std::experimental::ranges::advance

 

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Technical specifications

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Iterators library

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Readable Writable WeaklyIncrementable Incrementable	Iterator Sentinel SizedSentinel	InputIterator ForwardIterator BidirectionalIterator RandomAccessIterator	OutputIterator
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IndirectUnaryInvocableIndirectRegularUnaryInvocable	IndirectUnaryPredicate	IndirectRelation	IndirectStrictWeakOrder
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IndirectlyMovable IndirectlyMovableStorable	IndirectlyCopyable IndirectlyCopyableStorable	IndirectlySwappable IndirectlyComparable	Permutable Mergeable Sortable
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indirect_result_of	projected
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iter_move iter_swap	advance distance	next prev
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difference_type value_type reference_trvalue_reference_titer_common_reference_t iterator_category	input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tag	ranges::iterator_traits std::iterator_traits<InputIterator>std::iterator_traits<OutputIterator>
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reverse_iterator move_iterator move_sentinel	back_insert_iterator front_insert_iterator insert_iterator	common_iterator counted_iterator default_sentinel	danglingborrowed_iterator_t unreachable
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istream_iterator	ostream_iterator	istreambuf_iterator	ostreambuf_iterator

 

Defined in header <experimental/ranges/iterator>
namespace {     constexpr /* unspecified */ advance = /* unspecified */; }		(ranges TS) (customization point object)
Call signature
template< Iterator I > constexpr void advance( I& i, ranges::difference_type_t<I> n );	(1)
template< Iterator I, Sentinel<I> S > constexpr void advance( I& i, S bound );	(2)
template< Iterator I, Sentinel<I> S > constexpr ranges::difference_type_t<I> advance( I& i, ranges::difference_type_t<I> n, S bound );	(3)

Advances the iterator i n times, or until bound is reached, whichever comes first.

1) If I models RandomAccessIterator, equivalent to i += n. Otherwise, increments (or decrements if n is negative) i n times. The behavior is undefined if n is negative and I does not model BidirectionalIterator.

2) If Assignable<I&, S> is satisfied, equivalent to i = std::move(bound).

Otherwise, if [i, bound) does not denote a range, the behavior is undefined.

Otherwise, if SizedSentinel<S, I> is satisfied, equivalent to ranges::advance(i, bound - i).

Otherwise, increments i until i == bound.

3) If SizedSentinel<S, I> is satisfied, equivalent to ranges::advance(i, bound) if |n| >= |bound - i|, and ranges::advance(i, n) otherwise.

Otherwise, increments (or decrements if n is negative) i either n times or until i == bound, whichever comes first.

If n > 0, [i, bound) shall denote a range; if n == 0, either [i, bound) or [bound, i) shall denote a range; if n < 0, [bound, i) shall denote a range, I and S shall be the same type, and I must model BidirectionalIterator. Otherwise, the behavior is undefined.

Customization point objects

The name ranges::advance denotes a customization point object, which is a function object of a literal Semiregular class type (denoted, for exposition purposes, as AdvanceT). All instances of AdvanceT are equal. Thus, ranges::advance can be copied freely and its copies can be used interchangeably.

Given a set of types Args..., if std::declval<Args>()... meet the requirements for arguments to ranges::advance above, AdvanceT will satisfy ranges::Invocable<const AdvanceT, Args...>. Otherwise, no function call operator of AdvanceT participates in overload resolution.

In every translation unit in which ranges::advance is defined, it refers to the same instance of the customization point object. (This means that it can be used freely in things like inline functions and function templates without violating the one-definition rule.)

Return value

1-2) (none)

3) The number of increment/decrements not performed due to reaching bound. In other words, n - M, where M is the distance from the starting position of i to the ending position and is negative if the ending position is before the starting position.

See also

advance	advances an iterator by given distance (function template)
distance	returns the distance between an iterator and a sentinel, or between the beginning and the end of a range (function template)
next	increment an iterator (function template)
prev	decrement an iterator (function template)