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util.h: add MACRO_MAP_CAT() and MACRO_MAP_CAT_N()

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This is like MACRO_MAP(), but it pastes the results together into a
single token. The result is kind of a fold of the ## operator.

I wasn't able to figure out a way to implement this using any of the
existing macros, so there's some more copy/pasting of handler macros
for different numbers of arguments.

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>
This commit is contained in:
Martí Bolívar 2020-02-26 20:48:05 -08:00 • committed by Kumar Gala
commit 7b2376b72e
1 changed files with 58 additions and 0 deletions
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58
include/sys/util.h
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@ -830,6 +830,64 @@ u8_t u8_to_dec(char *buf, u8_t buflen, u8_t value);
#define MACRO_MAP_13(macro, a, ...) macro(a)MACRO_MAP_12(macro, __VA_ARGS__,)
#define MACRO_MAP_14(macro, a, ...) macro(a)MACRO_MAP_13(macro, __VA_ARGS__,)
#define MACRO_MAP_15(macro, a, ...) macro(a)MACRO_MAP_14(macro, __VA_ARGS__,)
/**
* @brief Mapping macro that pastes results together
*
* Like @ref MACRO_MAP(), but pastes the results together into a
* single token by repeated application of @ref UTIL_CAT().
*
* For example, with this macro FOO:
*
* #define FOO(x) item_##x##_
*
* MACRO_MAP_CAT(FOO, a, b, c) expands to the token:
*
* item_a_item_b_item_c_
*
* @param ... Macro to expand on each argument, followed by its
* arguments. (The macro should take exactly one argument.)
* @return The results of expanding the macro on each argument, all pasted
* together
*/
#define MACRO_MAP_CAT(...) MACRO_MAP_CAT_(__VA_ARGS__)
#define MACRO_MAP_CAT_(...) \
/* To make sure it works also for 2 arguments in total */ \
MACRO_MAP_CAT_N(NUM_VA_ARGS_LESS_1(__VA_ARGS__), __VA_ARGS__)
/**
* @brief Mapping macro that pastes a fixed number of results together
*
* Similar to @ref MACRO_MAP_CAT(), but expects a fixed number of
* arguments. If more arguments are given than are expected, the rest
* are ignored.
*
* @param N Number of arguments to map
* @param ... Macro to expand on each argument, followed by its
* arguments. (The macro should take exactly one argument.)
* @return The results of expanding the macro on each argument, all pasted
* together
*/
#define MACRO_MAP_CAT_N(N, ...) MACRO_MAP_CAT_N_(N, __VA_ARGS__)
#define MACRO_MAP_CAT_N_(N, ...) UTIL_CAT(MACRO_MC_, N)(__VA_ARGS__,)
#define MACRO_MC_0(...)
#define MACRO_MC_1(m, a, ...) m(a)
#define MACRO_MC_2(m, a, ...) UTIL_CAT(m(a), MACRO_MC_1(m, __VA_ARGS__,))
#define MACRO_MC_3(m, a, ...) UTIL_CAT(m(a), MACRO_MC_2(m, __VA_ARGS__,))
#define MACRO_MC_4(m, a, ...) UTIL_CAT(m(a), MACRO_MC_3(m, __VA_ARGS__,))
#define MACRO_MC_5(m, a, ...) UTIL_CAT(m(a), MACRO_MC_4(m, __VA_ARGS__,))
#define MACRO_MC_6(m, a, ...) UTIL_CAT(m(a), MACRO_MC_5(m, __VA_ARGS__,))
#define MACRO_MC_7(m, a, ...) UTIL_CAT(m(a), MACRO_MC_6(m, __VA_ARGS__,))
#define MACRO_MC_8(m, a, ...) UTIL_CAT(m(a), MACRO_MC_7(m, __VA_ARGS__,))
#define MACRO_MC_9(m, a, ...) UTIL_CAT(m(a), MACRO_MC_8(m, __VA_ARGS__,))
#define MACRO_MC_10(m, a, ...) UTIL_CAT(m(a), MACRO_MC_9(m, __VA_ARGS__,))
#define MACRO_MC_11(m, a, ...) UTIL_CAT(m(a), MACRO_MC_10(m, __VA_ARGS__,))
#define MACRO_MC_12(m, a, ...) UTIL_CAT(m(a), MACRO_MC_11(m, __VA_ARGS__,))
#define MACRO_MC_13(m, a, ...) UTIL_CAT(m(a), MACRO_MC_12(m, __VA_ARGS__,))
#define MACRO_MC_14(m, a, ...) UTIL_CAT(m(a), MACRO_MC_13(m, __VA_ARGS__,))
#define MACRO_MC_15(m, a, ...) UTIL_CAT(m(a), MACRO_MC_14(m, __VA_ARGS__,))
/*
* The following provides variadic preprocessor macro support to
* help eliminate multiple, repetitive function/macro calls. This