(* SymbolKey.def binary tree operations for storing symbols.

Copyright (C) 2001-2026 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 SymbolKey ;

(*
   Author     : Gaius Mulley
   Title      : SymbolKey
   Date       : 4/3/87
   Description: Provides binary tree operations for storing symbols.
                Used by the MODULE SymbolTable to provide scoping of symbols.
   Last update: Date: Wed 31-01-1990 Time: 18:20:32.63
                Mon Aug 30 12:07:12 BST 1999
*)

FROM SYSTEM IMPORT WORD ;
FROM NameKey IMPORT Name ;
EXPORT QUALIFIED NulKey, SymbolTree,
                 IsSymbol, PerformOperation,
                 InitTree, KillTree, GetSymKey, PutSymKey, DelSymKey,
                 IsEmptyTree,
                 DoesTreeContainAny, ForeachNodeDo, ContainsSymKey,
                 NoOfNodes, ForeachNodeConditionDo ;

CONST
   NulKey = 0 ;

TYPE
   SymbolTree ;

   IsSymbol         = PROCEDURE (WORD) : BOOLEAN ;
   PerformOperation = PROCEDURE (WORD) ;


(*
   InitTree - Initializes a SymbolTree pointed to by t.
*)

PROCEDURE InitTree (VAR t: SymbolTree) ;


(*
   KillTree - Destroys the SymbolTree pointed to by t.
*)

PROCEDURE KillTree (VAR t: SymbolTree) ;


(*
   GetSymKey - Searches the SymbolTree t for an entry NameKey. If
               found then the SymKey is returned. NulKey = not found.
*)

PROCEDURE GetSymKey (t: SymbolTree; NameKey: Name) : WORD ;


(*
   PutSymKey - Puts an symbol entry NameKey in the SymbolTree t.
               SymKey is the value stored with NameKey.
*)

PROCEDURE PutSymKey (t: SymbolTree; NameKey: Name; SymKey: WORD) ;


(*
   DelSymKey - Deletes a symbol entry NameKey in the SymbolTree t.
*)

PROCEDURE DelSymKey (t: SymbolTree; NameKey: 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) ;


(*
   ContainsSymKey - return TRUE if tree, t, contains an entry for, NameKey.
*)

PROCEDURE ContainsSymKey (t: SymbolTree; NameKey: Name) : BOOLEAN ;


(*
   NoOfNodes - returns the number of nodes in the tree t.
*)

PROCEDURE NoOfNodes (t: SymbolTree; condition: IsSymbol) : CARDINAL ;


(*
   ForeachNodeConditionDo - traverse the tree t and for any node which satisfied
                            condition call P.
*)

PROCEDURE ForeachNodeConditionDo (t: SymbolTree;
                                  condition: IsSymbol;
                                  P: PerformOperation) ;


END SymbolKey.