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) {} 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); }