feat(common): also traverse nodes used as dictionary keys (#9041)

This change allows repr-ing node mappings, like the dereference mappings
for easier inspection.

Inevitably this is slowing down the traversals, but changing the
instance checks to use a plain dict instead of `(dict, frozendict)`
maintains the previous traversal speed.

ibis/common/graph.py

@@ -2,13 +2,13 @@
 
 from __future__ import annotations
 
+import itertools
 from abc import abstractmethod
 from collections import deque
 from collections.abc import Iterable, Iterator, KeysView, Mapping, Sequence
 from typing import TYPE_CHECKING, Any, Callable, Optional, TypeVar, Union
 
 from ibis.common.bases import Hashable
-from ibis.common.collections import frozendict
 from ibis.common.patterns import NoMatch, Pattern
 from ibis.common.typing import _ClassInfo
 from ibis.util import experimental, promote_list
@@ -66,8 +66,9 @@ def _flatten_collections(node: Any) -> Iterator[N]:
             yield item
         elif isinstance(item, (tuple, list)):
             yield from _flatten_collections(item)
-        elif isinstance(item, (dict, frozendict)):
-            yield from _flatten_collections(item.values())
+        elif isinstance(item, dict):
+            items = itertools.chain.from_iterable(item.items())
+            yield from _flatten_collections(items)
 
 
 def _recursive_lookup(obj: Any, dct: dict) -> Any:
@@ -89,6 +90,7 @@ def _recursive_lookup(obj: Any, dct: dict) -> Any:
 
     Examples
     --------
+    >>> from ibis.common.collections import frozendict
     >>> from ibis.common.grounds import Concrete
     >>> from ibis.common.graph import Node
     >>>
@@ -117,8 +119,10 @@ def _recursive_lookup(obj: Any, dct: dict) -> Any:
         return dct.get(obj, obj)
     elif isinstance(obj, (tuple, list)):
         return tuple(_recursive_lookup(o, dct) for o in obj)
-    elif isinstance(obj, (dict, frozendict)):
-        return {k: _recursive_lookup(v, dct) for k, v in obj.items()}
+    elif isinstance(obj, dict):
+        return {
+            _recursive_lookup(k, dct): _recursive_lookup(v, dct) for k, v in obj.items()
+        }
     else:
         return obj
 

ibis/common/tests/test_graph.py

@@ -55,6 +55,7 @@ def copy(self, name=None, children=None):
 E = MyNode(name="E", children=[])
 B = MyNode(name="B", children=[D, E])
 A = MyNode(name="A", children=[B, C])
+F = MyNode(name="F", children=[{C: D, E: None}])
 
 
 def test_bfs():
@@ -68,8 +69,8 @@ def test_construction():
 
 
 def test_graph_nodes():
-    g = Graph(A)
-    assert g.nodes() == {A, B, C, D, E}
+    assert Graph(A).nodes() == {A, B, C, D, E}
+    assert Graph(F).nodes() == {F, C, D, E}
 
 
 def test_graph_repr():
@@ -286,6 +287,10 @@ def test_flatten_collections():
     )
     assert list(result) == [A, C, D]
 
+    # test that dictionary keys are also flattened
+    result = _flatten_collections([0.0, {A: B, C: [D]}, frozendict({E: 6})])
+    assert list(result) == [A, B, C, D, E]
+
 
 def test_recursive_lookup():
     results = {A: "A", B: "B", C: "C", D: "D"}
@@ -312,6 +317,9 @@ def test_recursive_lookup():
         my_map,
     )
 
+    # test that dictionary nodes as dictionary keys are also looked up
+    assert _recursive_lookup({A: B, C: D}, results) == {"A": "B", "C": "D"}
+
 
 def test_coerce_finder():
     f = _coerce_finder(int)