variadics.h File Reference

Variadic arguments: x, y, z. More...

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Macros
#define	ML99_variadicsCount(...)
	Computes a count of its arguments.
#define	ML99_variadicsIsSingle(...)
	Tells if it received only one argument or not.
#define	ML99_variadicsGet(i)
	Expands to a metafunction extracting the i -indexed argument.
#define	ML99_variadicsTail(...)
	Extracts the tail of its arguments.
#define	ML99_variadicsForEach(f, ...)
	Applies f to each argument.
#define	ML99_variadicsForEachI(f, ...)
	Applies f to each argument with an index.
#define	ML99_OVERLOAD(f, ...)
	Overloads f on a number of arguments.
#define	ML99_VARIADICS_COUNT(...)
#define	ML99_VARIADICS_IS_SINGLE(...)
#define	ML99_VARIADICS_GET(i)
#define	ML99_VARIADICS_TAIL(...)

Detailed Description

Variadic arguments: x, y, z.

Note

Variadics are more time and space-efficient than lists, but export less functionality; if a needed function is missed, invoking ML99_list and then manipulating with the resulting Cons-list might be helpful.

Macro Definition Documentation

ML99_OVERLOAD

#define ML99_OVERLOAD	(		f,
			... )

Value:

ML99_PRIV_CAT(f, ML99_PRIV_VARIADICS_COUNT(__VA_ARGS__))(__VA_ARGS__)

Overloads f on a number of arguments.

This function counts the number of provided arguments, appends it to f and calls the resulting macro identifier with provided arguments.

At most 63 variadic arguments are acceptable.

Examples

#include <metalang99/variadics.h>
 
#define X(...)    ML99_OVERLOAD(X_, __VA_ARGS__)
#define X_1(a)    Billie & a
#define X_2(a, b) Jean & a & b
 
// Billie & 4
X(4)
 
// Jean & 5 & 6
X(5, 6)

Note

f need not be postfixed with _IMPL. It is literally invoked as ML99_CAT(f, ML99_VARIADICS_COUNT(...))(...).

ML99_VARIADICS_COUNT

#define ML99_VARIADICS_COUNT

(

...

)

Value:

ML99_PRIV_VARIADICS_COUNT(__VA_ARGS__)

ML99_VARIADICS_GET

#define ML99_VARIADICS_GET

(

i

)

Value:

ML99_PRIV_CAT(ML99_PRIV_VARIADICS_GET_, i)

ML99_VARIADICS_IS_SINGLE

#define ML99_VARIADICS_IS_SINGLE

(

...

)

Value:

ML99_PRIV_NOT(ML99_PRIV_CONTAINS_COMMA(__VA_ARGS__))

ML99_VARIADICS_TAIL

#define ML99_VARIADICS_TAIL

(

...

)

Value:

ML99_PRIV_TAIL(__VA_ARGS__)

ML99_variadicsCount

#define ML99_variadicsCount

(

...

)

Value:

ML99_call(ML99_variadicsCount, __VA_ARGS__)

Computes a count of its arguments.

At most 63 arguments are acceptable.

Examples

#include <metalang99/variadics.h>
 
// 3
ML99_variadicsCount(v(~, ~, ~))
 
// 1
ML99_variadicsCount()

ML99_variadicsForEach

#define ML99_variadicsForEach	(		f,
			... )

Value:

ML99_call(ML99_variadicsForEach, f, __VA_ARGS__)

Applies f to each argument.

The result is ML99_appl(f, x1) ... ML99_appl(f, xN).

Examples

#include <metalang99/variadics.h>
 
#define F_IMPL(x) v(@x)
#define F_ARITY   1
 
// @x @y @z
ML99_variadicsForEach(v(F), v(x, y, z))

ML99_variadicsForEachI

#define ML99_variadicsForEachI	(		f,
			... )

Value:

ML99_call(ML99_variadicsForEachI, f, __VA_ARGS__)

Applies f to each argument with an index.

The result is ML99_appl2(f, x1, 0) ... ML99_appl2(f, xN, N - 1).

#include <metalang99/variadics.h>
 
#define F_IMPL(x, i) v(@x##i)
#define F_ARITY      2
 
// @x0 @y1 @z2
ML99_variadicsForEachI(v(F), v(x, y, z))

ML99_variadicsGet

#define ML99_variadicsGet

(

i

)

Value:

ML99_PRIV_CAT(ML99_PRIV_variadicsGet_, i)

Expands to a metafunction extracting the i -indexed argument.

i can range from 0 to 7, inclusively.

Examples

#include <metalang99/variadics.h>
 
// 2
ML99_variadicsGet(1)(v(1, 2, 3))

ML99_variadicsIsSingle

#define ML99_variadicsIsSingle

(

...

)

Value:

ML99_call(ML99_variadicsIsSingle, __VA_ARGS__)

Tells if it received only one argument or not.

Examples

#include <metalang99/variadics.h>
 
// 1
ML99_variadicsIsSingle(v(~))
 
// 0
ML99_variadicsIsSingle(v(~, ~, ~))

ML99_variadicsTail

#define ML99_variadicsTail

(

...

)

Value:

ML99_call(ML99_variadicsTail, __VA_ARGS__)

Extracts the tail of its arguments.

At least two arguments must be specified.

Examples

#include <metalang99/variadics.h>
 
// 2, 3
ML99_variadicsTail(v(1, 2, 3))