gcc/ada/s-valcha.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                      S Y S T E M . V A L _ C H A R                       --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --                                                                          --
  10 --        Copyright (C) 1992,1993,1994 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
  37 package body System.Val_Char is
  38
  39    ---------------------
  40    -- Value_Character --
  41    ---------------------
  42
  43    function Value_Character (Str : String) return Character is
  44       F : Natural;
  45       L : Natural;
  46       S : String (Str'Range) := Str;
  47
  48    begin
  49       Normalize_String (S, F, L);
  50
  51       --  Accept any single character enclosed in quotes
  52
  53       if L - F = 2 and then S (F) = ''' and then S (L) = ''' then
  54          return Character'Val (Character'Pos (S (F + 1)));
  55
  56       --  Check control character cases
  57
  58       else
  59          for C in Character'Val (16#00#) .. Character'Val (16#1F#) loop
  60             if S (F .. L) = Character'Image (C) then
  61                return C;
  62             end if;
  63          end loop;
  64
  65          for C in Character'Val (16#7F#) .. Character'Val (16#9F#) loop
  66             if S (F .. L) = Character'Image (C) then
  67                return C;
  68             end if;
  69          end loop;
  70
  71          raise Constraint_Error;
  72       end if;
  73
  74    end Value_Character;
  75
  76 end System.Val_Char;