Method operator()

cpp/src/arrow/util/async_generator.h:2007–2012

template <typename T>
struct CancellableGenerator {
  Future<T> operator()() {
    if (stop_token.IsStopRequested()) {
      return stop_token.Poll();
    }
    return source();
  }

  AsyncGenerator<T> source;
  StopToken stop_token;