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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                     S Y S T E M . V A L _ W C H A R                      --

--                                                                          --

--                                 B o d y                                  --

--                                                                          --

--          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.      --

--                                                                          --

------------------------------------------------------------------------------

with Interfaces;      use Interfaces;

with System.Val_Util; use System.Val_Util;

with System.WCh_Cnv;  use System.WCh_Cnv;

with System.WCh_Con;  use System.WCh_Con;

package body System.Val_WChar is

   --------------------------

   -- Value_Wide_Character --

   --------------------------

   function Value_Wide_Character

     (Str : String;

      EM  : System.WCh_Con.WC_Encoding_Method) return Wide_Character

   is

      WC : constant Wide_Wide_Character := Value_Wide_Wide_Character (Str, EM);

      WV : constant Unsigned_32         := Wide_Wide_Character'Pos (WC);

   begin

      if WV > 16#FFFF# then

         raise Constraint_Error with

           "out of range character for Value attribute";

      else

         return Wide_Character'Val (WV);

      end if;

   end Value_Wide_Character;

   -------------------------------

   -- Value_Wide_Wide_Character --

   -------------------------------

   function Value_Wide_Wide_Character

     (Str : String;

      EM  : System.WCh_Con.WC_Encoding_Method) return Wide_Wide_Character

   is

      F : Natural;

      L : Natural;

      S : String (Str'Range) := Str;

   begin

      Normalize_String (S, F, L);

      --  Character literal case

      if S (F) = ''' and then S (L) = ''' then

         --  Must be at least three characters

         if L - F < 2 then

            raise Constraint_Error;

         --  If just three characters, simple character case

         elsif L - F = 2 then

            return Wide_Wide_Character'Val (Character'Pos (S (F + 1)));

         --  Only other possibility for quoted string is wide char sequence

         else

            declare

               P : Natural;

               W : Wide_Wide_Character;

               function In_Char return Character;

               --  Function for instantiations of Char_Sequence_To_UTF_32

               -------------

               -- In_Char --

               -------------

               function In_Char return Character is

               begin

                  P := P + 1;

                  if P = Str'Last then

                     raise Constraint_Error;

                  end if;

                  return Str (P);

               end In_Char;

               function UTF_32 is

                 new Char_Sequence_To_UTF_32 (In_Char);

            begin

               P := F + 1;

               --  Brackets encoding

               if S (F + 1) = '[' then

                  W := Wide_Wide_Character'Val (UTF_32 ('[', WCEM_Brackets));

               else

                  W := Wide_Wide_Character'Val (UTF_32 (S (F + 1), EM));

               end if;

               if P /= L - 1 then

                  raise Constraint_Error;

               end if;

               return W;

            end;

         end if;

      --  Deal with Hex_hhhhhhhh cases for wide_[wide_]character cases

      elsif Str'Length = 12

        and then Str (Str'First .. Str'First + 3) = "Hex_"

      then

         declare

            W : Unsigned_32 := 0;

         begin

            for J in Str'First + 4 .. Str'First + 11 loop

               W := W * 16 + Character'Pos (Str (J));

               if Str (J) in '0' .. '9' then

                  W := W - Character'Pos ('0');

               elsif Str (J) in 'A' .. 'F' then

                  W := W - Character'Pos ('A') + 10;

               elsif Str (J) in 'a' .. 'f' then

                  W := W - Character'Pos ('a') + 10;

               else

                  raise Constraint_Error;

               end if;

            end loop;

            if W > 16#7FFF_FFFF# then

               raise Constraint_Error;

            else

               return Wide_Wide_Character'Val (W);

            end if;

         end;

      --  Otherwise must be one of the special names for Character

      else

         return

           Wide_Wide_Character'Val (Character'Pos (Character'Value (Str)));

      end if;

   exception

      when Constraint_Error =>

         raise Constraint_Error with "invalid string for value attribute";

   end Value_Wide_Wide_Character;

end System.Val_WChar;