| use super::*; |
| use core::iter::*; |
| |
| #[test] |
| fn test_iterator_flatten() { |
| let xs = [0, 3, 6]; |
| let ys = [0, 1, 2, 3, 4, 5, 6, 7, 8]; |
| let it = xs.iter().map(|&x| (x..).step_by(1).take(3)).flatten(); |
| let mut i = 0; |
| for x in it { |
| assert_eq!(x, ys[i]); |
| i += 1; |
| } |
| assert_eq!(i, ys.len()); |
| } |
| |
| /// Tests `Flatten::fold` with items already picked off the front and back, |
| /// to make sure all parts of the `Flatten` are folded correctly. |
| #[test] |
| fn test_iterator_flatten_fold() { |
| let xs = [0, 3, 6]; |
| let ys = [1, 2, 3, 4, 5, 6, 7]; |
| let mut it = xs.iter().map(|&x| x..x + 3).flatten(); |
| assert_eq!(it.next(), Some(0)); |
| assert_eq!(it.next_back(), Some(8)); |
| let i = it.fold(0, |i, x| { |
| assert_eq!(x, ys[i]); |
| i + 1 |
| }); |
| assert_eq!(i, ys.len()); |
| |
| let mut it = xs.iter().map(|&x| x..x + 3).flatten(); |
| assert_eq!(it.next(), Some(0)); |
| assert_eq!(it.next_back(), Some(8)); |
| let i = it.rfold(ys.len(), |i, x| { |
| assert_eq!(x, ys[i - 1]); |
| i - 1 |
| }); |
| assert_eq!(i, 0); |
| } |
| |
| #[test] |
| fn test_flatten_try_folds() { |
| let f = &|acc, x| i32::checked_add(acc * 2 / 3, x); |
| let mr = &|x| (5 * x)..(5 * x + 5); |
| assert_eq!((0..10).map(mr).flatten().try_fold(7, f), (0..50).try_fold(7, f)); |
| assert_eq!((0..10).map(mr).flatten().try_rfold(7, f), (0..50).try_rfold(7, f)); |
| let mut iter = (0..10).map(mr).flatten(); |
| iter.next(); |
| iter.next_back(); // have front and back iters in progress |
| assert_eq!(iter.try_rfold(7, f), (1..49).try_rfold(7, f)); |
| |
| let mut iter = (0..10).map(|x| (4 * x)..(4 * x + 4)).flatten(); |
| assert_eq!(iter.try_fold(0, i8::checked_add), None); |
| assert_eq!(iter.next(), Some(17)); |
| assert_eq!(iter.try_rfold(0, i8::checked_add), None); |
| assert_eq!(iter.next_back(), Some(35)); |
| } |
| |
| #[test] |
| fn test_flatten_advance_by() { |
| let mut it = once(0..10).chain(once(10..30)).chain(once(30..40)).flatten(); |
| |
| it.advance_by(5).unwrap(); |
| assert_eq!(it.next(), Some(5)); |
| it.advance_by(9).unwrap(); |
| assert_eq!(it.next(), Some(15)); |
| it.advance_back_by(4).unwrap(); |
| assert_eq!(it.next_back(), Some(35)); |
| it.advance_back_by(9).unwrap(); |
| assert_eq!(it.next_back(), Some(25)); |
| |
| assert_eq!(it.advance_by(usize::MAX), Err(9)); |
| assert_eq!(it.advance_back_by(usize::MAX), Err(0)); |
| it.advance_by(0).unwrap(); |
| it.advance_back_by(0).unwrap(); |
| assert_eq!(it.size_hint(), (0, Some(0))); |
| } |
| |
| #[test] |
| fn test_flatten_non_fused_outer() { |
| let mut iter = NonFused::new(once(0..2)).flatten(); |
| |
| assert_eq!(iter.next_back(), Some(1)); |
| assert_eq!(iter.next(), Some(0)); |
| assert_eq!(iter.next(), None); |
| assert_eq!(iter.next(), None); |
| |
| let mut iter = NonFused::new(once(0..2)).flatten(); |
| |
| assert_eq!(iter.next(), Some(0)); |
| assert_eq!(iter.next_back(), Some(1)); |
| assert_eq!(iter.next_back(), None); |
| assert_eq!(iter.next_back(), None); |
| } |
| |
| #[test] |
| fn test_flatten_non_fused_inner() { |
| let mut iter = once(0..1).chain(once(1..3)).flat_map(NonFused::new); |
| |
| assert_eq!(iter.next_back(), Some(2)); |
| assert_eq!(iter.next(), Some(0)); |
| assert_eq!(iter.next(), Some(1)); |
| assert_eq!(iter.next(), None); |
| assert_eq!(iter.next(), None); |
| |
| let mut iter = once(0..1).chain(once(1..3)).flat_map(NonFused::new); |
| |
| assert_eq!(iter.next(), Some(0)); |
| assert_eq!(iter.next_back(), Some(2)); |
| assert_eq!(iter.next_back(), Some(1)); |
| assert_eq!(iter.next_back(), None); |
| assert_eq!(iter.next_back(), None); |
| } |
| |
| #[test] |
| fn test_double_ended_flatten() { |
| let u = [0, 1]; |
| let v = [5, 6, 7, 8]; |
| let mut it = u.iter().map(|x| &v[*x..v.len()]).flatten(); |
| assert_eq!(it.next_back().unwrap(), &8); |
| assert_eq!(it.next().unwrap(), &5); |
| assert_eq!(it.next_back().unwrap(), &7); |
| assert_eq!(it.next_back().unwrap(), &6); |
| assert_eq!(it.next_back().unwrap(), &8); |
| assert_eq!(it.next().unwrap(), &6); |
| assert_eq!(it.next_back().unwrap(), &7); |
| assert_eq!(it.next_back(), None); |
| assert_eq!(it.next(), None); |
| assert_eq!(it.next_back(), None); |
| } |
| |
| #[test] |
| fn test_trusted_len_flatten() { |
| fn assert_trusted_len<T: TrustedLen>(_: &T) {} |
| let mut iter = IntoIterator::into_iter([[0; 3]; 4]).flatten(); |
| assert_trusted_len(&iter); |
| |
| assert_eq!(iter.size_hint(), (12, Some(12))); |
| iter.next(); |
| assert_eq!(iter.size_hint(), (11, Some(11))); |
| iter.next_back(); |
| assert_eq!(iter.size_hint(), (10, Some(10))); |
| |
| let iter = IntoIterator::into_iter([[(); usize::MAX]; 1]).flatten(); |
| assert_eq!(iter.size_hint(), (usize::MAX, Some(usize::MAX))); |
| |
| let iter = IntoIterator::into_iter([[(); usize::MAX]; 2]).flatten(); |
| assert_eq!(iter.size_hint(), (usize::MAX, None)); |
| |
| let mut a = [(); 10]; |
| let mut b = [(); 10]; |
| |
| let iter = IntoIterator::into_iter([&mut a, &mut b]).flatten(); |
| assert_trusted_len(&iter); |
| assert_eq!(iter.size_hint(), (20, Some(20))); |
| core::mem::drop(iter); |
| |
| let iter = IntoIterator::into_iter([&a, &b]).flatten(); |
| assert_trusted_len(&iter); |
| assert_eq!(iter.size_hint(), (20, Some(20))); |
| |
| let iter = [(), (), ()].iter().flat_map(|_| [(); 1000]); |
| assert_trusted_len(&iter); |
| assert_eq!(iter.size_hint(), (3000, Some(3000))); |
| |
| let iter = [(), ()].iter().flat_map(|_| &a); |
| assert_trusted_len(&iter); |
| assert_eq!(iter.size_hint(), (20, Some(20))); |
| } |
| |
| #[test] |
| fn test_flatten_count() { |
| let mut it = once(0..10).chain(once(10..30)).chain(once(30..40)).flatten(); |
| |
| assert_eq!(it.clone().count(), 40); |
| it.advance_by(5).unwrap(); |
| assert_eq!(it.clone().count(), 35); |
| it.advance_back_by(5).unwrap(); |
| assert_eq!(it.clone().count(), 30); |
| it.advance_by(10).unwrap(); |
| assert_eq!(it.clone().count(), 20); |
| it.advance_back_by(8).unwrap(); |
| assert_eq!(it.clone().count(), 12); |
| it.advance_by(4).unwrap(); |
| assert_eq!(it.clone().count(), 8); |
| it.advance_back_by(5).unwrap(); |
| assert_eq!(it.clone().count(), 3); |
| it.advance_by(3).unwrap(); |
| assert_eq!(it.clone().count(), 0); |
| } |
| |
| #[test] |
| fn test_flatten_last() { |
| let mut it = once(0..10).chain(once(10..30)).chain(once(30..40)).flatten(); |
| |
| assert_eq!(it.clone().last(), Some(39)); |
| it.advance_by(5).unwrap(); // 5..40 |
| assert_eq!(it.clone().last(), Some(39)); |
| it.advance_back_by(5).unwrap(); // 5..35 |
| assert_eq!(it.clone().last(), Some(34)); |
| it.advance_by(10).unwrap(); // 15..35 |
| assert_eq!(it.clone().last(), Some(34)); |
| it.advance_back_by(8).unwrap(); // 15..27 |
| assert_eq!(it.clone().last(), Some(26)); |
| it.advance_by(4).unwrap(); // 19..27 |
| assert_eq!(it.clone().last(), Some(26)); |
| it.advance_back_by(5).unwrap(); // 19..22 |
| assert_eq!(it.clone().last(), Some(21)); |
| it.advance_by(3).unwrap(); // 22..22 |
| assert_eq!(it.clone().last(), None); |
| } |