106 lines
3.9 KiB
C
106 lines
3.9 KiB
C
|
/* Copyright (C) 2001, 2002, 2003, 2005 Free Software Foundation, Inc.
|
||
|
|
Written by Bruno Haible <haible@clisp.cons.org>, 2001.
|
||
|
|
|
||
|
|
This program is free software; you can redistribute it and/or modify
|
||
|
|
it under the terms of the GNU General Public License as published by
|
||
|
|
the Free Software Foundation; either version 2, or (at your option)
|
||
|
|
any later version.
|
||
|
|
|
||
|
|
This program is distributed in the hope that it will be useful,
|
||
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
|
|
GNU General Public License for more details.
|
||
|
|
|
||
|
|
You should have received a copy of the GNU General Public License
|
||
|
|
along with this program; if not, write to the Free Software Foundation,
|
||
|
|
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
|
||
|
|
|
||
|
|
#ifndef _STDBOOL_H
|
||
|
|
#define _STDBOOL_H
|
||
|
|
|
||
|
|
/* ISO C 99 <stdbool.h> for platforms that lack it. */
|
||
|
|
|
||
|
|
/* Usage suggestions:
|
||
|
|
|
||
|
|
Programs that use <stdbool.h> should be aware of some limitations
|
||
|
|
and standards compliance issues.
|
||
|
|
|
||
|
|
Standards compliance:
|
||
|
|
|
||
|
|
- <stdbool.h> must be #included before 'bool', 'false', 'true'
|
||
|
|
can be used.
|
||
|
|
|
||
|
|
- You cannot assume that sizeof (bool) == 1.
|
||
|
|
|
||
|
|
- Programs should not undefine the macros bool, true, and false,
|
||
|
|
as C99 lists that as an "obsolescent feature".
|
||
|
|
|
||
|
|
Limitations of this substitute, when used in a C89 environment:
|
||
|
|
|
||
|
|
- <stdbool.h> must be #included before the '_Bool' type can be used.
|
||
|
|
|
||
|
|
- You cannot assume that _Bool is a typedef; it might be a macro.
|
||
|
|
|
||
|
|
- In C99, casts and automatic conversions to '_Bool' or 'bool' are
|
||
|
|
performed in such a way that every nonzero value gets converted
|
||
|
|
to 'true', and zero gets converted to 'false'. This doesn't work
|
||
|
|
with this substitute. With this substitute, only the values 0 and 1
|
||
|
|
give the expected result when converted to _Bool' or 'bool'.
|
||
|
|
|
||
|
|
Also, it is suggested that programs use 'bool' rather than '_Bool';
|
||
|
|
this isn't required, but 'bool' is more common. */
|
||
|
|
|
||
|
|
|
||
|
|
/* 7.16. Boolean type and values */
|
||
|
|
|
||
|
|
/* BeOS <sys/socket.h> already #defines false 0, true 1. We use the same
|
||
|
|
definitions below, which is OK. */
|
||
|
|
#ifdef __BEOS__
|
||
|
|
# include <OS.h> /* defines bool but not _Bool */
|
||
|
|
#endif
|
||
|
|
|
||
|
|
/* C++ and BeOS have a reliable bool (and _Bool, if it exists).
|
||
|
|
Otherwise, since this file is being compiled, the system
|
||
|
|
<stdbool.h> is not reliable so assume that the system _Bool is not
|
||
|
|
reliable either. Under that assumption, it is tempting to write
|
||
|
|
|
||
|
|
typedef enum { false, true } _Bool;
|
||
|
|
|
||
|
|
so that gdb prints values of type 'bool' symbolically. But if we do
|
||
|
|
this, values of type '_Bool' may promote to 'int' or 'unsigned int'
|
||
|
|
(see ISO C 99 6.7.2.2.(4)); however, '_Bool' must promote to 'int'
|
||
|
|
(see ISO C 99 6.3.1.1.(2)). We could instead try this:
|
||
|
|
|
||
|
|
typedef enum { _Bool_dummy = -1, false, true } _Bool;
|
||
|
|
|
||
|
|
as the negative value ensures that '_Bool' promotes to 'int'.
|
||
|
|
However, this runs into some other problems. First, Sun's C
|
||
|
|
compiler when (__SUNPRO_C < 0x550 || __STDC__ == 1) issues a stupid
|
||
|
|
"warning: _Bool is a keyword in ISO C99". Second, IBM's AIX cc
|
||
|
|
compiler 6.0.0.0 (and presumably other versions) mishandles
|
||
|
|
subscripts involving _Bool (effectively, _Bool promotes to unsigned
|
||
|
|
int in this case), and we need to redefine _Bool in that case.
|
||
|
|
Third, HP-UX 10.20's C compiler lacks <stdbool.h> but has _Bool and
|
||
|
|
mishandles comparisons of _Bool to int (it promotes _Bool to
|
||
|
|
unsigned int).
|
||
|
|
|
||
|
|
The simplest way to work around these problems is to ignore any
|
||
|
|
existing definition of _Bool and use our own. */
|
||
|
|
|
||
|
|
#if defined __cplusplus || defined __BEOS__
|
||
|
|
# if !@HAVE__BOOL@
|
||
|
|
typedef bool _Bool;
|
||
|
|
# endif
|
||
|
|
#else
|
||
|
|
# define _Bool signed char
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#define bool _Bool
|
||
|
|
|
||
|
|
/* The other macros must be usable in preprocessor directives. */
|
||
|
|
#define false 0
|
||
|
|
#define true 1
|
||
|
|
#define __bool_true_false_are_defined 1
|
||
|
|
|
||
|
|
#endif /* _STDBOOL_H */
|