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