File : s-valrea.ads
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) 1992-2014, 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 -- --
19 -- --
20 -- --
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 package 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
74 end System.Val_Real;