Function VisitAsyncGenerator

cpp/src/arrow/util/async_generator.h:86–116

/// returning a future that completes when all have been visited
template <typename T, typename Visitor>
Future<> VisitAsyncGenerator(AsyncGenerator<T> generator, Visitor visitor) {
  struct LoopBody {
    struct Callback {
      Result<ControlFlow<>> operator()(const T& next) {
        if (IsIterationEnd(next)) {
          return Break();
        } else {
          auto visited = visitor(next);
          if (visited.ok()) {
            return Continue();
          } else {
            return visited;
          }
        }
      }

      Visitor visitor;
    };

    Future<ControlFlow<>> operator()() {
      Callback callback{visitor};
      auto next = generator();
      return next.Then(std::move(callback));
    }

    AsyncGenerator<T> generator;
    Visitor visitor;
  };

  return Loop(LoopBody{std::move(generator), std::move(visitor)});
}

/// \brief Wait for an async generator to complete, discarding results.
template <typename T>