<html><head><meta name="color-scheme" content="light dark"></head><body><pre style="word-wrap: break-word; white-space: pre-wrap;">(* symbolKey.def provides binary tree operations for storing symbols.

Copyright (C) 2015-2025 Free Software Foundation, Inc.
Contributed by Gaius Mulley &lt;gaius@glam.ac.uk&gt;.

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
&lt;http://www.gnu.org/licenses/&gt;.  *)

DEFINITION MODULE symbolKey ;

(* Provides binary tree operations for storing symbols.
   Used by the decl module to provide scoping of symbols.  *)

FROM SYSTEM IMPORT ADDRESS ;
FROM nameKey IMPORT Name ;


CONST
   NulKey = NIL ;

TYPE
   symbolTree ;

   isSymbol         = PROCEDURE (ADDRESS) : BOOLEAN ;
   performOperation = PROCEDURE (ADDRESS) ;


(*
   initTree - initializes a symbolTree pointed to by t.
*)

PROCEDURE initTree () : symbolTree ;


(*
   killTree - destroys the symbolTree pointed to by t.
*)

PROCEDURE killTree (VAR t: symbolTree) ;


(*
   getSymKey - searches the symbolTree t for an entry name. If
               found then the key is returned otherwise NulKey
               is returned.
*)

PROCEDURE getSymKey (t: symbolTree; name: Name) : ADDRESS ;


(*
   putSymKey - puts an symbol entry, name, in the symbolTree t.
               SymKey is the value stored with name.
*)

PROCEDURE putSymKey (t: symbolTree; name: Name; key: ADDRESS) ;


(*
   delSymKey - deletes a symbol entry name in the symbolTree, t.
*)

PROCEDURE delSymKey (t: symbolTree; name: Name) ;


(*
   isEmptyTree - returns true if symbolTree, t, is empty.
*)

PROCEDURE isEmptyTree (t: symbolTree) : BOOLEAN ;


(*
   doesTreeContainAny - returns true if symbolTree, t, contains any
                        symbols which in turn return true when procedure,
                        p, is called with a symbol as its parameter.
*)

PROCEDURE doesTreeContainAny (t: symbolTree; p: isSymbol) : BOOLEAN ;


(*
   foreachNodeDo - for each node in symbolTree, t, a procedure, p,
                   is called with the node symbol as its parameter.
                   It traverse the tree in order.
*)

PROCEDURE foreachNodeDo (t: symbolTree; p: performOperation) ;


END symbolKey.
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