Trig improvements

rdflib/plugins/serializers/trig.py

@@ -60,6 +60,8 @@ def serialize(self, stream, base=None, encoding=None,
 
         firstTime = True
         for store, (ordered_subjects, subjects, ref) in self._contexts.items():
+            if not ordered_subjects: continue
+
             self._references = ref
             self._serialized = {}
             self.store = store

rdflib/plugins/serializers/turtle.py

@@ -47,6 +47,8 @@ def __init__(self, store):
         self.reset()
 
     def addNamespace(self, prefix, uri):
+        if prefix in self.namespaces and self.namespaces[prefix]!=uri:
+            raise Exception("Trying to override namespace prefix %s => %s, but it's already bound to %s"%(prefix, uri, self.namespaces[prefix]))
         self.namespaces[prefix] = uri
 
     def checkSubject(self, subject):
@@ -195,7 +197,8 @@ def addNamespace(self, prefix, namespace):
                     p = "p" + p
                 self._ns_rewrite[prefix] = p
 
-        prefix = self._ns_rewrite.get(prefix, prefix)
+            prefix = self._ns_rewrite.get(prefix, prefix)
+
         super(TurtleSerializer, self).addNamespace(prefix, namespace)
         return prefix
 

test/test_trig.py

@@ -2,6 +2,7 @@
 import rdflib
 import re
 
+from nose import SkipTest
 from rdflib.py3compat import b
 
 TRIPLE = (rdflib.URIRef("http://example.com/s"),
@@ -80,5 +81,99 @@ def testBlankGraphIdentifier(self):
         g.add(TRIPLE + (rdflib.BNode(),))
         out = g.serialize(format='trig')
         graph_label_line = out.splitlines()[-4]
+
         self.assertTrue(re.match(br'^_:[a-zA-Z0-9]+ \{', graph_label_line))
-
+
+    def testGraphParsing(self):
+        # should parse into single default graph context
+        data = """
+<http://example.com/thing#thing_a> <http://example.com/knows> <http://example.com/thing#thing_b> .
+"""
+        g = rdflib.ConjunctiveGraph()
+        g.parse(data=data, format='trig')
+        self.assertEqual(len(list(g.contexts())), 1)
+
+        # should parse into single default graph context
+        data = """
+<http://example.com/thing#thing_a> <http://example.com/knows> <http://example.com/thing#thing_b> .
+
+{ <http://example.com/thing#thing_c> <http://example.com/knows> <http://example.com/thing#thing_d> . }
+"""
+        g = rdflib.ConjunctiveGraph()
+        g.parse(data=data, format='trig')
+        self.assertEqual(len(list(g.contexts())), 1)
+
+        # should parse into 2 contexts, one default, one named
+        data = """
+<http://example.com/thing#thing_a> <http://example.com/knows> <http://example.com/thing#thing_b> .
+
+{ <http://example.com/thing#thing_c> <http://example.com/knows> <http://example.com/thing#thing_d> . }
+
+<http://example.com/graph#graph_a> {
+    <http://example.com/thing/thing_e> <http://example.com/knows> <http://example.com/thing#thing_f> .
+}
+"""
+        g = rdflib.ConjunctiveGraph()
+        g.parse(data=data, format='trig')
+        self.assertEqual(len(list(g.contexts())), 2)
+
+    def testRoundTrips(self):
+
+        raise SkipTest('skipped until 5.0')
+
+        data = """
+<http://example.com/thing#thing_a> <http://example.com/knows> <http://example.com/thing#thing_b> .
+
+{ <http://example.com/thing#thing_c> <http://example.com/knows> <http://example.com/thing#thing_d> . }
+
+<http://example.com/graph#graph_a> {
+    <http://example.com/thing/thing_e> <http://example.com/knows> <http://example.com/thing#thing_f> .
+}
+"""
+        g = rdflib.ConjunctiveGraph()
+        for i in range(5):
+            g.parse(data=data, format='trig')
+            data = g.serialize(format='trig')
+
+        # output should only contain 1 mention of each resource/graph name
+        self.assertEqual(data.count('thing_a'), 1)
+        self.assertEqual(data.count('thing_b'), 1)
+        self.assertEqual(data.count('thing_c'), 1)
+        self.assertEqual(data.count('thing_d'), 1)
+        self.assertEqual(data.count('thing_e'), 1)
+        self.assertEqual(data.count('thing_f'), 1)
+        self.assertEqual(data.count('graph_a'), 1)
+
+    def testDefaultGraphSerializesWithoutName(self):
+        data = """
+<http://example.com/thing#thing_a> <http://example.com/knows> <http://example.com/thing#thing_b> .
+
+{ <http://example.com/thing#thing_c> <http://example.com/knows> <http://example.com/thing#thing_d> . }
+"""
+        g = rdflib.ConjunctiveGraph()
+        g.parse(data=data, format='trig')
+        data = g.serialize(format='trig')
+
+        self.assertTrue(b('None') not in data)
+
+    def testPrefixes(self):
+
+        data = """
+        @prefix ns1: <http://ex.org/schema#> .
+        <http://ex.org/docs/document1> = {
+            ns1:Person_A a ns1:Person ;
+                ns1:TextSpan "Simon" .
+        }
+        <http://ex.org/docs/document2> = {
+            ns1:Person_C a ns1:Person ;
+                ns1:TextSpan "Agnes" .
+        }
+        """
+
+        cg = rdflib.ConjunctiveGraph()
+        cg.parse(data=data, format='trig')
+        data = cg.serialize(format='trig')
+
+        self.assert_(b('ns2: <http://ex.org/docs/') in data, data)
+        self.assert_(b('<ns2:document1>') not in data, data)
+        self.assert_(b('ns2:document1') in data, data)