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std::mdspan::mdspan(3) C++ Standard Libary std::mdspan::mdspan(3) NAME std::mdspan::mdspan - std::mdspan::mdspan Synopsis constexpr mdspan(); (1) (since C++23) template< class... OtherIndexTypes > constexpr explicit mdspan( data_handle_type p, (2) (since C++23) OtherIndexTypes... exts ); template< class OtherIndexType, std::size_t N > constexpr explicit(N != rank_dynamic()) (3) (since C++23) mdspan( data_handle_type p, std::span<OtherIndexType, N> exts ); template< class OtherIndexType, std::size_t N > constexpr explicit(N != rank_dynamic()) (4) (since C++23) mdspan( data_handle_type p, const std::array<OtherIndexType, N>& exts ); 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, (7) (since C++23) const accessor_type& a ); template< class OtherElementType, class OtherExtents, class OtherLayoutPolicy, class OtherAccessor > constexpr explicit(/* see below */) (8) (since C++23) mdspan( const mdspan<OtherElementType, OtherExtents, OtherLayoutPolicy, OtherAccessor>& other ); 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. 1) Constructs an empty mdspan. Value-initializes ptr_, map_, and acc_. * The behavior is undefined 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. * This overload participates in overload resolution only if * rank_dynamic() > 0 is true, * std::is_default_constructible_v<data_handle_type> is true, * std::is_default_constructible_v<mapping_type> is true, and * std::is_default_constructible_v<accessor_type> is true. 2) Constructs an mdspan over the underlying data referred by p with extents represented by exts.... Value-initializes acc_, direct-non-list-ini- tializes ptr_ with std::move(p) and map_ with extents_type(static_cast<index_type>(std::move(exts))...). * The behavior is undefined 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. * Let N be sizeof...(OtherIndexTypes). This overload participates in overload resolution only if * (std::is_convertible_v<OtherIndexTypes, index_type> && ...) is true, * (std::is_nothrow_constructible<index_type, OtherIndexTypes> && ...) is true, * N == rank() || N == rank_dynamic() is true, * std::is_constructible_v<mapping_type, extents_type> is true, and * std::is_default_constructible_v<accessor_type> is true. 3,4) Constructs an mdspan over the underlying data referred by p with extents represented by pack exts. Value-initializes acc_, direct-non-list- initializes ptr_ with std::move(p) and map_ with extents_type(exts). * The behavior is undefined 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. * This overload participates in overload resolution only if * std::is_convertible_v<const OtherIndexTypes&, index_type> is true, * std::is_nothrow_constructible<index_type, const OtherIndex- Types&> is true, * N == rank() || N == rank_dynamic() is true, * std::is_constructible_v<mapping_type, extents_type> is true, and * std::is_default_constructible_v<accessor_type> is true. 5) Constructs an mdspan over the underlying data referred by p with extents represented by ext. Value-initializes acc_, direct-non-list-initial- izes ptr_ with std::move(p) and map_ with exts. * The behavior is undefined 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 this constructor. * This overload participates in overload resolution only if * std::is_constructible_v<mapping_type, const mapping_type&> is true, and * std::is_default_constructible_v<accessor_type> is true. 6) Constructs an mdspan over the underlying data referred by p with layout mapping m. Value-initializes acc_, direct-non-list-initializes ptr_ with std::move(p) and map_ with m. * The behavior is undefined if [0, m.required_span_size()) is not an accessible range of p and acc_ for the values of acc_ after the invocation of this constructor. * This overload participates in overload resolution only if std::is_default_constructible_v<accessor_type> is true. 7) Constructs an mdspan over the underlying data referred by p with layout mapping m and accessor a. Direct-non-list-initializes ptr_ with std::move(p), map_ with m and acc_ with a. * The behavior is undefined if [0, m.required_span_size()) is not an accessible range of p and a after the invocation of this constructor. 8) Converting constructor from another mdspan. Direct-non-list-ini- tializes ptr_ with other.ptr_, map_ with other.map_ and acc_ with other.acc_. * The behavior is undefined 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 con- structor, or * for each rank index r of extents_type, extents_type::sta- tic_extent(r) == std::dynamic_extent || extents_type::static_extent(r) == other.extent(r) is false. * This overload participates in overload resolution only if * std::is_constructible_v<mapping_type, const OtherLayoutPolicy:: template mapping<OtherExtents>&> is true, and * std::is_constructible_v<accessor_type, const OtherAccessor&> is true. * The program is ill-formed if: * std::is_constructible_v<data_handle_type, const OtherAccessor::data_handle_type&> is false, or * std::is_constructible_v<extents_type, OtherExtents> is false. * 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> 9) Defaulted copy constructor. 10) Defaulted move constructor. 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 Example This section is incomplete Reason: no example References * C++23 standard (ISO/IEC 14882:2023): * 24.7.3.6.2 Constructors [mdspan.mdspan.cons] See also This section is incomplete Categories: * Todo no example * Todo without reason http://cppreference.com 2024.06.10 std::mdspan::mdspan(3)
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