std::mdspan<T,Extents,LayoutPolicy,AccessorPolicy>::mdspan
From cppreference.com
C++
Feature test macros (C++20)
Concepts library (C++20)
Metaprogramming library (C++11)
Ranges library (C++20)
Filesystem library (C++17)
Concurrency support library (C++11)
Execution control library (C++26)
Containers library
(C++17)
(C++11)
(C++26)
(C++26)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++23)
(C++23)
(C++23)
(C++23)
(C++20)
(C++23)
Tables
constexpr mdspan();
(1)
(since C++23)
template< class... OtherIndexTypes >
constexpr explicit mdspan( data_handle_type p, OtherIndexTypes... exts );
(2)
(since C++23)
constexpr explicit mdspan( data_handle_type p, OtherIndexTypes... exts );
template< class OtherIndexType, std::size_t N >
(3)
(since C++23)
constexpr explicit(N != rank_dynamic())
template< class OtherIndexType, std::size_t N >
(4)
(since C++23)
constexpr explicit(N != rank_dynamic())
mdspan( data_handle_type p,
constexpr mdspan( data_handle_type p, const extents_type& ext );
(5)
(since C++23)
constexpr mdspan( data_handle_type p, const mapping_type& m );
(6)
(since C++23)
constexpr mdspan( data_handle_type p, const mapping_type& m,
const accessor_type& a );
(7)
(since C++23)
const accessor_type& a );
template< class OtherElementType, class OtherExtents,
(8)
(since C++23)
class OtherLayoutPolicy, class OtherAccessor >
constexpr explicit(/* see below */)
mdspan( const mdspan<OtherElementType, OtherExtents,
constexpr mdspan( const mdspan& rhs ) = default;
(9)
(since C++23)
constexpr mdspan( mdspan&& rhs ) = default;
(10)
(since C++23)
Constructs an mdspan, optionally using user-supplied data handle p, layout mapping m, and accessor a. If extents exts or ext are supplied, they are converted to extents_type and used to initialize the layout mapping.
Contents
[edit] Parameters
p
-
a handle to the underlying data
m
-
a layout mapping
a
-
an accessor
ext
-
a
std::extents object
exts
-
represents a multi-dimensional extents
other
-
another mdspan to convert from
rhs
-
another mdspan to copy or move from
[edit] Effects
For the data members listed in the table below:
- If the corresponding initializer is empty, the data member is value-initialized.
- If the corresponding intiializer is not empty, the data member is direct-non-list-initialized with that initializer.
| Overload | Initializer for... | ||
|---|---|---|---|
ptr_
|
map_
|
acc_
| |
| (1) | (empty) | ||
| (2) | std::move(p) | extents_type (static_cast<index_type> (std::move(exts))...) |
(empty) |
| (3) | extents_type(exts) | ||
| (4) | |||
| (5) | ext | ||
| (6) | m | ||
| (7) | a | ||
| (8) | other.ptr_
|
other.map_
|
other.acc_
|
[edit] Constraints and supplement information
1) This overload participates in overload resolution only if all following values are true:
- rank_dynamic() > 0
- std::is_default_constructible_v <data_handle_type>
- std::is_default_constructible_v <mapping_type>
- std::is_default_constructible_v <accessor_type>
If
[0, map_ .required_span_size()) is not an accessible range of ptr_ and acc_ for the values of map_ and acc_ after the invocation of this constructor, the behavior is undefined.2) This overload participates in overload resolution only if all following values are true:
- (std::is_convertible_v <OtherIndexTypes, index_type> && ...)
- (std::is_nothrow_constructible <index_type, OtherIndexTypes> && ...)
- sizeof...(OtherIndexTypes) == rank() || sizeof...(OtherIndexTypes) == rank_dynamic()
- std::is_constructible_v <mapping_type, extents_type>
- std::is_default_constructible_v <accessor_type>
If
[0, map_ .required_span_size()) is not an accessible range of p and acc_ for the values of map_ and acc_ after the invocation of these constructors, the behavior is undefined.3,4) These overloads participate in overload resolution only if all following values are true:
- std::is_convertible_v <const OtherIndexType&, index_type>
- std::is_nothrow_constructible_v <index_type, const OtherIndexType&>
- N == rank() || N == rank_dynamic()
- std::is_constructible_v <mapping_type, extents_type>
- std::is_default_constructible_v <accessor_type>
If
[0, map_ .required_span_size()) is not an accessible range of p and acc_ for the values of map_ and acc_ after the invocation of these constructors, the behavior is undefined.5) This overload participates in overload resolution only if all following values are true:
- std::is_constructible_v <mapping_type, const extents_type&>
- std::is_default_constructible_v <accessor_type>
If
[0, map_ .required_span_size()) is not an accessible range of p and acc_ for the values of map_ and acc_ after the invocation of these constructors, the behavior is undefined.6) This overload participates in overload resolution only if std::is_default_constructible_v <accessor_type> is true.
If
[0, m.required_span_size()) is an accessible range of p and acc_ for the value of acc_ after the invocation of this constructor, the behavior is undefined.7) If
[0, m.required_span_size()) is not an accessible range of p and a, the behavior is undefined.8) The expression inside explicit is equivalent to !std::is_convertible_v <const OtherLayoutPolicy::template mapping<OtherExtents>&,
mapping_type>
|| !std::is_convertible_v <const OtherAccessor&, accessor_type>.
mapping_type>
|| !std::is_convertible_v <const OtherAccessor&, accessor_type>.
This overload participates in overload resolution only if all following values are true:
- std::is_constructible_v
<mapping_type, const OtherLayoutPolicy::template mapping<OtherExtents>&> - std::is_default_constructible_v <accessor_type>
If any of the following values is false, the program is ill-formed:
- std::is_constructible_v <data_handle_type, const OtherAccessor::data_handle_type&>
- std::is_constructible_v <extents_type, OtherExtents>
If
[0, map_ .required_span_size()) is not an accessible range of ptr_ and acc_ for the values of ptr_ , map_ and acc_ after the invocation of this constructor, the behavior is undefined.If static_extent(r) == std::dynamic_extent
|| static_extent(r) == other.extent(r) is false for some rank index r of extents_type, the behavior is undefined.
If static_extent(r) == std::dynamic_extent
|| static_extent(r) == other.extent(r) is false for some rank index r of extents_type:
- If the implementation is hardened, a contract violation occurs. Moreover, if the contract-violation handler returns under "observe" evaluation semantic, the behavior is undefined.
- If the implementation is not hardened, the behavior is undefined.
[edit] Example
This section is incomplete
Reason: no example
Reason: no example
[edit] References
- C++23 standard (ISO/IEC 14882:2024):
- 24.7.3.6.2 Constructors [mdspan.mdspan.cons]
[edit] See also
This section is incomplete