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   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --                       S Y S T E M . V A L _ I N T                        --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2009, 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 3,  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.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNAT was originally developed  by the GNAT team at  New York University. --
  28 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  This package contains routines for scanning signed Integer values for use
  33 --  in Text_IO.Integer_IO, and the Value attribute.
  34
  35 package System.Val_Int is
  36    pragma Pure;
  37
  38    function Scan_Integer
  39      (Str : String;
  40       Ptr : not null access Integer;
  41       Max : Integer) return Integer;
  42    --  This function scans the string starting at Str (Ptr.all) for a valid
  43    --  integer according to the syntax described in (RM 3.5(43)). The substring
  44    --  scanned extends no further than Str (Max). There are three cases for the
  45    --  return:
  46    --
  47    --  If a valid integer is found after scanning past any initial spaces, then
  48    --  Ptr.all is updated past the last character of the integer (but trailing
  49    --  spaces are not scanned out).
  50    --
  51    --  If no valid integer is found, then Ptr.all points either to an initial
  52    --  non-digit character, or to Max + 1 if the field is all spaces and the
  53    --  exception Constraint_Error is raised.
  54    --
  55    --  If a syntactically valid integer is scanned, but the value is out of
  56    --  range, or, in the based case, the base value is out of range or there
  57    --  is an out of range digit, then Ptr.all points past the integer, and
  58    --  Constraint_Error is raised.
  59    --
  60    --  Note: these rules correspond to the requirements for leaving the pointer
  61    --  positioned in Text_Io.Get
  62    --
  63    --  Note: if Str is null, i.e. if Max is less than Ptr, then this is a
  64    --  special case of an all-blank string, and Ptr is unchanged, and hence
  65    --  is greater than Max as required in this case.
  66
  67    function Value_Integer (Str : String) return Integer;
  68    --  Used in computing X'Value (Str) where X is a signed integer type whose
  69    --  base range does not exceed the base range of Integer. Str is the string
  70    --  argument of the attribute. Constraint_Error is raised if the string is
  71    --  malformed, or if the value is out of range.
  72
  73 end System.Val_Int;