Method take

3rdparty/cppdap/src/chan.h:57–66

template <typename T>
optional<T> Chan<T>::take() {
  std::unique_lock<std::mutex> lock(mutex);
  cv.wait(lock, [&] { return queue.size() > 0 || closed; });
  if (queue.size() == 0) {
    return optional<T>();
  }
  auto out = std::move(queue.front());
  queue.pop();
  return optional<T>(std::move(out));
}

template <typename T>
void Chan<T>::put(T&& in) {