1 files changed, 20 insertions, 7 deletions
diff --git a/bsfs/graph/ac/base.py b/bsfs/graph/ac/base.py
index 79b09e5..e85c1dd 100644
--- a/bsfs/graph/ac/base.py
+++ b/bsfs/graph/ac/base.py
@@ -1,9 +1,4 @@
-"""
 
-Part of the BlackStar filesystem (bsfs) module.
-A copy of the license is provided with the project.
-Author: Matthias Baumgartner, 2022
-"""
 # imports
 import abc
 import typing
@@ -12,7 +7,7 @@ import typing
 from bsfs import schema
 from bsfs.query import ast
 from bsfs.triple_store import TripleStoreBase
-from bsfs.utils import URI
+from bsfs.utils import URI, typename
 
 # exports
 __all__: typing.Sequence[str] = (
@@ -44,6 +39,20 @@ class AccessControlBase(abc.ABC):
         self._backend = backend
         self._user = URI(user)
 
+    def __str__(self) -> str:
+        return f'{typename(self)}({self._user})'
+
+    def __repr__(self) -> str:
+        return f'{typename(self)}({self._user})'
+
+    def __eq__(self, other: typing.Any) -> bool:
+        return isinstance(other, type(self)) \
+           and self._backend == other._backend \
+           and self._user == other._user
+
+    def __hash__(self) -> int:
+        return hash((type(self), self._backend, self._user))
+
     @abc.abstractmethod
     def is_protected_predicate(self, pred: schema.Predicate) -> bool:
         """Return True if a predicate cannot be modified manually."""
@@ -69,7 +78,11 @@ class AccessControlBase(abc.ABC):
         """Return nodes that are allowed to be created."""
 
     @abc.abstractmethod
-    def filter_read(self, node_type: schema.Node, query: ast.filter.FilterExpression) -> ast.filter.FilterExpression:
+    def filter_read(
+            self,
+            node_type: schema.Node,
+            query: typing.Optional[ast.filter.FilterExpression],
+            ) -> typing.Optional[ast.filter.FilterExpression]:
         """Re-write a filter *query* to get (i.e., read) *node_type* nodes."""
 
     @abc.abstractmethod