mirror of
https://github.com/rust-lang/rust.git
synced 2024-12-23 22:14:15 +00:00
37 lines
1.1 KiB
Rust
37 lines
1.1 KiB
Rust
// run-pass
|
|
// zip!(a1,a2,a3,a4) is equivalent to:
|
|
// a1.zip(a2).zip(a3).zip(a4).map(|(((x1,x2),x3),x4)| (x1,x2,x3,x4))
|
|
macro_rules! zip {
|
|
// Entry point
|
|
([$a:expr, $b:expr, $($rest:expr),*]) => {
|
|
zip!([$($rest),*], $a.zip($b), (x,y), [x,y])
|
|
};
|
|
|
|
// Intermediate steps to build the zipped expression, the match pattern
|
|
// and the output tuple of the closure, using macro hygiene to repeatedly
|
|
// introduce new variables named 'x'.
|
|
([$a:expr, $($rest:expr),*], $zip:expr, $pat:pat, [$($flat:expr),*]) => {
|
|
zip!([$($rest),*], $zip.zip($a), ($pat,x), [$($flat),*, x])
|
|
};
|
|
|
|
// Final step
|
|
([], $zip:expr, $pat:pat, [$($flat:expr),+]) => {
|
|
$zip.map(|$pat| ($($flat),+))
|
|
};
|
|
|
|
// Comma
|
|
([$a:expr], $zip:expr, $pat:pat, [$($flat:expr),*]) => {
|
|
zip!([$a,], $zip, $pat, [$($flat),*])
|
|
};
|
|
}
|
|
|
|
fn main() {
|
|
let p1 = vec![1i32, 2].into_iter();
|
|
let p2 = vec!["10", "20"].into_iter();
|
|
let p3 = vec![100u16, 200].into_iter();
|
|
let p4 = vec![1000i64, 2000].into_iter();
|
|
|
|
let e = zip!([p1,p2,p3,p4]).collect::<Vec<_>>();
|
|
assert_eq!(e[0], (1i32,"10",100u16,1000i64));
|
|
}
|