std::experimental::ranges::search_n (3) - Linux Manuals

std::experimental::ranges::search_n: std::experimental::ranges::search_n

Command to display std::experimental::ranges::search_n manual in Linux: $ man 3 std::experimental::ranges::search_n

NAME

std::experimental::ranges::search_n - std::experimental::ranges::search_n

Synopsis

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

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 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 (!ranges::invoke(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 (!ranges::invoke(pred, ranges::invoke(proj, *first), value)) {
                  // too few in a row
                  break;
              }
          }
      }
      return first;
  }

Example

This section is incomplete
Reason: no example