From 47e2930114811d27a1c4e1a337e310f74f282048 Mon Sep 17 00:00:00 2001
From: Jerven bolleman <jerven.bolleman@sib.swiss>
Date: Wed, 4 Mar 2020 20:57:51 +0100
Subject: [PATCH] Working on #955 Parsing passes, now into the algebra

---
 rdflib/plugins/sparql/algebra.py | 17 ++++++++---
 rdflib/plugins/sparql/parser.py  |  5 ++--
 test/test_sparql_star.py         | 50 ++++++++++++++++++++------------
 3 files changed, 48 insertions(+), 24 deletions(-)

diff --git a/rdflib/plugins/sparql/algebra.py b/rdflib/plugins/sparql/algebra.py
index 5fa445c70..18c9bdc6e 100644
--- a/rdflib/plugins/sparql/algebra.py
+++ b/rdflib/plugins/sparql/algebra.py
@@ -67,6 +67,8 @@ def Filter(expr, p):
 def Extend(p, expr, var):
     return CompValue('Extend', p=p, expr=expr, var=var)
 
+def EmpTP(p, o):
+    return CompValue('EmpTP', var=o)
 
 def Values(res):
     return CompValue('values', res=res)
@@ -133,6 +135,7 @@ def triples(l):
     l = reduce(lambda x, y: x + y, l)
     if (len(l) % 3) != 0:
         raise Exception('these aint triples')
+
     return reorderTriples((l[x], l[x + 1], l[x + 2])
                           for x in range(0, len(l), 3))
 
@@ -307,7 +310,8 @@ def translateGroupGraphPattern(graphPattern):
             G = Join(p1=G, p2=p)
         elif p.name == 'Bind':
             G = Extend(G, p.expr, p.var)
-
+        elif p.name == "EmpTP":
+            G = Project(p, p.o)
         else:
             raise Exception('Unknown part in GroupGraphPattern: %s - %s' %
                             (type(p), p.name))
@@ -342,9 +346,11 @@ def _traverse(e, visitPre=lambda n: None, visitPost=lambda n: None):
         return tuple([_traverse(x, visitPre, visitPost) for x in e])
 
     elif isinstance(e, CompValue):
-        for k, val in e.items():
-            e[k] = _traverse(val, visitPre, visitPost)
-
+        if e.name != 'EmpTP':
+            for k, val in e.items():
+                e[k] = _traverse(val, visitPre, visitPost)
+        else:
+            raise Exception("Sparql star not tied into the algebra jet")
     _e = visitPost(e)
     if _e is not None:
         return _e
@@ -682,6 +688,9 @@ def translatePrologue(p, base, initNs=None, prologue=None):
     return prologue
 
 
+def translateEmbTP(u):
+    return u
+
 def translateQuads(quads):
     if quads.triples:
         alltriples = triples(quads.triples)
diff --git a/rdflib/plugins/sparql/parser.py b/rdflib/plugins/sparql/parser.py
index 6a9d47fe6..20553fe32 100644
--- a/rdflib/plugins/sparql/parser.py
+++ b/rdflib/plugins/sparql/parser.py
@@ -24,7 +24,7 @@
 
 import rdflib
 
-DEBUG = False
+DEBUG = True
 
 # ---------------- ACTIONS
 
@@ -431,8 +431,9 @@ def _hexExpand(match):
 # [104] GraphNode ::= VarOrTerm | TriplesNode
 GraphNode = VarOrTerm | TriplesNode
 
+#Should be recursive but it is not yet so
 VarOrBlankNodeOrIriOrLitOrEmbTP = Var | BlankNode | iri | RDFLiteral | NumericLiteral | BooleanLiteral
-EmbTP = Suppress('<<') + VarOrBlankNodeOrIriOrLitOrEmbTP + Verb + VarOrBlankNodeOrIriOrLitOrEmbTP + Suppress('>>')
+EmbTP = Suppress('<<') + Comp('EmpTP',ParamList('s', VarOrBlankNodeOrIriOrLitOrEmbTP) + ParamList('p', Verb) + ParamList('o', VarOrBlankNodeOrIriOrLitOrEmbTP)) + Suppress('>>')
 
 VarOrTermOrEmbTP = Var | GraphTerm | EmbTP
 
diff --git a/test/test_sparql_star.py b/test/test_sparql_star.py
index 07eb99787..ddaf86c6a 100644
--- a/test/test_sparql_star.py
+++ b/test/test_sparql_star.py
@@ -1,26 +1,40 @@
 from rdflib import Graph
+from rdflib.plugins.sparql.parser import VarOrBlankNodeOrIriOrLitOrEmbTP
+import  pyparsing
+import unittest
 
+class SparqlStarTests(unittest.TestCase):
 
-def test_basic_sparql_star_subject():
-    g = Graph()
-    res = g.query('''SELECT * WHERE {
-<< ?s ?p ?o >> ?p2 ?o2 . 
-}''')
+    @staticmethod
+    def test_basic_sparql_star_subject():
+        g = Graph()
+        res = g.query('''SELECT * WHERE {
+    << ?s ?p ?o >> ?p2 ?o2 . 
+    }''')
+
+    @staticmethod
+    def test_basic_sparql_star_object():
+        g = Graph()
+        res = g.query('''SELECT * WHERE {
+    ?s ?p << ?s2 ?p2 ?o2 >> . 
+    }''')
 
+    @staticmethod
+    def test_basic_sparql():
+        g = Graph()
+        res = g.query('''SELECT * WHERE {
+        ?s ?p ?o . 
+        }''')
 
-def test_basic_sparql_star_object():
-    g = Graph()
-    res = g.query('''SELECT * WHERE {
-?s ?p << ?s2 ?p2 ?o2 >> . 
-}''')
+    @staticmethod
+    def test_bind_sparql_star():
+        g = Graph()
+        res = g.query('''SELECT * WHERE { BIND(<< ?s2 ?p2 ?o2 >> AS ?b) }''')
 
-def test_basic_sparql():
-    g = Graph()
-    res = g.query('''SELECT * WHERE {
-    ?s ?p ?o . 
-    }''')
+    @staticmethod
+    def test_parser():
+        assert VarOrBlankNodeOrIriOrLitOrEmbTP.matches("<<?s ?p ?o>>")
 
 
-def test_bind_sparql_star():
-    g = Graph()
-    res = g.query('''SELECT * WHERE { BIND(<< ?s2 ?p2 ?o2 >> AS ?b) }''')
\ No newline at end of file
+if __name__ == '__main__':
+    unittest.main()
\ No newline at end of file