| 1 | /* Copyright (C) 2001, 2002, 2003, 2006, 2007 Free Software Foundation, Inc.
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| 2 | Written by Bruno Haible <haible@clisp.cons.org>, 2001.
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| 3 |
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| 4 | This program is free software; you can redistribute it and/or modify
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| 5 | it under the terms of the GNU General Public License as published by
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| 6 | the Free Software Foundation; either version 2, or (at your option)
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| 7 | any later version.
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| 8 |
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| 9 | This program is distributed in the hope that it will be useful,
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| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 12 | GNU General Public License for more details.
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| 13 |
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| 14 | You should have received a copy of the GNU General Public License
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| 15 | along with this program; if not, write to the Free Software Foundation,
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| 16 | Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
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| 17 |
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| 18 | #ifndef _STDBOOL_H
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| 19 | #define _STDBOOL_H
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| 20 |
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| 21 | /* ISO C 99 <stdbool.h> for platforms that lack it. */
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| 22 |
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| 23 | /* Usage suggestions:
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| 24 |
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| 25 | Programs that use <stdbool.h> should be aware of some limitations
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| 26 | and standards compliance issues.
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| 27 |
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| 28 | Standards compliance:
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| 29 |
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| 30 | - <stdbool.h> must be #included before 'bool', 'false', 'true'
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| 31 | can be used.
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| 32 |
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| 33 | - You cannot assume that sizeof (bool) == 1.
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| 34 |
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| 35 | - Programs should not undefine the macros bool, true, and false,
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| 36 | as C99 lists that as an "obsolescent feature".
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| 37 |
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| 38 | Limitations of this substitute, when used in a C89 environment:
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| 39 |
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| 40 | - <stdbool.h> must be #included before the '_Bool' type can be used.
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| 41 |
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| 42 | - You cannot assume that _Bool is a typedef; it might be a macro.
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| 43 |
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| 44 | - Bit-fields of type 'bool' are not supported. Portable code
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| 45 | should use 'unsigned int foo : 1;' rather than 'bool foo : 1;'.
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| 46 |
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| 47 | - In C99, casts and automatic conversions to '_Bool' or 'bool' are
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| 48 | performed in such a way that every nonzero value gets converted
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| 49 | to 'true', and zero gets converted to 'false'. This doesn't work
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| 50 | with this substitute. With this substitute, only the values 0 and 1
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| 51 | give the expected result when converted to _Bool' or 'bool'.
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| 52 |
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| 53 | Also, it is suggested that programs use 'bool' rather than '_Bool';
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| 54 | this isn't required, but 'bool' is more common. */
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| 55 |
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| 56 |
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| 57 | /* 7.16. Boolean type and values */
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| 58 |
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| 59 | /* BeOS <sys/socket.h> already #defines false 0, true 1. We use the same
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| 60 | definitions below, but temporarily we have to #undef them. */
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| 61 | #ifdef __BEOS__
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| 62 | # include <OS.h> /* defines bool but not _Bool */
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| 63 | # undef false
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| 64 | # undef true
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| 65 | #endif
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| 66 |
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| 67 | /* For the sake of symbolic names in gdb, we define true and false as
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| 68 | enum constants, not only as macros.
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| 69 | It is tempting to write
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| 70 | typedef enum { false = 0, true = 1 } _Bool;
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| 71 | so that gdb prints values of type 'bool' symbolically. But if we do
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| 72 | this, values of type '_Bool' may promote to 'int' or 'unsigned int'
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| 73 | (see ISO C 99 6.7.2.2.(4)); however, '_Bool' must promote to 'int'
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| 74 | (see ISO C 99 6.3.1.1.(2)). So we add a negative value to the
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| 75 | enum; this ensures that '_Bool' promotes to 'int'. */
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| 76 | #if defined __cplusplus || defined __BEOS__
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| 77 | /* A compiler known to have 'bool'. */
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| 78 | /* If the compiler already has both 'bool' and '_Bool', we can assume they
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| 79 | are the same types. */
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| 80 | # if !@HAVE__BOOL@
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| 81 | typedef bool _Bool;
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| 82 | # endif
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| 83 | #else
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| 84 | # if !defined __GNUC__
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| 85 | /* If @HAVE__BOOL@:
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| 86 | Some HP-UX cc and AIX IBM C compiler versions have compiler bugs when
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| 87 | the built-in _Bool type is used. See
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| 88 | http://gcc.gnu.org/ml/gcc-patches/2003-12/msg02303.html
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| 89 | http://lists.gnu.org/archive/html/bug-coreutils/2005-11/msg00161.html
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| 90 | http://lists.gnu.org/archive/html/bug-coreutils/2005-10/msg00086.html
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| 91 | Similar bugs are likely with other compilers as well; this file
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| 92 | wouldn't be used if <stdbool.h> was working.
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| 93 | So we override the _Bool type.
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| 94 | If !@HAVE__BOOL@:
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| 95 | Need to define _Bool ourselves. As 'signed char' or as an enum type?
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| 96 | Use of a typedef, with SunPRO C, leads to a stupid
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| 97 | "warning: _Bool is a keyword in ISO C99".
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| 98 | Use of an enum type, with IRIX cc, leads to a stupid
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| 99 | "warning(1185): enumerated type mixed with another type".
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| 100 | The only benefit of the enum type, debuggability, is not important
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| 101 | with these compilers. So use 'signed char' and no typedef. */
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| 102 | # define _Bool signed char
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| 103 | enum { false = 0, true = 1 };
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| 104 | # else
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| 105 | /* With this compiler, trust the _Bool type if the compiler has it. */
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| 106 | # if !@HAVE__BOOL@
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| 107 | typedef enum { _Bool_must_promote_to_int = -1, false = 0, true = 1 } _Bool;
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| 108 | # endif
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| 109 | # endif
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| 110 | #endif
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| 111 | #define bool _Bool
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| 112 |
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| 113 | /* The other macros must be usable in preprocessor directives. */
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| 114 | #define false 0
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| 115 | #define true 1
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| 116 | #define __bool_true_false_are_defined 1
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| 117 |
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| 118 | #endif /* _STDBOOL_H */
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