filter

Header pipe/algorithm.h, in namespace pipe::algorithm.

template <typename Predicate>
auto filter(Predicate pred);

filter returns an object which can act as a rhs when applying operator| to a lhs generator. When applied, it filters out elements yielded by the input generator that don't conform to the given Predicate, yielding the remaining elements.

Example:

std::vector<int> out { };
count<int>() | take_n(6) | filter([](auto& item) { return item % 2 == 0; }) | collect(std::back_inserter(out));
// out contains { 0, 2, 4 }