/* PSPP - computes sample statistics.
Copyright (C) 1997-9, 2000 Free Software Foundation, Inc.
- Written by Ben Pfaff <blp@gnu.org>.
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
};
void ctl_stack_clear (void);
-void ctl_stack_push (struct ctl_class *, void *private);
-void *ctl_stack_top (struct ctl_class *);
-void *ctl_stack_search (struct ctl_class *);
+void ctl_stack_push (const struct ctl_class *, void *private);
+void *ctl_stack_top (const struct ctl_class *);
+void *ctl_stack_search (const struct ctl_class *);
void ctl_stack_pop (void *);
bool ctl_stack_is_empty (void);