[tracker/wip/carlosg/sparql1.1: 109/145] libtracker-data: Fetch type variables, where available

[Carlos Garnacho <carlosg src gnome org>]

commit 953daf4f55a85ee2754e53989495b0ca80bdae0a
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sat Jul 6 13:21:35 2019 +0200

    libtracker-data: Fetch type variables, where available
    
    So they are available to isNumeric/isLiteral/datatype and friends.

 src/libtracker-data/tracker-sparql.c | 56 +++++++++++++++++++++++++++++++++++-
 1 file changed, 55 insertions(+), 1 deletion(-)
---
diff --git a/src/libtracker-data/tracker-sparql.c b/src/libtracker-data/tracker-sparql.c
index 2c3e6691a..16d131b86 100644
--- a/src/libtracker-data/tracker-sparql.c
+++ b/src/libtracker-data/tracker-sparql.c
@@ -1084,6 +1084,21 @@ introspect_fts_snippet (TrackerSparql         *sparql,
        return TRUE;
 }
 
+static TrackerVariable *
+reserve_subvariable (TrackerSparql   *sparql,
+                     TrackerVariable *var,
+                     const gchar     *suffix)
+{
+       TrackerVariable *subvar;
+       gchar *name;
+
+       name = g_strdup_printf ("%s:%s", var->name, suffix);
+       subvar = _ensure_variable (sparql, name);
+       g_free (name);
+
+       return subvar;
+}
+
 static gboolean
 _add_quad (TrackerSparql  *sparql,
            TrackerToken   *graph,
@@ -1224,12 +1239,47 @@ _add_quad (TrackerSparql  *sparql,
                tracker_binding_set_db_column_name (binding, "predicate");
                _add_binding (sparql, binding);
                g_object_unref (binding);
+
+               /* If object is variable, add another variable to hold its type */
+               if (tracker_token_get_variable (object)) {
+                       TrackerVariable *type_var;
+
+                       type_var = reserve_subvariable (sparql, tracker_token_get_variable (object), "type");
+
+                       binding = tracker_variable_binding_new (type_var, NULL, table);
+                       tracker_binding_set_db_column_name (binding, "object_type");
+                       _add_binding (sparql, binding);
+                       g_object_unref (binding);
+               }
        } else if (tracker_token_get_path (predicate)) {
                table = tracker_triple_context_add_table (triple_context,
                                                          graph_db,
                                                          tracker_token_get_idstring (predicate));
                tracker_data_table_set_predicate_path (table, TRUE);
                new_table = TRUE;
+
+               /* If subject/object are variable, add variables to hold their type */
+               if (tracker_token_get_variable (subject)) {
+                       TrackerVariable *type_var;
+
+                       type_var = reserve_subvariable (sparql, tracker_token_get_variable (subject), "type");
+
+                       binding = tracker_variable_binding_new (type_var, NULL, table);
+                       tracker_binding_set_db_column_name (binding, "ID_type");
+                       _add_binding (sparql, binding);
+                       g_object_unref (binding);
+               }
+
+               if (tracker_token_get_variable (object)) {
+                       TrackerVariable *type_var;
+
+                       type_var = reserve_subvariable (sparql, tracker_token_get_variable (object), "type");
+
+                       binding = tracker_variable_binding_new (type_var, NULL, table);
+                       tracker_binding_set_db_column_name (binding, "value_type");
+                       _add_binding (sparql, binding);
+                       g_object_unref (binding);
+               }
        } else {
                /* The parser disallows parameter predicates */
                g_assert_not_reached ();
@@ -1618,7 +1668,7 @@ _end_triples_block (TrackerSparql  *sparql,
                if (table->predicate_variable) {
                        _append_string (sparql,
                                        "(SELECT subject AS ID, predicate, "
-                                       "object, graph FROM tracker_triples) ");
+                                       "object, object_type, graph FROM tracker_triples) ");
                } else if (table->predicate_path) {
                        _append_string_printf (sparql, "\"%s\"", table->sql_db_tablename);
                } else {
@@ -1871,6 +1921,10 @@ translate_SelectClause (TrackerSparql  *sparql,
                g_hash_table_iter_init (&iter, select_context->variables);
 
                while (g_hash_table_iter_next (&iter, NULL, (gpointer *) &var)) {
+                       /* Skip our own internal variables */
+                       if (strchr (var->name, ':'))
+                               continue;
+
                        if (!first)
                                _append_string (sparql, ", ");