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--                                                                          --

--                         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.      --

--                                                                          --

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--  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;