| use core::iter::*; |
| |
| #[test] |
| fn test_iterator_flat_map() { |
| let xs = [0, 3, 6]; |
| let ys = [0, 1, 2, 3, 4, 5, 6, 7, 8]; |
| let it = xs.iter().flat_map(|&x| (x..).step_by(1).take(3)); |
| let mut i = 0; |
| for x in it { |
| assert_eq!(x, ys[i]); |
| i += 1; |
| } |
| assert_eq!(i, ys.len()); |
| } |
| |
| /// Tests `FlatMap::fold` with items already picked off the front and back, |
| /// to make sure all parts of the `FlatMap` are folded correctly. |
| #[test] |
| fn test_iterator_flat_map_fold() { |
| let xs = [0, 3, 6]; |
| let ys = [1, 2, 3, 4, 5, 6, 7]; |
| let mut it = xs.iter().flat_map(|&x| x..x + 3); |
| 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().flat_map(|&x| x..x + 3); |
| 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_flat_map_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).flat_map(mr).try_fold(7, f), (0..50).try_fold(7, f)); |
| assert_eq!((0..10).flat_map(mr).try_rfold(7, f), (0..50).try_rfold(7, f)); |
| let mut iter = (0..10).flat_map(mr); |
| 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).flat_map(|x| (4 * x)..(4 * x + 4)); |
| 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_double_ended_flat_map() { |
| let u = [0, 1]; |
| let v = [5, 6, 7, 8]; |
| let mut it = u.iter().flat_map(|x| &v[*x..v.len()]); |
| 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); |
| } |
