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// run-pass
trait ConstChunksExactTrait<T> {
fn const_chunks_exact<const N: usize>(&self) -> ConstChunksExact<'_, T, {N}>;
}
impl <T> ConstChunksExactTrait<T> for [T] {
fn const_chunks_exact<const N: usize>(&self) -> ConstChunksExact<'_, T, {N}> {
assert!(N != 0);
let rem = self.len() % N;
let len = self.len() - rem;
let (fst, _) = self.split_at(len);
ConstChunksExact { v: fst, }
}
}
struct ConstChunksExact<'a, T: 'a, const N: usize> {
v: &'a [T],
}
impl <'a, T: std::fmt::Debug, const N: usize> Iterator for ConstChunksExact<'a, T, {N}> {
type Item = &'a [T; N];
fn next(&mut self) -> Option<Self::Item> {
if self.v.len() < N {
None
} else {
let (fst, snd) = self.v.split_at(N);
self.v = snd;
let ptr = fst.as_ptr() as *const _;
Some(unsafe { &*ptr})
}
}
}
fn main() {
let slice = &[1i32, 2, 3, 4, 5, 6, 7, 8, 9, 10];
let mut iter = [[1, 2, 3], [4, 5, 6], [7, 8, 9]].iter();
for a in slice.const_chunks_exact::<3>() {
assert_eq!(a, iter.next().unwrap());
}
}
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