gcc/ada/s-valllu.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                       S Y S T E M . V A L _ L L U                        --
   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 modular Long_Long_Unsigned
  33 --  values for use in Text_IO.Modular_IO, and the Value attribute.
  34
  35 with System.Unsigned_Types;
  36
  37 package System.Val_LLU is
  38    pragma Pure;
  39
  40    function Scan_Raw_Long_Long_Unsigned
  41      (Str : String;
  42       Ptr : not null access Integer;
  43       Max : Integer) return System.Unsigned_Types.Long_Long_Unsigned;
  44    --  This function scans the string starting at Str (Ptr.all) for a valid
  45    --  integer according to the syntax described in (RM 3.5(43)). The substring
  46    --  scanned extends no further than Str (Max).  Note: this does not scan
  47    --  leading or trailing blanks, nor leading sign.
  48    --
  49    --  There are three cases for the return:
  50    --
  51    --  If a valid integer is found, then Ptr.all is updated past the last
  52    --  character of the integer.
  53    --
  54    --  If no valid integer is found, then Ptr.all points either to an initial
  55    --  non-digit character, or to Max + 1 if the field is all spaces and the
  56    --  exception Constraint_Error is raised.
  57    --
  58    --  If a syntactically valid integer is scanned, but the value is out of
  59    --  range, or, in the based case, the base value is out of range or there
  60    --  is an out of range digit, then Ptr.all points past the integer, and
  61    --  Constraint_Error is raised.
  62    --
  63    --  Note: these rules correspond to the requirements for leaving the pointer
  64    --  positioned in Text_IO.Get. Note that the rules as stated in the RM would
  65    --  seem to imply that for a case like
  66    --
  67    --    8#12345670009#
  68
  69    --  the pointer should be left at the first # having scanned out the longest
  70    --  valid integer literal (8), but in fact in this case the pointer points
  71    --  to the invalid based digit (9 in this case). Not only would the strict
  72    --  reading of the RM require unlimited backup, which is unreasonable, but
  73    --  in addition, the intepretation as given here is the one expected and
  74    --  enforced by the ACATS tests.
  75    --
  76    --  Note: if Str is empty, i.e. if Max is less than Ptr, then this is a
  77    --  special case of an all-blank string, and Ptr is unchanged, and hence
  78    --  is greater than Max as required in this case.
  79    --
  80    --  Note: this routine should not be called with Str'Last = Positive'Last.
  81    --  If this occurs Program_Error is raised with a message noting that this
  82    --  case is not supported. Most such cases are eliminated by the caller.
  83
  84    function Scan_Long_Long_Unsigned
  85      (Str : String;
  86       Ptr : not null access Integer;
  87       Max : Integer) return System.Unsigned_Types.Long_Long_Unsigned;
  88    --  Same as Scan_Raw_Long_Long_Unsigned, except scans optional leading
  89    --  blanks, and an optional leading plus sign.
  90    --
  91    --  Note: if a minus sign is present, Constraint_Error will be raised.
  92    --  Note: trailing blanks are not scanned.
  93
  94    function Value_Long_Long_Unsigned
  95      (Str : String) return System.Unsigned_Types.Long_Long_Unsigned;
  96    --  Used in computing X'Value (Str) where X is a modular integer type whose
  97    --  modulus exceeds the range of System.Unsigned_Types.Unsigned. Str is the
  98    --  string argument of the attribute. Constraint_Error is raised if the
  99    --  string is malformed, or if the value is out of range.
 100
 101 end System.Val_LLU;