HalfedgeDS_default<Traits,HalfedgeDSItems,Alloc>

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CGAL::HalfedgeDS_default<Traits,HalfedgeDSItems,Alloc>

Definition

template <	class Traits,
	class HalfedgeDSItems = CGAL::HalfedgeDS_items_2,
	class Alloc = CGAL_ALLOCATOR(int)>
class HalfedgeDS_default;

The class HalfedgeDS_default<Traits,HalfedgeDSItems,Alloc> is a model for the HalfedgeDS concept. The second template parameter HalfedgeDSItems has a default argument CGAL::HalfedgeDS_items_2. The third template parameter Alloc uses the Cgal default allocator as default setting. HalfedgeDS_default<Traits,HalfedgeDSItems,Alloc> is a list-based representation with bidirectional iterators that supports removal.

#include <CGAL/HalfedgeDS_default.h>

Is Model for the Concepts

HalfedgeDS<Traits,Items,Alloc>

Types

typedef bidirectional_iterator_tag
	iterator_category;
typedef CGAL::Tag_true	Supports_removal;

Implementation

Currently, HalfedgeDS_default<Traits,HalfedgeDSItems,Alloc> is derived from CGAL::HalfedgeDS_list<Traits>. The copy constructor and the assignment operator need O(n) time with n the total number of vertices, halfedges, and faces. The former suboptimal implementation with an O(n log n) runtime has been replaced with a faster implementation based on hashing for the pointer lookup.

Due to a workaround for the flag CGAL_CFG_NO_TMPL_IN_TMPL_PARAM, a halfedge data structure cannot be instantiated directly. For the HalfedgeDS_default<Traits,HalfedgeDSItems,Alloc> a macro simplifies its direct use. However, when using a halfedge data structure as an argument for another class template, the class template name HalfedgeDS_default must be used, not the macro.

// The macro definition.
#ifndef CGAL_CFG_NO_TMPL_IN_TMPL_PARAM
    #define CGAL_HALFEDGEDS_DEFAULT  ::CGAL::HalfedgeDS_default
#else
    #define CGAL_HALFEDGEDS_DEFAULT  ::CGAL::HalfedgeDS_default::HDS
#endif

// The direct instantiation of the default HalfedgeDS given a Traits class.
typedef CGAL_HALFEDGEDS_DEFAULT<Traits> HDS;

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