[range.reverse.overview] (original) (raw)

25 Ranges library [ranges]

25.7 Range adaptors [range.adaptors]

25.7.21 Reverse view [range.reverse]

25.7.21.1 Overview [range.reverse.overview]

reverse_view takes a bidirectional view and produces another view that iterates the same elements in reverse order.

Given a subexpression E, the expressionviews​::​reverse(E) is expression-equivalent to:

• If the type of E is a (possibly cv-qualified) specialization of reverse_view, then E.base().
• Otherwise, if the type of E is cv subrange<reverse_iterator<I>, reverse_iterator<I>, K> for some iterator type I and value K of type subrange_kind,
  • if K is subrange_kind​::​sized, thensubrange<I, I, K>(E.end().base(), E.begin().base(), E.size());
  • otherwise, subrange<I, I, K>(E.end().base(), E.begin().base()).
    However, in either case E is evaluated only once.
• Otherwise, reverse_view{E}.

[Example 1: vector<int> is {0,1,2,3,4};for (int i : is | views::reverse) cout << i << ' '; — _end example_]