Function test_linked_list_forward

python/pathway/tests/test_examples.py:172–217

()

def test_linked_list_forward():
    nodes = T(
        """
      | next
    1 | 2
    2 | 3
    3 | 4
    4 | 5
    5 | 6
    6 | 7
    7 | 8
    8 |
    """,
    )
    nodes = nodes.select(next=nodes.pointer_from(this.next, optional=True))

    linked_list = linked_list_transformer(linked_list=nodes).linked_list

    queries = T(
        """
    node_id | steps
    1       | 0
    2       | 1
    6       | 2
    6       | 3
    8       | 0
    8       | 2
        """,
    ).with_columns(node_id=nodes.pointer_from(this.node_id))
    ret = queries.select(result=linked_list.ix(queries.node_id).forward(queries.steps))
    expected = (
        T(
            """
      | result
    0 | 1
    1 | 3
    2 | 8
    3 |
    4 | 8
    5 |
    """,
        )
        .update_types(result=Any)
        .select(result=nodes.pointer_from(this.result, optional=True))
    )
    assert_table_equality(ret, expected)