[mdspan.layout.stride.overview] (original) (raw)

23 Containers library [containers]

23.7 Views [views]

23.7.3 Multidimensional access [views.multidim]

23.7.3.4 Layout mapping [mdspan.layout]

23.7.3.4.7 Class template layout_stride​::​mapping [mdspan.layout.stride]

23.7.3.4.7.1 Overview [mdspan.layout.stride.overview]

layout_stride provides a layout mapping where the strides are user-defined.

namespace std { template<class Extents> class layout_stride::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_stride;private: static constexpr rank_type rank_ = extents_type::rank(); public: constexpr mapping() noexcept;constexpr mapping(const mapping&) noexcept = default;template<class OtherIndexType> constexpr mapping(const extents_type&, span<OtherIndexType, _rank__>) noexcept;template<class OtherIndexType> constexpr mapping(const extents_type&, const array<OtherIndexType, _rank__>&) noexcept;template<class StridedLayoutMapping> constexpr explicit(see below) mapping(const StridedLayoutMapping&) noexcept;constexpr mapping& operator=(const mapping&) noexcept = default;constexpr const extents_type& extents() const noexcept { return extents_; } constexpr array<index_type, _rank__> strides() const noexcept { return strides_; } 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 false; } static constexpr bool is_always_strided() noexcept { return true; } static constexpr bool is_unique() noexcept { return true; } constexpr bool is_exhaustive() const noexcept;static constexpr bool is_strided() noexcept { return true; } constexpr index_type stride(rank_type i) const noexcept { return _strides__[i]; } template<class OtherMapping> friend constexpr bool operator==(const mapping&, const OtherMapping&) noexcept;private: extents_type extents_{}; array<index_type, _rank__> strides_{}; template<class... SliceSpecifiers> constexpr auto submdspan-mapping-impl(SliceSpecifiers...) const -> 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_stride​::​mapping<E> 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.