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// run-pass
#![feature(generic_associated_types)]
pub trait Iter {
type Item<'a> where Self: 'a;
fn next<'a>(&'a mut self) -> Option<Self::Item<'a>>;
fn for_each<F>(mut self, mut f: F)
where Self: Sized, F: for<'a> FnMut(Self::Item<'a>)
{
while let Some(item) = self.next() {
f(item);
}
}
}
pub struct Windows<T> {
items: Vec<T>,
start: usize,
len: usize,
}
impl<T> Windows<T> {
pub fn new(items: Vec<T>, len: usize) -> Self {
Self { items, start: 0, len }
}
}
impl<T> Iter for Windows<T> {
type Item<'a> = &'a mut [T] where T: 'a;
fn next<'a>(&'a mut self) -> Option<Self::Item<'a>> {
let slice = self.items.get_mut(self.start..self.start + self.len)?;
self.start += 1;
Some(slice)
}
}
fn main() {
Windows::new(vec![1, 2, 3, 4, 5], 3)
.for_each(|slice| println!("{:?}", slice));
}
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