Function if

cpp/src/arrow/array/array_nested.cc:1093–1096

  ARROW_SUPPRESS_DEPRECATION_WARNING
  std::shared_ptr<Array> result = std::atomic_load(&impl_->boxed_fields_[i]);
  ARROW_UNSUPPRESS_DEPRECATION_WARNING
  if (result) {
    return result;
  }
  std::shared_ptr<ArrayData> field_data;
  if (data_->offset != 0 || data_->child_data[i]->length != data_->length) {
    field_data = data_->child_data[i]->Slice(data_->offset, data_->length);