gcc/ada/s-valwch.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                     S Y S T E M . V A L _ W C H A R                      --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --                                                                          --
  10 --          Copyright (C) 1992-1997, Free Software Foundation, Inc.         --
  11 --                                                                          --
  12 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  13 -- terms of the  GNU General Public License as published  by the Free Soft- --
  14 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  15 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  16 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  17 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  18 -- for  more details.  You should have  received  a copy of the GNU General --
  19 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  20 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  21 -- MA 02111-1307, USA.                                                      --
  22 --                                                                          --
  23 -- As a special exception,  if other files  instantiate  generics from this --
  24 -- unit, or you link  this unit with other files  to produce an executable, --
  25 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  26 -- covered  by the  GNU  General  Public  License.  This exception does not --
  27 -- however invalidate  any other reasons why  the executable file  might be --
  28 -- covered by the  GNU Public License.                                      --
  29 --                                                                          --
  30 -- GNAT was originally developed  by the GNAT team at  New York University. --
  31 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  32 --                                                                          --
  33 ------------------------------------------------------------------------------
  34
  35 with System.Val_Util; use System.Val_Util;
  36 with System.WCh_Con;  use System.WCh_Con;
  37 with System.WCh_StW;  use System.WCh_StW;
  38
  39 package body System.Val_WChar is
  40
  41    --------------------------
  42    -- Value_Wide_Character --
  43    --------------------------
  44
  45    function Value_Wide_Character
  46       (Str  : String;
  47        EM   : WC_Encoding_Method)
  48        return Wide_Character
  49    is
  50       F : Natural;
  51       L : Natural;
  52       S : String (Str'Range) := Str;
  53
  54    begin
  55       Normalize_String (S, F, L);
  56
  57       --  Character literal case
  58
  59       if S (F) = ''' and then S (L) = ''' then
  60
  61          --  If just three characters, simple character case
  62
  63          if L - F = 2 then
  64             return Wide_Character'Val (Character'Pos (S (F + 1)));
  65
  66          --  Otherwise must be a wide character in quotes. The easiest
  67          --  thing is to convert the string to a wide string and then
  68          --  pick up the single character that it should contain.
  69
  70          else
  71             declare
  72                WS : constant Wide_String :=
  73                       String_To_Wide_String (S (F + 1 .. L - 1), EM);
  74
  75             begin
  76                if WS'Length /= 1 then
  77                   raise Constraint_Error;
  78
  79                else
  80                   return WS (WS'First);
  81                end if;
  82             end;
  83          end if;
  84
  85       --  the last two values of the type have language-defined names:
  86
  87       elsif S = "FFFE" then
  88          return Wide_Character'Val (16#FFFE#);
  89
  90       elsif S = "FFFF" then
  91          return Wide_Character'Val (16#FFFF#);
  92
  93       --  Otherwise must be a control character
  94
  95       else
  96          for C in Character'Val (16#00#) .. Character'Val (16#1F#) loop
  97             if S (F .. L) = Character'Image (C) then
  98                return Wide_Character'Val (Character'Pos (C));
  99             end if;
 100          end loop;
 101
 102          for C in Character'Val (16#7F#) .. Character'Val (16#9F#) loop
 103             if S (F .. L) = Character'Image (C) then
 104                return Wide_Character'Val (Character'Pos (C));
 105             end if;
 106          end loop;
 107
 108          raise Constraint_Error;
 109       end if;
 110
 111    end Value_Wide_Character;
 112
 113 end System.Val_WChar;