std::extents, std::dextents

< cpp‎ | container‎ | mdspan
Defined in header <mdspan>
template< class IndexType, std::size_t... Extents >
class extents;
(1) (since C++23)
template< class IndexType, std::size_t Rank >
using dextents = /* see below */
(2) (since C++23)
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.


[edit] Template parameters

IndexType - the type of each non-dynamic Extents. Shall be a signed or unsigned integer type. Otherwise, the program is ill-formed
Extents - 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, 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

[edit] Member types

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

[edit] Member objects

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

[edit] Member functions

constructs an extents
(public member function) [edit]
returns the static rank of an extents
(public static member function) [edit]
returns the dynamic rank of an extents
(public static member function) [edit]
returns static extent size of an extents at a certain rank index
(public static member function) [edit]
returns dynamic extent size of an extents at a certain rank index
(public member function) [edit]
returns the product of extent size in range [0i)
(exposition-only member function*)[edit]
returns the product of extents size in range [i + 1rank())
(exposition-only member function*)[edit]
casts the input into an integer type
(exposition-only member function*)[edit]
returns the number of dynamic extents below a certain rank index
(exposition-only member function*)[edit]
returns the number r such that in range [0r + 1) there is exactly i + 1 dynamic extents for a certain argument i
(exposition-only member function*)[edit]

[edit] Non-member functions

compare underlying extents in each dimension of two extents
(function) [edit]

[edit] Deduction guides(C++23)

[edit] Example

[edit] See also

obtains the number of dimensions of an array type
(class template) [edit]
obtains the size of an array type along a specified dimension
(class template) [edit]