| use core::iter::*; |
| |
| #[test] |
| fn test_iterator_take() { |
| let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19]; |
| let ys = [0, 1, 2, 3, 5]; |
| |
| let mut it = xs.iter().take(ys.len()); |
| let mut i = 0; |
| assert_eq!(it.len(), ys.len()); |
| while let Some(&x) = it.next() { |
| assert_eq!(x, ys[i]); |
| i += 1; |
| assert_eq!(it.len(), ys.len() - i); |
| } |
| assert_eq!(i, ys.len()); |
| assert_eq!(it.len(), 0); |
| |
| let mut it = xs.iter().take(ys.len()); |
| let mut i = 0; |
| assert_eq!(it.len(), ys.len()); |
| while let Some(&x) = it.next_back() { |
| i += 1; |
| assert_eq!(x, ys[ys.len() - i]); |
| assert_eq!(it.len(), ys.len() - i); |
| } |
| assert_eq!(i, ys.len()); |
| assert_eq!(it.len(), 0); |
| } |
| |
| #[test] |
| fn test_iterator_take_nth() { |
| let xs = [0, 1, 2, 4, 5]; |
| let mut it = xs.iter(); |
| { |
| let mut take = it.by_ref().take(3); |
| let mut i = 0; |
| while let Some(&x) = take.nth(0) { |
| assert_eq!(x, i); |
| i += 1; |
| } |
| } |
| assert_eq!(it.nth(1), Some(&5)); |
| assert_eq!(it.nth(0), None); |
| |
| let xs = [0, 1, 2, 3, 4]; |
| let mut it = xs.iter().take(7); |
| let mut i = 1; |
| while let Some(&x) = it.nth(1) { |
| assert_eq!(x, i); |
| i += 2; |
| } |
| } |
| |
| #[test] |
| fn test_iterator_take_nth_back() { |
| let xs = [0, 1, 2, 4, 5]; |
| let mut it = xs.iter(); |
| { |
| let mut take = it.by_ref().take(3); |
| let mut i = 0; |
| while let Some(&x) = take.nth_back(0) { |
| i += 1; |
| assert_eq!(x, 3 - i); |
| } |
| } |
| assert_eq!(it.nth_back(0), None); |
| |
| let xs = [0, 1, 2, 3, 4]; |
| let mut it = xs.iter().take(7); |
| assert_eq!(it.nth_back(1), Some(&3)); |
| assert_eq!(it.nth_back(1), Some(&1)); |
| assert_eq!(it.nth_back(1), None); |
| } |
| |
| #[test] |
| fn test_take_advance_by() { |
| let mut take = (0..10).take(3); |
| assert_eq!(take.advance_by(2), Ok(())); |
| assert_eq!(take.next(), Some(2)); |
| assert_eq!(take.advance_by(1), Err(0)); |
| |
| assert_eq!((0..0).take(10).advance_by(0), Ok(())); |
| assert_eq!((0..0).take(10).advance_by(1), Err(0)); |
| assert_eq!((0..10).take(4).advance_by(5), Err(4)); |
| |
| let mut take = (0..10).take(3); |
| assert_eq!(take.advance_back_by(2), Ok(())); |
| assert_eq!(take.next(), Some(0)); |
| assert_eq!(take.advance_back_by(1), Err(0)); |
| |
| assert_eq!((0..2).take(1).advance_back_by(10), Err(1)); |
| assert_eq!((0..0).take(1).advance_back_by(1), Err(0)); |
| assert_eq!((0..0).take(1).advance_back_by(0), Ok(())); |
| assert_eq!((0..usize::MAX).take(100).advance_back_by(usize::MAX), Err(100)); |
| } |
| |
| #[test] |
| fn test_iterator_take_short() { |
| let xs = [0, 1, 2, 3]; |
| |
| let mut it = xs.iter().take(5); |
| let mut i = 0; |
| assert_eq!(it.len(), xs.len()); |
| while let Some(&x) = it.next() { |
| assert_eq!(x, xs[i]); |
| i += 1; |
| assert_eq!(it.len(), xs.len() - i); |
| } |
| assert_eq!(i, xs.len()); |
| assert_eq!(it.len(), 0); |
| |
| let mut it = xs.iter().take(5); |
| let mut i = 0; |
| assert_eq!(it.len(), xs.len()); |
| while let Some(&x) = it.next_back() { |
| i += 1; |
| assert_eq!(x, xs[xs.len() - i]); |
| assert_eq!(it.len(), xs.len() - i); |
| } |
| assert_eq!(i, xs.len()); |
| assert_eq!(it.len(), 0); |
| } |
| |
| #[test] |
| fn test_take_try_folds() { |
| let f = &|acc, x| i32::checked_add(2 * acc, x); |
| assert_eq!((10..30).take(10).try_fold(7, f), (10..20).try_fold(7, f)); |
| assert_eq!((10..30).take(10).try_rfold(7, f), (10..20).try_rfold(7, f)); |
| |
| let mut iter = (10..30).take(20); |
| assert_eq!(iter.try_fold(0, i8::checked_add), None); |
| assert_eq!(iter.next(), Some(20)); |
| assert_eq!(iter.try_rfold(0, i8::checked_add), None); |
| assert_eq!(iter.next_back(), Some(24)); |
| |
| let mut iter = (2..20).take(3); |
| assert_eq!(iter.try_for_each(Err), Err(2)); |
| assert_eq!(iter.try_for_each(Err), Err(3)); |
| assert_eq!(iter.try_for_each(Err), Err(4)); |
| assert_eq!(iter.try_for_each(Err), Ok(())); |
| |
| let mut iter = (2..20).take(3).rev(); |
| assert_eq!(iter.try_for_each(Err), Err(4)); |
| assert_eq!(iter.try_for_each(Err), Err(3)); |
| assert_eq!(iter.try_for_each(Err), Err(2)); |
| assert_eq!(iter.try_for_each(Err), Ok(())); |
| } |
| |
| #[test] |
| fn test_byref_take_consumed_items() { |
| let mut inner = 10..90; |
| |
| let mut count = 0; |
| inner.by_ref().take(0).for_each(|_| count += 1); |
| assert_eq!(count, 0); |
| assert_eq!(inner, 10..90); |
| |
| let mut count = 0; |
| inner.by_ref().take(10).for_each(|_| count += 1); |
| assert_eq!(count, 10); |
| assert_eq!(inner, 20..90); |
| |
| let mut count = 0; |
| inner.by_ref().take(100).for_each(|_| count += 1); |
| assert_eq!(count, 70); |
| assert_eq!(inner, 90..90); |
| } |