4.1 KiB
[mdspan.layout.right.overview]
23 Containers library [containers]
23.7 Views [views]
23.7.3 Multidimensional access [views.multidim]
23.7.3.4 Layout mapping [mdspan.layout]
23.7.3.4.6 Class template layout_right::mapping [mdspan.layout.right]
23.7.3.4.6.1 Overview [mdspan.layout.right.overview]
layout_right provides a layout mapping where the rightmost extent is stride 1, and strides increase right-to-left as the product of extents.
namespace std {templateclass layout_right::mapping {public:using extents_type = Extents; 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 layout_type = layout_right; // [mdspan.layout.right.cons], constructorsconstexpr mapping() noexcept = default; constexpr mapping(const mapping&) noexcept = default; constexpr mapping(const extents_type&) noexcept; templateconstexpr explicit(!is_convertible_v<OtherExtents, extents_type>) mapping(const mapping&) noexcept; templateconstexpr explicit(!is_convertible_v<OtherExtents, extents_type>) mapping(const layout_left::mapping&) noexcept; templateconstexpr explicit(!is_convertible_v<typename LayoutRightPaddedMapping::extents_type, extents_type>) mapping(const LayoutRightPaddedMapping&) noexcept; templateconstexpr explicit(extents_type::rank() > 0) mapping(const layout_stride::mapping&) noexcept; constexpr mapping& operator=(const mapping&) noexcept = default; // [mdspan.layout.right.obs], observersconstexpr const extents_type& extents() const noexcept { return extents_; }constexpr index_type required_span_size() const noexcept; template<class... Indices>constexpr index_type operator()(Indices...) const noexcept; static constexpr bool is_always_unique() noexcept { return true; }static constexpr bool is_always_exhaustive() noexcept { return true; }static constexpr bool is_always_strided() noexcept { return true; }static constexpr bool is_unique() noexcept { return true; }static constexpr bool is_exhaustive() noexcept { return true; }static constexpr bool is_strided() noexcept { return true; }constexpr index_type stride(rank_type) const noexcept; templatefriend constexpr bool operator==(const mapping&, const mapping&) noexcept; private: extents_type extents_{}; // exposition only// [mdspan.sub.map], submdspan mapping specializationtemplate<class... SliceSpecifiers>constexpr auto submdspan-mapping-impl(SliceSpecifiers...) const // exposition only-> see below; template<class... SliceSpecifiers>friend constexpr auto submdspan_mapping(const mapping& src, SliceSpecifiers... slices) {return src.submdspan-mapping-impl(slices...); }};}
If Extents is not a specialization of extents, then the program is ill-formed.
layout_right::mapping is a trivially copyable type that models regular for each E.
Mandates: If Extents::rank_dynamic() == 0 is true, then the size of the multidimensional index space Extents() is representable as a value of type typename Extents::index_type.