3 #![cfg_attr(full, feature(const_generics))]
4 #![cfg_attr(full, allow(incomplete_features))]
5 #![cfg_attr(min, feature(min_const_generics))]
7 trait SliceExt<T: Clone> {
8 fn array_windows<'a, const N: usize>(&'a self) -> ArrayWindows<'a, T, N>;
11 impl <T: Clone> SliceExt<T> for [T] {
12 fn array_windows<'a, const N: usize>(&'a self) -> ArrayWindows<'a, T, N> {
13 ArrayWindows{ idx: 0, slice: &self }
17 struct ArrayWindows<'a, T, const N: usize> {
22 impl <'a, T: Clone, const N: usize> Iterator for ArrayWindows<'a, T, N> {
24 fn next(&mut self) -> Option<Self::Item> {
25 // Note: this is unsound for some `T` and not meant as an example
26 // on how to implement `ArrayWindows`.
27 let mut res = unsafe{ std::mem::zeroed() };
28 let mut ptr = &mut res as *mut [T; N] as *mut T;
31 match self.slice[self.idx..].get(i) {
33 Some(elem) => unsafe { std::ptr::write_volatile(ptr, elem.clone())},
35 ptr = ptr.wrapping_add(1);
43 const FOUR: usize = 4;
46 let v: Vec<usize> = vec![0; 100];
48 for array in v.as_slice().array_windows::<FOUR>() {
49 assert_eq!(array, [0, 0, 0, 0])