libtracker-data: Allow looking up variables in context by name

Getting a TrackerVariable first is a bit of an egg/chicken problem,
since getting a TrackerVariable ensures it's referenced in the context
in all code paths.

Soften this a bit, and allow to look up variables by name, without
necessarily creating a TrackerVariable for it.

3 files changed, 21 insertions, 13 deletions

diff --git a/src/libtracker-data/tracker-sparql-types.c b/src/libtracker-data/tracker-sparql-types.c
index a029a275e..a638620b2 100644
--- a/src/libtracker-data/tracker-sparql-types.c
+++ b/src/libtracker-data/tracker-sparql-types.c
@@ -653,8 +653,7 @@ tracker_context_class_init (TrackerContextClass *klass)
 static void
 tracker_context_init (TrackerContext *context)
 {
-	context->variable_set = g_hash_table_new (tracker_variable_hash,
-	                                          tracker_variable_equal);
+	context->variable_set = g_hash_table_new (g_str_hash, g_str_equal);
 }
 
 TrackerContext *
@@ -684,27 +683,34 @@ void
 tracker_context_add_variable_ref (TrackerContext  *context,
 				  TrackerVariable *variable)
 {
-	g_hash_table_add (context->variable_set, variable);
+	g_hash_table_insert (context->variable_set, variable->name, variable);
 }
 
 gboolean
 tracker_context_lookup_variable_ref (TrackerContext  *context,
                                      TrackerVariable *variable)
 {
-	return g_hash_table_lookup (context->variable_set, variable) != NULL;
+	return g_hash_table_lookup (context->variable_set, variable->name) != NULL;
+}
+
+gboolean
+tracker_context_lookup_variable_by_name (TrackerContext  *context,
+                                         const gchar     *name)
+{
+	return g_hash_table_lookup (context->variable_set, name) != NULL;
 }
 
 void
 tracker_context_propagate_variables (TrackerContext *context)
 {
 	GHashTableIter iter;
-	gpointer key;
+	gpointer key, value;
 
 	g_assert (context->parent != NULL);
 	g_hash_table_iter_init (&iter, context->variable_set);
 
-	while (g_hash_table_iter_next (&iter, &key, NULL))
-		g_hash_table_add (context->parent->variable_set, key);
+	while (g_hash_table_iter_next (&iter, &key, &value))
+		g_hash_table_insert (context->parent->variable_set, key, value);
 }
 
 /* Select context */
@@ -985,7 +991,7 @@ tracker_triple_context_get_variable_binding_list (TrackerTripleContext *context,
 				 */
 				if (TRACKER_IS_SELECT_CONTEXT (current_context) &&
 				    tracker_context_get_parent (current_context) &&
-				    g_hash_table_lookup (parent_context->variable_set, variable)) {
+				    g_hash_table_lookup (parent_context->variable_set, variable->name)) {
 					TrackerVariableBinding *sample;
 					TrackerBinding *binding;
 
diff --git a/src/libtracker-data/tracker-sparql-types.h b/src/libtracker-data/tracker-sparql-types.h
index fc79798b7..8dc551234 100644
--- a/src/libtracker-data/tracker-sparql-types.h
+++ b/src/libtracker-data/tracker-sparql-types.h
@@ -346,6 +346,8 @@ void tracker_context_add_variable_ref    (TrackerContext  *context,
 					  TrackerVariable *variable);
 gboolean tracker_context_lookup_variable_ref (TrackerContext  *context,
                                               TrackerVariable *variable);
+gboolean tracker_context_lookup_variable_by_name (TrackerContext  *context,
+                                                  const gchar     *name);
 
 /* Select context */
 GType            tracker_select_context_get_type (void) G_GNUC_CONST;
diff --git a/src/libtracker-data/tracker-sparql.c b/src/libtracker-data/tracker-sparql.c
index 5a2795af9..91382f5db 100644
--- a/src/libtracker-data/tracker-sparql.c
+++ b/src/libtracker-data/tracker-sparql.c
@@ -5550,13 +5550,13 @@ intersect_var_set (GHashTable *ht1,
 {
 	GHashTableIter iter;
 	GList *intersection = NULL;
-	gpointer key;
+	gpointer key, value;
 
 	g_hash_table_iter_init (&iter, ht1);
 
-	while (g_hash_table_iter_next (&iter, &key, NULL)) {
+	while (g_hash_table_iter_next (&iter, &key, &value)) {
 		if (g_hash_table_contains (ht2, key))
-			intersection = g_list_prepend (intersection, key);
+			intersection = g_list_prepend (intersection, value);
 	}
 
 	return intersection;
@@ -5587,7 +5587,7 @@ translate_MinusGraphPattern (TrackerSparql  *sparql,
 
 	intersection = intersect_var_set (cur_context->variable_set, context->variable_set);
 
-	vars = g_hash_table_get_keys (cur_context->variable_set);
+	vars = g_hash_table_get_values (cur_context->variable_set);
 	cur = tracker_sparql_swap_builder (sparql, pre);
 	append_subquery_select_vars (sparql, cur_context, vars);
 	tracker_sparql_swap_builder (sparql, cur);
@@ -5654,7 +5654,7 @@ translate_GroupOrUnionGraphPattern (TrackerSparql  *sparql,
 		}
 	} while (_accept (sparql, RULE_TYPE_LITERAL, LITERAL_UNION));
 
-	vars = g_hash_table_get_keys (context->variable_set);
+	vars = g_hash_table_get_values (context->variable_set);
 
 	if (placeholders->len > 1) {
 		/* We are performing an union of multiple GroupGraphPattern,