filterx: add isset/unset virtual functions to FilterXExpr

Signed-off-by: Balazs Scheidler <[email protected]>

lib/filterx/filterx-expr.h

@@ -43,6 +43,11 @@ struct _FilterXExpr
   /* assign a new value to this expr */
   gboolean (*assign)(FilterXExpr *self, FilterXObject *new_value);
 
+  /* is the expression set? */
+  gboolean (*isset)(FilterXExpr *self);
+  /* unset the expression */
+  gboolean (*unset)(FilterXExpr *self);
+
   void (*free_fn)(FilterXExpr *self);
 };
 
@@ -109,6 +114,22 @@ filterx_expr_assign(FilterXExpr *self, FilterXObject *new_value)
   return FALSE;
 }
 
+static inline gboolean
+filterx_expr_isset(FilterXExpr *self)
+{
+  if (self->isset)
+    return self->isset(self);
+  return FALSE;
+}
+
+static inline gboolean
+filterx_expr_unset(FilterXExpr *self)
+{
+  if (self->unset)
+    return self->unset(self);
+  return FALSE;
+}
+
 void filterx_expr_init_instance(FilterXExpr *self);
 FilterXExpr *filterx_expr_new(void);
 FilterXExpr *filterx_expr_ref(FilterXExpr *self);