[IR] introduce slice support on graph

onnxscript/ir/_core.py

@@ -2282,7 +2282,12 @@
     def opset_imports(self) -> dict[str, int]:
         return self._opset_imports
 
-    def __getitem__(self, index: int) -> Node:
+    @typing.overload
+    def __getitem__(self, index: int) -> Node: ...
+    @typing.overload
+    def __getitem__(self, index: slice) -> Sequence[Node]: ...
+
+    def __getitem__(self, index):
         return self._nodes[index]
 
     def __len__(self) -> int:
@@ -2712,7 +2717,12 @@
         self._metadata_props: dict[str, str] | None = metadata_props
         self._nodes: tuple[Node, ...] = tuple(nodes)
 
-    def __getitem__(self, index: int) -> Node:
+    @typing.overload
+    def __getitem__(self, index: int) -> Node: ...
+    @typing.overload
+    def __getitem__(self, index: slice) -> Sequence[Node]: ...
+
+    def __getitem__(self, index):
         return self._nodes[index]
 
     def __len__(self) -> int:
@@ -2961,7 +2971,12 @@
     def attributes(self) -> OrderedDict[str, Attr]:
         return self._attributes
 
-    def __getitem__(self, index: int) -> Node:
+    @typing.overload
+    def __getitem__(self, index: int) -> Node: ...
+    @typing.overload
+    def __getitem__(self, index: slice) -> Sequence[Node]: ...
+
+    def __getitem__(self, index):
         return self._graph.__getitem__(index)
 
     def __len__(self) -> int:

onnxscript/ir/_linked_list.py

@@ -4,7 +4,7 @@
 
 from __future__ import annotations
 
-from typing import Generic, Iterable, Iterator, Sequence, TypeVar
+from typing import Generic, Iterable, Iterator, Sequence, TypeVar, overload
 
 T = TypeVar("T")
 
@@ -136,11 +136,18 @@
         )
         return self._length
 
-    def __getitem__(self, index: int) -> T:
+    @overload
+    def __getitem__(self, index: int) -> T: ...
+    @overload
+    def __getitem__(self, index: slice) -> Sequence[T]: ...
+
+    def __getitem__(self, index):
         """Get the node at the given index.
 
         Complexity is O(n).
         """
+        if isinstance(index, slice):
+            return tuple(self)[index]
         if index >= self._length or index < -self._length:
             raise IndexError(
                 f"Index out of range: {index} not in range [-{self._length}, {self._length})"

onnxscript/ir/_linked_list_test.py

@@ -373,6 +373,15 @@ def test_insert_after_supports_taking_elements_from_another_doubly_linked_list(
         self.assertEqual(len(other_linked_list), 1)
         self.assertEqual([elem.value for elem in other_linked_list], [42])
 
+    @parameterized.parameterized.expand(
+        [(s, t, p) for s in [-2, 0, 2, 3] for t in [2, -1, -2] for p in [-3, -1, 1, 2]]
+    )
+    def test_get_item_slice(self, start, stop, step):
+        elems = [_TestElement(i) for i in range(5)]
+        linked_list = _linked_list.DoublyLinkedSet(elems)
+        self.assertEqual(len(linked_list), 5)
+        self.assertEqual(list(linked_list[start:stop:step]), elems[start:stop:step])
+
 
 if __name__ == "__main__":
     unittest.main()