std::experimental::ranges::search_n - cppreference.com (original) (raw)
| 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) |
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.Same as (1), but uses r as the source range, as if using ranges::begin(r) as first and ranges::end(r) as last.
Contents
[edit] 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 |
[edit] 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.
[edit] Complexity
At most last - first applications of the predicate and the projection.
[edit] Possible implementation
template<ForwardIterator I, Sentinel 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 count,
const T& value, Pred pred = Pred{}, Proj proj = Proj{})
{
for (; first != last; ++first)
{
if ((pred, ranges::invoke(proj, *first), value))
continue;
I candidate = first;
ranges::difference_type_t cur_count = 0;
while (true)
{
++cur_count;
if (cur_count == count)
// success
return candidate;
++first;
if (first == last)
// exhausted the list
return first;
if (
(pred, ranges::invoke(proj, *first), value))
// too few in a row
break;
}
}
return first;
}
[edit] Example
[edit] See also
| | searches for the first occurrence of a number consecutive copies of an element in a range (function template) [edit] | | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | finds the last sequence of elements in a certain range (function template) [edit] | | | finds the first element satisfying specific criteria (function template) [edit] | | | searches for a range of elements (function template) [edit] |