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.