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Diffstat (limited to 'library/core/tests/iter/adapters/chain.rs')
-rw-r--r-- | library/core/tests/iter/adapters/chain.rs | 280 |
1 files changed, 280 insertions, 0 deletions
diff --git a/library/core/tests/iter/adapters/chain.rs b/library/core/tests/iter/adapters/chain.rs new file mode 100644 index 000000000..f419f9cec --- /dev/null +++ b/library/core/tests/iter/adapters/chain.rs @@ -0,0 +1,280 @@ +use super::*; +use core::iter::*; + +#[test] +fn test_iterator_chain() { + let xs = [0, 1, 2, 3, 4, 5]; + let ys = [30, 40, 50, 60]; + let expected = [0, 1, 2, 3, 4, 5, 30, 40, 50, 60]; + let it = xs.iter().chain(&ys); + let mut i = 0; + for &x in it { + assert_eq!(x, expected[i]); + i += 1; + } + assert_eq!(i, expected.len()); + + let ys = (30..).step_by(10).take(4); + let it = xs.iter().cloned().chain(ys); + let mut i = 0; + for x in it { + assert_eq!(x, expected[i]); + i += 1; + } + assert_eq!(i, expected.len()); +} + +#[test] +fn test_iterator_chain_advance_by() { + fn test_chain(xs: &[i32], ys: &[i32]) { + let len = xs.len() + ys.len(); + + for i in 0..xs.len() { + let mut iter = Unfuse::new(xs).chain(Unfuse::new(ys)); + iter.advance_by(i).unwrap(); + assert_eq!(iter.next(), Some(&xs[i])); + assert_eq!(iter.advance_by(100), Err(len - i - 1)); + iter.advance_by(0).unwrap(); + } + + for i in 0..ys.len() { + let mut iter = Unfuse::new(xs).chain(Unfuse::new(ys)); + iter.advance_by(xs.len() + i).unwrap(); + assert_eq!(iter.next(), Some(&ys[i])); + assert_eq!(iter.advance_by(100), Err(ys.len() - i - 1)); + iter.advance_by(0).unwrap(); + } + + let mut iter = xs.iter().chain(ys); + iter.advance_by(len).unwrap(); + assert_eq!(iter.next(), None); + iter.advance_by(0).unwrap(); + + let mut iter = xs.iter().chain(ys); + assert_eq!(iter.advance_by(len + 1), Err(len)); + iter.advance_by(0).unwrap(); + } + + test_chain(&[], &[]); + test_chain(&[], &[0, 1, 2, 3, 4, 5]); + test_chain(&[0, 1, 2, 3, 4, 5], &[]); + test_chain(&[0, 1, 2, 3, 4, 5], &[30, 40, 50, 60]); +} + +#[test] +fn test_iterator_chain_advance_back_by() { + fn test_chain(xs: &[i32], ys: &[i32]) { + let len = xs.len() + ys.len(); + + for i in 0..ys.len() { + let mut iter = Unfuse::new(xs).chain(Unfuse::new(ys)); + iter.advance_back_by(i).unwrap(); + assert_eq!(iter.next_back(), Some(&ys[ys.len() - i - 1])); + assert_eq!(iter.advance_back_by(100), Err(len - i - 1)); + iter.advance_back_by(0).unwrap(); + } + + for i in 0..xs.len() { + let mut iter = Unfuse::new(xs).chain(Unfuse::new(ys)); + iter.advance_back_by(ys.len() + i).unwrap(); + assert_eq!(iter.next_back(), Some(&xs[xs.len() - i - 1])); + assert_eq!(iter.advance_back_by(100), Err(xs.len() - i - 1)); + iter.advance_back_by(0).unwrap(); + } + + let mut iter = xs.iter().chain(ys); + iter.advance_back_by(len).unwrap(); + assert_eq!(iter.next_back(), None); + iter.advance_back_by(0).unwrap(); + + let mut iter = xs.iter().chain(ys); + assert_eq!(iter.advance_back_by(len + 1), Err(len)); + iter.advance_back_by(0).unwrap(); + } + + test_chain(&[], &[]); + test_chain(&[], &[0, 1, 2, 3, 4, 5]); + test_chain(&[0, 1, 2, 3, 4, 5], &[]); + test_chain(&[0, 1, 2, 3, 4, 5], &[30, 40, 50, 60]); +} + +#[test] +fn test_iterator_chain_nth() { + let xs = [0, 1, 2, 3, 4, 5]; + let ys = [30, 40, 50, 60]; + let zs = []; + let expected = [0, 1, 2, 3, 4, 5, 30, 40, 50, 60]; + for (i, x) in expected.iter().enumerate() { + assert_eq!(Some(x), xs.iter().chain(&ys).nth(i)); + } + assert_eq!(zs.iter().chain(&xs).nth(0), Some(&0)); + + let mut it = xs.iter().chain(&zs); + assert_eq!(it.nth(5), Some(&5)); + assert_eq!(it.next(), None); +} + +#[test] +fn test_iterator_chain_nth_back() { + let xs = [0, 1, 2, 3, 4, 5]; + let ys = [30, 40, 50, 60]; + let zs = []; + let expected = [0, 1, 2, 3, 4, 5, 30, 40, 50, 60]; + for (i, x) in expected.iter().rev().enumerate() { + assert_eq!(Some(x), xs.iter().chain(&ys).nth_back(i)); + } + assert_eq!(zs.iter().chain(&xs).nth_back(0), Some(&5)); + + let mut it = xs.iter().chain(&zs); + assert_eq!(it.nth_back(5), Some(&0)); + assert_eq!(it.next(), None); +} + +#[test] +fn test_iterator_chain_last() { + let xs = [0, 1, 2, 3, 4, 5]; + let ys = [30, 40, 50, 60]; + let zs = []; + assert_eq!(xs.iter().chain(&ys).last(), Some(&60)); + assert_eq!(zs.iter().chain(&ys).last(), Some(&60)); + assert_eq!(ys.iter().chain(&zs).last(), Some(&60)); + assert_eq!(zs.iter().chain(&zs).last(), None); +} + +#[test] +fn test_iterator_chain_count() { + let xs = [0, 1, 2, 3, 4, 5]; + let ys = [30, 40, 50, 60]; + let zs = []; + assert_eq!(xs.iter().chain(&ys).count(), 10); + assert_eq!(zs.iter().chain(&ys).count(), 4); +} + +#[test] +fn test_iterator_chain_find() { + let xs = [0, 1, 2, 3, 4, 5]; + let ys = [30, 40, 50, 60]; + let mut iter = xs.iter().chain(&ys); + assert_eq!(iter.find(|&&i| i == 4), Some(&4)); + assert_eq!(iter.next(), Some(&5)); + assert_eq!(iter.find(|&&i| i == 40), Some(&40)); + assert_eq!(iter.next(), Some(&50)); + assert_eq!(iter.find(|&&i| i == 100), None); + assert_eq!(iter.next(), None); +} + +#[test] +fn test_iterator_chain_size_hint() { + // this chains an iterator of length 0 with an iterator of length 1, + // so after calling `.next()` once, the iterator is empty and the + // state is `ChainState::Back`. `.size_hint()` should now disregard + // the size hint of the left iterator + let mut iter = Toggle { is_empty: true }.chain(once(())); + assert_eq!(iter.next(), Some(())); + assert_eq!(iter.size_hint(), (0, Some(0))); + + let mut iter = once(()).chain(Toggle { is_empty: true }); + assert_eq!(iter.next_back(), Some(())); + assert_eq!(iter.size_hint(), (0, Some(0))); +} + +#[test] +fn test_iterator_chain_unfused() { + // Chain shouldn't be fused in its second iterator, depending on direction + let mut iter = NonFused::new(empty()).chain(Toggle { is_empty: true }); + assert!(iter.next().is_none()); + assert!(iter.next().is_some()); + assert!(iter.next().is_none()); + + let mut iter = Toggle { is_empty: true }.chain(NonFused::new(empty())); + assert!(iter.next_back().is_none()); + assert!(iter.next_back().is_some()); + assert!(iter.next_back().is_none()); +} + +#[test] +fn test_chain_fold() { + let xs = [1, 2, 3]; + let ys = [1, 2, 0]; + + let mut iter = xs.iter().chain(&ys); + iter.next(); + let mut result = Vec::new(); + iter.fold((), |(), &elt| result.push(elt)); + assert_eq!(&[2, 3, 1, 2, 0], &result[..]); +} + +#[test] +fn test_chain_try_folds() { + let c = || (0..10).chain(10..20); + + let f = &|acc, x| i32::checked_add(2 * acc, x); + assert_eq!(c().try_fold(7, f), (0..20).try_fold(7, f)); + assert_eq!(c().try_rfold(7, f), (0..20).rev().try_fold(7, f)); + + let mut iter = c(); + assert_eq!(iter.position(|x| x == 5), Some(5)); + assert_eq!(iter.next(), Some(6), "stopped in front, state Both"); + assert_eq!(iter.position(|x| x == 13), Some(6)); + assert_eq!(iter.next(), Some(14), "stopped in back, state Back"); + assert_eq!(iter.try_fold(0, |acc, x| Some(acc + x)), Some((15..20).sum())); + + let mut iter = c().rev(); // use rev to access try_rfold + assert_eq!(iter.position(|x| x == 15), Some(4)); + assert_eq!(iter.next(), Some(14), "stopped in back, state Both"); + assert_eq!(iter.position(|x| x == 5), Some(8)); + assert_eq!(iter.next(), Some(4), "stopped in front, state Front"); + assert_eq!(iter.try_fold(0, |acc, x| Some(acc + x)), Some((0..4).sum())); + + let mut iter = c(); + iter.by_ref().rev().nth(14); // skip the last 15, ending in state Front + assert_eq!(iter.try_fold(7, f), (0..5).try_fold(7, f)); + + let mut iter = c(); + iter.nth(14); // skip the first 15, ending in state Back + assert_eq!(iter.try_rfold(7, f), (15..20).try_rfold(7, f)); +} + +#[test] +fn test_double_ended_chain() { + let xs = [1, 2, 3, 4, 5]; + let ys = [7, 9, 11]; + let mut it = xs.iter().chain(&ys).rev(); + assert_eq!(it.next().unwrap(), &11); + assert_eq!(it.next().unwrap(), &9); + assert_eq!(it.next_back().unwrap(), &1); + assert_eq!(it.next_back().unwrap(), &2); + assert_eq!(it.next_back().unwrap(), &3); + assert_eq!(it.next_back().unwrap(), &4); + assert_eq!(it.next_back().unwrap(), &5); + assert_eq!(it.next_back().unwrap(), &7); + assert_eq!(it.next_back(), None); + + // test that .chain() is well behaved with an unfused iterator + struct CrazyIterator(bool); + impl CrazyIterator { + fn new() -> CrazyIterator { + CrazyIterator(false) + } + } + impl Iterator for CrazyIterator { + type Item = i32; + fn next(&mut self) -> Option<i32> { + if self.0 { + Some(99) + } else { + self.0 = true; + None + } + } + } + + impl DoubleEndedIterator for CrazyIterator { + fn next_back(&mut self) -> Option<i32> { + self.next() + } + } + + assert_eq!(CrazyIterator::new().chain(0..10).rev().last(), Some(0)); + assert!((0..10).chain(CrazyIterator::new()).rev().any(|i| i == 0)); +} |