2 #![feature(const_generics)]
3 #![allow(incomplete_features)]
5 trait SliceExt<T: Clone> {
6 fn array_windows<'a, const N: usize>(&'a self) -> ArrayWindows<'a, T, N>;
9 impl <T: Clone> SliceExt<T> for [T] {
10 fn array_windows<'a, const N: usize>(&'a self) -> ArrayWindows<'a, T, N> {
11 ArrayWindows{ idx: 0, slice: &self }
15 struct ArrayWindows<'a, T, const N: usize> {
20 impl <'a, T: Clone, const N: usize> Iterator for ArrayWindows<'a, T, N> {
22 fn next(&mut self) -> Option<Self::Item> {
23 // Note: this is unsound for some `T` and not meant as an example
24 // on how to implement `ArrayWindows`.
25 let mut res = unsafe{ std::mem::zeroed() };
26 let mut ptr = &mut res as *mut [T; N] as *mut T;
29 match self.slice[self.idx..].get(i) {
31 Some(elem) => unsafe { std::ptr::write_volatile(ptr, elem.clone())},
33 ptr = ptr.wrapping_add(1);
41 const FOUR: usize = 4;
44 let v: Vec<usize> = vec![0; 100];
46 for array in v.as_slice().array_windows::<FOUR>() {
47 assert_eq!(array, [0, 0, 0, 0])