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% | Reference manual page: HalfedgeDSItems.tex
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% | 22.03.1999   Lutz Kettner
% | Package: HalfedgeDS
% | 
\RCSdef{\RCSHalfedgeDSItemsRev}{$Id$}
\RCSdefDate{\RCSHalfedgeDSItemsDate}{$Date$}
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\ccRefPageBegin

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\begin{ccRefConcept}{HalfedgeDSItems}

\ccDefinition
  
The concept \ccRefName\ wraps the three item types -- vertex,
halfedge, and face -- for a halfedge data structure. A \ccRefName\ 
contains three member class templates named \ccc{Vertex_wrapper},
\ccc{Halfedge_wrapper}, and \ccc{Face_wrapper}, each with two template
parameters, \ccc{Refs} and \ccc{Traits}. \ccc{Refs} requires an
instantiated halfedge data structure \ccc{HalfedgeDS} as argument,
\ccc{Traits} is a geometric traits class supplied by the class that
uses the halfedge data structure as internal representation. \ccc{Traits}
is not used by the halfedge data structure itself. These three member 
class templates provide a local type named \ccc{Vertex}, \ccc{Halfedge},
and \ccc{Face} respectively. The requirements on these
types are described on page~\pageref{pageHalfedgeDSItemsVertexRef},
page~\pageref{pageHalfedgeDSItemsHalfedgeRef}, and
page~\pageref{pageHalfedgeDSItemsFaceRef} respectively.

\ccTypes
\ccTwo{HalfedgeDSItems:: Halfedge_wrapper<Refs,Traits>::HalfedgeM}{}

\ccNestedType{Vertex_wrapper<Refs,Traits>::Vertex}
    {model of \ccc{HalfedgeDSVertex}.}
\ccGlue
\ccNestedType{Halfedge_wrapper<Refs,Traits>::Halfedge}
    {model of \ccc{HalfedgeDSHalfedge}.}
\ccGlue
\ccNestedType{Face_wrapper<Refs,Traits>::Face}
    {model of \ccc{HalfedgeDSFace}.}

\ccHasModels

\ccRefIdfierPage{CGAL::HalfedgeDS_min_items}\\
\ccRefIdfierPage{CGAL::HalfedgeDS_items_2}\\
\ccRefIdfierPage{CGAL::Polyhedron_items_3}

\ccSeeAlso

\ccRefConceptPage{HalfedgeDS<Traits,Items,Alloc>}\\
\ccRefConceptPage{HalfedgeDSVertex}\\
\ccRefConceptPage{HalfedgeDSHalfedge}\\
\ccRefConceptPage{HalfedgeDSFace}\\
\ccRefConceptPage{PolyhedronItems_3}\\
\ccRefIdfierPage{CGAL::HalfedgeDS_vertex_base<Refs>}\\
\ccRefIdfierPage{CGAL::HalfedgeDS_halfedge_base<Refs>}\\
\ccRefIdfierPage{CGAL::HalfedgeDS_face_base<Refs>}

\ccExample

The following example shows the canonical implementation of the
\ccc{CGAL::HalfedgeDS_min_items} class. It uses the base classes for the
item types that are provided in the library.

\begin{ccExampleCode}
struct HalfedgeDS_min_items {
    template < class Refs, class Traits>
    struct Vertex_wrapper {
        typedef CGAL::HalfedgeDS_vertex_min_base< Refs>   Vertex;
    };
    template < class Refs, class Traits>
    struct Halfedge_wrapper {
        typedef CGAL::HalfedgeDS_halfedge_min_base< Refs> Halfedge;
    };
    template < class Refs, class Traits>
    struct Face_wrapper {
        typedef CGAL::HalfedgeDS_face_min_base< Refs>     Face;
    };
};
\end{ccExampleCode}

See page~\pageref{pageHalfedgeDSitemsRef} for an example implementation 
of the \ccc{CGAL::HalfedgeDS_items_2} class.

\end{ccRefConcept}

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