cppdraft_translate/cppdraft/range/access/rbegin.md

[range.access.rbegin]

25 Ranges library [ranges]

25.3 Range access [range.access]

25.3.6 ranges​::​rbegin [range.access.rbegin]

1

#

The name ranges​::​rbegin denotes a customization point object ([customization.point.object]).

2

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Given a subexpression E with type T, let t be an lvalue that denotes the reified object for E.

Then:

• (2.1)

  If E is an rvalue and enable_borrowed_range<remove_cv_t> is false, ranges​::​rbegin(E) is ill-formed.

• (2.2)

  Otherwise, if T is an array type ([dcl.array]) and remove_all_extents_t is an incomplete type, ranges​::​rbegin(E) is ill-formed with no diagnostic required.

• (2.3)

  Otherwise, if auto(t.rbegin()) is a valid expression whose type models input_or_output_iterator, ranges​::​rbegin(E) is expression-equivalent to auto(t.rbegin()).

• (2.4)

  Otherwise, if T is a class or enumeration type and auto(rbegin(t)) is a valid expression whose type models input_or_output_iterator where the meaning of rbegin is established as-if by performing argument-dependent lookup only ([basic.lookup.argdep]), then ranges​::​rbegin(E) is expression-equivalent to that expression.

• (2.5)

  Otherwise, if both ranges​::​begin(t) and ranges​::​end(t) are valid expressions of the same type which models bidirectional_iterator ([iterator.concept.bidir]), ranges​::​rbegin(E) is expression-equivalent to make_reverse_iterator(ranges​::​end(t)).

• (2.6)

  Otherwise, ranges​::​rbegin(E) is ill-formed.

3

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[Note 1:

Diagnosable ill-formed cases above result in substitution failure when ranges​::​rbegin(E) appears in the immediate context of a template instantiation.

— end note]

4

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[Note 2:

Whenever ranges​::​rbegin(E) is a valid expression, its type modelsinput_or_output_iterator.

— end note]