23 Containers library [containers]

23.7 Views [views]

23.7.3 Multidimensional access [views.multidim]

23.7.3.4 Layout mapping [mdspan.layout]

23.7.3.4.8 Class template layout_left_padded​::​mapping [mdspan.layout.leftpad]

23.7.3.4.8.4 Observers [mdspan.layout.leftpad.obs]

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constexpr array<index_type, rank_> strides() const noexcept;
1
#
Returns: array<index_type, rank_>({stride(P_rank)...}).
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constexpr index_type required_span_size() const noexcept;
2
#
Returns:
  • (2.1)
    0 if the multidimensional index space extents_ is empty,
  • (2.2)
    otherwise, *this(((extents_(P_rank) - index_type(1))...)) + 1.
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template<class... Indices> constexpr size_t operator()(Indices... idxs) const noexcept;
3
#
Constraints:
  • (3.1)
    sizeof...(Indices) == rank_ is true.
  • (3.2)
    (is_convertible_v<Indices, index_type> && ...) is true.
  • (3.3)
    (is_nothrow_constructible_v<index_type, Indices> && ...) is true.
4
#
Preconditions: extents_type​::​index-cast(idxs) is a multidimensional index in extents() ([mdspan.overview]).
5
#
Returns: ((static_cast<index_type>(idxs) * stride(P_rank)) + ... + 0).
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static constexpr bool is_always_exhaustive() noexcept;
6
#
Returns:
  • (6.1)
    If rank_ equals zero or one, then true;
  • (6.2)
    otherwise, if neither static-padding-stride nor first-static-extent equal dynamic_extent, then static-padding-stride == first-static-extent;
  • (6.3)
    otherwise, false.
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constexpr bool is_exhaustive() const noexcept;
7
#
Returns: true if rank_ equals zero or one; otherwise, extents_.extent(0) == stride(1).
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constexpr index_type stride(rank_type r) const noexcept;
8
#
Preconditions: r is smaller than rank_.
9
#
Returns:
  • (9.1)
    If r equals zero: 1;
  • (9.2)
    otherwise, if r equals one: stride-1;
  • (9.3)
    otherwise, the product of stride-1 and all values extents_.extent(k) with k in the range [1, r).
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template<class LayoutLeftPaddedMapping> friend constexpr bool operator==(const mapping& x, const LayoutLeftPaddedMapping& y) noexcept;
10
#
Constraints:
  • (10.1)
    is-layout-left-padded-mapping-of<LayoutLeftPaddedMapping> is true.
  • (10.2)
    LayoutLeftPaddedMapping​::​extents_type​::​rank() == rank_ is true.
11
#
Returns: true if x.extents() == y.extents() is true and rank_ < 2 || x.stride(1) == y.
stride(1) is true.
Otherwise, false.