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]

23.7.3.4.7.4 Observers [mdspan.layout.stride.obs]

constexpr index_type required_span_size() const noexcept;

Returns: REQUIRED-SPAN-SIZE(extents(), strides_).

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template<class... Indices>
  constexpr index_type operator()(Indices... i) const noexcept;

Constraints:

(2.1)
sizeof...(Indices) == rank_ is true,
(2.2)
(is_convertible_v<Indices, index_type> && ...) is true, and
(2.3)
(is_nothrow_constructible_v<index_type, Indices> && ...) is true.

Preconditions: extents_type::index-cast(i) is a multidimensional index in extents_ ([mdspan.overview]).

Effects: Let P be a parameter pack such that is_same_v<index_sequence_for<Indices...>, index_sequence<P...>> is true.

Equivalent to: return ((static_cast<index_type>(i) * stride(P)) + ... + 0);

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static constexpr bool is_always_exhaustive() noexcept;

Returns: true if rank_ is 0 or if there is a rank index r of extents() such that extents_type::static_extent(r) is 0, otherwise false.

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constexpr bool is_exhaustive() const noexcept;

Returns:

(6.1)
true if rank_ or the size of the multidimensional index space m.extents() is 0.
(6.2)
Otherwise, true if there is a permutation P of the integers in the range [0, rank_) such that stride( $p_{0}$ ) equals 1, and stride( $p_{i}$ ) equals stride( $p_{i - 1}$ ) * extents().extent( $p_{i - 1}$ ) for i in the range [1, rank_), where $p_{i}$ is the $i^{th}$ element of P.
(6.3)
Otherwise, false.

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

Constraints:

(7.1)
layout-mapping-alike<OtherMapping> is satisfied.
(7.2)
rank_ == OtherMapping::extents_type::rank() is true.
(7.3)
OtherMapping::is_always_strided() is true.

Preconditions: OtherMapping meets the layout mapping requirements ([mdspan.layout.policy.reqmts]).

Returns: true if x.extents() == y.extents() is true, OFFSET(y) == 0 is true, and each of x.stride(r) == y.stride(r) is true for r in the range [0, x.extents().rank()).