gcc/ada/libgnat/s-valued.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                       S Y S T E M . V A L U E _ D                        --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --            Copyright (C) 2020-2023, 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 the routines for supporting the Value attribute for
  33 --  decimal fixed point types, and also for conversion operations required in
  34 --  Text_IO.Decimal_IO for such types.
  35
  36 generic
  37
  38    type Int is range <>;
  39
  40    type Uns is mod <>;
  41
  42    with procedure Scaled_Divide
  43           (X, Y, Z : Int;
  44            Q, R : out Int;
  45            Round : Boolean);
  46
  47 package System.Value_D is
  48    pragma Preelaborate;
  49
  50    function Scan_Decimal
  51      (Str   : String;
  52       Ptr   : not null access Integer;
  53       Max   : Integer;
  54       Scale : Integer) return Int;
  55    --  This function scans the string starting at Str (Ptr.all) for a valid
  56    --  real literal according to the syntax described in (RM 3.5(43)). The
  57    --  substring scanned extends no further than Str (Max). There are three
  58    --  cases for the return:
  59    --
  60    --  If a valid real literal is found after scanning past any initial spaces,
  61    --  then Ptr.all is updated past the last character of the literal (but
  62    --  trailing spaces are not scanned out). The value returned is the value
  63    --  Int'Integer_Value (decimal-literal-value), using the given Scale to
  64    --  determine this value.
  65    --
  66    --  If no valid real literal is found, then Ptr.all points either to an
  67    --  initial non-digit character, or to Max + 1 if the field is all spaces
  68    --  and the exception Constraint_Error is raised.
  69    --
  70    --  If a syntactically valid integer is scanned, but the value is out of
  71    --  range, or, in the based case, the base value is out of range or there
  72    --  is an out of range digit, then Ptr.all points past the integer, and
  73    --  Constraint_Error is raised.
  74    --
  75    --  Note: these rules correspond to the requirements for leaving the
  76    --  pointer positioned in Text_Io.Get
  77    --
  78    --  Note: if Str is null, i.e. if Max is less than Ptr, then this is a
  79    --  special case of an all-blank string, and Ptr is unchanged, and hence
  80    --  is greater than Max as required in this case.
  81
  82    function Value_Decimal (Str : String; Scale : Integer) return Int;
  83    --  Used in computing X'Value (Str) where X is a decimal fixed-point type.
  84    --  Str is the string argument of the attribute. Constraint_Error is raised
  85    --  if the string is malformed or if the value is out of range of Int (not
  86    --  the range of the fixed-point type, which must be done by the caller).
  87    --  Otherwise the value returned is the value Int'Integer_Value
  88    --  (decimal-literal-value), using Scale to determine this value.
  89
  90 end System.Value_D;