std::layout_left::mapping

Defined in header `<mdspan>`
template< class Extents > class layout_left::mapping;		(since C++23)

The class template layout_left::mapping controls how multidimensional indices are mapped in a column-major manner to a one-dimensional value representing the offset. The mapping has stride 1 at leftmost extent and strides increase left-to-right as the products of extents.

Every specialization of mapping is a LayoutMapping and a TriviallyCopyable type which satisfies regular.

The program is ill-formed if the size of the multidimensional index space Extents() is not representable as a value of type Extents::index_type when Extents::rank_dynamic() is 0.

Template parameters

Extents - specifies number of dimensions, their sizes, and which are known at compile time. Must be a specialization of std::extents.

Member types

Member type	Definition
`extents_type`	`Extents`
`index_type`	`extents_type::index_type`
`size_type`	`extents_type::size_type`
`rank_type`	`extents_type::rank_type`
`layout_type`	`std::layout_left`

Data members

Member	Definition
`extents_type` `extents_` (private)	the extents object (exposition-only member object*)

Member functions

(constructor)	constructs a new mapping (public member function)
operator= (explicitly defaulted)	assigns a mapping (public member function)
Observers
extents	obtains the extents object (public member function)
required_span_size	returns the required size of the mapping (public member function)
operator()	maps a multidimensional index into an offset value (public member function)
is_unique [static]	determines if this mapping is unique (every combination of indices maps to a different underlying element) (public static member function)
is_exhaustive [static]	determines if this mapping is exhaustive (every underlying element can be accessed with some combination of indices) (public static member function)
is_strided [static]	determines if this mapping is strided (in each dimension, incrementing an index jumps over the same number of underlying elements every time) (public static member function)
is_always_unique [static]	determines if this layout mapping is always unique (public static member function)
is_always_exhaustive [static]	determines if this layout mapping is always exhaustive (public static member function)
is_always_strided [static]	determines if this layout mapping is always strided (public static member function)
stride	obtains the stride along the specified dimension (public member function)

Non-member functions

operator==	compares this layout mapping of `layout_left` with other mapping (function template)
submdspan_mapping(std::layout_left::mapping) (C++26)	calculates the mapping and data handle offset used for `subdmspan` (public member function)

mapping	a layout mapping of `layout_right` (public member class template of `std::layout_right`)
mapping	a layout mapping of `layout_stride` (public member class template of `std::layout_stride`)