std::experimental::ranges::adjacent_find

 

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all_ofany_ofnone_of countcount_if	findfind_iffind_if_not find_end find_first_of	adjacent_find search search_n mismatch	equal for_each lexicographical_compare
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copycopy_if copy_n copy_backward move move_backward	fill fill_n generate generate_n swap_ranges shuffle transform	removeremove_if replacereplace_if reverse rotate unique	remove_copyremove_copy_if replace_copyreplace_copy_if reverse_copy rotate_copy unique_copy
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max max_element	min min_element	minmax minmax_element
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is_permutation	next_permutation	prev_permutation

 

Defined in header <experimental/ranges/algorithm>
template< ForwardIterator I, Sentinel<I> S, class Proj = ranges::identity,           IndirectRelation<projected<I, Proj>> Pred = ranges::equal_to<> > I adjacent_find( I first, S last, Pred pred = Pred{}, Proj proj = Proj{} );	(1)	(ranges TS)
template< ForwardRange R, class Proj = ranges::identity,           IndirectRelation<projected<ranges::iterator_t<R>, Proj>> Pred = ranges::equal_to<> > ranges::safe_iterator_t<R> adjacent_find( R&& r, Pred pred = Pred{}, Proj proj = Proj{} );	(2)	(ranges TS)

1) Searches the range [first, last) for two consecutive identical elements. Elements are compared using pred after being projected with proj.

2) Same as (1), but uses r as the source range, as if using ranges::begin(r) as first and ranges::end(r) as last.

Notwithstanding the declarations depicted above, the actual number and order of template parameters for algorithm declarations is unspecified. Thus, if explicit template arguments are used when calling an algorithm, the program is probably non-portable.

Parameters

first, last	-	the range of elements to examine
r	-	the range of elements to examine
pred	-	predicate to use to compare the projected elements
proj	-	projection to apply to the elements

Return value

An iterator to the first of the first pair of identical elements, that is, the first iterator i such that both i and i + 1 are in the range [first, last) and ranges::invoke(pred, ranges::invoke(proj, *i), ranges::invoke(proj, *(i + 1))) != false.

If no such elements are found, an iterator that compares equal to last is returned.

Complexity

If the range is nonempty, exactly min((result - first) + 1, (last - first) - 1) applications of the predicate where result is the return value, and at most twice as many applications of the projection.

Possible implementation

template<ForwardIterator I, Sentinel<I> S, class Proj = ranges::identity, IndirectRelation<projected<I, Proj>> Pred = ranges::equal_to<>> I adjacent_find(I first, S last, Pred pred = Pred{}, Proj proj = Proj{}) { if (first == last) return first; I next = first; ++next; while (next != last) { if (ranges::invoke(pred, ranges::invoke(proj, *first), ranges::invoke(proj, *next))) return first; ++next; ++first; } return next; }

See also

adjacent_find	finds the first two adjacent items that are equal (or satisfy a given predicate) (function template)
unique	removes consecutive duplicate elements in a range (function template)