[tracker/wip/carlosg/sparql-parser-ng: 3/6] libtracker-data: Prepare for property paths

[Carlos Garnacho <carlosg src gnome org>]

commit 9483afc068261a30d81e2433b9fce31e4a3bc2c0
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sat Nov 3 13:07:04 2018 +0100

    libtracker-data: Prepare for property paths
    
    Property paths may introduce intermediate anonymous resources, or
    shuffle subject/object. We still do the bulk of the job while parsing
    the predicate, so prepare for the predicate being pre-filled, and
    the Path grammar element to alter the next parsed token.

 src/libtracker-data/tracker-sparql.c | 39 ++++++++++++++++++++++--------------
 1 file changed, 24 insertions(+), 15 deletions(-)
---
diff --git a/src/libtracker-data/tracker-sparql.c b/src/libtracker-data/tracker-sparql.c
index 54e48a1d2..10ba7b2ca 100644
--- a/src/libtracker-data/tracker-sparql.c
+++ b/src/libtracker-data/tracker-sparql.c
@@ -3761,21 +3761,23 @@ translate_TriplesSameSubject (TrackerSparql  *sparql,
        /* TriplesSameSubject ::= VarOrTerm PropertyListNotEmpty | TriplesNode PropertyList
         */
        rule = _current_rule (sparql);
+       sparql->current_state.token = &sparql->current_state.subject;
 
        if (rule == NAMED_RULE_VarOrTerm) {
-               sparql->current_state.token = &sparql->current_state.subject;
                _call_rule (sparql, rule, error);
                g_assert (!tracker_token_is_empty (&sparql->current_state.subject));
+               sparql->current_state.token = &sparql->current_state.object;
                _call_rule (sparql, NAMED_RULE_PropertyListNotEmpty, error);
        } else if (rule == NAMED_RULE_TriplesNode) {
-               sparql->current_state.token = &sparql->current_state.subject;
                _call_rule (sparql, rule, error);
                g_assert (!tracker_token_is_empty (&sparql->current_state.subject));
+               sparql->current_state.token = &sparql->current_state.object;
                _call_rule (sparql, NAMED_RULE_PropertyList, error);
        }
 
        tracker_token_unset (&sparql->current_state.subject);
        sparql->current_state.subject = old_subject;
+       sparql->current_state.token = NULL;
 
        return TRUE;
 }
@@ -3906,23 +3908,23 @@ translate_TriplesSameSubjectPath (TrackerSparql  *sparql,
        /* TriplesSameSubjectPath ::= VarOrTerm PropertyListPathNotEmpty | TriplesNodePath PropertyListPath
         */
        rule = _current_rule (sparql);
+       sparql->current_state.token = &sparql->current_state.subject;
 
        if (rule == NAMED_RULE_VarOrTerm) {
-               sparql->current_state.token = &sparql->current_state.subject;
                _call_rule (sparql, rule, error);
                g_assert (!tracker_token_is_empty (&sparql->current_state.subject));
-
+               sparql->current_state.token = &sparql->current_state.object;
                _call_rule (sparql, NAMED_RULE_PropertyListPathNotEmpty, error);
        } else if (rule == NAMED_RULE_TriplesNodePath) {
-               sparql->current_state.token = &sparql->current_state.subject;
                _call_rule (sparql, rule, error);
                g_assert (!tracker_token_is_empty (&sparql->current_state.subject));
-
+               sparql->current_state.token = &sparql->current_state.object;
                _call_rule (sparql, NAMED_RULE_PropertyListPath, error);
        }
 
        tracker_token_unset (&sparql->current_state.subject);
        sparql->current_state.subject = old_subject;
+       sparql->current_state.token = NULL;
 
        return TRUE;
 }
@@ -4044,9 +4046,14 @@ static gboolean
 translate_Path (TrackerSparql  *sparql,
                 GError        **error)
 {
+       TrackerToken *prev_token;
+
        /* Path ::= PathAlternative
         */
+       prev_token = sparql->current_state.token;
+       sparql->current_state.token = &sparql->current_state.object;
        _call_rule (sparql, NAMED_RULE_PathAlternative, error);
+       sparql->current_state.token = prev_token;
        return TRUE;
 }
 
@@ -4109,11 +4116,17 @@ translate_PathElt (TrackerSparql  *sparql,
                _call_rule (sparql, NAMED_RULE_PathMod, error);
        }
 
-       if (!_postprocess_rule (sparql, sparql->current_state.object_list,
-                               NULL, error))
-               return FALSE;
-
-       return TRUE;
+       if (!tracker_token_is_empty (sparql->current_state.token)) {
+               return _add_quad (sparql,
+                                 &sparql->current_state.graph,
+                                 &sparql->current_state.subject,
+                                 &sparql->current_state.predicate,
+                                 &sparql->current_state.object,
+                                 error);
+       } else {
+               return _postprocess_rule (sparql, sparql->current_state.object_list,
+                                         NULL, error);
+       }
 }
 
 static gboolean
@@ -4320,11 +4333,9 @@ translate_GraphNode (TrackerSparql  *sparql,
         *   VarOrTerm | TriplesNode | 'NULL'
         */
        if (_check_in_rule (sparql, NAMED_RULE_VarOrTerm)) {
-               sparql->current_state.token = &sparql->current_state.object;
                _call_rule (sparql, NAMED_RULE_VarOrTerm, error);
                g_assert (!tracker_token_is_empty (&sparql->current_state.object));
        } else if (_check_in_rule (sparql, NAMED_RULE_TriplesNode)) {
-               sparql->current_state.token = &sparql->current_state.object;
                _call_rule (sparql, NAMED_RULE_TriplesNode, error);
                g_assert (!tracker_token_is_empty (&sparql->current_state.object));
        } else if (_accept (sparql, RULE_TYPE_LITERAL, LITERAL_NULL)) {
@@ -4390,11 +4401,9 @@ translate_GraphNodePath (TrackerSparql  *sparql,
        /* GraphNodePath ::= VarOrTerm | TriplesNodePath
         */
        if (_check_in_rule (sparql, NAMED_RULE_VarOrTerm)) {
-               sparql->current_state.token = &sparql->current_state.object;
                _call_rule (sparql, NAMED_RULE_VarOrTerm, error);
                g_assert (!tracker_token_is_empty (&sparql->current_state.object));
        } else if (_check_in_rule (sparql, NAMED_RULE_TriplesNodePath)) {
-               sparql->current_state.token = &sparql->current_state.object;
                _call_rule (sparql, NAMED_RULE_TriplesNodePath, error);
                g_assert (!tracker_token_is_empty (&sparql->current_state.object));
        } else {