mirror of
https://gitlab.labs.nic.cz/labs/bird.git
synced 2024-05-11 16:54:54 +00:00
906092534b
Included are Makefile implicit rules to show the preprocessed source. When debugging something around this, it may be handy.
99 lines
3.6 KiB
C
99 lines
3.6 KiB
C
/*
|
|
* BIRD Macro Tricks
|
|
*
|
|
* (c) 2018 Jan Maria Matejka <mq@jmq.cz>
|
|
*
|
|
* Can be freely distributed and used under the terms of the GNU GPL.
|
|
*
|
|
* Contains useful but dirty macro tricks:
|
|
* MACRO_CONCAT(a, b) -> concatenates a##b
|
|
* MACRO_BOOL(x) -> convert 0 to 0, anything else to 1
|
|
* MACRO_IFELSE(b)(true-branch)(false-branch)
|
|
* -> b shall be 0 or 1; expands to the appropriate branch
|
|
* MACRO_ISEMPTY(...) -> 1 for empty argument list, 0 otherwise
|
|
* MACRO_FOREACH(func, ...)
|
|
* -> calling FOREACH(func, a, b, c, d) expands to
|
|
* func(a) func(b) func(c) func(d)
|
|
* MACRO_RPACK(func, terminator, ...)
|
|
* -> packs the list into recursive calls:
|
|
* func(func(func(func(terminator, a), b), c), d)
|
|
*/
|
|
|
|
#ifndef _BIRD_MACRO_H_
|
|
#define _BIRD_MACRO_H_
|
|
|
|
/* What to do with args */
|
|
#define MACRO_DROP(...)
|
|
#define MACRO_UNPAREN(...) __VA_ARGS__
|
|
#define MACRO_SEP(a, b, sep) a sep b
|
|
|
|
/* Aliases for some special chars */
|
|
#define MACRO_COMMA ,
|
|
#define MACRO_LPAREN (
|
|
#define MACRO_RPAREN )
|
|
#define MACRO_LPAREN_() (
|
|
#define MACRO_RPAREN_() )
|
|
|
|
/* Multiple expansion trick */
|
|
#define MACRO_EXPAND0(...) __VA_ARGS__
|
|
#define MACRO_EXPAND1(...) MACRO_EXPAND0(MACRO_EXPAND0(__VA_ARGS__))
|
|
#define MACRO_EXPAND2(...) MACRO_EXPAND1(MACRO_EXPAND1(__VA_ARGS__))
|
|
#define MACRO_EXPAND3(...) MACRO_EXPAND2(MACRO_EXPAND2(__VA_ARGS__))
|
|
#define MACRO_EXPAND(...) MACRO_EXPAND3(MACRO_EXPAND3(__VA_ARGS__))
|
|
|
|
/* Deferring expansion in the expansion trick */
|
|
#define MACRO_EMPTY()
|
|
#define MACRO_DEFER(t) t MACRO_EMPTY()
|
|
#define MACRO_DEFER2(t) t MACRO_EMPTY MACRO_EMPTY()()
|
|
#define MACRO_DEFER3(t) t MACRO_EMPTY MACRO_EMPTY MACRO_EMPTY()()()
|
|
|
|
/* Token concatenation */
|
|
#define MACRO_CONCAT(prefix, ...) prefix##__VA_ARGS__
|
|
#define MACRO_CONCAT_AFTER(...) MACRO_CONCAT(__VA_ARGS__)
|
|
|
|
/* Get first or second argument only */
|
|
#define MACRO_FIRST(a, ...) a
|
|
#define MACRO_SECOND(a, b, ...) b
|
|
#define MACRO_SECOND_OR_ZERO(...) MACRO_SECOND(__VA_ARGS__, 0,)
|
|
|
|
/* Macro Boolean auxiliary macros */
|
|
#define MACRO_BOOL_CHECK_0 ~, 1
|
|
#define MACRO_BOOL_NEG(x) MACRO_SECOND_OR_ZERO(MACRO_CONCAT(MACRO_BOOL_CHECK_, x))
|
|
|
|
#define MACRO_BOOL_NOT_0 1
|
|
#define MACRO_BOOL_NOT_1 0
|
|
|
|
/* Macro Boolean negation */
|
|
#define MACRO_NOT(x) MACRO_CONCAT(MACRO_BOOL_NOT_, x)
|
|
|
|
/* Convert anything to bool (anything -> 1, 0 -> 0) */
|
|
#define MACRO_BOOL(x) MACRO_NOT(MACRO_BOOL_NEG(x))
|
|
|
|
/*
|
|
* Macro If/Else condition
|
|
* Usage: MACRO_IFELSE(condition)(true-branch)(false-branch)
|
|
* Expands to true-branch if condition is true, otherwise to false-branch.
|
|
*/
|
|
#define MACRO_IFELSE(b) MACRO_CONCAT(MACRO_IFELSE_, b)
|
|
#define MACRO_IFELSE_0(...) MACRO_UNPAREN
|
|
#define MACRO_IFELSE_1(...) __VA_ARGS__ MACRO_DROP
|
|
|
|
/* Auxiliary macros for MACRO_FOREACH */
|
|
#define MACRO_ISLAST(...) MACRO_BOOL_NEG(MACRO_FIRST(MACRO_ISLAST_CHECK __VA_ARGS__)())
|
|
#define MACRO_ISLAST_CHECK() 0
|
|
|
|
#define MACRO_FOREACH_EXPAND(call, a, ...) MACRO_IFELSE(MACRO_ISLAST(__VA_ARGS__))(call(a))(call(a) MACRO_DEFER2(MACRO_FOREACH_PAREN)()(call, __VA_ARGS__))
|
|
#define MACRO_FOREACH_PAREN() MACRO_FOREACH_EXPAND
|
|
|
|
#define MACRO_RPACK_EXPAND(call, terminator, a, ...) MACRO_IFELSE(MACRO_ISLAST(__VA_ARGS__))(call(terminator, a))(call(MACRO_DEFER2(MACRO_RPACK_PAREN)()(call, terminator, __VA_ARGS__), a))
|
|
#define MACRO_RPACK_PAREN() MACRO_RPACK_EXPAND
|
|
/*
|
|
* Call the first argument for each following:
|
|
* MACRO_FOREACH(func, a, b, c, d) expands to func(a) func(b) func(c) func(d).
|
|
* It supports also macros as func.
|
|
*/
|
|
#define MACRO_FOREACH(call, ...) MACRO_EXPAND(MACRO_FOREACH_EXPAND(call, __VA_ARGS__))
|
|
#define MACRO_RPACK(call, terminator, ...) MACRO_EXPAND(MACRO_RPACK_EXPAND(call, terminator, __VA_ARGS__))
|
|
|
|
#endif
|