------------------------------------------------------------------------------
--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
--                                                                          --
--                                  S C N                                   --
--                                                                          --
--                                 S p e c                                  --
--                                                                          --
--          Copyright (C) 1992-2008, Free Software Foundation, Inc.         --
--                                                                          --
-- GNAT is free software;  you can  redistribute it  and/or modify it under --
-- terms of the  GNU General Public License as published  by the Free Soft- --
-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT 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  distributed with GNAT; see file COPYING3.  If not, go to --
-- http://www.gnu.org/licenses for a complete copy of the license.          --
--                                                                          --
-- GNAT was originally developed  by the GNAT team at  New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc.      --
--                                                                          --
------------------------------------------------------------------------------

--  This package contains the lexical analyzer routines. This is used by the
--  compiler for scanning Ada source files.

with Casing; use Casing;
with Errout; use Errout;
with Scng;
with Style;  use Style;
with Types;  use Types;

package Scn is

   procedure Initialize_Scanner
     (Unit  : Unit_Number_Type;
      Index : Source_File_Index);
   --  Initialize lexical scanner for scanning a new file. The caller has
   --  completed the construction of the Units.Table entry for the specified
   --  Unit and Index references the corresponding source file. A special
   --  case is when Unit = No_Unit_Number, and Index corresponds to the
   --  source index for reading the configuration pragma file.

   function Determine_Token_Casing return Casing_Type;
   --  Determines the casing style of the current token, which is
   --  either a keyword or an identifier. See also package Casing.

   procedure Obsolescent_Check (S : Source_Ptr);
   --  Called to handle pragma restrictions check for usage of obsolescent
   --  character replacements during the scan.

   procedure Set_Obsolescent_Check (Value : Boolean);
   --  Activate or not obsolescent check

   procedure Post_Scan;
   pragma Inline (Post_Scan);
   --  Create nodes for tokens: Char_Literal, Identifier, Real_Literal,
   --  Integer_Literal, String_Literal and Operator_Symbol.

   procedure Scan_Reserved_Identifier (Force_Msg : Boolean);
   --  This procedure is called to convert the current token, which the caller
   --  has checked is for a reserved word, to an equivalent identifier. This is
   --  of course only used in error situations where the parser can detect that
   --  a reserved word is being used as an identifier. An appropriate error
   --  message, pointing to the token, is also issued if either this is the
   --  first occurrence of misuse of this identifier, or if Force_Msg is True.

   -------------
   -- Scanner --
   -------------

   --  The scanner used by the compiler is an instantiation of the
   --  generic package Scng with routines appropriate to the compiler

   package Scanner is new Scng
     (Post_Scan         => Post_Scan,
      Error_Msg         => Error_Msg,
      Error_Msg_S       => Error_Msg_S,
      Error_Msg_SC      => Error_Msg_SC,
      Error_Msg_SP      => Error_Msg_SP,
      Obsolescent_Check => Obsolescent_Check,
      Style             => Style.Style_Inst);

   procedure Scan renames Scanner.Scan;
   --  Scan scans out the next token, and advances the scan state accordingly
   --  (see package Scans for details). If the scan encounters an illegal
   --  token, then an error message is issued pointing to the bad character,
   --  and Scan returns a reasonable substitute token of some kind.

end Scn;
