mirror of https://github.com/rust-lang/rust
46 lines
1.1 KiB
Rust
46 lines
1.1 KiB
Rust
//@ 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());
|
|
}
|
|
}
|