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--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                             W I D E C H A R                              --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--          Copyright (C) 1992-2009  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.                                     --

--                                                                          --

-- As a special exception 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/>.                                          --

--                                                                          --

-- 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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--  Subprograms for manipulation of wide character sequences. Note that in

--  this package, wide character and wide wide character are not distinguished

--  since this package is basically concerned with syntactic notions, and it

--  deals with Char_Code values, rather than values of actual Ada types.

with Types; use Types;

package Widechar is

   Wide_Char_Byte_Count : Nat := 0;

   --  This value is incremented whenever Scan_Wide or Skip_Wide is called.

   --  The amount added is the length of the wide character sequence minus

   --  one. This means that the count that accumulates here represents the

   --  difference between the length in characters and the length in bytes.

   --  This is used for checking the line length in characters.

   function Length_Wide return Nat;

   --  Returns the maximum length in characters for the escape sequence that

   --  is used to encode wide character literals outside the ASCII range. Used

   --  only in the implementation of the attribute Width for Wide_Character

   --  and Wide_Wide_Character.

   procedure Scan_Wide

     (S   : Source_Buffer_Ptr;

      P   : in out Source_Ptr;

      C   : out Char_Code;

      Err : out Boolean);

   --  On entry S (P) points to the first character in the source text for

   --  a wide character (i.e. to an ESC character, a left bracket, or an

   --  upper half character, depending on the representation method). A

   --  single wide character is scanned. If no error is found, the value

   --  stored in C is the code for this wide character, P is updated past

   --  the sequence and Err is set to False. If an error is found, then

   --  P points to the improper character, C is undefined, and Err is

   --  set to True.

   procedure Set_Wide

     (C : Char_Code;

      S : in out String;

      P : in out Natural);

   --  The escape sequence (including any leading ESC character) for the

   --  given character code is stored starting at S (P + 1), and on return

   --  P points to the last stored character (i.e. P is the count of stored

   --  characters on entry and exit, and the escape sequence is appended to

   --  the end of the stored string). The character code C represents a code

   --  originally constructed by Scan_Wide, so it is known to be in a range

   --  that is appropriate for the encoding method in use.

   procedure Skip_Wide (S : String; P : in out Natural);

   --  On entry, S (P) points to an ESC character for a wide character escape

   --  sequence or to an upper half character if the encoding method uses the

   --  upper bit, or to a left bracket if the brackets encoding method is in

   --  use. On exit, P is bumped past the wide character sequence. No error

   --  checking is done, since this is only used on escape sequences generated

   --  by Set_Wide, which are known to be correct.

   procedure Skip_Wide (S : Source_Buffer_Ptr; P : in out Source_Ptr);

   --  Similar to the above procedure, but operates on a source buffer

   --  instead of a string, with P being a Source_Ptr referencing the

   --  contents of the source buffer.

   function Is_Start_Of_Wide_Char

     (S : Source_Buffer_Ptr;

      P : Source_Ptr) return Boolean;

   --  Determines if S (P) is the start of a wide character sequence

end Widechar;