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// run-pass
trait SliceExt<T: Clone> {
fn array_windows_example<'a, const N: usize>(&'a self) -> ArrayWindowsExample<'a, T, N>;
}
impl <T: Clone> SliceExt<T> for [T] {
fn array_windows_example<'a, const N: usize>(&'a self) -> ArrayWindowsExample<'a, T, N> {
ArrayWindowsExample{ idx: 0, slice: &self }
}
}
struct ArrayWindowsExample<'a, T, const N: usize> {
slice: &'a [T],
idx: usize,
}
impl <'a, T: Clone, const N: usize> Iterator for ArrayWindowsExample<'a, T, N> {
type Item = [T; N];
fn next(&mut self) -> Option<Self::Item> {
// Note: this is unsound for some `T` and not meant as an example
// on how to implement `ArrayWindows`.
let mut res = unsafe{ std::mem::zeroed() };
let mut ptr = &mut res as *mut [T; N] as *mut T;
for i in 0..N {
match self.slice[self.idx..].get(i) {
None => return None,
Some(elem) => unsafe { std::ptr::write_volatile(ptr, elem.clone())},
};
ptr = ptr.wrapping_add(1);
self.idx += 1;
}
Some(res)
}
}
const FOUR: usize = 4;
fn main() {
let v: Vec<usize> = vec![0; 100];
for array in v.as_slice().array_windows_example::<FOUR>() {
assert_eq!(array, [0, 0, 0, 0])
}
}
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