gcc/ada/s-valint.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                       S Y S T E M . V A L _ I N T                        --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --                                                                          --
  10 --   Copyright (C) 1992,1993,1994,1995,1996 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.Unsigned_Types; use System.Unsigned_Types;
  36 with System.Val_Uns;        use System.Val_Uns;
  37 with System.Val_Util;       use System.Val_Util;
  38
  39 package body System.Val_Int is
  40
  41    ------------------
  42    -- Scan_Integer --
  43    ------------------
  44
  45    function Scan_Integer
  46      (Str  : String;
  47       Ptr  : access Integer;
  48       Max  : Integer)
  49       return Integer
  50    is
  51       Uval : Unsigned;
  52       --  Unsigned result
  53
  54       Minus : Boolean := False;
  55       --  Set to True if minus sign is present, otherwise to False
  56
  57       Start : Positive;
  58       --  Saves location of first non-blank (not used in this case)
  59
  60    begin
  61       Scan_Sign (Str, Ptr, Max, Minus, Start);
  62       Uval := Scan_Unsigned (Str, Ptr, Max);
  63
  64       --  Deal with overflow cases, and also with maximum negative number
  65
  66       if Uval > Unsigned (Integer'Last) then
  67          if Minus and then Uval = Unsigned (-(Integer'First)) then
  68             return Integer'First;
  69          else
  70             raise Constraint_Error;
  71          end if;
  72
  73       --  Negative values
  74
  75       elsif Minus then
  76          return -(Integer (Uval));
  77
  78       --  Positive values
  79
  80       else
  81          return Integer (Uval);
  82       end if;
  83
  84    end Scan_Integer;
  85
  86    -------------------
  87    -- Value_Integer --
  88    -------------------
  89
  90    function Value_Integer (Str : String) return Integer is
  91       V : Integer;
  92       P : aliased Integer := Str'First;
  93
  94    begin
  95       V := Scan_Integer (Str, P'Access, Str'Last);
  96       Scan_Trailing_Blanks (Str, P);
  97       return V;
  98    end Value_Integer;
  99
 100 end System.Val_Int;