pub trait IteratorExtras: Iterator {
fn adjacent_pairs(mut self) -> AdjacentPairs<Self>
where
Self: Sized,
Self::Item: Clone,
{
let elem = self.next();
AdjacentPairs { iter: self, elem }
}
}
impl<T> IteratorExtras for T where T: Iterator {}
pub struct AdjacentPairs<I>
where
I: Iterator,
I::Item: Clone,
{
iter: I,
elem: Option<I::Item>,
}
impl<I> Iterator for AdjacentPairs<I>
where
I: Iterator,
I::Item: Clone,
{
type Item = (I::Item, I::Item);
fn next(&mut self) -> Option<Self::Item> {
self.elem.take().and_then(|e| {
self.elem = self.iter.next();
self.elem.clone().map(|n| (e, n))
})
}
}
#[cfg(test)]
mod tests {
use alloc::vec::Vec;
#[test]
fn adjpairs() {
use super::IteratorExtras;
assert_eq!(
[1, 2, 3, 4]
.iter()
.cloned()
.adjacent_pairs()
.collect::<Vec<_>>(),
vec![(1, 2), (2, 3), (3, 4)]
);
assert_eq!(
[2, 3, 4]
.iter()
.cloned()
.adjacent_pairs()
.collect::<Vec<_>>(),
vec![(2, 3), (3, 4)]
);
assert_eq!(
[2, 3, 4]
.iter()
.cloned()
.adjacent_pairs()
.collect::<Vec<_>>(),
vec![(2, 3), (3, 4)]
);
assert_eq!(
[3, 4].iter().cloned().adjacent_pairs().collect::<Vec<_>>(),
vec![(3, 4)]
);
assert_eq!(
[4].iter().cloned().adjacent_pairs().collect::<Vec<_>>(),
vec![]
);
assert_eq!(
[].iter()
.cloned()
.adjacent_pairs()
.collect::<Vec<(i32, i32)>>(),
vec![]
);
}
}