mdspan is a view of a multidimensional array of elements
. namespace std {
template<class ElementType, class Extents, class LayoutPolicy = layout_right,
class AccessorPolicy = default_accessor<ElementType>>
class mdspan {
public:
using extents_type = Extents;
using layout_type = LayoutPolicy;
using accessor_type = AccessorPolicy;
using mapping_type = typename layout_type::template mapping<extents_type>;
using element_type = ElementType;
using value_type = remove_cv_t<element_type>;
using index_type = typename extents_type::index_type;
using size_type = typename extents_type::size_type;
using rank_type = typename extents_type::rank_type;
using data_handle_type = typename accessor_type::data_handle_type;
using reference = typename accessor_type::reference;
static constexpr rank_type rank() noexcept { return extents_type::rank(); }
static constexpr rank_type rank_dynamic() noexcept { return extents_type::rank_dynamic(); }
static constexpr size_t static_extent(rank_type r) noexcept
{ return extents_type::static_extent(r); }
constexpr index_type extent(rank_type r) const noexcept { return extents().extent(r); }
constexpr mdspan();
constexpr mdspan(const mdspan& rhs) = default;
constexpr mdspan(mdspan&& rhs) = default;
template<class... OtherIndexTypes>
constexpr explicit mdspan(data_handle_type ptr, OtherIndexTypes... exts);
template<class OtherIndexType, size_t N>
constexpr explicit(N != rank_dynamic())
mdspan(data_handle_type p, span<OtherIndexType, N> exts);
template<class OtherIndexType, size_t N>
constexpr explicit(N != rank_dynamic())
mdspan(data_handle_type p, const array<OtherIndexType, N>& exts);
constexpr mdspan(data_handle_type p, const extents_type& ext);
constexpr mdspan(data_handle_type p, const mapping_type& m);
constexpr mdspan(data_handle_type p, const mapping_type& m, const accessor_type& a);
template<class OtherElementType, class OtherExtents,
class OtherLayoutPolicy, class OtherAccessorPolicy>
constexpr explicit(see below)
mdspan(const mdspan<OtherElementType, OtherExtents,
OtherLayoutPolicy, OtherAccessorPolicy>& other);
constexpr mdspan& operator=(const mdspan& rhs) = default;
constexpr mdspan& operator=(mdspan&& rhs) = default;
template<class... OtherIndexTypes>
constexpr reference operator[](OtherIndexTypes... indices) const;
template<class OtherIndexType>
constexpr reference operator[](span<OtherIndexType, rank()> indices) const;
template<class OtherIndexType>
constexpr reference operator[](const array<OtherIndexType, rank()>& indices) const;
constexpr size_type size() const noexcept;
[[nodiscard]] constexpr bool empty() const noexcept;
friend constexpr void swap(mdspan& x, mdspan& y) noexcept;
constexpr const extents_type& extents() const noexcept { return map_.extents(); }
constexpr const data_handle_type& data_handle() const noexcept { return ptr_; }
constexpr const mapping_type& mapping() const noexcept { return map_; }
constexpr const accessor_type& accessor() const noexcept { return acc_; }
static constexpr bool is_always_unique()
{ return mapping_type::is_always_unique(); }
static constexpr bool is_always_exhaustive()
{ return mapping_type::is_always_exhaustive(); }
static constexpr bool is_always_strided()
{ return mapping_type::is_always_strided(); }
constexpr bool is_unique() const
{ return map_.is_unique(); }
constexpr bool is_exhaustive() const
{ return map_.is_exhaustive(); }
constexpr bool is_strided() const
{ return map_.is_strided(); }
constexpr index_type stride(rank_type r) const
{ return map_.stride(r); }
private:
accessor_type acc_;
mapping_type map_;
data_handle_type ptr_;
};
template<class CArray>
requires (is_array_v<CArray> && rank_v<CArray> == 1)
mdspan(CArray&)
-> mdspan<remove_all_extents_t<CArray>, extents<size_t, extent_v<CArray, 0>>>;
template<class Pointer>
requires (is_pointer_v<remove_reference_t<Pointer>>)
mdspan(Pointer&&)
-> mdspan<remove_pointer_t<remove_reference_t<Pointer>>, extents<size_t>>;
template<class ElementType, class... Integrals>
requires ((is_convertible_v<Integrals, size_t> && ...) && sizeof...(Integrals) > 0)
explicit mdspan(ElementType*, Integrals...)
-> mdspan<ElementType, dextents<size_t, sizeof...(Integrals)>>;
template<class ElementType, class OtherIndexType, size_t N>
mdspan(ElementType*, span<OtherIndexType, N>)
-> mdspan<ElementType, dextents<size_t, N>>;
template<class ElementType, class OtherIndexType, size_t N>
mdspan(ElementType*, const array<OtherIndexType, N>&)
-> mdspan<ElementType, dextents<size_t, N>>;
template<class ElementType, class IndexType, size_t... ExtentsPack>
mdspan(ElementType*, const extents<IndexType, ExtentsPack...>&)
-> mdspan<ElementType, extents<IndexType, ExtentsPack...>>;
template<class ElementType, class MappingType>
mdspan(ElementType*, const MappingType&)
-> mdspan<ElementType, typename MappingType::extents_type,
typename MappingType::layout_type>;
template<class MappingType, class AccessorType>
mdspan(const typename AccessorType::data_handle_type&, const MappingType&,
const AccessorType&)
-> mdspan<typename AccessorType::element_type, typename MappingType::extents_type,
typename MappingType::layout_type, AccessorType>;
}