forked from rust-lang/glacier
/
61936.rs
45 lines (36 loc) · 1.13 KB
/
61936.rs
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#![feature(const_generics)]
trait SliceExt<T: Clone> {
fn array_windows<'a, const N: usize>(&'a self) -> ArrayWindows<'a, T, {N}>;
}
impl <T: Clone> SliceExt<T> for [T] {
fn array_windows<'a, const N: usize>(&'a self) -> ArrayWindows<'a, T, {N}> {
ArrayWindows{ idx: 0, slice: &self }
}
}
struct ArrayWindows<'a, T, const N: usize> {
slice: &'a [T],
idx: usize,
}
impl <'a, T: Clone, const N: usize> Iterator for ArrayWindows<'a, T, {N}> {
type Item = [T; N];
fn next(&mut self) -> Option<Self::Item> {
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[i..].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![100; 0usize];
for array in v.as_slice().array_windows::<{FOUR}>() {
// println!("{:?}", array);
}
}