File : s-valint.adb
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- S Y S T E M . V A L _ I N T --
6 -- --
7 -- B o d y --
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 with System.Unsigned_Types; use System.Unsigned_Types;
33 with System.Val_Uns; use System.Val_Uns;
34 with System.Val_Util; use System.Val_Util;
35
36 package body System.Val_Int is
37
38 ------------------
39 -- Scan_Integer --
40 ------------------
41
42 function Scan_Integer
43 (Str : String;
44 Ptr : not null access Integer;
45 Max : Integer) return Integer
46 is
47 Uval : Unsigned;
48 -- Unsigned result
49
50 Minus : Boolean := False;
51 -- Set to True if minus sign is present, otherwise to False
52
53 Start : Positive;
54 -- Saves location of first non-blank (not used in this case)
55
56 begin
57 Scan_Sign (Str, Ptr, Max, Minus, Start);
58
59 if Str (Ptr.all) not in '0' .. '9' then
60 Ptr.all := Start;
61 Bad_Value (Str);
62 end if;
63
64 Uval := Scan_Raw_Unsigned (Str, Ptr, Max);
65
66 -- Deal with overflow cases, and also with maximum negative number
67
68 if Uval > Unsigned (Integer'Last) then
69 if Minus and then Uval = Unsigned (-(Integer'First)) then
70 return Integer'First;
71 else
72 Bad_Value (Str);
73 end if;
74
75 -- Negative values
76
77 elsif Minus then
78 return -(Integer (Uval));
79
80 -- Positive values
81
82 else
83 return Integer (Uval);
84 end if;
85 end Scan_Integer;
86
87 -------------------
88 -- Value_Integer --
89 -------------------
90
91 function Value_Integer (Str : String) return Integer is
92 begin
93 -- We have to special case Str'Last = Positive'Last because the normal
94 -- circuit ends up setting P to Str'Last + 1 which is out of bounds. We
95 -- deal with this by converting to a subtype which fixes the bounds.
96
97 if Str'Last = Positive'Last then
98 declare
99 subtype NT is String (1 .. Str'Length);
100 begin
101 return Value_Integer (NT (Str));
102 end;
103
104 -- Normal case where Str'Last < Positive'Last
105
106 else
107 declare
108 V : Integer;
109 P : aliased Integer := Str'First;
110 begin
111 V := Scan_Integer (Str, P'Access, Str'Last);
112 Scan_Trailing_Blanks (Str, P);
113 return V;
114 end;
115 end if;
116 end Value_Integer;
117
118 end System.Val_Int;