(* M2FileName.mod construct file names.

Copyright (C) 2001-2023 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/>.  *)

IMPLEMENTATION MODULE M2FileName ;


FROM ASCII IMPORT nul ;
FROM DynamicStrings IMPORT InitString, Mark, Slice, Dup, ConCatChar, ConCat, Length, Equal, Index ;


CONST
   MaxFileName = 0 ;   (* zero means no limits *)
   MaxStemName = 0 ;
   Directory   = '/' ;


(*
   currently there are no limits on filename length, this may
   be incorrect on some systems.
*)


(*
   CalculateFileName - calculates and returns a new string filename given a module
                       and an extension. String, Extension, is concatenated onto
                       Module and thus it is safe to `Mark' the extension for garbage
                       collection.
*)

PROCEDURE CalculateFileName (Module, Extension: String) : String ;
BEGIN
   IF MaxFileName=0
   THEN
      RETURN ConCat (Slice (Module, 0, MaxFileName), Extension)
   ELSE
      RETURN ConCat (Slice (Module, 0, MaxFileName-Length (Extension)), Extension)
   END
END CalculateFileName ;


(*
   CalculateStemName - calculates the stem name for given a module.
                       This name length will be operating system and
      	       	       compiler specific.
*)

PROCEDURE CalculateStemName (Module: String) : String ;
BEGIN
   RETURN Slice (Module, 0, MaxStemName)
END CalculateStemName ;


(*
   ExtractExtension - given a, filename, return the filename without
                      the extension, Ext.
*)

PROCEDURE ExtractExtension (filename, ext: String) : String ;
BEGIN
   IF Equal (ext, Mark (Slice (filename, -Length (ext), 0)))
   THEN
      RETURN Slice (filename, 0, -Length (ext))
   ELSE
      RETURN filename
   END
END ExtractExtension ;


(*
   ExtractModule - given a, filename, return the module name including any
                   extension. A new string is returned.
*)

PROCEDURE ExtractModule (filename: String) : String ;
VAR
   i: INTEGER ;
BEGIN
   i := Index (filename, Directory, 0) ;
   IF i=-1
   THEN
      RETURN Dup (filename)
   ELSE
      RETURN Slice (filename, i+1, 0)
   END
END ExtractModule ;


END M2FileName.