std:: extents, std:: dextents, std:: dims
From cppreference.com
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Defined in header
<mdspan>
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template
<
class
IndexType,
std::
size_t
...
Extents
>
class extents ; |
(1) | (since C++23) |
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template
<
class
IndexType,
std::
size_t
Rank
>
using dextents = /* see below */ |
(2) | (since C++23) |
|
template
<
std::
size_t
Rank,
class
IndexType
=
std::
size_t
>
using dims = std :: dextents < IndexType, Rank > ; |
(3) | (since C++26) |
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).
3)
A convenient alias template for an all-dynamic
extents
with
std::
size_t
as the default index type.
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
|
| 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
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| 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 |
Data members
| Member name | Definition |
std::
array
<
index_type, rank_dynamic
(
)
>
dynamic-extents
(private)
|
An array which stores the size of each dynamic extents.
( exposition-only member object* ) |
Member functions
constructs an
extents
(public member function) |
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Observers |
|
|
[static]
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returns the static rank of an
extents
(public static member function) |
|
[static]
|
returns the dynamic rank of an
extents
(public static member function) |
|
[static]
|
returns static extent size of an
extents
at a certain rank index
(public static member function) |
returns dynamic extent size of an
extents
at a certain rank index
(public member function) |
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Helpers |
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returns the product of extent size in range
[
0
,
i
)
( exposition-only member function* ) |
|
returns the product of extents size in range
[
i
+
1
,
rank
(
)
)
( exposition-only member function* ) |
|
|
casts the input into an integer type
( exposition-only member function* ) |
|
|
(private)
|
returns the number of dynamic extents below a certain rank index
( exposition-only member function* ) |
|
(private)
|
returns the number
r
such that in range
[
0
,
r
+
1
)
there is exactly
i + 1
dynamic extents for a certain argument
i
( exposition-only member function* ) |
Non-member functions
|
(C++23)
|
compare underlying extents in each dimension of two
extents
(function) |
Deduction guides (C++23)
Example
|
This section is incomplete
Reason: no example |
See also
|
(C++11)
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obtains the number of dimensions of an array type
(class template) |
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(C++11)
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obtains the size of an array type along a specified dimension
(class template) |