std::experimental::ranges::search_n

 

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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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Defined in header <experimental/ranges/algorithm>
template< ForwardIterator I, Sentinel<I> S, class T,           class Pred = ranges::equal_to<>, class Proj = ranges::identity >     requires IndirectlyComparable<I, const T*, Pred, Proj> I search_n( I first, S last, ranges::difference_type_t<I> count,             const T& value, Pred pred = Pred{}, Proj proj = Proj{} );	(1)	(ranges TS)
template< ForwardRange R, class T, class Pred = ranges::equal_to<>,           class Proj = ranges::identity >     requires IndirectlyComparable<ranges::iterator_t<R>, const T*, Pred, Proj> ranges::safe_iterator_t<R> search_n( R&& r,                                      ranges::difference_type_t<ranges::iterator_t<R>> count,                                      const T& value, Pred pred = Pred{}, Proj proj = Proj{} );	(2)	(ranges TS)

1) Searches the range [first, last) for the first sequence of count elements whose projected values are each equal to the given value value according to the predicate pred.

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.

Parameters

first, last	-	the range of elements to examine
r	-	the range of elements to examine
count	-	the length of the sequence to search for
value	-	the value to search for
pred	-	the predicate that compares the projected elements with value
proj	-	the projection to apply to the elements

Return value

Iterator to the beginning of the found sequence in the range [first, last). If no such sequence is found, an iterator that compares equal to last is returned.

Complexity

At most last - first applications of the predicate and the projection.

Possible implementation

template<ForwardIterator I, Sentinel<I> S, class T, class Pred = ranges::equal_to<>, class Proj = ranges::identity> requires IndirectlyComparable<I, const T*, Pred, Proj> I search_n(I first, S last, ranges::difference_type_t<I> count, const T& value, Pred pred = Pred{}, Proj proj = Proj{}) { for (; first != last; ++first) { if (!ranges::invoke(pred, ranges::invoke(proj, *first), value)) continue;   I candidate = first; ranges::difference_type_t<I> cur_count = 0;   while (true) { ++cur_count; if (cur_count == count) // success return candidate;   ++first; if (first == last) // exhausted the list return first;   if (!ranges::invoke(pred, ranges::invoke(proj, *first), value)) // too few in a row break; } } return first; }

See also

search_n	searches for the first occurrence of a number consecutive copies of an element in a range (function template)
find_end	finds the last sequence of elements in a certain range (function template)
findfind_iffind_if_not	finds the first element satisfying specific criteria (function template)
search	searches for a range of elements (function template)