VA_ARGS List Metaprogramming module

This module provides various macros for metaprogramming with VA_ARGS lists

Defines

#define PP_REVERSE_SEQUENCE_N(): Creates a comma separated reverse sequence from 127 to 0.
#define PP_NUM_ARGS(...): Returns the number of arguments passed in the __VA_ARGS__ parameter pack.
#define PP_NTH_ARG(N, ...): Returns the Nth argument from the __VA_ARGS__ parameter pack.
#define APPEND_TO_LIST(what, ...): Appends a space followed by what to each element of the __VA_ARGS__ parameter pack.
#define DELIMIT_LIST(what, ...): Applies a different delimiter to the list elements of the __VA_ARGS__ parameter pack.
#define APPLY_TO_LIST(what, ...): Calls what on the arguments in the parameter pack.
#define APPEND_EACH_TO_LIST(what, ...): Appends the Nth element in what to the Nth element in the __VA_ARGS__ parameter pack.
#define SELECTOR_LIST(N): Returns a numeric token (number prefixed by underscore, eg _1) representing the given number.
#define EMPTY(...): Converts any list of arguments into an empty list.
#define DEFER(...): Defers the preprocessing of the list of arguments one step.
#define EXPAND(...): Expands the list of arguments.
#define COMMA(...): Converts the list of arguments into a single comma.
#define CONTAINS_COMMA(...): Determines if the list of arguments contains a comma (contains more than one element)
#define FIRST(...): Returns the first element from the list.
#define SECOND(...): Returns the second element from the list.
#define SECOND_IMPL(first, second, ...): Returns the second element from the list.
#define REMOVE_FIRST(...): Removes the first element from the list, and returns the remaining elements.

Define documentation

#define PP_REVERSE_SEQUENCE_N()
#include <include/Cnx/mpl/ArgLists.h>

Creates a comma separated reverse sequence from 127 to 0.

Useful for macro meta-programming that requires determining the number of arguments passed in a __VA_ARGS__ pack

#define PP_NUM_ARGS(...)
#include <include/Cnx/mpl/ArgLists.h>

Returns the number of arguments passed in the __VA_ARGS__ parameter pack.

Parameters
...	- The `__VA_ARGS__` parameter pack to get the length of
Returns	The number of args in the parameter pack

Useful for macro meta-programming that requires determining the number of arguments passed in a parameter pack

#define PP_NTH_ARG(N, ...)
#include <include/Cnx/mpl/ArgLists.h>

Returns the Nth argument from the __VA_ARGS__ parameter pack.

Parameters
N	- The 1-indexed index of the argument to get
...	- The `__VA_ARGS__` parameter pack to index into
Returns	The Nth argument

#define APPEND_TO_LIST(what, ...)
#include <include/Cnx/mpl/ArgLists.h>

Appends a space followed by what to each element of the __VA_ARGS__ parameter pack.

Parameters
what	- The text/token/etc to append to each element of the `__VA_ARGS__` parameter pack
...	- The `__VA_ARGS__` parameter pack to modify
Returns	The modified `__VA_ARGS__` parameter pack

#define DELIMIT_LIST(what, ...)
#include <include/Cnx/mpl/ArgLists.h>

Applies a different delimiter to the list elements of the __VA_ARGS__ parameter pack.

Parameters
what	- The text/token/etc to delimit each element of the `__VA_ARGS__` parameter pack
...	- The `__VA_ARGS__` parameter pack to modify
Returns	The resulting text from changing the list delimiter

#define APPLY_TO_LIST(what, ...)
#include <include/Cnx/mpl/ArgLists.h>

Calls what on the arguments in the parameter pack.

Parameters
what	- The function or function-like macro to apply to the arguments in the pack
...	- The parameter pack to apply `what` to
Returns	The parameter pack, with `what` applied

Supports up to 12 arguments in the parameter pack. For every argument, what is called/applied on it in place in the pack, eg., what(x), what(y), where x and y are arguments in the pack. Example:

i32* add_one(i32* i) {
    ++(*i);
    return i;
}
i32 zero = 0, one = 1, two = 2;
// prints "1, 2, 3" to `stdout`
println("{}, {}, {}", APPLY_TO_LIST(&, APPLY_TO_LIST(add_one, &zero, &one, &two)));

This is most useful for applying a macro or function to a list of values before passing them into another macro or variadic function.

#define APPEND_EACH_TO_LIST(what, ...)
#include <include/Cnx/mpl/ArgLists.h>

Appends the Nth element in what to the Nth element in the __VA_ARGS__ parameter pack.

Parameters
what	- The 1-indexible macro generating the token(s) to append to the element in the `__VA_ARGS__` parameter pack with the associated index
...	- The `__VA_ARGS__` parameter pack to modify
Returns	The modified `__VA_ARGS__` parameter pack