Function AsyncAddArrowTextColumn

catboost/python-package/catboost/arrow.cpp:798–837

    void AsyncAddArrowTextColumn(
        ui32 flatFeatureIdx,
        PyObject* capsule,
        IRawFeaturesOrderDataVisitor* builderVisitor,
        TVector<std::future<void>>* result
    ) {
        auto callback = [=] (TArrowSchemaHolderPtr schema, TArrowArrayHolderPtr array) {
            auto process = [=] () {
                try {
                    CB_ENSURE(
                        array->Data.null_count <= 0,
                        "Data with nulls is not supported for text columns"
                    );

                    TVector<TString> result(array->Data.length);

                    ProcessNonNullableStringColumn(
                        schema,
                        array,
                        "text",
                        [&, flatFeatureIdx](size_t dstObjIdx, TStringBuf value) {
                            result[dstObjIdx] = TString(value);
                        }
                    );

                    builderVisitor->AddTextFeature(flatFeatureIdx, result);
                } catch (...) {
                    ythrow TCatBoostException() << "Error while processing column '" << schema->Data.name << "': "
                        << CurrentExceptionMessage();
                }
            };

            result->push_back(std::async(std::move(process)));
        };

        ProcessArrowArrayStream(
            capsule,
            std::move(callback)
        );
    }

}