Dynamic filepath key completion

datatree/datatree.py

@@ -517,28 +517,39 @@ def _item_sources(self) -> Iterable[Mapping[Any, Any]]:
         # immediate child nodes
         yield self.children
 
-    def _ipython_key_completions_(self) -> List[str]:
-        """Provide method for the key-autocompletions in IPython.
-        See http://ipython.readthedocs.io/en/stable/config/integrating.html#tab-completion
-        For the details.
+    # Argument `prefix` requires changes to ipython's autocompleter, see https://github.com/ipython/ipython/issues/12420
+    # TODO should I overload this method with the old signature too? Is that even possible?
+    def _ipython_key_completions_(self, prefix: str) -> List[str]:
         """
+        Provide method for the key-autocompletions in IPython.
+        See http://ipython.readthedocs.io/en/stable/config/integrating.html#tab-completion
+        for the details.
 
-        # TODO allow auto-completing relative string paths, e.g. `dt['path/to/../ <tab> node'`
-        # Would require changes to ipython's autocompleter, see https://github.com/ipython/ipython/issues/12420
-        # Instead for now we only list direct paths to all node in subtree explicitly
-
-        items_on_this_node = self._item_sources
-        full_file_like_paths_to_all_nodes_in_subtree = {
-            node.path[1:]: node for node in self.subtree
-        }
+        Provides dynamic auto-completion based on path typed out so far, including
+        allowing auto-completing relative string paths, e.g. `dt['path/to/../ <tab> node'`
+        """
 
-        all_item_sources = itertools.chain(
-            items_on_this_node, [full_file_like_paths_to_all_nodes_in_subtree]
-        )
+        # TODO allow for possiblity of error being raised here?
+        resolvable_path_prefix = NodePath(prefix).parent
 
+        try:
+            current_node = self[resolvable_path_prefix]
+        except KeyError:
+            # no matches
+            # TODO is it correct to return literally nothing here?
+            return []
+
+        # TODO ensure absolute paths are supported also
+        # suggest path-like syntax as autocompletion options too
+        path_syntax_sources = ["./"]
+        if current_node is not self.root:
+            # suggest pointing up to parent node
+            path_syntax_sources.append("../")
+
+        all_item_sources = itertools.chain(current_node._item_sources, path_syntax_sources)
         items = {
             item
-            for source in all_item_sources
+            for source in all_item_sources,
             for item in source
             if isinstance(item, str)
         }

datatree/tests/test_datatree.py

@@ -577,14 +577,33 @@ def test_attribute_access(self, create_test_datatree):
 
     def test_ipython_key_completions(self, create_test_datatree):
         dt = create_test_datatree()
-        key_completions = dt._ipython_key_completions_()
-
-        node_keys = [node.path[1:] for node in dt.subtree]
-        assert all(node_key in key_completions for node_key in node_keys)
 
+        # vars / coords
         var_keys = list(dt.variables.keys())
         assert all(var_key in key_completions for var_key in var_keys)
 
+        # dims
+        dim_keys = list(dt.dims.keys())
+
+        # immediate children
+        children_keys = dt.children.keys()
+        assert children_keys in dt._ipython_key_completions_(prefix='s')
+
+        # grandchildren
+        list_of_childrens_children = [list(gc.path for gc in c.children.values()) for c in dt.children.values()]
+        grandchild_keys = list(itertools.chain.from_iterable(list_of_childrens_children))
+        assert grandchild_keys in dt._ipython_key_completions_(prefix='set1/s')
+        assert grandchild_keys not in dt._ipython_key_completions_(prefix='set')
+
+        # relative paths
+        child = dt["set1"]
+        parent_keys = ["../set1", "../set2", ...]
+        assert parent_keys in child._ipython_key_completions_(prefix="../")
+
+        # TODO absolute paths
+
+        # TODO same directory (single dot)
+
 
 class TestRestructuring:
     def test_drop_nodes(self):