1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--                      S Y S T E M . V A L _ R E A L                       --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 1992-2018, 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
32package System.Val_Real is
33   pragma Pure;
34
35   function Scan_Real
36     (Str : String;
37      Ptr : not null access Integer;
38      Max : Integer) return Long_Long_Float;
39   --  This function scans the string starting at Str (Ptr.all) for a valid
40   --  real literal according to the syntax described in (RM 3.5(43)). The
41   --  substring scanned extends no further than Str (Max). There are three
42   --  cases for the return:
43   --
44   --  If a valid real is found after scanning past any initial spaces, then
45   --  Ptr.all is updated past the last character of the real (but trailing
46   --  spaces are not scanned out).
47   --
48   --  If no valid real is found, then Ptr.all points either to an initial
49   --  non-blank character, or to Max + 1 if the field is all spaces and the
50   --  exception Constraint_Error is raised.
51   --
52   --  If a syntactically valid real is scanned, but the value is out of
53   --  range, or, in the based case, the base value is out of range or there
54   --  is an out of range digit, then Ptr.all points past the real literal,
55   --  and Constraint_Error is raised.
56   --
57   --  Note: these rules correspond to the requirements for leaving the
58   --  pointer positioned in Text_Io.Get
59   --
60   --  Note: if Str is null, i.e. if Max is less than Ptr, then this is a
61   --  special case of an all-blank string, and Ptr is unchanged, and hence
62   --  is greater than Max as required in this case.
63   --
64   --  Note: this routine should not be called with Str'Last = Positive'Last.
65   --  If this occurs Program_Error is raised with a message noting that this
66   --  case is not supported. Most such cases are eliminated by the caller.
67
68   function Value_Real (Str : String) return Long_Long_Float;
69   --  Used in computing X'Value (Str) where X is a floating-point type or an
70   --  ordinary fixed-point type. Str is the string argument of the attribute.
71   --  Constraint_Error is raised if the string is malformed, or if the value
72   --  out of range of Long_Long_Float.
73
74end System.Val_Real;
75