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132 lines
5.0 KiB
132 lines
5.0 KiB
/* Copyright (C) 2001-2003, 2006-2017 Free Software Foundation, Inc. |
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Written by Bruno Haible <haible@clisp.cons.org>, 2001. |
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This program is free software; you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation; either version 3, or (at your option) |
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any later version. |
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This program is distributed in the hope that it will be useful, |
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but WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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GNU General Public License for more details. |
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You should have received a copy of the GNU General Public License |
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along with this program; if not, see <http://www.gnu.org/licenses/>. */ |
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#ifndef _GL_STDBOOL_H |
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#define _GL_STDBOOL_H |
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/* ISO C 99 <stdbool.h> for platforms that lack it. */ |
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/* Usage suggestions: |
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Programs that use <stdbool.h> should be aware of some limitations |
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and standards compliance issues. |
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Standards compliance: |
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- <stdbool.h> must be #included before 'bool', 'false', 'true' |
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can be used. |
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- You cannot assume that sizeof (bool) == 1. |
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- Programs should not undefine the macros bool, true, and false, |
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as C99 lists that as an "obsolescent feature". |
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Limitations of this substitute, when used in a C89 environment: |
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- <stdbool.h> must be #included before the '_Bool' type can be used. |
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- You cannot assume that _Bool is a typedef; it might be a macro. |
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- Bit-fields of type 'bool' are not supported. Portable code |
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should use 'unsigned int foo : 1;' rather than 'bool foo : 1;'. |
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- In C99, casts and automatic conversions to '_Bool' or 'bool' are |
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performed in such a way that every nonzero value gets converted |
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to 'true', and zero gets converted to 'false'. This doesn't work |
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with this substitute. With this substitute, only the values 0 and 1 |
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give the expected result when converted to _Bool' or 'bool'. |
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- C99 allows the use of (_Bool)0.0 in constant expressions, but |
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this substitute cannot always provide this property. |
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Also, it is suggested that programs use 'bool' rather than '_Bool'; |
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this isn't required, but 'bool' is more common. */ |
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/* 7.16. Boolean type and values */ |
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/* BeOS <sys/socket.h> already #defines false 0, true 1. We use the same |
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definitions below, but temporarily we have to #undef them. */ |
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#if defined __BEOS__ && !defined __HAIKU__ |
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# include <OS.h> /* defines bool but not _Bool */ |
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# undef false |
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# undef true |
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#endif |
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#ifdef __cplusplus |
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# define _Bool bool |
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# define bool bool |
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#else |
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# if defined __BEOS__ && !defined __HAIKU__ |
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/* A compiler known to have 'bool'. */ |
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/* If the compiler already has both 'bool' and '_Bool', we can assume they |
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are the same types. */ |
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# if !@HAVE__BOOL@ |
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typedef bool _Bool; |
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# endif |
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# else |
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# if !defined __GNUC__ |
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/* If @HAVE__BOOL@: |
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Some HP-UX cc and AIX IBM C compiler versions have compiler bugs when |
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the built-in _Bool type is used. See |
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http://gcc.gnu.org/ml/gcc-patches/2003-12/msg02303.html |
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http://lists.gnu.org/archive/html/bug-coreutils/2005-11/msg00161.html |
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http://lists.gnu.org/archive/html/bug-coreutils/2005-10/msg00086.html |
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Similar bugs are likely with other compilers as well; this file |
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wouldn't be used if <stdbool.h> was working. |
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So we override the _Bool type. |
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If !@HAVE__BOOL@: |
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Need to define _Bool ourselves. As 'signed char' or as an enum type? |
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Use of a typedef, with SunPRO C, leads to a stupid |
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"warning: _Bool is a keyword in ISO C99". |
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Use of an enum type, with IRIX cc, leads to a stupid |
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"warning(1185): enumerated type mixed with another type". |
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Even the existence of an enum type, without a typedef, |
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"Invalid enumerator. (badenum)" with HP-UX cc on Tru64. |
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The only benefit of the enum, debuggability, is not important |
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with these compilers. So use 'signed char' and no enum. */ |
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# define _Bool signed char |
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# else |
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/* With this compiler, trust the _Bool type if the compiler has it. */ |
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# if !@HAVE__BOOL@ |
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/* For the sake of symbolic names in gdb, define true and false as |
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enum constants, not only as macros. |
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It is tempting to write |
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typedef enum { false = 0, true = 1 } _Bool; |
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so that gdb prints values of type 'bool' symbolically. But then |
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values of type '_Bool' might promote to 'int' or 'unsigned int' |
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(see ISO C 99 6.7.2.2.(4)); however, '_Bool' must promote to 'int' |
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(see ISO C 99 6.3.1.1.(2)). So add a negative value to the |
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enum; this ensures that '_Bool' promotes to 'int'. */ |
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typedef enum { _Bool_must_promote_to_int = -1, false = 0, true = 1 } _Bool; |
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# endif |
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# endif |
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# endif |
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# define bool _Bool |
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#endif |
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/* The other macros must be usable in preprocessor directives. */ |
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#ifdef __cplusplus |
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# define false false |
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# define true true |
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#else |
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# define false 0 |
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# define true 1 |
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#endif |
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#define __bool_true_false_are_defined 1 |
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#endif /* _GL_STDBOOL_H */
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