Preprocessor.h File Reference

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Macros
#define	FB_VA_GLUE(a, b)   a b
#define	FB_ONE_OR_NONE(a, ...)   FB_VA_GLUE(FB_THIRD, (a, ##__VA_ARGS__, a))
#define	FB_THIRD(a, b, ...)   __VA_ARGS__
#define	FB_ARG_1(a, ...)   a
#define	FB_ARG_2_OR_1(...)   FB_ARG_2_OR_1_IMPL(__VA_ARGS__, __VA_ARGS__)
#define	FB_ARG_2_OR_1_IMPL(a, b, ...)   b
#define	FB_SINGLE_ARG(...)   __VA_ARGS__
#define	FOLLY_PP_DETAIL_APPEND_VA_ARG(...)   , ##__VA_ARGS__
#define	FOLLY_IGNORE(...)
#define	FOLLY_SEMICOLON(...)   ;
#define	FB_CONCATENATE_IMPL(s1, s2)   s1##s2
#define	FB_CONCATENATE(s1, s2)   FB_CONCATENATE_IMPL(s1, s2)
#define	FB_ANONYMOUS_VARIABLE(str)   FB_CONCATENATE(str, __LINE__)
#define	FB_STRINGIZE(x)   #x
#define	FOLLY_PP_DETAIL_NARGS_1(dummy, _7, _6, _5, _4, _3, _2, _1, _0, ...)   _0
#define	FOLLY_PP_DETAIL_NARGS(...)   FOLLY_PP_DETAIL_NARGS_1(dummy, ##__VA_ARGS__, 7, 6, 5, 4, 3, 2, 1, 0)
#define	FOLLY_PP_DETAIL_FOR_EACH_REC_0(fn, ...)
#define	FOLLY_PP_DETAIL_FOR_EACH_REC_1(fn, a, ...)   fn(a) FOLLY_PP_DETAIL_FOR_EACH_REC_0(fn, __VA_ARGS__)
#define	FOLLY_PP_DETAIL_FOR_EACH_REC_2(fn, a, ...)   fn(a) FOLLY_PP_DETAIL_FOR_EACH_REC_1(fn, __VA_ARGS__)
#define	FOLLY_PP_DETAIL_FOR_EACH_REC_3(fn, a, ...)   fn(a) FOLLY_PP_DETAIL_FOR_EACH_REC_2(fn, __VA_ARGS__)
#define	FOLLY_PP_DETAIL_FOR_EACH_REC_4(fn, a, ...)   fn(a) FOLLY_PP_DETAIL_FOR_EACH_REC_3(fn, __VA_ARGS__)
#define	FOLLY_PP_DETAIL_FOR_EACH_REC_5(fn, a, ...)   fn(a) FOLLY_PP_DETAIL_FOR_EACH_REC_4(fn, __VA_ARGS__)
#define	FOLLY_PP_DETAIL_FOR_EACH_REC_6(fn, a, ...)   fn(a) FOLLY_PP_DETAIL_FOR_EACH_REC_5(fn, __VA_ARGS__)
#define	FOLLY_PP_DETAIL_FOR_EACH_REC_7(fn, a, ...)   fn(a) FOLLY_PP_DETAIL_FOR_EACH_REC_6(fn, __VA_ARGS__)
#define	FOLLY_PP_DETAIL_FOR_EACH_2(fn, n, ...)   FOLLY_PP_DETAIL_FOR_EACH_REC_##n(fn, __VA_ARGS__)
#define	FOLLY_PP_DETAIL_FOR_EACH_1(fn, n, ...)   FOLLY_PP_DETAIL_FOR_EACH_2(fn, n, __VA_ARGS__)
#define	FOLLY_PP_FOR_EACH(fn, ...)

Macro Definition Documentation

#define FB_ANONYMOUS_VARIABLE

(

str

)

FB_CONCATENATE(str, __LINE__)

Definition at line 92 of file Preprocessor.h.

#define FB_ARG_1	(		a,
			...
	)		a

Helper macro that extracts the first argument out of a list of any number of arguments.

Definition at line 41 of file Preprocessor.h.

#define FB_ARG_2_OR_1

(

...

)

FB_ARG_2_OR_1_IMPL(__VA_ARGS__, __VA_ARGS__)

Helper macro that extracts the second argument out of a list of any number of arguments. If only one argument is given, it returns that.

Definition at line 54 of file Preprocessor.h.

Referenced by folly::sync_tests::testDeprecated().

#define FB_ARG_2_OR_1_IMPL	(		a,
			b,
			...
	)		b

Definition at line 57 of file Preprocessor.h.

#define FB_CONCATENATE	(		s1,
			s2
	)		FB_CONCATENATE_IMPL(s1, s2)

Definition at line 88 of file Preprocessor.h.

#define FB_CONCATENATE_IMPL	(		s1,
			s2
	)		s1##s2

FB_ANONYMOUS_VARIABLE(str) introduces an identifier starting with str and ending with a number that varies with the line.

Definition at line 87 of file Preprocessor.h.

#define FB_ONE_OR_NONE	(		a,
			...
	)		FB_VA_GLUE(FB_THIRD, (a, ##__VA_ARGS__, a))

FB_ONE_OR_NONE(hello, world) expands to hello and FB_ONE_OR_NONE(hello) expands to nothing. This macro is used to insert or eliminate text based on the presence of another argument.

Definition at line 34 of file Preprocessor.h.

#define FB_SINGLE_ARG

(

...

)

__VA_ARGS__

Helper macro that provides a way to pass argument with commas in it to some other macro whose syntax doesn't allow using extra parentheses. Example:

#define MACRO(type, name) type name MACRO(FB_SINGLE_ARG(std::pair<size_t, size_t>), x);

Definition at line 68 of file Preprocessor.h.

#define FB_STRINGIZE

(

x

)

#x

Use FB_STRINGIZE(x) when you'd want to do what x does inside another macro expansion.

Definition at line 100 of file Preprocessor.h.

#define FB_THIRD	(		a,
			b,
			...
	)		__VA_ARGS__

Definition at line 35 of file Preprocessor.h.

#define FB_VA_GLUE	(		a,
			b
	)		a b

Necessarily evil preprocessor-related amenities.

Definition at line 27 of file Preprocessor.h.

#define FOLLY_IGNORE

(

...

)

Helper macro that just ignores its parameters.

Definition at line 75 of file Preprocessor.h.

#define FOLLY_PP_DETAIL_APPEND_VA_ARG

(

...

)

, ##__VA_ARGS__

Definition at line 70 of file Preprocessor.h.

#define FOLLY_PP_DETAIL_FOR_EACH_1	(		fn,
			n,
			...
	)		FOLLY_PP_DETAIL_FOR_EACH_2(fn, n, __VA_ARGS__)

Definition at line 124 of file Preprocessor.h.

#define FOLLY_PP_DETAIL_FOR_EACH_2	(		fn,
			n,
			...
	)		FOLLY_PP_DETAIL_FOR_EACH_REC_##n(fn, __VA_ARGS__)

Definition at line 122 of file Preprocessor.h.

#define FOLLY_PP_DETAIL_FOR_EACH_REC_0	(		fn,
			...
	)

Definition at line 106 of file Preprocessor.h.

#define FOLLY_PP_DETAIL_FOR_EACH_REC_1	(		fn,
			a,
			...
	)		fn(a) FOLLY_PP_DETAIL_FOR_EACH_REC_0(fn, __VA_ARGS__)

Definition at line 107 of file Preprocessor.h.

#define FOLLY_PP_DETAIL_FOR_EACH_REC_2	(		fn,
			a,
			...
	)		fn(a) FOLLY_PP_DETAIL_FOR_EACH_REC_1(fn, __VA_ARGS__)

Definition at line 109 of file Preprocessor.h.

#define FOLLY_PP_DETAIL_FOR_EACH_REC_3	(		fn,
			a,
			...
	)		fn(a) FOLLY_PP_DETAIL_FOR_EACH_REC_2(fn, __VA_ARGS__)

Definition at line 111 of file Preprocessor.h.

#define FOLLY_PP_DETAIL_FOR_EACH_REC_4	(		fn,
			a,
			...
	)		fn(a) FOLLY_PP_DETAIL_FOR_EACH_REC_3(fn, __VA_ARGS__)

Definition at line 113 of file Preprocessor.h.

#define FOLLY_PP_DETAIL_FOR_EACH_REC_5	(		fn,
			a,
			...
	)		fn(a) FOLLY_PP_DETAIL_FOR_EACH_REC_4(fn, __VA_ARGS__)

Definition at line 115 of file Preprocessor.h.

#define FOLLY_PP_DETAIL_FOR_EACH_REC_6	(		fn,
			a,
			...
	)		fn(a) FOLLY_PP_DETAIL_FOR_EACH_REC_5(fn, __VA_ARGS__)

Definition at line 117 of file Preprocessor.h.

#define FOLLY_PP_DETAIL_FOR_EACH_REC_7	(		fn,
			a,
			...
	)		fn(a) FOLLY_PP_DETAIL_FOR_EACH_REC_6(fn, __VA_ARGS__)

Definition at line 119 of file Preprocessor.h.

#define FOLLY_PP_DETAIL_NARGS

(

...

)

FOLLY_PP_DETAIL_NARGS_1(dummy, ##__VA_ARGS__, 7, 6, 5, 4, 3, 2, 1, 0)

Definition at line 103 of file Preprocessor.h.

#define FOLLY_PP_DETAIL_NARGS_1	(		dummy,
			_7,
			_6,
			_5,
			_4,
			_3,
			_2,
			_1,
			_0,
			...
	)		_0

Definition at line 102 of file Preprocessor.h.

#define FOLLY_PP_FOR_EACH	(		fn,
			...
	)

Value:

FOLLY_PP_DETAIL_FOR_EACH_1(      \
      fn, FOLLY_PP_DETAIL_NARGS(__VA_ARGS__), __VA_ARGS__)

FOLLY_PP_FOR_EACH

Used to invoke a preprocessor macro, the name of which is passed as the first argument, once for each subsequent variadic argument.

At present, supports [0, 8) arguments.

This input:

#define DOIT(a) go_do_it(a); FOLLY_PP_FOR_EACH(DOIT, 3, 5, 7) #undef DOIT

Expands to this output (with whitespace adjusted for clarity):

go_do_it(3); go_do_it(5); go_do_it(7);

Definition at line 147 of file Preprocessor.h.

#define FOLLY_SEMICOLON

(

...

)

;

Helper macro that just ignores its parameters and inserts a semicolon.

Definition at line 80 of file Preprocessor.h.