Macro ifor

macro_rules! ifor {
    ($($label:lifetime:)? for $pat:pat in $($rest:tt)*) => { ... };
    ($pat:pat in $($rest:tt)*) => { ... };
}

An extension of for in loops with better support for infinite iterators.

This macro presents a superset of regular for loops: it works both with finite and infinite iterators.

Examples

Use with a finite iterator:

use infinite_iterator::ifor;

ifor!(item in [1, 2, 3] {
    println!("{item}");
});

Use with an infinite iterator:

use infinite_iterator::ifor;

ifor!(item in 0.. {
    println!("{item}");
    std::thread::sleep(std::time::Duration::from_secs(5));
})

Infinite iterators additionally support breaking with a value:

use infinite_iterator::ifor;

let item = ifor!(item in 0.. {
    if item > 10 {
        break item;
    }
});

assert_eq!(item, 11);

You can use loop labels with an ifor! too, as long as you write out the keyword for:

use infinite_iterator::ifor;

ifor!('outer: for a in 0..10 {
    ifor!('inner: for b in 0..10 {
        println!("{a}, {b}");
        if a + b > 16 {
            break 'outer;
        }
    });
});