Function operator()

cpp/src/arrow/dataset/file_orc.cc:170–194

  };
  struct {
    Future<std::shared_ptr<RecordBatch>> operator()() {
      auto state = state_;
      return ::arrow::DeferNotOk(
          state->io_executor->Submit([state]() -> Result<std::shared_ptr<RecordBatch>> {
            if (state->first) {
              ARROW_ASSIGN_OR_RAISE(auto task, state->iter.Next());
              ARROW_ASSIGN_OR_RAISE(state->curr_iter, task->Execute());
              state->first = false;
            }
            while (!IsIterationEnd(state->curr_iter)) {
              ARROW_ASSIGN_OR_RAISE(auto next_batch, state->curr_iter.Next());
              if (IsIterationEnd(next_batch)) {
                ARROW_ASSIGN_OR_RAISE(auto task, state->iter.Next());
                if (IsIterationEnd(task)) {
                  state->curr_iter = IterationEnd<RecordBatchIterator>();
                } else {
                  ARROW_ASSIGN_OR_RAISE(state->curr_iter, task->Execute());
                }
              } else {
                return next_batch;
              }
            }
            return IterationEnd<std::shared_ptr<RecordBatch>>();
          }));
    }
    std::shared_ptr<IterState> state_;
  } iter_to_gen{std::shared_ptr<IterState>(
      new IterState{std::move(task_iter), {}, true, options->io_context.executor()})};