Function test_generic_list

arrow-array/src/ffi.rs:791–842

()

    }

    fn test_generic_list<Offset: OffsetSizeTrait>() -> Result<()> {
        // Construct a value array
        let value_data = ArrayData::builder(DataType::Int32)
            .len(8)
            .add_buffer(Buffer::from_slice_ref([0, 1, 2, 3, 4, 5, 6, 7]))
            .build()
            .unwrap();

        // Construct a buffer for value offsets, for the nested array:
        //  [[0, 1, 2], [3, 4, 5], [6, 7]]
        let value_offsets = [0_usize, 3, 6, 8]
            .iter()
            .map(|i| Offset::from_usize(*i).unwrap())
            .collect::<Buffer>();

        // Construct a list array from the above two
        let list_data_type = GenericListArray::<Offset>::DATA_TYPE_CONSTRUCTOR(Arc::new(
            Field::new_list_field(DataType::Int32, false),
        ));

        let list_data = ArrayData::builder(list_data_type)
            .len(3)
            .add_buffer(value_offsets)
            .add_child_data(value_data)
            .build()
            .unwrap();

        // create an array natively
        let array = GenericListArray::<Offset>::from(list_data.clone());

        // export it
        let (array, schema) = to_ffi(&array.to_data())?;

        // (simulate consumer) import it
        let data = unsafe { from_ffi(array, &schema) }?;
        let array = make_array(data);

        // downcast
        let array = array
            .as_any()
            .downcast_ref::<GenericListArray<Offset>>()
            .unwrap();

        // verify
        let expected = GenericListArray::<Offset>::from(list_data);
        assert_eq!(&array.value(0), &expected.value(0));
        assert_eq!(&array.value(1), &expected.value(1));
        assert_eq!(&array.value(2), &expected.value(2));

        // (drop/release)
        Ok(())
    }

    #[test]
    fn test_list() -> Result<()> {