reorganize "traversable" detection

Leave search usage as a hasattr(__asdf_traverse__) check
since search doesn't have access to an extension manager

Update info usage to allow use of an extension manager

asdf/_node_info.py

@@ -120,6 +120,11 @@ def _get_extension_manager(refresh_extension_manager):
     return af.extension_manager
 
 
+def _traversable(node, extension_manager):
+    # TODO use extension_manager
+    return hasattr(node, "__asdf_traverse__")
+
+
 _SchemaInfo = namedtuple("SchemaInfo", ["info", "value"])
 
 
@@ -268,7 +273,7 @@ def from_root_node(
             next_nodes = []
 
             for parent, identifier, node in current_nodes:
-                if (isinstance(node, (dict, tuple)) or cls.traversable(node)) and id(node) in seen:
+                if (isinstance(node, (dict, tuple)) or _traversable(node, extension_manager)) and id(node) in seen:
                     info = NodeSchemaInfo(
                         key,
                         parent,
@@ -289,14 +294,14 @@ def from_root_node(
                         root_info = info
 
                     if parent is not None:
-                        if parent.schema is not None and not cls.traversable(node):
+                        if parent.schema is not None and not _traversable(node, extension_manager):
                             info.set_schema_for_property(parent, identifier)
 
                         parent.children.append(info)
 
                     seen.add(id(node))
 
-                    if cls.traversable(node):
+                    if _traversable(node, extension_manager):
                         t_node = node.__asdf_traverse__()
                         if hasattr(node, "_tag") and isinstance(node._tag, str):
                             try:

asdf/search.py

@@ -8,7 +8,7 @@
 import typing
 
 from ._display import DEFAULT_MAX_COLS, DEFAULT_MAX_ROWS, DEFAULT_SHOW_VALUES, format_faint, format_italic, render_tree
-from ._node_info import NodeSchemaInfo, collect_schema_info
+from ._node_info import collect_schema_info
 from .treeutil import get_children, is_container
 from .util import NotSet
 
@@ -353,8 +353,8 @@ def schema_info(self, key="description", preserve_list=True, refresh_extension_m
         )
 
     def __getitem__(self, key):
-        if isinstance(self._node, (dict, list, tuple)) or NodeSchemaInfo.traversable(self._node):
-            child = self._node.__asdf_traverse__()[key] if NodeSchemaInfo.traversable(self._node) else self._node[key]
+        if isinstance(self._node, (dict, list, tuple)) or hasattr(self._node, "__asdf_traverse__"):
+            child = self._node.__asdf_traverse__()[key] if hasattr(self._node, "__asdf_traverse__") else self._node[key]
         else:
             msg = "This node cannot be indexed"
             raise TypeError(msg)
@@ -381,9 +381,9 @@ def _walk_tree_breadth_first(root_identifiers, root_node, callback):
         next_nodes = []
 
         for identifiers, parent, node in current_nodes:
-            if (isinstance(node, (dict, list, tuple)) or NodeSchemaInfo.traversable(node)) and id(node) in seen:
+            if (isinstance(node, (dict, list, tuple)) or hasattr(node, "__asdf_traverse__")) and id(node) in seen:
                 continue
-            tnode = node.__asdf_traverse__() if NodeSchemaInfo.traversable(node) else node
+            tnode = node.__asdf_traverse__() if hasattr(node, "__asdf_traverse__") else node
             children = get_children(tnode)
             callback(identifiers, parent, node, [c for _, c in children])
             next_nodes.extend([([*identifiers, i], node, c) for i, c in children])