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 --                                                                          --
  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 --  This package contains routines for scanning decimal values where the size
  36 --  of the type is no greater than Standard.Integer'Size, for use in Text_IO.
  37 --  Decimal_IO, and the Value attribute for such decimal types.
  38
  39 package System.Val_Dec is
  40 pragma Pure (Val_Dec);
  41
  42    function Scan_Decimal
  43      (Str   : String;
  44       Ptr   : access Integer;
  45       Max   : Integer;
  46       Scale : Integer)
  47       return  Integer;
  48    --  This function scans the string starting at Str (Ptr.all) for a valid
  49    --  real literal according to the syntax described in (RM 3.5(43)). The
  50    --  substring scanned extends no further than Str (Max). There are three
  51    --  cases for the return:
  52    --
  53    --  If a valid real literal is found after scanning past any initial spaces,
  54    --  then Ptr.all is updated past the last character of the literal (but
  55    --  trailing spaces are not scanned out). The value returned is the value
  56    --  Integer'Integer_Value (decimal-literal-value), using the given Scale
  57    --  to determine this value.
  58    --
  59    --  If no valid real literal is found, then Ptr.all points either to an
  60    --  initial non-digit character, or to Max + 1 if the field is all spaces
  61    --  and the exception Constraint_Error is raised.
  62    --
  63    --  If a syntactically valid integer is scanned, but the value is out of
  64    --  range, or, in the based case, the base value is out of range or there
  65    --  is an out of range digit, then Ptr.all points past the integer, and
  66    --  Constraint_Error is raised.
  67    --
  68    --  Note: these rules correspond to the requirements for leaving the
  69    --  pointer positioned in Text_Io.Get
  70    --
  71    --  Note: if Str is null, i.e. if Max is less than Ptr, then this is a
  72    --  special case of an all-blank string, and Ptr is unchanged, and hence
  73    --  is greater than Max as required in this case.
  74
  75    function Value_Decimal (Str : String; Scale : Integer) return Integer;
  76    --  Used in computing X'Value (Str) where X is a decimal types whose size
  77    --  does not exceed Standard.Integer'Size. Str is the string argument of
  78    --  the attribute. Constraint_Error is raised if the string is malformed
  79    --  or if the value is out of range, otherwise the value returned is the
  80    --  value Integer'Integer_Value (decimal-literal-value), using the given
  81    --  Scale to determine this value.
  82
  83 end System.Val_Dec;