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1/* Copyright (C) 2001, 2002, 2003 Free Software Foundation, Inc.
2 Written by Bruno Haible <haible@clisp.cons.org>, 2001.
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2, or (at your option)
7 any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software Foundation,
16 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
17
18#ifndef _STDBOOL_H
19#define _STDBOOL_H
20
21/* ISO C 99 <stdbool.h> for platforms that lack it. */
22
23/* Usage suggestions:
24
25 Programs that use <stdbool.h> should be aware of some limitations
26 and standards compliance issues.
27
28 Standards compliance:
29
30 - <stdbool.h> must be #included before 'bool', 'false', 'true'
31 can be used.
32
33 - You cannot assume that sizeof (bool) == 1.
34
35 - Programs should not undefine the macros bool, true, and false,
36 as C99 lists that as an "obsolescent feature".
37
38 Limitations of this substitute, when used in a C89 environment:
39
40 - <stdbool.h> must be #included before the '_Bool' type can be used.
41
42 - You cannot assume that _Bool is a typedef; it might be a macro.
43
44 - In C99, casts and automatic conversions to '_Bool' or 'bool' are
45 performed in such a way that every nonzero value gets converted
46 to 'true', and zero gets converted to 'false'. This doesn't work
47 with this substitute. With this substitute, only the values 0 and 1
48 give the expected result when converted to _Bool' or 'bool'.
49
50 Also, it is suggested that programs use 'bool' rather than '_Bool';
51 this isn't required, but 'bool' is more common. */
52
53
54/* 7.16. Boolean type and values */
55
56/* BeOS <sys/socket.h> already #defines false 0, true 1. We use the same
57 definitions below, but temporarily we have to #undef them. */
58#ifdef __BEOS__
59# include <OS.h> /* defines bool but not _Bool */
60# undef false
61# undef true
62#endif
63
64/* For the sake of symbolic names in gdb, we define true and false as
65 enum constants, not only as macros.
66 It is tempting to write
67 typedef enum { false = 0, true = 1 } _Bool;
68 so that gdb prints values of type 'bool' symbolically. But if we do
69 this, values of type '_Bool' may promote to 'int' or 'unsigned int'
70 (see ISO C 99 6.7.2.2.(4)); however, '_Bool' must promote to 'int'
71 (see ISO C 99 6.3.1.1.(2)). So we add a negative value to the
72 enum; this ensures that '_Bool' promotes to 'int'. */
73#if !(defined __cplusplus || defined __BEOS__)
74# if !@HAVE__BOOL@
75# if defined __SUNPRO_C && (__SUNPRO_C < 0x550 || __STDC__ == 1)
76 /* Avoid stupid "warning: _Bool is a keyword in ISO C99". */
77# define _Bool signed char
78enum { false = 0, true = 1 };
79# else
80typedef enum { _Bool_must_promote_to_int = -1, false = 0, true = 1 } _Bool;
81# endif
82# endif
83#else
84typedef bool _Bool;
85#endif
86#define bool _Bool
87
88/* The other macros must be usable in preprocessor directives. */
89#define false 0
90#define true 1
91#define __bool_true_false_are_defined 1
92
93#endif /* _STDBOOL_H */