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Diffstat (limited to '')
-rw-r--r-- | library/core/tests/iter/adapters/flat_map.rs | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/library/core/tests/iter/adapters/flat_map.rs b/library/core/tests/iter/adapters/flat_map.rs new file mode 100644 index 000000000..ee945e698 --- /dev/null +++ b/library/core/tests/iter/adapters/flat_map.rs @@ -0,0 +1,74 @@ +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); +} |