| use core::iter::*; |
| |
| #[test] |
| fn test_iterator_filter_count() { |
| let xs = [0, 1, 2, 3, 4, 5, 6, 7, 8]; |
| assert_eq!(xs.iter().filter(|&&x| x % 2 == 0).count(), 5); |
| } |
| |
| #[test] |
| fn test_iterator_filter_fold() { |
| let xs = [0, 1, 2, 3, 4, 5, 6, 7, 8]; |
| let ys = [0, 2, 4, 6, 8]; |
| let it = xs.iter().filter(|&&x| x % 2 == 0); |
| let i = it.fold(0, |i, &x| { |
| assert_eq!(x, ys[i]); |
| i + 1 |
| }); |
| assert_eq!(i, ys.len()); |
| |
| let it = xs.iter().filter(|&&x| x % 2 == 0); |
| let i = it.rfold(ys.len(), |i, &x| { |
| assert_eq!(x, ys[i - 1]); |
| i - 1 |
| }); |
| assert_eq!(i, 0); |
| } |
| |
| #[test] |
| fn test_filter_try_folds() { |
| fn p(&x: &i32) -> bool { |
| 0 <= x && x < 10 |
| } |
| let f = &|acc, x| i32::checked_add(2 * acc, x); |
| assert_eq!((-10..20).filter(p).try_fold(7, f), (0..10).try_fold(7, f)); |
| assert_eq!((-10..20).filter(p).try_rfold(7, f), (0..10).try_rfold(7, f)); |
| |
| let mut iter = (0..40).filter(|&x| x % 2 == 1); |
| assert_eq!(iter.try_fold(0, i8::checked_add), None); |
| assert_eq!(iter.next(), Some(25)); |
| assert_eq!(iter.try_rfold(0, i8::checked_add), None); |
| assert_eq!(iter.next_back(), Some(31)); |
| } |
| |
| #[test] |
| fn test_double_ended_filter() { |
| let xs = [1, 2, 3, 4, 5, 6]; |
| let mut it = xs.iter().filter(|&x| *x & 1 == 0); |
| assert_eq!(it.next_back().unwrap(), &6); |
| assert_eq!(it.next_back().unwrap(), &4); |
| assert_eq!(it.next().unwrap(), &2); |
| assert_eq!(it.next_back(), None); |
| } |
