(* mcStack.def provides a stack data type and associated procedures.

Copyright (C) 2015-2025 Free Software Foundation, Inc.
Contributed by Gaius Mulley <gaius.mulley@southwales.ac.uk>.

This file is part of GNU Modula-2.

GNU Modula-2 is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.

GNU Modula-2 is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Modula-2; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  *)

DEFINITION MODULE mcStack ;


FROM SYSTEM IMPORT ADDRESS ;

TYPE
   stack ;


(*
   init - create and return a stack.
*)

PROCEDURE init () : stack ;


(*
   kill - deletes stack, s.
*)

PROCEDURE kill (VAR s: stack) ;


(*
   push - an address, a, onto the stack, s.
          It returns, a.
*)

PROCEDURE push (s: stack; a: ADDRESS) : ADDRESS ;


(*
   pop - and return the top element from stack, s.
*)

PROCEDURE pop (s: stack) : ADDRESS ;


(*
   replace - performs a pop; push (a); return a.
*)

PROCEDURE replace (s: stack; a: ADDRESS) : ADDRESS ;


(*
   depth - returns the depth of the stack.
*)

PROCEDURE depth (s: stack) : CARDINAL ;


(*
   access - returns the, i, th stack element.
            The top of stack is defined by:

            access (s, depth (s)).
*)

PROCEDURE access (s: stack; i: CARDINAL) : ADDRESS ;


END mcStack.
