[tracker/wip/carlosg/serialize-api: 5/13] libtracker-data: Handle annotating value types in cursors

[Carlos Garnacho <carlosg src gnome org>]

commit 3a1414162ef2d00b6a744d0cce3e8fe45437cb9d
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sun Jan 30 13:32:55 2022 +0100

    libtracker-data: Handle annotating value types in cursors
    
    These annotations come as extra internal columns held in the cursor
    itself, existing after the user-visible columns. Each of the user
    visible columns may have an extra column (in the same order) holding
    the TrackerPropertyType that applies to that column and row.
    
    If these extra columns do not exist, we ATM still resort to the
    traditional ways (static value type, then second guess from SQLite).

 src/libtracker-data/tracker-db-interface-sqlite.c | 66 +++++++++++++++++++++++
 1 file changed, 66 insertions(+)
---
diff --git a/src/libtracker-data/tracker-db-interface-sqlite.c 
b/src/libtracker-data/tracker-db-interface-sqlite.c
index 53a53af2d..9659b561f 100644
--- a/src/libtracker-data/tracker-db-interface-sqlite.c
+++ b/src/libtracker-data/tracker-db-interface-sqlite.c
@@ -3570,6 +3570,68 @@ tracker_db_cursor_get_boolean (TrackerSparqlCursor *sparql_cursor,
        return (g_strcmp0 (tracker_db_cursor_get_string (cursor, column, NULL), "true") == 0);
 }
 
+static gboolean
+tracker_db_cursor_get_annotated_value_type (TrackerDBCursor        *cursor,
+                                            guint                   column,
+                                            TrackerSparqlValueType *value_type)
+{
+       TrackerDBInterface *iface;
+       TrackerPropertyType property_type;
+       gboolean is_null;
+
+       if (cursor->n_columns == 0)
+               return FALSE;
+
+       iface = cursor->ref_stmt->db_interface;
+
+       tracker_db_interface_lock (iface);
+
+       /* The value type may be annotated in extra columns, one per
+        * user-visible column.
+        */
+       property_type = sqlite3_column_int64 (cursor->stmt, column + cursor->n_columns);
+       is_null = sqlite3_column_type (cursor->stmt, column) == SQLITE_NULL;
+
+       tracker_db_interface_unlock (iface);
+
+       if (is_null) {
+               *value_type = TRACKER_SPARQL_VALUE_TYPE_UNBOUND;
+               return TRUE;
+       }
+
+       switch (property_type) {
+       case TRACKER_PROPERTY_TYPE_UNKNOWN:
+               return FALSE;
+       case TRACKER_PROPERTY_TYPE_STRING:
+       case TRACKER_PROPERTY_TYPE_LANGSTRING:
+               *value_type = TRACKER_SPARQL_VALUE_TYPE_STRING;
+               return TRUE;
+       case TRACKER_PROPERTY_TYPE_BOOLEAN:
+               *value_type = TRACKER_SPARQL_VALUE_TYPE_BOOLEAN;
+               return TRUE;
+       case TRACKER_PROPERTY_TYPE_INTEGER:
+               *value_type = TRACKER_SPARQL_VALUE_TYPE_INTEGER;
+               return TRUE;
+       case TRACKER_PROPERTY_TYPE_DOUBLE:
+               *value_type = TRACKER_SPARQL_VALUE_TYPE_DOUBLE;
+               return TRUE;
+       case TRACKER_PROPERTY_TYPE_DATE:
+       case TRACKER_PROPERTY_TYPE_DATETIME:
+               *value_type = TRACKER_SPARQL_VALUE_TYPE_DATETIME;
+               return TRUE;
+       case TRACKER_PROPERTY_TYPE_RESOURCE:
+               if (g_str_has_prefix (tracker_db_cursor_get_string (cursor, column, NULL),
+                                     "urn:bnode:"))
+                       *value_type = TRACKER_SPARQL_VALUE_TYPE_BLANK_NODE;
+               else
+                       *value_type = TRACKER_SPARQL_VALUE_TYPE_URI;
+
+               return TRUE;
+       };
+
+       g_assert_not_reached ();
+}
+
 TrackerSparqlValueType
 tracker_db_cursor_get_value_type (TrackerDBCursor *cursor,
                                   guint            column)
@@ -3577,9 +3639,13 @@ tracker_db_cursor_get_value_type (TrackerDBCursor *cursor,
        TrackerDBInterface *iface;
        gint column_type;
        guint n_columns = tracker_db_cursor_get_n_columns (cursor);
+       TrackerSparqlValueType value_type;
 
        g_return_val_if_fail (column < n_columns, TRACKER_SPARQL_VALUE_TYPE_UNBOUND);
 
+       if (tracker_db_cursor_get_annotated_value_type (cursor, column, &value_type))
+               return value_type;
+
        iface = cursor->ref_stmt->db_interface;
 
        tracker_db_interface_lock (iface);