How to use multiple macros inside macros in Rust? - rust

Question

I’d like to have a code that supposed to achieve this in end.
counters!(NAME1, “unit1”, NAME2, “unit2”)
// generates
const NAME1 = 0;
const NAME2 = 1;
static mut counters = [AtomicUsize::new(0), AtomicUsize::new(0)];
static units = [“unit1”, “unit2”];
So far I’ve been able to create indices names and the array of arbitrary values, but I have troubles combining this things together.
playgound link
use std::sync::atomic::AtomicUsize;
macro_rules! gen_array {
($out:expr; ) => { $out };
([$($out:tt)*]; $name:ident, $($names:tt)*) => {
gen_array!([$($out)* $name,]; $($names)*)
};
}
macro_rules! gen_vars {
($cnt:expr; ) => {};
($cnt:expr; $name:ident, $($names:tt)*) => {
const $name: usize = $cnt;
gen_vars!($cnt + 1; $($names)*)
};
}
macro_rules! counters {
($($name:ident),+) => {
gen_vars!(0; $($name),+,);
gen_array!([]; $($name),+,);
};
}
fn main() {
let arr = counters!(ONE, TWO);
dbg!(arr);
}

Answer 1

This seems to do what you want.
use std::sync::atomic::AtomicUsize;
macro_rules! gen_array {
($out:expr; ) => { $out };
([$($out:tt)*]; $name:literal, $($names:tt)*) => {
gen_array!([$($out)* $name,]; $($names)*)
};
}
macro_rules! gen_vars {
($cnt:expr; ) => {};
($cnt:expr; $name:ident, $($names:tt)*) => {
const $name: usize = $cnt;
gen_vars!($cnt + 1; $($names)*)
};
}
macro_rules! counters {
($($name:ident,$value:literal),+) => {
gen_vars!(0; $($name),+,);
gen_array!([]; $($value),+,);
};
}
fn main() {
counters!(ONE, "unit1", TWO, "unit2");
}
Playground