/*!
\ingroup PkgCombinatorialMapsConcepts
\cgalConcept

The concept `GenericMapItems` allows to customize a <I>d</I>D generic map by choosing the information associated with darts, by enabling and disabling some attributes, \tred{and by choosing to use indices or handles}. For that, it defines an inner class template named \link GenericMapItems::Dart_wrapper `Dart_wrapper`\endlink, with one template parameter, `Map`, a model of the `GenericMap` concept. This inner class can define the two types `%Dart_info` and `%Attributes`.

\cgalHasModel \link CGAL::Generic_map_min_items `CGAL::Generic_map_min_items`\endlink

\sa `GenericMap`

\cgalHeading{Example}

The following examples show two possible models of the `GenericMapItems` concept: the first one for a generic map without dart information, nor enabled attributes, the second one for a generic map \tred{that uses std::uint16_t as indices,} with a `double` associated with each dart, and edge attributes enabled, and associated with a \link CGAL::Cell_attribute `Cell_attribute`\endlink containing an `int`.

  \code{.cpp}
  struct Exemple_Item_1
  {
    template < class CMap >
    struct Dart_wrapper
    {};
  };

  struct Exemple_Item_2
  {
    typedef CGAL::Tag_true Use_index; // CGAL::Tag_false by default
    typedef std::uint16_t Index_type; // std::uint32_t by default
    template < class GMap >
    struct Dart_wrapper
    {
      typedef double Dart_info;
      typedef CGAL::Cell_attribute<GMap, int> Edge_attrib;
      typedef std::tuple<void,Edge_attrib> Attributes;
    };
  };
  \endcode
*/
class GenericMapItems {
public:
  /*!
    \cgalModifBegin
    If Use_index is equal to CGAL::Tag_true, use indices as descriptors. Otherwise (if this type is not defined or different than CGAL::Tag_true), use handles.
    \cgalModifEnd
  */
  typedef unspecified_type Use_index;

  /*!
    \cgalModifBegin
    Number type used for indices when Use_index is CGAL::Tag_true. By default, use std::uint32_t.
    \cgalModifEnd
  */
  typedef unspecified_type Index_type;

  /*!
    Wrapper class defining type of information associated with darts and types of attributes. The class `%Dart_wrapper<Map>` must provide:

  - `%Dart_wrapper<Map>::%Dart_info`, the type of information associated with darts. Not defined or equal to `void` to have no information.
  - `%Dart_wrapper<Map>::%Attributes` The tuple of attributes, containing at most \link GenericMap::dimension `Map::dimension+1`\endlink types (one for each possible cell of the generic map). Each type of the tuple must be either a model of the `CellAttribute` concept or `void`. The first type corresponds to 0-attributes, the second to 1-attributes and so on. If the \f$ i^{\mbox{th}}\f$ type in the tuple is `void`, (<I>i</I>-1)-attributes are disabled. Otherwise, (<I>i</I>-1)-attributes are enabled and have the given type. If the size of the tuple is <I>k</I>, with <I>k</I><\link GenericMap::dimension `Map::dimension`\endlink+1, \f$ \forall\f$<I>i</I>: <I>k</I>\f$ \leq\f$<I>i</I>\f$ \leq\f$\link GenericMap::dimension `Map::dimension`\endlink, <I>i</I>-attributes are disabled. If this type is not defined, all attributes are disabled.

  \note It can be implemented using a nested template class.
  */
  template <typename Map>
  using Dart_wrapper = unspecified_type;

}; /* end #GenericMapItems */