va_pp.h

#include <va_pp.h>

Defines

VA_DO_STRINGIZE(arg)

VA_STRINGIZE(arg)

Converts the argument to a string.

const char* name = VA_STRINGIZE(ClassName);
// const char* name == "ClassName";

VA_DO_JOIN(a, b)

VA_JOIN(a, b)

Joins arguments a and b.

struct VA_JOIN(Class, Name);
// struct ClassName.

VA_DO_JOIN3(a, b, c)

VA_DO_JOIN4(a, b, c, d)

VA_DO_JOIN5(a, b, c, d, e)

VA_JOIN3(a, b, c)

Joins arguments a, b and c to form abc.

See

VA_JOIN

VA_JOIN4(a, b, c, d)

Joins arguments a, b, c and d to form abcd.

See

VA_JOIN

VA_JOIN5(a, b, c, d, e)

Joins arguments a, b, c, d and e to form abcde.

See

VA_JOIN

VA_COMMA()

Expands to a comma (,).

VA_LPAREN()

Expands to a left parenthesis.

VA_RPAREN()

Expands to a right parenthesis.

VA_EXPAND(PARAM)

Expands to PARAM.

This macro is useful if you need to format the arguments of a macro using another macro.

#define PRINTF(FORMAT, ARG1, ARG2) printf(FORMAT, ARG1, ARG2);

#define ARGS1 "%s%d", "abc"
#define ARGS2 1

#define CALL(MACRO) VA_EXPAND(MACRO VA_LPAREN() ARGS1 VA_COMMA() ARGS2 VA_RPAREN())

CALL(PRINTF);
// expands to
// printf ("%s%d", "abc", 1);

VA_REMOVE_PARENS(N, PARAMS)

Remove parentheses around PARAMS.

The number of comma-separated elements in PARAMS must be N.

VA_REMOVE_PARENS(3, (a, b, c))
// Expands to a, b, c

VA_FOR_N(MACRO, N, ELEMENTS)

Repeats MACRO for each of the N elements in ELEMENTS.

MACRO will be called with two parameters: the (zero-based) index of the current element and the element.

#define PRINTF(N, X) printf(#X);

VA_FOR_N(PRINTF, 3, (a, b, c))
// Expands to
// printf("a"); printf("b"); printf("c");

VA_FOR_N_ARG(MACRO, ARG, N, ELEMENTS)

Same as [VA_FOR_N], but passes ARG(N) as the first parameter to MACRO instead of N.

#define MYMACRO(A, B) A B;

VA_FOR_N_ARG(MYMACRO, int VA_NULL, 3, (a, b, c));
// Expands to
// int a; int b; int c;

VA_FOR_N_SEP(MACRO, SEPARATOR, N, ELEMENTS)

Repeats MACRO for each of the N elements in ELEMENTS, placing SEPARATOR(N) between each element.

SEPARATOR will be called with one parameter: the (zero-based) index of the current element and the element itself. Use VA_COMMA_SEP to place a comma between elements.

#define MYMACRO(N, X) i##X = N

int VA_FOR_N_SEP(MYMACRO, VA_COMMA_SEP, 3, (a, b, c));
// Expands to
// int ia = 0 , ib = 1 , ic = 2;

VA_FOR_N_SEP_ARG(MACRO, SEPARATOR, ARG, N, ELEMENTS)

Same as [VA_FOR_N_SEP], but passes ARG(N) as the first parameter to MACRO instead of N.

VA_REPEAT_N(MACRO, N)

Repeats MACRO N times.

The expanded result is MACRO(0) MACRO(1) ... MACRO(N-1).

VA_NULL(N)

VA_COMMA_SEP(N)

VA_1ST_ARG(_1, ...)

VA_REST_ARGS(_1, ...)

VA_2ND_ARG(_1, _2, ...)

VA_3RD_ARG(_1, _2, _3, ...)

VA_INDIRECT(MACRO, ARGS)

VA_EVAL(...)

Evaluates up to 243 levels of deferred macros.

Since the C preprocessor cannot evaluate macros recursively, one must instead defer the evaluation of a recursive macro call and then force another pass using this macro.

#define A() 123
A() // 123
VA_DEFER(A)() // A()
VA_EVAL(VA_DEFER(A)()) // 123

VA_EVAL1(...)

VA_EVAL2(...)

VA_EVAL3(...)

VA_EVAL4(...)

VA_EVAL5(...)

VA_EMPTY()

VA_DEFER(X)

Defers the expansion of X.

Can be used with VA_EVAL to implement recursive macros.

VA_ARGS_EXPAND(X)

VA_NARGS(...)

Expands to the number of variable arguments.

The maximum allowed number of arguments is 64.

VA_NARGS(1)    // 1
VA_NARGS(a, b) // 2

VA_DO_NARGS(...)

VA_ARGS_N(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, _41, _42, _43, _44, _45, _46, _47, _48, _49, _50, _51, _52, _53, _54, _55, _56, _57, _58, _59, _60, _61, _62, _63, N, ...)

VA_RSEQ_64()

VA_FOR(MACRO, ELEMENTS)

For loop macros for C preprocessors that support variadic macros.

VA_FOR_SEP(MACRO, SEPARATOR, ELEMENTS)

VA_FOR_ARG(MACRO, ARG, ELEMENTS)

VA_FOR_SEP_ARG(MACRO, SEPARATOR, ARG, ELEMENTS)