(* PushBackInput.def provides a method for pushing back and consuming input.

Copyright (C) 2001-2025 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.

Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
<http://www.gnu.org/licenses/>.  *)

DEFINITION MODULE PushBackInput ;

FROM FIO IMPORT File ;
FROM DynamicStrings IMPORT String ;

EXPORT QUALIFIED Open, PutCh, GetCh, Error, WarnError, WarnString,
                 Close, SetDebug, GetExitStatus, PutStr,
                 PutString, GetColumnPosition, GetCurrentLine ;


(*
   Open - opens a file for reading.
*)

PROCEDURE Open (a: ARRAY OF CHAR) : File ;


(*
   GetCh - gets a character from either the push back stack or
           from file, f.
*)

PROCEDURE GetCh (f: File) : CHAR ;


(*
   PutCh - pushes a character onto the push back stack, it also
           returns the character which has been pushed.
*)

PROCEDURE PutCh (ch: CHAR) : CHAR ;


(*
   PutString - pushes a string onto the push back stack.
*)

PROCEDURE PutString (a: ARRAY OF CHAR) ;


(*
   PutStr - pushes a dynamic string onto the push back stack.
            The string, s, is not deallocated.
*)

PROCEDURE PutStr (s: String) ;


(*
   Error - emits an error message with the appropriate file, line combination.
*)

PROCEDURE Error (a: ARRAY OF CHAR) ;


(*
   WarnError - emits an error message with the appropriate file, line combination.
               It does not terminate but when the program finishes an exit status of
               1 will be issued.
*)

PROCEDURE WarnError (a: ARRAY OF CHAR) ;


(*
   WarnString - emits an error message with the appropriate file, line combination.
                It does not terminate but when the program finishes an exit status of
                1 will be issued.
*)

PROCEDURE WarnString (s: String) ;


(*
   Close - closes the opened file.
*)

PROCEDURE Close (f: File) ;


(*
   GetExitStatus - returns the exit status which will be 1 if any warnings were issued.
*)

PROCEDURE GetExitStatus () : CARDINAL ;


(*
   SetDebug - sets the debug flag on or off.
*)

PROCEDURE SetDebug (d: BOOLEAN) ;


(*
   GetColumnPosition - returns the column position of the current character.
*)

PROCEDURE GetColumnPosition () : CARDINAL ;


(*
   GetCurrentLine - returns the current line number.
*)

PROCEDURE GetCurrentLine () : CARDINAL ;


END PushBackInput.
