24 Containers library [containers]

24.7 Views [views]

24.7.3 Multidimensional access [views.multidim]

24.7.3.3 Class template extents [mdspan.extents]

24.7.3.3.2 Exposition-only helpers [mdspan.extents.expo]

static constexpr rank_type dynamic-index(rank_type i) noexcept;

Preconditions: i <= rank() is true.

Returns: The number of

E_{r}

with

r < i

for which

E_{r}

is a dynamic extent.

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static constexpr rank_type dynamic-index-inv(rank_type i) noexcept;

Preconditions: i < rank_dynamic() is true.

Returns: The minimum value of r such that dynamic-index(r + 1) == i + 1 is true.

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constexpr size_t fwd-prod-of-extents(rank_type i) const noexcept;

Preconditions: i <= rank() is true.

Returns: If i > 0 is true, the product of extent(k) for all k in the range [0, i), otherwise 1.

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constexpr size_t rev-prod-of-extents(rank_type i) const noexcept;

Preconditions: i < rank() is true.

Returns: If i + 1 < rank() is true, the product of extent(k) for all k in the range [i + 1, rank()), otherwise 1.

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template<class OtherIndexType>
  static constexpr auto index-cast(OtherIndexType&& i) noexcept;

Effects:

(9.1)
If OtherIndexType is an integral type other than bool, then equivalent to return i;,
(9.2)
otherwise, equivalent to return static_cast<index_type>(i);.

[Note 1:

This function will always return an integral type other than bool.

Since this function's call sites are constrained on convertibility of OtherIndexType to index_type, integer-class types can use the static_cast branch without loss of precision.

— end note]