fix: namespace rebinding in Memory, SimpleMemory and BerkelyDB stores.

rdflib/graph.py

@@ -1018,6 +1018,13 @@ def bind(self, prefix, namespace, override=True, replace=False) -> None:
         for example:  graph.bind("foaf", "http://xmlns.com/foaf/0.1/")
 
         """
+        # TODO FIXME: This method's behaviour should be simplified and made
+        # more robust. If the method cannot do what it is asked it should raise
+        # an exception, it is also unclear why this method has all the
+        # different modes. It seems to just make it more complex to use, maybe
+        # it should be clarified when someone will need to use override=False
+        # and replace=False. And also why silent failure here is preferred over
+        # raising an excpetion.
         return self.namespace_manager.bind(
             prefix, namespace, override=override, replace=replace
         )

rdflib/plugins/stores/berkeleydb.py

@@ -471,10 +471,17 @@ def bind(self, prefix, namespace, override=True):
         prefix = prefix.encode("utf-8")
         namespace = namespace.encode("utf-8")
         bound_prefix = self.__prefix.get(namespace)
-        if override and bound_prefix:
-            self.__namespace.delete(bound_prefix)
-        self.__prefix[namespace] = prefix
-        self.__namespace[prefix] = namespace
+        bound_namespace = self.__namespace.get(prefix)
+        if override:
+            if bound_prefix:
+                self.__namespace.delete(bound_prefix)
+            if bound_namespace:
+                self.__prefix.delete(bound_namespace)
+            self.__prefix[namespace] = prefix
+            self.__namespace[prefix] = namespace
+        else:
+            self.__prefix[bound_namespace or namespace] = bound_prefix or prefix
+            self.__namespace[bound_prefix or prefix] = bound_namespace or namespace
 
     def namespace(self, prefix):
         prefix = prefix.encode("utf-8")

rdflib/plugins/stores/memory.py

@@ -1,6 +1,7 @@
 #
 #
 from rdflib.store import Store
+from rdflib.util import _coalesce
 
 __all__ = ["SimpleMemory", "Memory"]
 
@@ -149,11 +150,26 @@ def __len__(self, context=None):
         return i
 
     def bind(self, prefix, namespace, override=True):
-        bound_prefix = self.__prefix.get(namespace)
-        if override and bound_prefix:
-            del self.__namespace[bound_prefix]
-        self.__prefix[namespace] = prefix
-        self.__namespace[prefix] = namespace
+        # should be identical to `Memory.bind`
+        bound_namespace = self.__namespace.get(prefix)
+        bound_prefix = _coalesce(
+            self.__prefix.get(namespace),
+            self.__prefix.get(bound_namespace),
+        )
+        if override:
+            if bound_prefix is not None:
+                del self.__namespace[bound_prefix]
+            if bound_namespace is not None:
+                del self.__prefix[bound_namespace]
+            self.__prefix[namespace] = prefix
+            self.__namespace[prefix] = namespace
+        else:
+            self.__prefix[_coalesce(bound_namespace, namespace)] = _coalesce(
+                bound_prefix, prefix
+            )
+            self.__namespace[_coalesce(bound_prefix, prefix)] = _coalesce(
+                bound_namespace, namespace
+            )
 
     def namespace(self, prefix):
         return self.__namespace.get(prefix, None)
@@ -403,11 +419,26 @@ def triples(self, triple_pattern, context=None):
                             yield triple, self.__contexts(triple)
 
     def bind(self, prefix, namespace, override=True):
-        bound_prefix = self.__prefix.get(namespace)
-        if override and bound_prefix:
-            del self.__namespace[bound_prefix]
-        self.__prefix[namespace] = prefix
-        self.__namespace[prefix] = namespace
+        # should be identical to `SimpleMemory.bind`
+        bound_namespace = self.__namespace.get(prefix)
+        bound_prefix = _coalesce(
+            self.__prefix.get(namespace),
+            self.__prefix.get(bound_namespace),
+        )
+        if override:
+            if bound_prefix is not None:
+                del self.__namespace[bound_prefix]
+            if bound_namespace is not None:
+                del self.__prefix[bound_namespace]
+            self.__prefix[namespace] = prefix
+            self.__namespace[prefix] = namespace
+        else:
+            self.__prefix[_coalesce(bound_namespace, namespace)] = _coalesce(
+                bound_prefix, prefix
+            )
+            self.__namespace[_coalesce(bound_prefix, prefix)] = _coalesce(
+                bound_namespace, namespace
+            )
 
     def namespace(self, prefix):
         return self.__namespace.get(prefix, None)

rdflib/util.py

@@ -25,7 +25,7 @@
 
 # from time import daylight
 from time import altzone, gmtime, localtime, time, timezone
-from typing import Optional
+from typing import Optional, TypeVar
 
 import rdflib.graph  # avoid circular dependency
 from rdflib.compat import sign
@@ -44,6 +44,7 @@
     "guess_format",
     "find_roots",
     "get_tree",
+    "_coalesce",
 ]
 
 
@@ -430,6 +431,29 @@ def get_tree(
     return (mapper(root), sorted(tree, key=sortkey))
 
 
+_AnyT = TypeVar("_AnyT")
+
+
+def _coalesce(*args: Optional[_AnyT]) -> Optional[_AnyT]:
+    """
+    This is a null coalescing function, it will return the first non-`None`
+    argument passed to it, otherwise it will return `None`.
+
+    For more info regarding the rationale of this function see deferred `PEP
+    505 <https://peps.python.org/pep-0505/>`_.
+
+    :param args: Values to consider as candidates to return, the first arg that
+        is not `None` will be returned. If no argument is passed this function
+        will return None.
+    :return: The first ``arg`` that is not `None`, otherwise `None` if there
+        are no args or if all args are `None`.
+    """
+    for arg in args:
+        if arg is not None:
+            return arg
+    return None
+
+
 def test():
     import doctest