[tracker/wip/carlosg/sparql1.1: 36/113] libtracker-data: Implement RDF collections

[Carlos Garnacho <carlosg src gnome org>]

commit 39730a657200b15c7e6c8e21c785cef01ce1f9c9
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sun Jun 9 23:58:39 2019 +0200

    libtracker-data: Implement RDF collections

 src/libtracker-data/tracker-sparql.c | 127 ++++++++++++++++++++++++++++++++++-
 1 file changed, 125 insertions(+), 2 deletions(-)
---
diff --git a/src/libtracker-data/tracker-sparql.c b/src/libtracker-data/tracker-sparql.c
index dd4161ff5..e5ff3cfd7 100644
--- a/src/libtracker-data/tracker-sparql.c
+++ b/src/libtracker-data/tracker-sparql.c
@@ -4999,18 +4999,141 @@ static gboolean
 translate_Collection (TrackerSparql  *sparql,
                       GError        **error)
 {
+       TrackerToken old_subject, old_predicate, old_object, *old_token;
+       TrackerVariable *cur, *first = NULL, *rest = NULL;
+
+       old_subject = sparql->current_state.subject;
+       old_predicate = sparql->current_state.predicate;
+       old_object = sparql->current_state.object;
+       old_token = sparql->current_state.token;
+
        /* Collection ::= '(' GraphNode+ ')'
         */
-       _unimplemented ("Collections are not supported");
+       _expect (sparql, RULE_TYPE_LITERAL, LITERAL_OPEN_PARENS);
+       while (_check_in_rule (sparql, NAMED_RULE_GraphNode)) {
+               if (rest) {
+                       cur = rest;
+                       rest = NULL;
+               } else {
+                       cur = tracker_select_context_add_generated_variable (TRACKER_SELECT_CONTEXT 
(sparql->context));
+                       first = cur;
+               }
+
+               tracker_token_variable_init (&sparql->current_state.subject, cur);
+
+               /* rdf:first */
+               tracker_token_literal_init (&sparql->current_state.predicate,
+                                           RDF_NS "first");
+               sparql->current_state.token = &sparql->current_state.object;
+               _call_rule (sparql, NAMED_RULE_GraphNode, error);
+               sparql->current_state.token = NULL;
+               tracker_token_unset (&sparql->current_state.predicate);
+
+               /* rdf:rest */
+               tracker_token_literal_init (&sparql->current_state.predicate,
+                                           RDF_NS "rest");
+
+               if (_check_in_rule (sparql, NAMED_RULE_GraphNode)) {
+                       /* Generate variable for next element */
+                       rest = tracker_select_context_add_generated_variable (TRACKER_SELECT_CONTEXT 
(sparql->context));
+                       tracker_token_variable_init (&sparql->current_state.object, rest);
+               } else {
+                       /* Make last element point to rdf:nil */
+                       tracker_token_literal_init (&sparql->current_state.object,
+                                                   RDF_NS "nil");
+               }
+
+               if (!tracker_sparql_apply_quad (sparql, error))
+                       return FALSE;
+
+               tracker_token_unset (&sparql->current_state.object);
+               tracker_token_unset (&sparql->current_state.predicate);
+
+               tracker_token_unset (&sparql->current_state.subject);
+       }
+
+       _expect (sparql, RULE_TYPE_LITERAL, LITERAL_CLOSE_PARENS);
+
+       sparql->current_state.subject = old_subject;
+       sparql->current_state.predicate = old_predicate;
+       sparql->current_state.object = old_object;
+       sparql->current_state.token = old_token;
+       tracker_token_variable_init (sparql->current_state.token, first);
+
+       return TRUE;
 }
 
 static gboolean
 translate_CollectionPath (TrackerSparql  *sparql,
                           GError        **error)
 {
+       TrackerToken old_subject, old_predicate, old_object, *old_token;
+       TrackerVariable *cur, *first = NULL, *rest = NULL;
+
+       old_subject = sparql->current_state.subject;
+       old_predicate = sparql->current_state.predicate;
+       old_object = sparql->current_state.object;
+       old_token = sparql->current_state.token;
+
        /* CollectionPath ::= '(' GraphNodePath+ ')'
         */
-       _unimplemented ("Collections are not supported");
+       _expect (sparql, RULE_TYPE_LITERAL, LITERAL_OPEN_PARENS);
+       while (_check_in_rule (sparql, NAMED_RULE_GraphNodePath)) {
+               if (rest) {
+                       cur = rest;
+                       rest = NULL;
+               } else {
+                       cur = tracker_select_context_add_generated_variable (TRACKER_SELECT_CONTEXT 
(sparql->context));
+                       first = cur;
+               }
+
+               tracker_token_variable_init (&sparql->current_state.subject, cur);
+
+               /* rdf:first */
+               tracker_token_literal_init (&sparql->current_state.predicate,
+                                           RDF_NS "first");
+               sparql->current_state.token = &sparql->current_state.object;
+               _call_rule (sparql, NAMED_RULE_GraphNodePath, error);
+               sparql->current_state.token = NULL;
+               tracker_token_unset (&sparql->current_state.predicate);
+
+               /* rdf:rest */
+               tracker_token_literal_init (&sparql->current_state.predicate,
+                                           RDF_NS "rest");
+
+               if (_check_in_rule (sparql, NAMED_RULE_GraphNodePath)) {
+                       /* Generate variable for next element */
+                       rest = tracker_select_context_add_generated_variable (TRACKER_SELECT_CONTEXT 
(sparql->context));
+                       tracker_token_variable_init (&sparql->current_state.object, rest);
+               } else {
+                       /* Make last element point to rdf:nil */
+                       tracker_token_literal_init (&sparql->current_state.object,
+                                                   RDF_NS "nil");
+               }
+
+               if (!_add_quad (sparql,
+                               &sparql->current_state.graph,
+                               &sparql->current_state.subject,
+                               &sparql->current_state.predicate,
+                               &sparql->current_state.object,
+                               error))
+                       return FALSE;
+
+               tracker_token_unset (&sparql->current_state.object);
+               tracker_token_unset (&sparql->current_state.predicate);
+
+               tracker_token_unset (&sparql->current_state.subject);
+       }
+
+       _expect (sparql, RULE_TYPE_LITERAL, LITERAL_CLOSE_PARENS);
+
+       sparql->current_state.subject = old_subject;
+       sparql->current_state.predicate = old_predicate;
+       sparql->current_state.object = old_object;
+       sparql->current_state.token = old_token;
+       tracker_token_variable_init (sparql->current_state.token, first);
+
+       return TRUE;
 }
 
 static gboolean