Messages in this thread | | | Date | Wed, 7 Oct 2015 08:57:47 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 1/2] linux/kconfig.h: generalize IS_ENABLED logic |
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* Rasmus Villemoes <linux@rasmusvillemoes.dk> wrote:
> +#define _COMMA , > +#define _COND_PUNCTUATION_0(p) > +#define _COND_PUNCTUATION_1(p) p > + > +#define CHOOSE_EXPR(cfg, expr, ...) _CHOOSE_EXPR(cfg, expr, ##__VA_ARGS__, /* empty defalt arg */) > +#define _CHOOSE_EXPR(cfg, expr, def, ...) __CHOOSE_EXPR(__ARG_PLACEHOLDER_##cfg, expr, def) > +#define __CHOOSE_EXPR(arg1_or_junk, expr, def) ___CHOOSE_EXPR(arg1_or_junk expr, def) > +#define ___CHOOSE_EXPR(__ignored, expr, ...) expr > + > +#define COND_DECLARATION(cfg, decl) _COND_DECLARATION(cfg, decl, CHOOSE_EXPR(cfg, 1, 0)) > +#define _COND_DECLARATION(cfg, decl, sfx) __COND_DECLARATION(cfg, decl, sfx) > +#define __COND_DECLARATION(cfg, decl, sfx) CHOOSE_EXPR(cfg, decl) _COND_PUNCTUATION_##sfx(;) > +#define COND_INITIALIZER(cfg, init) _COND_INITIALIZER(cfg, init, CHOOSE_EXPR(cfg, 1, 0)) > +#define _COND_INITIALIZER(cfg, init, sfx) __COND_INITIALIZER(cfg, init, sfx) > +#define __COND_INITIALIZER(cfg, init, sfx) CHOOSE_EXPR(cfg, init) _COND_PUNCTUATION_##sfx(_COMMA)
Pet peeve, mind structuring this in a typographically more readable fashion, by adding some common-sense vertical structure to the definitions:
#define CHOOSE_EXPR(cfg, expr, ...) _CHOOSE_EXPR(cfg, expr, ##__VA_ARGS__, /* empty defalt arg */) #define _CHOOSE_EXPR(cfg, expr, def, ...) __CHOOSE_EXPR(__ARG_PLACEHOLDER_##cfg, expr, def) #define __CHOOSE_EXPR(arg1_or_junk, expr, def) ___CHOOSE_EXPR(arg1_or_junk expr, def) #define ___CHOOSE_EXPR(__ignored, expr, ...) expr
#define COND_DECLARATION(cfg, decl) _COND_DECLARATION(cfg, decl, CHOOSE_EXPR(cfg, 1, 0)) #define _COND_DECLARATION(cfg, decl, sfx) __COND_DECLARATION(cfg, decl, sfx) #define __COND_DECLARATION(cfg, decl, sfx) CHOOSE_EXPR(cfg, decl) _COND_PUNCTUATION_##sfx(;)
#define COND_INITIALIZER(cfg, init) _COND_INITIALIZER(cfg, init, CHOOSE_EXPR(cfg, 1, 0)) #define _COND_INITIALIZER(cfg, init, sfx) __COND_INITIALIZER(cfg, init, sfx) #define __COND_INITIALIZER(cfg, init, sfx) CHOOSE_EXPR(cfg, init) _COND_PUNCTUATION_##sfx(_COMMA)
?
It's still a mouthful, but at least readable at a glance.
Thanks,
Ingo
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