feat: vertex and edge attribute maps are now extended if needed

Author: ntamas

src/igraph_ctypes/_internal/attributes/storage.py

@@ -30,7 +30,7 @@ def add_vertices(self, graph, n: int) -> None:
         raise NotImplementedError
 
     @abstractmethod
-    def add_edges(self, graph, edges) -> None:
+    def add_edges(self, graph, edges: IntArray) -> None:
         """Notifies the attribute storage object that the given edges were
         added to the graph.
         """
@@ -84,10 +84,13 @@ class DictAttributeStorage(AttributeStorage):
     edge_attributes: dict[str, AttributeValueList[Any]] = field(default_factory=dict)
 
     def add_vertices(self, graph, n: int) -> None:
-        pass
+        for value_list in self.vertex_attributes.values():
+            value_list._extend_length(n)
 
     def add_edges(self, graph, edges: IntArray) -> None:
-        pass
+        n = edges.shape[0]
+        for value_list in self.edge_attributes.values():
+            value_list._extend_length(n)
 
     def clear(self) -> None:
         self.graph_attributes.clear()

src/igraph_ctypes/_internal/attributes/value_list.py

@@ -307,6 +307,14 @@ def _check_boolean_mask(self, index: Sequence[Any]) -> bool:
         else:
             self._raise_invalid_index_error()
 
+    def _extend_length(self, n: int) -> None:
+        """Extends the list with a given number of new items at the end, even
+        if the list is marked as fixed-length.
+
+        Do not use this method unless you know what you are doing.
+        """
+        self._items.extend([None] * n)  # type: ignore
+
     def _raise_invalid_index_error(self) -> NoReturn:
         # Wording of error message similar to NumPy
         raise IndexError(