From 6c026d0922a392efdc1434122c081a383d9c415f Mon Sep 17 00:00:00 2001
From: Gunnar Aastrand Grimnes <gromgull@gmail.com>
Date: Mon, 29 Jul 2013 11:31:20 +0200
Subject: [PATCH] Dataset and graph_aware store fixes

Add graphs when parsing, so also empty graphs are added.
---
 rdflib/graph.py                 | 39 ++++++++++++++++++++-------------
 rdflib/plugins/memory.py        |  6 ++++-
 rdflib/plugins/sparql/update.py | 18 ++++++++++++---
 test/test_graph.py              |  2 +-
 4 files changed, 45 insertions(+), 20 deletions(-)

diff --git a/rdflib/graph.py b/rdflib/graph.py
index 232e601be..42bb7cac5 100644
--- a/rdflib/graph.py
+++ b/rdflib/graph.py
@@ -1308,8 +1308,9 @@ def add(self, triple_or_quad):
 
         self.store.add((s, p, o), context=c, quoted=False)
 
-    def _graph(self, c): 
-        if not isinstance(c, Graph): 
+    def _graph(self, c):
+        if c is None: return None
+        if not isinstance(c, Graph):
             return self.get_context(c)
         else:
             return c
@@ -1348,10 +1349,14 @@ def triples(self, triple_or_quad, context=None):
         s,p,o,c = self._spoc(triple_or_quad)
         context = self._graph(context or c)
 
-        if not self.default_union and context is None: 
-            context=self.default_context
-        
-        if isinstance(p, Path): 
+        if self.default_union:
+            if context==self.default_context:
+                context = None
+        else:
+            if context is None:
+                context = self.default_context
+
+        if isinstance(p, Path):
             if context is None:
                 context = self
 
@@ -1443,7 +1448,7 @@ def parse(self, source=None, publicID=None, format="xml",
             g_id = URIRef(g_id)
 
         context = Graph(store=self.store, identifier=g_id)
-        context.remove((None, None, None))
+        context.remove((None, None, None)) # hmm ?
         context.parse(source, publicID=publicID, format=format,
                       location=location, file=file, data=data, **args)
         return context
@@ -1580,17 +1585,21 @@ def graph(self, identifier=None):
                 "genid", "http://rdflib.net" + rdflib_skolem_genid,
                 override=False)
             identifier = BNode().skolemize()
-        else:
-            if isinstance(identifier, BNode):
-                raise Exception(
-                    "Blank nodes cannot be Graph identifiers in RDF Datasets")
-            if not isinstance(identifier, URIRef):
-                identifier = URIRef(identifier)
-                
-        g = self.get_context(identifier)
+
+        g = self._graph(identifier)
+
         self.store.add_graph(g)
         return g
 
+    def parse(self, source=None, publicID=None, format="xml",
+              location=None, file=None, data=None, **args):
+        c = ConjunctiveGraph.parse(self, source, publicID, format, location, file, data, **args)
+        self.graph(c)
+
+    def add_graph(self, g):
+        """alias of graph for consistency"""
+        return self.graph(g)
+
     def remove_graph(self, g):
         if not isinstance(g, Graph):
             g = self.get_context(g)
diff --git a/rdflib/plugins/memory.py b/rdflib/plugins/memory.py
index 085c0d880..cbabad097 100644
--- a/rdflib/plugins/memory.py
+++ b/rdflib/plugins/memory.py
@@ -368,7 +368,11 @@ def remove_graph(self, graph):
             Store.remove_graph(self, graph)
         else:
             self.remove((None,None,None), graph)
-            self.__all_contexts.remove(graph)
+            try:
+                self.__all_contexts.remove(graph)
+            except KeyError:
+                pass # we didn't know this graph, no problem
+
 
 
     # internal utility methods below
diff --git a/rdflib/plugins/sparql/update.py b/rdflib/plugins/sparql/update.py
index a4607d69d..57c5bf461 100644
--- a/rdflib/plugins/sparql/update.py
+++ b/rdflib/plugins/sparql/update.py
@@ -62,6 +62,16 @@ def evalClear(ctx, u):
     for g in _graphAll(ctx, u.graphiri):
         g.remove((None, None, None))
 
+def evalDrop(ctx, u):
+    """
+    http://www.w3.org/TR/sparql11-update/#drop
+    """
+    if ctx.dataset.store.graph_aware:
+        for g in _graphAll(ctx, u.graphiri):
+            ctx.dataset.store.remove_graph(g)
+    else:
+        evalClear(ctx, u)
+
 
 def evalInsertData(ctx, u):
     """
@@ -214,7 +224,10 @@ def evalMove(ctx, u):
 
     dstg += srcg
 
-    srcg.remove((None, None, None))
+    if ctx.dataset.store.graph_aware:
+        ctx.dataset.store.remove_graph(srcg)
+    else:
+        srcg.remove((None, None, None))
 
 
 def evalCopy(ctx, u):
@@ -277,8 +290,7 @@ def evalUpdate(graph, update, initBindings=None):
             elif u.name == 'Clear':
                 evalClear(ctx, u)
             elif u.name == 'Drop':
-                # rdflib does not record empty graphs, so clear == drop
-                evalClear(ctx, u)
+                evalDrop(ctx, u)
             elif u.name == 'Create':
                 evalCreate(ctx, u)
             elif u.name == 'Add':
diff --git a/test/test_graph.py b/test/test_graph.py
index 3dfd4442b..c459694dd 100644
--- a/test/test_graph.py
+++ b/test/test_graph.py
@@ -178,7 +178,7 @@ def testConnected(self):
 
     def testSub(self):
         g1 = self.graph
-        g2 = Graph(store=g2.store)
+        g2 = Graph(store=g1.store)
 
         tarek = self.tarek
         # michel = self.michel