cppdraft_translate/cppdraft/range/iter/op/advance.md

[range.iter.op.advance]

24 Iterators library [iterators]

24.4 Iterator primitives [iterator.primitives]

24.4.4 Range iterator operations [range.iter.ops]

24.4.4.2 ranges​::​advance [range.iter.op.advance]

🔗

template<[input_or_output_iterator](iterator.concept.iterator#concept:input_or_output_iterator "24.3.4.6 Concept input_­or_­output_­iterator [iterator.concept.iterator]") I> constexpr void ranges::advance(I& i, iter_difference_t<I> n);

1

#

Preconditions: If I does not model bidirectional_iterator,n is not negative.

2

#

Effects:

• (2.1)

  If I models random_access_iterator, equivalent to i += n.

• (2.2)

  Otherwise, if n is non-negative, increments i by n.

• (2.3)

  Otherwise, decrements i by -n.

🔗

template<[input_or_output_iterator](iterator.concept.iterator#concept:input_or_output_iterator "24.3.4.6 Concept input_­or_­output_­iterator [iterator.concept.iterator]") I, [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7 Concept sentinel_­for [iterator.concept.sentinel]")<I> S> constexpr void ranges::advance(I& i, S bound);

3

#

Preconditions: Either assignable_from<I&, S> || sized_sentinel_for<S, I> is modeled, or [i, bound) denotes a range.

4

#

Effects:

• (4.1)

  If I and S model assignable_from<I&, S>, equivalent to i = std​::​move(bound).

• (4.2)

  Otherwise, if S and I model sized_sentinel_for<S, I>, equivalent to ranges​::​advance(i, bound - i).

• (4.3)

  Otherwise, while bool(i != bound) is true, increments i.

🔗

template<[input_or_output_iterator](iterator.concept.iterator#concept:input_or_output_iterator "24.3.4.6 Concept input_­or_­output_­iterator [iterator.concept.iterator]") I, [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7 Concept sentinel_­for [iterator.concept.sentinel]")<I> S> constexpr iter_difference_t<I> ranges::advance(I& i, iter_difference_t<I> n, S bound);

5

#

Preconditions: If n > 0, [i, bound) denotes a range.

If n == 0, [i, bound) or [bound, i) denotes a range.

If n < 0, [bound, i) denotes a range,I models bidirectional_iterator, andI and S model same_as<I, S>.

6

#

Effects:

• (6.1)

  If S and I model sized_sentinel_for<S, I>:

  • (6.1.1)

    If ​|n| ≥ |bound - i|, equivalent to ranges​::​advance(i, bound).

  • (6.1.2)

    Otherwise, equivalent to ranges​::​advance(i, n).

• (6.2)

  Otherwise,

  • (6.2.1)

    if n is non-negative, while bool(i != bound) is true, increments i but at most n times.

  • (6.2.2)

    Otherwise, while bool(i != bound) is true, decrements i but at most -n times.

7

#

Returns: n - M, where M is the difference between the ending and starting positions of i.