[mdspan.layout.general] (original) (raw)

23 Containers library [containers]

M denotes a layout mapping class.
m denotes a (possibly const) value of type M.
i and j are packs of (possibly const) integers that are multidimensional indices in m.extents() ([mdspan.overview]).
[Note 1:
The type of each element of the packs can be a different integer type.
— _end note_]
r is a (possibly const) rank index of typename M::extents_type.
is a pack of (possibly const) integers for which sizeof...() == M::extents_type::rank() is true, the element is equal to 1, and all other elements are equal to 0.

Let is-mapping-of be the exposition-only variable template defined as follows:template<class Layout, class Mapping> constexpr bool is-mapping-of = is_same_v<typename Layout::template mapping<typename Mapping::extents_type>, Mapping>;
Let is-layout-left-padded-mapping-of be the exposition-only variable template defined as follows:template<class Mapping> constexpr bool is-layout-left-padded-mapping-of = see below; where is-layout-left-padded-mapping-of<Mapping> is trueif and only if Mapping denotes a specialization of layout_left_padded<S>::mappingfor some value S of type size_t.
Let is-layout-right-padded-mapping-of be the exposition-only variable template defined as follows:template<class Mapping> constexpr bool is-layout-right-padded-mapping-of = see below; where is-layout-right-padded-mapping-of<Mapping> is trueif and only if Mapping denotes a specialization of layout_right_padded<S>::mappingfor some value S of type size_t.
For nonnegative integers x and y, let denote
- y if x is zero,
- otherwise, the least multiple of x that is greater than or equal to y.