulation_data_structure_2::Vertex`.

Has models
  `CGAL::Triangulation_ds_vertex_base_2<Tds>`

See also
  `TriangulationDSFaceBase_2`
  `CGAL::Triangulation_data_structure_2<Vb,Fb>`

## Types
The concept `TriangulationDSVertexBase_2` has to provide the following types.
template<typename TDS2 >
using | Rebind_TDS = unspecified_type
| This template class has to define a type `Rebind_TDS<TDS2>::Other` which is the rebound vertex base , where the actual `CGAL::Triangulation_data_structure_2` is plugged in.
typedef TriangulationDataStructure_2 | Triangulation_data_structure
typedef TriangulationDataStructure_2::Vertex_handle | Vertex_handle
typedef TriangulationDataStructure_2::Face_handle | Face_handle

## Creation
| TriangulationDSVertexBase_2 ()
| default constructor.
| TriangulationDSVertexBase_2 (Face_handle f)
| Constructs a vertex pointing to face `f`.

## Various
These member functions are required by `CGAL::Triangulation_data_structure_2` because it uses `CGAL::Compact_container` to store its faces. See the documentation of `CGAL::Compact_container` for the exact requirements.
void * | for_compact_container () const
void | for_compact_container (void *p)

## Member Typedef Documentation

## ◆ Rebind_TDS

template<typename TDS2 >

using TriangulationDSVertexBase_2::Rebind_TDS = unspecified_type

This template class has to define a type `Rebind_TDS<TDS2>::Other` which is the rebound vertex base , where the actual `CGAL::Triangulation_data_structure_2` is plugged in.

This type `Other` will be the actual base of the class `CGAL::Triangulation_data_structure_2::Vertex`.

Note
  It can be implemented using a nested template class.

See also
  Section The Rebind Mechanism