std::extents,std::dextents(3)

NAME
std::extents,std::dextents - std::extents,std::dextents

Synopsis
   Defined in header <mdspan>
   template< class IndexType, std::size_t... Extents > (1) (since C++23)
   class extents;
   template< class IndexType, std::size_t Rank > (2) (since C++23)
   using dextents = /* see below */
   1) Represents a multidimensional index space of rank equal to sizeof...(Extents).
   2) A convenient alias template for an all-dynamic extents. Let d denote
   std::dynamic_extent, each specialization of it dextents<IndexType, Rank> is
   equivalent to extents<IndexType /*, d, d, ..., d*/> (i.e. d is repeated a total of
   Rank times).
   Each specialization of extents models regular and is TriviallyCopyable.

Template parameters
   IndexType - the type of each non-dynamic Extents. Shall be a signed or unsigned
               integer type. Otherwise, the program is ill-formed
               represents extent (size of an integer interval) for each rank index.
               Each element of it is either equal to std::dynamic_extent (in this case,
   Extents - it represents a dynamic extent and the extent size will be determined
               dynamically), or is representable as a value of type IndexType (then it
               represents a static extent and the extent size is just the value of it),
               or else the program is ill-formed
   Rank - denotes the rank of an all-dynamic extents

Member types
   Member type Definition
   index_type IndexType
   size_type std::make_unsigned_t<index_type>
   rank_type std::size_t

Member objects
   Member name Definition
                        An array of type std::array<index_type, rank_dynamic()>,
   dynamic-extents (private) which stores the size of each dynamic extents.
                        (exposition-only member object*)

Member functions
   constructor constructs an extents
                       (public member function)

Observers
   rank returns the static rank of an extents
   [static] (public static member function)
   rank_dynamic returns the dynamic rank of an extents
   [static] (public static member function)
   static_extent returns static extent size of an extents at a certain rank index
   [static] (public static member function)
                       returns dynamic extent size of an extents at a certain rank
   extent index
                       (public member function)
         Helpers
   fwd-prod-of-extents returns the product of extent size in range [0, i)
                       (exposition-only member function*)
   rev-prod-of-extents returns the product of extents size in range [i + 1, rank())
                       (exposition-only member function*)
   index-cast casts the input into an integer type
                       (exposition-only member function*)
   dynamic-index returns the number of dynamic extents below a certain rank index
   (private) (exposition-only member function*)
   dynamic-index-inv returns the number r such that in range [0, r + 1) there is
   (private) exactly i + 1 dynamic extents for a certain argument i
                       (exposition-only member function*)

Non-member functions
   operator== compare underlying extents in each dimension of two extents
   (C++23) (function)
   Deduction guides(C++23)

Example
    This section is incomplete
    Reason: no example

See also
   rank obtains the number of dimensions of an array type
   (C++11) (class template)
   extent obtains the size of an array type along a specified dimension
   (C++11) (class template)

Category:
     * Todo no example