Merge pull request #1680 from ajnelson-nist/add_identified_node

Add IdentifiedNode abstract intermediary class

3 files changed, 28 insertions, 31 deletions

diff --git a/rdflib/__init__.py b/rdflib/__init__.py
index b55aa76e..3067556d 100644
--- a/rdflib/__init__.py
+++ b/rdflib/__init__.py
@@ -51,6 +51,7 @@ __date__ = "2021-12-20"
 __all__ = [
     "URIRef",
     "BNode",
+    "IdentifiedNode",
     "Literal",
     "Variable",
     "Namespace",
@@ -155,7 +156,7 @@ In particular, this determines how the rich comparison operators for
 Literal work, eq, __neq__, __lt__, etc.
 """
 
-from rdflib.term import URIRef, BNode, Literal, Variable
+from rdflib.term import URIRef, BNode, IdentifiedNode, Literal, Variable
 
 from rdflib.graph import Dataset, Graph, ConjunctiveGraph
 
diff --git a/rdflib/term.py b/rdflib/term.py
index 1182ecb8..7b0123e4 100644
--- a/rdflib/term.py
+++ b/rdflib/term.py
@@ -27,6 +27,7 @@ from fractions import Fraction
 __all__ = [
     "bind",
     "Node",
+    "IdentifiedNode",
     "Identifier",
     "URIRef",
     "BNode",
@@ -218,7 +219,21 @@ class Identifier(Node, str):  # allow Identifiers to be Nodes in the Graph
     __hash__ = str.__hash__
 
 
-class URIRef(Identifier):
+class IdentifiedNode(Identifier):
+    """
+    An abstract class, primarily defined to identify Nodes that are not Literals.
+
+    The name "Identified Node" is not explicitly defined in the RDF specification, but can be drawn from this section: https://www.w3.org/TR/rdf-concepts/#section-URI-Vocabulary
+    """
+
+    def __getnewargs__(self):
+        return (str(self),)
+
+    def toPython(self) -> str:
+        return str(self)
+
+
+class URIRef(IdentifiedNode):
     """
     RDF URI Reference: http://www.w3.org/TR/rdf-concepts/#section-Graph-URIref
     """
@@ -250,9 +265,6 @@ class URIRef(Identifier):
             rt = str.__new__(cls, value, "utf-8")  # type: ignore[call-overload]
         return rt
 
-    def toPython(self) -> str:
-        return str(self)
-
     def n3(self, namespace_manager=None) -> str:
         """
         This will do a limited check for valid URIs,
@@ -284,9 +296,6 @@ class URIRef(Identifier):
     def __reduce__(self):
         return (URIRef, (str(self),))
 
-    def __getnewargs__(self):
-        return (str(self),)
-
     def __repr__(self):
         if self.__class__ is URIRef:
             clsName = "rdflib.term.URIRef"
@@ -386,7 +395,7 @@ def _serial_number_generator():
     return _generator
 
 
-class BNode(Identifier):
+class BNode(IdentifiedNode):
     """
     Blank Node: http://www.w3.org/TR/rdf-concepts/#section-blank-nodes
 
@@ -418,15 +427,9 @@ class BNode(Identifier):
             # http://www.w3.org/TR/2004/REC-rdf-testcases-20040210/#nodeID
         return Identifier.__new__(cls, value)  # type: ignore[return-value]
 
-    def toPython(self) -> str:
-        return str(self)
-
     def n3(self, namespace_manager=None):
         return "_:%s" % self
 
-    def __getnewargs__(self):
-        return (str(self),)
-
     def __reduce__(self):
         return (BNode, (str(self),))
 
diff --git a/test/test_typing.py b/test/test_typing.py
index 2696e593..c3295ed4 100644
--- a/test/test_typing.py
+++ b/test/test_typing.py
@@ -27,13 +27,6 @@ from typing import Set, Tuple, Union
 import rdflib.plugins.sparql.processor
 
 
-# TODO Question - is there a usable type name or class name for
-# 'typing.Union[rdflib.BNode, rdflib.URIRef]'?
-# Conversation to resolve:
-# https://github.com/RDFLib/rdflib/issues/1526
-example_BlankNodeOrIRI = Union[rdflib.BNode, rdflib.URIRef]
-
-
 def test_rdflib_query_exercise() -> None:
     """
     The purpose of this test is to exercise a selection of rdflib features under "mypy --strict" review.
@@ -63,10 +56,10 @@ def test_rdflib_query_exercise() -> None:
     graph.add((kb_https_uriref, predicate_q, literal_two))
     graph.add((kb_bnode, predicate_p, literal_one))
 
-    expected_nodes_using_predicate_q: Set[example_BlankNodeOrIRI] = {
+    expected_nodes_using_predicate_q: Set[rdflib.IdentifiedNode] = {
         kb_https_uriref
     }
-    computed_nodes_using_predicate_q: Set[example_BlankNodeOrIRI] = set()
+    computed_nodes_using_predicate_q: Set[rdflib.IdentifiedNode] = set()
     for triple in graph.triples((None, predicate_q, None)):
         computed_nodes_using_predicate_q.add(triple[0])
     assert expected_nodes_using_predicate_q == computed_nodes_using_predicate_q
@@ -78,13 +71,13 @@ WHERE {
 }
 """
 
-    expected_one_usage: Set[example_BlankNodeOrIRI] = {
+    expected_one_usage: Set[rdflib.IdentifiedNode] = {
         kb_bnode,
         kb_http_uriref,
         kb_https_uriref,
         kb_urn_uriref,
     }
-    computed_one_usage: Set[example_BlankNodeOrIRI] = set()
+    computed_one_usage: Set[rdflib.IdentifiedNode] = set()
     for one_usage_result in graph.query(one_usage_query):
         computed_one_usage.add(one_usage_result[0])
     assert expected_one_usage == computed_one_usage
@@ -103,14 +96,14 @@ WHERE {
 
     expected_two_usage: Set[
         Tuple[
-            example_BlankNodeOrIRI,
-            example_BlankNodeOrIRI,
+            rdflib.IdentifiedNode,
+            rdflib.IdentifiedNode,
         ]
     ] = {(kb_https_uriref, predicate_p), (kb_https_uriref, predicate_q)}
     computed_two_usage: Set[
         Tuple[
-            example_BlankNodeOrIRI,
-            example_BlankNodeOrIRI,
+            rdflib.IdentifiedNode,
+            rdflib.IdentifiedNode,
         ]
     ] = set()
     for two_usage_result in graph.query(two_usage_query):
@@ -122,7 +115,7 @@ WHERE {
     prepared_one_usage_query = rdflib.plugins.sparql.processor.prepareQuery(
         one_usage_query, initNs=nsdict
     )
-    computed_one_usage_from_prepared_query: Set[example_BlankNodeOrIRI] = set()
+    computed_one_usage_from_prepared_query: Set[rdflib.IdentifiedNode] = set()
     for prepared_one_usage_result in graph.query(prepared_one_usage_query):
         computed_one_usage_from_prepared_query.add(prepared_one_usage_result[0])
     assert expected_one_usage == computed_one_usage_from_prepared_query