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Add MSVC support by using a DEFER macro and increasing the evaluation depth. #7

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Add MSVC support by using a DEFER macro and increasing the evaluation depth. #7

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07f39ec
Added macros MAP_UD, MAP_LIST_UD, MAP_UD_I, MAP_LIST_UD_I.
Erlkoenig90 Mar 17, 2018
37c567d
Add MSVC support by using a DEFER macro and increasing the evaluation…
Erlkoenig90 Mar 23, 2018
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18 changes: 17 additions & 1 deletion README.md
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Expand Up @@ -134,7 +134,23 @@ Other interesting combinations include:

Special thanks to [pfultz2](https://github.com/pfultz2/Cloak/wiki/Is-the-C-preprocessor-Turing-complete%3F) for inventing the EVAL idea.

## Usage

The [map.h](map.h) file defines several "map"-style macros for different use cases. The [example.c](example.c) file shows how to use them. A quick overview is:

C-Code | Evaluates to
-------| ------------
MAP(f,a,b,c) | f(a) f(b) f(c)
MAP_LIST(f,a,b,c) | f(a), f(b), f(c)
MAP_UD(f,x,a,b,c) | f(a,x) f(b,x) f(c,x)
MAP_LIST_UD(f,x,a,b,c) | f(a,x), f(b,x), f(c,x)
MAP_UD_I(f,x,a,b,c) | f(a,x,0) f(b,x,1) f(c,x,2)
MAP_LIST_UD_I(f,x,a,b,c) | f(a,x,0), f(b,x,1), f(c,x,2)

The maximum number of variadic arguments for all macros is 365.

## See Also

C++ users may be intersted in the ['visit_struct' library](https://github.com/cbeck88/visit_struct),
which uses a version of this macro to implement structure visitors in C++11.
which uses a version of this macro to implement structure visitors in C++11. The ['µSer' library](https://github.com/Erlkoenig90/uSer)
uses another variant to define serializable structs in C++17.
16 changes: 16 additions & 0 deletions example.c
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Expand Up @@ -18,3 +18,19 @@ MAP(CALL, ('a'), ('b'), ('c'))
/* Test `MAP_LIST` with parentheses in the arguments: */
#define CALL_LIST(x) putchar x
MAP_LIST(CALL_LIST, ('a'), ('b'), ('c'));

/* Pass user-defined data to each invocation */
#define PRINT_STREAM(x, stream) fprintf (stream, "%d\n", x);
MAP_UD(PRINT_STREAM, stderr, 1, 2, 3, 4, 5)

/* Pass user-defined data to each list invocation */
#define INVOKE(x, fun) fun(x)
int arr [] = { MAP_LIST_UD(INVOKE, map, 1, 2, 3, 4, 5) };

/* Pass user-defined data and an index to each invocation */
#define PRINT_STREAM_I(x, stream, index) fprintf (stream, "%d: %d\n", index, x);
MAP_UD_I(PRINT_STREAM_I, stderr, 1, 2, 3, 4, 5)

/* Pass user-defined data and an index to each list invocation */
#define INVOKE_I(x, fun, index) fun(index, x)
int arr2 [] = { MAP_LIST_UD_I(INVOKE_I, map2, 1, 2, 3, 4, 5) };
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