Some(snd)
}
}
+
+ #[inline]
+ fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
+ let len = self.len();
+ if n >= len {
+ self.v = &[];
+ None
+ } else {
+ let start = (len - 1 - n) * self.chunk_size;
+ let end = start + self.chunk_size;
+ let nth_back = &self.v[start..end];
+ self.v = &self.v[..start];
+ Some(nth_back)
+ }
+ }
}
#[stable(feature = "chunks_exact", since = "1.31.0")]
assert_eq!(c2.next(), None);
}
+#[test]
+fn test_chunks_exact_nth_back() {
+ let v: &[i32] = &[0, 1, 2, 3, 4, 5];
+ let mut c = v.chunks_exact(2);
+ assert_eq!(c.nth_back(1).unwrap(), &[2, 3]);
+ assert_eq!(c.next().unwrap(), &[0, 1]);
+ assert_eq!(c.next(), None);
+
+ let v2: &[i32] = &[0, 1, 2, 3, 4];
+ let mut c2 = v2.chunks_exact(3);
+ assert_eq!(c2.nth_back(0).unwrap(), &[0, 1, 2]);
+ assert_eq!(c2.next(), None);
+ assert_eq!(c2.next_back(), None);
+
+ let v3: &[i32] = &[0, 1, 2, 3, 4];
+ let mut c3 = v3.chunks_exact(10);
+ assert_eq!(c3.nth_back(0), None);
+}
+
#[test]
fn test_chunks_exact_last() {
let v: &[i32] = &[0, 1, 2, 3, 4, 5];