Account for a property path in an uupdate coming after a BGP.

Fixes #53.

Author: gkellogg

etc/sparql12.bnf

@@ -115,13 +115,13 @@ GraphNode                 ::= VarOrTerm | TriplesNode | ReifiedTriple
 GraphNodePath             ::= VarOrTerm | TriplesNodePath | ReifiedTriple
 VarOrTerm                 ::= Var | iri | RDFLiteral | NumericLiteral | BooleanLiteral | BlankNode | NIL | TripleTerm
 ReifiedTriple             ::= '<<' ReifiedTripleSubject Verb ReifiedTripleObject Reifier? '>>'
-ReifiedTripleSubject      ::= Var | iri | RDFLiteral | NumericLiteral | BooleanLiteral | BlankNode | ReifiedTriple
+ReifiedTripleSubject      ::= Var | iri | RDFLiteral | NumericLiteral | BooleanLiteral | BlankNode | ReifiedTriple | TripleTerm
 ReifiedTripleObject       ::= Var | iri | RDFLiteral | NumericLiteral | BooleanLiteral | BlankNode | ReifiedTriple | TripleTerm
 TripleTerm                ::= '<<(' TripleTermSubject Verb TripleTermObject ')>>'
-TripleTermSubject         ::= Var | iri | RDFLiteral | NumericLiteral | BooleanLiteral | BlankNode
+TripleTermSubject         ::= Var | iri | RDFLiteral | NumericLiteral | BooleanLiteral | BlankNode | TripleTerm
 TripleTermObject          ::= Var | iri | RDFLiteral | NumericLiteral | BooleanLiteral | BlankNode | TripleTerm
 TripleTermData            ::= '<<(' TripleTermDataSubject ( iri | 'a' ) TripleTermDataObject ')>>'
-TripleTermDataSubject     ::= iri | RDFLiteral | NumericLiteral | BooleanLiteral
+TripleTermDataSubject     ::= iri | RDFLiteral | NumericLiteral | BooleanLiteral | TripleTermData
 TripleTermDataObject      ::= iri | RDFLiteral | NumericLiteral | BooleanLiteral | TripleTermData
 VarOrIri                  ::= Var | iri
 Var                       ::= VAR1 | VAR2
@@ -152,7 +152,7 @@ UnaryExpression           ::= '!' PrimaryExpression
 PrimaryExpression         ::= BrackettedExpression | BuiltInCall | iriOrFunction
                             | RDFLiteral | NumericLiteral | BooleanLiteral | Var | ExprTripleTerm
 ExprTripleTerm            ::= '<<(' ExprTripleTermSubject Verb ExprTripleTermObject ')>>'
-ExprTripleTermSubject     ::= iri | RDFLiteral | NumericLiteral | BooleanLiteral | Var
+ExprTripleTermSubject     ::= iri | RDFLiteral | NumericLiteral | BooleanLiteral | Var | ExprTripleTerm
 ExprTripleTermObject      ::= iri | RDFLiteral | NumericLiteral | BooleanLiteral | Var | ExprTripleTerm
 BrackettedExpression      ::= '(' Expression ')'
 BuiltInCall               ::= Aggregate

lib/sparql/algebra/update.rb

@@ -25,6 +25,11 @@ def variables
       operands.inject({}) {|hash, o| o.executable? ? hash.merge(o.variables) : hash}
     end
 
+    # Determine if this is an empty query, having no operands
+    def empty?
+      self.operands.empty?
+    end
+
     ##
     # Executes this upate on the given `queryable` graph or repository.
     #

lib/sparql/grammar/parser.rb

@@ -895,6 +895,8 @@ class Parser
             bgp
           elsif bgp.empty?
             query
+          elsif bgp.is_a?(SPARQL::Algebra::Operator::Sequence)
+            SPARQL::Algebra::Operator::Sequence.new(query, *bgp.operands)
           elsif bgp.is_a?(SPARQL::Algebra::Operator::Path)
             SPARQL::Algebra::Operator::Sequence.new(query, bgp)
           else

spec/grammar/misc_spec.rb

@@ -140,6 +140,48 @@
                    (triple ?ev <http://example.org/b> ?b)))))
         }
       },
+      "issue 53": {
+        query: %(
+          SELECT ?s
+          WHERE {
+            ?s a skos:Concept .
+            ?s skos:related|^skos:related ?c .
+          }
+        ),
+        sse: %{(project (?s)
+                (sequence
+                  (bgp (triple ?s a <Concept>))
+                  (path ?s (alt <related> (reverse <related>)) ?c)))}
+      },
+      "issue 53 full": {
+        query: %(
+          PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
+          DESCRIBE ?s
+          WHERE {
+            VALUES ?c {
+              <urn:uuid:f5a254ac-4a2b-405e-91be-7de9fbf7174d>
+            }
+            ?s a skos:Concept .
+            ?s (skos:related|^skos:related|skos:broader|^skos:broader|skos:narrower|^skos:narrower)* ?c .
+          }
+        ),
+        sse: %{(describe (?s)
+                 (sequence
+                  (table (vars ?c) (row (?c <urn:uuid:f5a254ac-4a2b-405e-91be-7de9fbf7174d>)))
+                  (bgp (triple ?s a <http://www.w3.org/2004/02/skos/core#Concept>))
+                  (path ?s
+                   (path*
+                    (alt
+                     (alt
+                      (alt
+                       (alt
+                        (alt <http://www.w3.org/2004/02/skos/core#related>
+                         (reverse <http://www.w3.org/2004/02/skos/core#related>))
+                        <http://www.w3.org/2004/02/skos/core#broader> )
+                       (reverse <http://www.w3.org/2004/02/skos/core#broader>))
+                      <http://www.w3.org/2004/02/skos/core#narrower> )
+                     (reverse <http://www.w3.org/2004/02/skos/core#narrower>)) ) ?c )) )}
+      }
       #"dawg-optional-filter-005-not-simplified" => {
       #  query: %(
       #    # Double curly braces do NOT get simplified to single curly braces early on, before filters are scoped