Supporting bnode_context for each call to parse (#980)

- Needed so you can access through Graph.parse which does not support
  passing args to Parser __init__

2 files changed, 43 insertions, 11 deletions

diff --git a/rdflib/plugins/parsers/ntriples.py b/rdflib/plugins/parsers/ntriples.py
index e2ee5ff3..f817cede 100644
--- a/rdflib/plugins/parsers/ntriples.py
+++ b/rdflib/plugins/parsers/ntriples.py
@@ -128,21 +128,23 @@ class NTriplesParser(object):
         else:
             self._bnode_ids = {}
 
+        self._parse_bnode_ids = None
+
         if sink is not None:
             self.sink = sink
         else:
             self.sink = Sink()
 
-    def parse(self, f):
+    def parse(self, f, bnode_context=None):
         """Parse f as an N-Triples file."""
         if not hasattr(f, "read"):
             raise ParseError("Item to parse must be a file-like object.")
-
         # since N-Triples 1.1 files can and should be utf-8 encoded
         f = codecs.getreader("utf-8")(f)
 
         self.file = f
         self.buffer = ""
+        self._parse_bnode_ids = bnode_context
         while True:
             self.line = self.readline()
             if self.line is None:
@@ -153,14 +155,14 @@ class NTriplesParser(object):
                 raise ParseError("Invalid line: %r" % self.line)
         return self.sink
 
-    def parsestring(self, s):
+    def parsestring(self, s, **kwargs):
         """Parse s as an N-Triples string."""
         if not isinstance(s, str):
             raise ParseError("Item to parse must be a string instance.")
         f = BytesIO()
         f.write(cast_bytes(s))
         f.seek(0)
-        self.parse(f)
+        self.parse(f, **kwargs)
 
     def readline(self):
         """Read an N-Triples line from buffered input."""
@@ -246,8 +248,12 @@ class NTriplesParser(object):
     def nodeid(self):
         if self.peek("_"):
             # Fix for https://github.com/RDFLib/rdflib/issues/204
+            if self._parse_bnode_ids is not None:
+                bnode_ids = self._parse_bnode_ids
+            else:
+                bnode_ids = self._bnode_ids
             bnode_id = self.eat(r_nodeid).group(1)
-            new_id = self._bnode_ids.get(bnode_id, None)
+            new_id = bnode_ids.get(bnode_id, None)
             if new_id is not None:
                 # Re-map to id specfic to this doc
                 return bNode(new_id)
diff --git a/test/test_nt_misc.py b/test/test_nt_misc.py
index 0c738c35..4a21fed9 100644
--- a/test/test_nt_misc.py
+++ b/test/test_nt_misc.py
@@ -131,21 +131,34 @@ class NTTestCase(unittest.TestCase):
 
 
 class BNodeContextTestCase(unittest.TestCase):
-    def test_bnode_shared_across_parse(self):
+    def test_bnode_shared_across_instances(self):
         my_sink = FakeSink()
         bnode_context = dict()
         p = ntriples.NTriplesParser(my_sink, bnode_context=bnode_context)
-
         p.parsestring('''
         _:0 <http://purl.obolibrary.org/obo/RO_0002350> <http://www.gbif.org/species/0000001> .
         ''')
 
-        p = ntriples.NTriplesParser(my_sink, bnode_context=bnode_context)
+        q = ntriples.NTriplesParser(my_sink, bnode_context=bnode_context)
+        q.parsestring('''
+        _:0 <http://purl.obolibrary.org/obo/RO_0002350> <http://www.gbif.org/species/0000002> .
+        ''')
+
+        self.assertEqual(len(my_sink.subs), 1)
+
+    def test_bnode_distinct_across_instances(self):
+        my_sink = FakeSink()
+        p = ntriples.NTriplesParser(my_sink)
         p.parsestring('''
+        _:0 <http://purl.obolibrary.org/obo/RO_0002350> <http://www.gbif.org/species/0000001> .
+        ''')
+
+        q = ntriples.NTriplesParser(my_sink)
+        q.parsestring('''
         _:0 <http://purl.obolibrary.org/obo/RO_0002350> <http://www.gbif.org/species/0000002> .
         ''')
 
-        assert len(my_sink.subs) == 1
+        self.assertEqual(len(my_sink.subs), 2)
 
     def test_bnode_distinct_across_parse(self):
         my_sink = FakeSink()
@@ -153,14 +166,27 @@ class BNodeContextTestCase(unittest.TestCase):
 
         p.parsestring('''
         _:0 <http://purl.obolibrary.org/obo/RO_0002350> <http://www.gbif.org/species/0000001> .
-        ''')
+        ''', bnode_context=dict())
+
+        p.parsestring('''
+        _:0 <http://purl.obolibrary.org/obo/RO_0002350> <http://www.gbif.org/species/0000002> .
+        ''', bnode_context=dict())
+
+        self.assertEqual(len(my_sink.subs), 2)
 
+    def test_bnode_shared_across_parse(self):
+        my_sink = FakeSink()
         p = ntriples.NTriplesParser(my_sink)
+
+        p.parsestring('''
+        _:0 <http://purl.obolibrary.org/obo/RO_0002350> <http://www.gbif.org/species/0000001> .
+        ''')
+
         p.parsestring('''
         _:0 <http://purl.obolibrary.org/obo/RO_0002350> <http://www.gbif.org/species/0000002> .
         ''')
 
-        assert len(my_sink.subs) == 2
+        self.assertEqual(len(my_sink.subs), 1)
 
 
 class FakeSink(object):