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