| //@ 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()); |
| } |
| } |