[mdspan.layout.rightpad.obs] (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]

23.7.3.4.9 Class template layout_right_padded​::​mapping [mdspan.layout.rightpad]

23.7.3.4.9.4 Observers [mdspan.layout.rightpad.obs]

constexpr array<index_type, _rank_> strides() const noexcept;

Returns: array<index_type, _rank__>(stride(P_rank)...).

constexpr index_type required_span_size() const noexcept;

Returns: 0 if the multidimensional index space extents_ is empty, otherwise *this(((extents_(P_rank) - index_type(1))...)) + 1.

template<class... Indices> constexpr size_t operator()(Indices... idxs) const noexcept;

Constraints:

• sizeof...(Indices) == rank_ is true.
• (is_convertible_v<Indices, index_type> && ...) is true.
• (is_nothrow_constructible_v<index_type, Indices> && ...) is true.

Preconditions: extents_type​::​index-cast(idxs) is a multidimensional index in extents() ([mdspan.overview]).

Returns: ((static_cast<index_type>(idxs) * stride(P_rank)) + ... + 0).

static constexpr bool is_always_exhaustive() noexcept;

Returns:

• If rank_ equals zero or one, then true;
• otherwise, if neither static-padding-stride nor _last-static-extent_equal dynamic_extent, then static-padding-stride == last-static-extent;
• otherwise, false.

constexpr bool is_exhaustive() const noexcept;

Returns: true if rank_ equals zero or one; otherwise,extents_.extent(rank_ - 1) == stride(rank_ - 2)

constexpr index_type stride(rank_type r) const noexcept;

Preconditions: r is smaller than rank_.

Returns:

• If r equals rank_ - 1: 1;
• otherwise, if r equals rank_ - 2: stride-rm2;
• otherwise, the product of stride-rm2 and all values extents_.extent(k)with k in the range of [r + 1, _rank__ - 1).

template<class LayoutRightPaddedMapping> friend constexpr bool operator==(const mapping& x, const LayoutRightPaddedMapping& y) noexcept;

Constraints:

• is-layout-right-padded-mapping-of<LayoutRightPaddedMapping>is true.
• LayoutRightPaddedMapping​::​extents_type​::​rank() == _rank__is true.

Returns: true if x.extents() == y.extents() is true and_rank__ < 2 || x.stride(rank_ - 2) == y.stride(rank_ - 2) is true.

Otherwise, false.