libtracker-data: Add builtin way to convert a Expression to a string

The Expression element may be used in several places (eg. ArgList or
ExpressionList in functions) that may require them to be converted
to string, add a builtin toggle in the state so this can ben done
easily.

1 files changed, 20 insertions, 0 deletions

diff --git a/src/libtracker-data/tracker-sparql.c b/src/libtracker-data/tracker-sparql.c
index 2a0f100ee..e32a4f2b0 100644
--- a/src/libtracker-data/tracker-sparql.c
+++ b/src/libtracker-data/tracker-sparql.c
@@ -142,6 +142,8 @@ struct _TrackerSparql
 		const gchar *expression_list_separator;
 		TrackerPropertyType expression_type;
 		guint type;
+
+		gboolean convert_to_string;
 	} current_state;
 };
 
@@ -4610,10 +4612,28 @@ static gboolean
 translate_Expression (TrackerSparql  *sparql,
                       GError        **error)
 {
+	TrackerStringBuilder *str, *old;
+	gboolean convert_to_string;
+
 	/* Expression ::= ConditionalOrExpression
 	 */
+	convert_to_string = sparql->current_state.convert_to_string;
+	sparql->current_state.convert_to_string = FALSE;
+
+	if (convert_to_string) {
+		str = _append_placeholder (sparql);
+		old = tracker_sparql_swap_builder (sparql, str);
+	}
+
 	_call_rule (sparql, NAMED_RULE_ConditionalOrExpression, error);
 
+	if (convert_to_string) {
+		convert_expression_to_string (sparql, sparql->current_state.expression_type);
+		tracker_sparql_swap_builder (sparql, old);
+	}
+
+	sparql->current_state.convert_to_string = convert_to_string;
+
 	return TRUE;
 
 }