std::experimental::ranges::search_n
From cppreference.com
| Defined in header <experimental/ranges/algorithm>
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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{} );
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(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{} );
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(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
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| 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;
}
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Example
| This section is incomplete Reason: no example |