Method EmitResult

cpp/src/arrow/compute/exec.cc:1092–1101

 protected:
  Status EmitResult(Datum result, ExecListener* listener) {
    if (!kernel_->finalize) {
      // If there is no result finalizer (e.g. for hash-based functions, we can
      // emit the processed batch right away rather than waiting
      RETURN_NOT_OK(listener->OnResult(std::move(result)));
    } else {
      results_.emplace_back(std::move(result));
    }
    return Status::OK();
  }

  Status Exec(const ExecSpan& span, ExecListener* listener) {
    ExecResult out;