File : s-valuns.ads
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- S Y S T E M . V A L _ U N S --
6 -- --
7 -- S p e c --
8 -- --
9 -- Copyright (C) 1992-2015, 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 -- This package contains routines for scanning modular 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_Uns is
38 pragma Pure;
39
40 function Scan_Raw_Unsigned
41 (Str : String;
42 Ptr : not null access Integer;
43 Max : Integer) return System.Unsigned_Types.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 -- past the final # and Constraint_Error is raised. This is the behavior
72 -- expected for Text_IO and enforced by the ACATS tests.
73 --
74 -- If a based literal is malformed in that a character other than a valid
75 -- hexadecimal digit is encountered during scanning out the digits after
76 -- the # (this includes the case of using the wrong terminator, : instead
77 -- of # or vice versa) there are two cases. If all the digits before the
78 -- non-digit are in range of the base, as in
79 --
80 -- 8#100x00#
81 -- 8#100:
82 --
83 -- then in this case, the "base" value before the initial # is returned as
84 -- the result, and the pointer points to the initial # character on return.
85 --
86 -- If an out of range digit has been detected before the invalid character,
87 -- as in:
88 --
89 -- 8#900x00#
90 -- 8#900:
91 --
92 -- then the pointer is also left at the initial # character, but constraint
93 -- error is raised reflecting the encounter of an out of range digit.
94 --
95 -- Finally if we have an unterminated fixed-point constant where the final
96 -- # or : character is missing, Constraint_Error is raised and the pointer
97 -- is left pointing past the last digit, as in:
98 --
99 -- 8#22
100 --
101 -- This string results in a Constraint_Error with the pointer pointing
102 -- past the second 2.
103 --
104 -- Note: if Str is empty, i.e. if Max is less than Ptr, then this is a
105 -- special case of an all-blank string, and Ptr is unchanged, and hence
106 -- is greater than Max as required in this case.
107 --
108 -- Note: this routine should not be called with Str'Last = Positive'Last.
109 -- If this occurs Program_Error is raised with a message noting that this
110 -- case is not supported. Most such cases are eliminated by the caller.
111
112 function Scan_Unsigned
113 (Str : String;
114 Ptr : not null access Integer;
115 Max : Integer) return System.Unsigned_Types.Unsigned;
116 -- Same as Scan_Raw_Unsigned, except scans optional leading
117 -- blanks, and an optional leading plus sign.
118 --
119 -- Note: if a minus sign is present, Constraint_Error will be raised.
120 -- Note: trailing blanks are not scanned.
121
122 function Value_Unsigned
123 (Str : String) return System.Unsigned_Types.Unsigned;
124 -- Used in computing X'Value (Str) where X is a modular integer type whose
125 -- modulus does not exceed the range of System.Unsigned_Types.Unsigned. Str
126 -- is the string argument of the attribute. Constraint_Error is raised if
127 -- the string is malformed, or if the value is out of range.
128
129 end System.Val_Uns;