gcc/ada/s-valdec.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                       S Y S T E M . V A L _ D E C                        --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --            Copyright (C) 1992-2014, 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 decimal values where the size
  33 --  of the type is no greater than Standard.Integer'Size, for use in Text_IO.
  34 --  Decimal_IO, and the Value attribute for such decimal types.
  35
  36 package System.Val_Dec is
  37    pragma Pure;
  38
  39    function Scan_Decimal
  40      (Str   : String;
  41       Ptr   : not null access Integer;
  42       Max   : Integer;
  43       Scale : Integer) return Integer;
  44    --  This function scans the string starting at Str (Ptr.all) for a valid
  45    --  real literal according to the syntax described in (RM 3.5(43)). The
  46    --  substring scanned extends no further than Str (Max). There are three
  47    --  cases for the return:
  48    --
  49    --  If a valid real literal is found after scanning past any initial spaces,
  50    --  then Ptr.all is updated past the last character of the literal (but
  51    --  trailing spaces are not scanned out). The value returned is the value
  52    --  Integer'Integer_Value (decimal-literal-value), using the given Scale
  53    --  to determine this value.
  54    --
  55    --  If no valid real literal is found, then Ptr.all points either to an
  56    --  initial non-digit character, or to Max + 1 if the field is all spaces
  57    --  and the exception Constraint_Error is raised.
  58    --
  59    --  If a syntactically valid integer is scanned, but the value is out of
  60    --  range, or, in the based case, the base value is out of range or there
  61    --  is an out of range digit, then Ptr.all points past the integer, and
  62    --  Constraint_Error is raised.
  63    --
  64    --  Note: these rules correspond to the requirements for leaving the
  65    --  pointer positioned in Text_Io.Get
  66    --
  67    --  Note: if Str is null, i.e. if Max is less than Ptr, then this is a
  68    --  special case of an all-blank string, and Ptr is unchanged, and hence
  69    --  is greater than Max as required in this case.
  70
  71    function Value_Decimal (Str : String; Scale : Integer) return Integer;
  72    --  Used in computing X'Value (Str) where X is a decimal fixed-point type
  73    --  whose size does not exceed Standard.Integer'Size. Str is the string
  74    --  argument of the attribute. Constraint_Error is raised if the string
  75    --  is malformed or if the value is out of range of Integer (not the
  76    --  range of the fixed-point type, that check must be done by the caller.
  77    --  Otherwise the value returned is the value Integer'Integer_Value
  78    --  (decimal-literal-value), using Scale to determine this value.
  79
  80 end System.Val_Dec;