From 3b1bad192a6f63851cfbacd6e95f74518963076e Mon Sep 17 00:00:00 2001 From: Folyd Date: Fri, 8 Jan 2021 00:22:46 +0800 Subject: [PATCH 1/8] Add Iterator::at_least() and Iterator::at_most() API --- library/core/src/iter/traits/iterator.rs | 138 + library/core/tests/iter.rs | 3615 ++++++++++++++++++++++ 2 files changed, 3753 insertions(+) create mode 100644 library/core/tests/iter.rs diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs index 9f7ced829b0ac..30993c636e781 100644 --- a/library/core/src/iter/traits/iterator.rs +++ b/library/core/src/iter/traits/iterator.rs @@ -2266,6 +2266,144 @@ pub trait Iterator { self.try_fold((), check(f)) == ControlFlow::BREAK } + /// Tests if at least `n` elements of the iterator matches a predicate. + /// + /// `at_least()` takes a usize `n` and a closure that returns `true` or `false`. It applies + /// this closure to each element of the iterator, and if more than `n` of them return + /// `true`, then so does `at_least()`. If less than `n` of them return `true`, it + /// returns `false`. + /// + /// `at_least()` is short-circuiting; in other words, it will stop processing + /// as soon as it finds `n` `true`, given that no matter what else happens, + /// the result will also be `true`. + /// + /// An empty iterator returns `false`. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ``` + /// let a = [1, 2, 3]; + /// + /// assert!(a.iter().at_least(1, |&x| x > 0)); + /// + /// assert!(!a.iter().at_least(1, |&x| x > 5)); + /// ``` + /// + /// Stopping at the `n`th `true`: + /// + /// ``` + /// let a = vec![1, 2, 3, 4, 5]; + /// + /// let mut iter = a.iter(); + /// + /// assert!(iter.at_least(0, |&x| x % 2 == 0)); + /// assert!(iter.at_least(1, |&x| x % 2 == 0)); + /// assert!(iter.at_least(2, |&x| x % 2 == 0)); + /// assert!(!iter.at_least(3, |&x| x % 2 == 0)); + /// + /// // we can still use `iter`, as there are more elements. + /// let a = [1, 2, 3]; + /// let mut iter = a.iter(); + /// assert!(iter.at_least(1, |&x| x > 0)); + /// assert_eq!(iter.next(), Some(&2)); + /// ``` + #[inline] + #[unstable(feature = "at_least", reason = "new API", issue = "none")] + fn at_least(&mut self, n: usize, f: F) -> bool + where + Self: Sized, + F: FnMut(Self::Item) -> bool, + { + #[inline] + fn check( + n: usize, + mut f: impl FnMut(T) -> bool, + ) -> impl FnMut(usize, T) -> ControlFlow { + move |mut i, x| { + i += f(x) as usize; + + if i < n { + ControlFlow::Continue(i) + } else { + ControlFlow::Break(i) + } + } + } + + matches!(self.try_fold(0, check(n, f)), ControlFlow::Break(_)) + } + + /// Tests if at most `n` elements of the iterator matches a predicate. + /// + /// `at_most()` takes a usize `n` and a closure that returns `true` or `false`. It applies + /// this closure to each element of the iterator, and if less than `n` of them return + /// `true`, then so does `at_least()`. If more than `n` of them return `true`, it + /// returns `false`. + /// + /// `at_most()` is short-circuiting; in other words, it will stop processing + /// as soon as it finds `n` `false`, given that no matter what else happens, + /// the result will also be `false`. + /// + /// An empty iterator returns `true`. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ``` + /// let a = [1, 2, 3]; + /// + /// assert!(a.iter().at_most(1, |&x| x > 3)); + /// + /// assert!(!a.iter().at_most(1, |&x| x > 0)); + /// ``` + /// + /// Stopping at the `n + 1`th `true`: + /// + /// ``` + /// let a = vec![1, 2, 3, 4, 5]; + /// + /// let mut iter = a.iter(); + /// + /// assert!(iter.at_least(0, |&x| x % 2 == 0)); + /// assert!(iter.at_least(1, |&x| x % 2 == 0)); + /// assert!(iter.at_least(2, |&x| x % 2 == 0)); + /// assert!(!iter.at_least(3, |&x| x % 2 == 0)); + /// + /// // we can still use `iter`, as there are more elements. + /// let a = [1, 1, 3]; + /// let mut iter = a.iter(); + /// assert!(!iter.at_most(1, |&x| x == 1)); + /// assert_eq!(iter.next(), Some(&3)); + /// ``` + #[inline] + #[unstable(feature = "at_most", reason = "new API", issue = "none")] + fn at_most(&mut self, n: usize, f: F) -> bool + where + Self: Sized, + F: FnMut(Self::Item) -> bool, + { + #[inline] + fn check( + n: usize, + mut f: impl FnMut(T) -> bool, + ) -> impl FnMut(usize, T) -> ControlFlow { + move |mut i, x| { + i += f(x) as usize; + + if i <= n { + ControlFlow::Continue(i) + } else { + ControlFlow::Break(i) + } + } + } + + matches!(self.try_fold(0, check(n, f)), ControlFlow::Continue(_)) + } + /// Searches for an element of an iterator that satisfies a predicate. /// /// `find()` takes a closure that returns `true` or `false`. It applies diff --git a/library/core/tests/iter.rs b/library/core/tests/iter.rs new file mode 100644 index 0000000000000..8fde885259af8 --- /dev/null +++ b/library/core/tests/iter.rs @@ -0,0 +1,3615 @@ +// ignore-tidy-filelength + +use core::cell::Cell; +use core::convert::TryFrom; +use core::iter::*; + +/// An iterator wrapper that panics whenever `next` or `next_back` is called +/// after `None` has been returned. +struct Unfuse { + iter: I, + exhausted: bool, +} + +fn unfuse(iter: I) -> Unfuse { + Unfuse { iter: iter.into_iter(), exhausted: false } +} + +impl Iterator for Unfuse +where + I: Iterator, +{ + type Item = I::Item; + + fn next(&mut self) -> Option { + assert!(!self.exhausted); + let next = self.iter.next(); + self.exhausted = next.is_none(); + next + } +} + +impl DoubleEndedIterator for Unfuse +where + I: DoubleEndedIterator, +{ + fn next_back(&mut self) -> Option { + assert!(!self.exhausted); + let next = self.iter.next_back(); + self.exhausted = next.is_none(); + next + } +} + +#[test] +fn test_lt() { + let empty: [isize; 0] = []; + let xs = [1, 2, 3]; + let ys = [1, 2, 0]; + + assert!(!xs.iter().lt(ys.iter())); + assert!(!xs.iter().le(ys.iter())); + assert!(xs.iter().gt(ys.iter())); + assert!(xs.iter().ge(ys.iter())); + + assert!(ys.iter().lt(xs.iter())); + assert!(ys.iter().le(xs.iter())); + assert!(!ys.iter().gt(xs.iter())); + assert!(!ys.iter().ge(xs.iter())); + + assert!(empty.iter().lt(xs.iter())); + assert!(empty.iter().le(xs.iter())); + assert!(!empty.iter().gt(xs.iter())); + assert!(!empty.iter().ge(xs.iter())); + + // Sequence with NaN + let u = [1.0f64, 2.0]; + let v = [0.0f64 / 0.0, 3.0]; + + assert!(!u.iter().lt(v.iter())); + assert!(!u.iter().le(v.iter())); + assert!(!u.iter().gt(v.iter())); + assert!(!u.iter().ge(v.iter())); + + let a = [0.0f64 / 0.0]; + let b = [1.0f64]; + let c = [2.0f64]; + + assert!(a.iter().lt(b.iter()) == (a[0] < b[0])); + assert!(a.iter().le(b.iter()) == (a[0] <= b[0])); + assert!(a.iter().gt(b.iter()) == (a[0] > b[0])); + assert!(a.iter().ge(b.iter()) == (a[0] >= b[0])); + + assert!(c.iter().lt(b.iter()) == (c[0] < b[0])); + assert!(c.iter().le(b.iter()) == (c[0] <= b[0])); + assert!(c.iter().gt(b.iter()) == (c[0] > b[0])); + assert!(c.iter().ge(b.iter()) == (c[0] >= b[0])); +} + +#[test] +fn test_multi_iter() { + let xs = [1, 2, 3, 4]; + let ys = [4, 3, 2, 1]; + assert!(xs.iter().eq(ys.iter().rev())); + assert!(xs.iter().lt(xs.iter().skip(2))); +} + +#[test] +fn test_cmp_by() { + use core::cmp::Ordering; + + let f = |x: i32, y: i32| (x * x).cmp(&y); + let xs = || [1, 2, 3, 4].iter().copied(); + let ys = || [1, 4, 16].iter().copied(); + + assert_eq!(xs().cmp_by(ys(), f), Ordering::Less); + assert_eq!(ys().cmp_by(xs(), f), Ordering::Greater); + assert_eq!(xs().cmp_by(xs().map(|x| x * x), f), Ordering::Equal); + assert_eq!(xs().rev().cmp_by(ys().rev(), f), Ordering::Greater); + assert_eq!(xs().cmp_by(ys().rev(), f), Ordering::Less); + assert_eq!(xs().cmp_by(ys().take(2), f), Ordering::Greater); +} + +#[test] +fn test_partial_cmp_by() { + use core::cmp::Ordering; + + let f = |x: i32, y: i32| (x * x).partial_cmp(&y); + let xs = || [1, 2, 3, 4].iter().copied(); + let ys = || [1, 4, 16].iter().copied(); + + assert_eq!(xs().partial_cmp_by(ys(), f), Some(Ordering::Less)); + assert_eq!(ys().partial_cmp_by(xs(), f), Some(Ordering::Greater)); + assert_eq!(xs().partial_cmp_by(xs().map(|x| x * x), f), Some(Ordering::Equal)); + assert_eq!(xs().rev().partial_cmp_by(ys().rev(), f), Some(Ordering::Greater)); + assert_eq!(xs().partial_cmp_by(xs().rev(), f), Some(Ordering::Less)); + assert_eq!(xs().partial_cmp_by(ys().take(2), f), Some(Ordering::Greater)); + + let f = |x: f64, y: f64| (x * x).partial_cmp(&y); + let xs = || [1.0, 2.0, 3.0, 4.0].iter().copied(); + let ys = || [1.0, 4.0, f64::NAN, 16.0].iter().copied(); + + assert_eq!(xs().partial_cmp_by(ys(), f), None); + assert_eq!(ys().partial_cmp_by(xs(), f), Some(Ordering::Greater)); +} + +#[test] +fn test_eq_by() { + let f = |x: i32, y: i32| x * x == y; + let xs = || [1, 2, 3, 4].iter().copied(); + let ys = || [1, 4, 9, 16].iter().copied(); + + assert!(xs().eq_by(ys(), f)); + assert!(!ys().eq_by(xs(), f)); + assert!(!xs().eq_by(xs(), f)); + assert!(!ys().eq_by(ys(), f)); + + assert!(!xs().take(3).eq_by(ys(), f)); + assert!(!xs().eq_by(ys().take(3), f)); + assert!(xs().take(3).eq_by(ys().take(3), f)); +} + +#[test] +fn test_counter_from_iter() { + let it = (0..).step_by(5).take(10); + let xs: Vec = FromIterator::from_iter(it); + assert_eq!(xs, [0, 5, 10, 15, 20, 25, 30, 35, 40, 45]); +} + +#[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(xs).chain(unfuse(ys)); + iter.advance_by(i).unwrap(); + assert_eq!(iter.next(), Some(&xs[i])); + assert_eq!(iter.advance_by(100), Err(len - i - 1)); + } + + for i in 0..ys.len() { + let mut iter = unfuse(xs).chain(unfuse(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)); + } + + let mut iter = xs.iter().chain(ys); + iter.advance_by(len).unwrap(); + assert_eq!(iter.next(), None); + + let mut iter = xs.iter().chain(ys); + assert_eq!(iter.advance_by(len + 1), Err(len)); + } + + 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(xs).chain(unfuse(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)); + } + + for i in 0..xs.len() { + let mut iter = unfuse(xs).chain(unfuse(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)); + } + + let mut iter = xs.iter().chain(ys); + iter.advance_back_by(len).unwrap(); + assert_eq!(iter.next_back(), None); + + let mut iter = xs.iter().chain(ys); + assert_eq!(iter.advance_back_by(len + 1), Err(len)); + } + + 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); +} + +struct Toggle { + is_empty: bool, +} + +impl Iterator for Toggle { + type Item = (); + + // alternates between `None` and `Some(())` + fn next(&mut self) -> Option { + if self.is_empty { + self.is_empty = false; + None + } else { + self.is_empty = true; + Some(()) + } + } + + fn size_hint(&self) -> (usize, Option) { + if self.is_empty { (0, Some(0)) } else { (1, Some(1)) } + } +} + +impl DoubleEndedIterator for Toggle { + fn next_back(&mut self) -> Option { + self.next() + } +} + +#[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 }); + iter.next().unwrap_none(); + iter.next().unwrap(); + iter.next().unwrap_none(); + + let mut iter = Toggle { is_empty: true }.chain(NonFused::new(empty())); + iter.next_back().unwrap_none(); + iter.next_back().unwrap(); + iter.next_back().unwrap_none(); +} + +#[test] +fn test_zip_nth() { + let xs = [0, 1, 2, 4, 5]; + let ys = [10, 11, 12]; + + let mut it = xs.iter().zip(&ys); + assert_eq!(it.nth(0), Some((&0, &10))); + assert_eq!(it.nth(1), Some((&2, &12))); + assert_eq!(it.nth(0), None); + + let mut it = xs.iter().zip(&ys); + assert_eq!(it.nth(3), None); + + let mut it = ys.iter().zip(&xs); + assert_eq!(it.nth(3), None); +} + +#[test] +fn test_zip_nth_side_effects() { + let mut a = Vec::new(); + let mut b = Vec::new(); + let value = [1, 2, 3, 4, 5, 6] + .iter() + .cloned() + .map(|n| { + a.push(n); + n * 10 + }) + .zip([2, 3, 4, 5, 6, 7, 8].iter().cloned().map(|n| { + b.push(n * 100); + n * 1000 + })) + .skip(1) + .nth(3); + assert_eq!(value, Some((50, 6000))); + assert_eq!(a, vec![1, 2, 3, 4, 5]); + assert_eq!(b, vec![200, 300, 400, 500, 600]); +} + +#[test] +fn test_zip_next_back_side_effects() { + let mut a = Vec::new(); + let mut b = Vec::new(); + let mut iter = [1, 2, 3, 4, 5, 6] + .iter() + .cloned() + .map(|n| { + a.push(n); + n * 10 + }) + .zip([2, 3, 4, 5, 6, 7, 8].iter().cloned().map(|n| { + b.push(n * 100); + n * 1000 + })); + + // The second iterator is one item longer, so `next_back` is called on it + // one more time. + assert_eq!(iter.next_back(), Some((60, 7000))); + assert_eq!(iter.next_back(), Some((50, 6000))); + assert_eq!(iter.next_back(), Some((40, 5000))); + assert_eq!(iter.next_back(), Some((30, 4000))); + assert_eq!(a, vec![6, 5, 4, 3]); + assert_eq!(b, vec![800, 700, 600, 500, 400]); +} + +#[test] +fn test_zip_nth_back_side_effects() { + let mut a = Vec::new(); + let mut b = Vec::new(); + let value = [1, 2, 3, 4, 5, 6] + .iter() + .cloned() + .map(|n| { + a.push(n); + n * 10 + }) + .zip([2, 3, 4, 5, 6, 7, 8].iter().cloned().map(|n| { + b.push(n * 100); + n * 1000 + })) + .nth_back(3); + assert_eq!(value, Some((30, 4000))); + assert_eq!(a, vec![6, 5, 4, 3]); + assert_eq!(b, vec![800, 700, 600, 500, 400]); +} + +#[test] +fn test_zip_next_back_side_effects_exhausted() { + let mut a = Vec::new(); + let mut b = Vec::new(); + let mut iter = [1, 2, 3, 4, 5, 6] + .iter() + .cloned() + .map(|n| { + a.push(n); + n * 10 + }) + .zip([2, 3, 4].iter().cloned().map(|n| { + b.push(n * 100); + n * 1000 + })); + + iter.next(); + iter.next(); + iter.next(); + iter.next(); + assert_eq!(iter.next_back(), None); + assert_eq!(a, vec![1, 2, 3, 4, 6, 5]); + assert_eq!(b, vec![200, 300, 400]); +} + +#[derive(Debug)] +struct CountClone(Cell); + +fn count_clone() -> CountClone { + CountClone(Cell::new(0)) +} + +impl PartialEq for CountClone { + fn eq(&self, rhs: &i32) -> bool { + self.0.get() == *rhs + } +} + +impl Clone for CountClone { + fn clone(&self) -> Self { + let ret = CountClone(self.0.clone()); + let n = self.0.get(); + self.0.set(n + 1); + ret + } +} + +#[test] +fn test_zip_cloned_sideffectful() { + let xs = [count_clone(), count_clone(), count_clone(), count_clone()]; + let ys = [count_clone(), count_clone()]; + + for _ in xs.iter().cloned().zip(ys.iter().cloned()) {} + + assert_eq!(&xs, &[1, 1, 1, 0][..]); + assert_eq!(&ys, &[1, 1][..]); + + let xs = [count_clone(), count_clone()]; + let ys = [count_clone(), count_clone(), count_clone(), count_clone()]; + + for _ in xs.iter().cloned().zip(ys.iter().cloned()) {} + + assert_eq!(&xs, &[1, 1][..]); + assert_eq!(&ys, &[1, 1, 0, 0][..]); +} + +#[test] +fn test_zip_map_sideffectful() { + let mut xs = [0; 6]; + let mut ys = [0; 4]; + + for _ in xs.iter_mut().map(|x| *x += 1).zip(ys.iter_mut().map(|y| *y += 1)) {} + + assert_eq!(&xs, &[1, 1, 1, 1, 1, 0]); + assert_eq!(&ys, &[1, 1, 1, 1]); + + let mut xs = [0; 4]; + let mut ys = [0; 6]; + + for _ in xs.iter_mut().map(|x| *x += 1).zip(ys.iter_mut().map(|y| *y += 1)) {} + + assert_eq!(&xs, &[1, 1, 1, 1]); + assert_eq!(&ys, &[1, 1, 1, 1, 0, 0]); +} + +#[test] +fn test_zip_map_rev_sideffectful() { + let mut xs = [0; 6]; + let mut ys = [0; 4]; + + { + let mut it = xs.iter_mut().map(|x| *x += 1).zip(ys.iter_mut().map(|y| *y += 1)); + it.next_back(); + } + assert_eq!(&xs, &[0, 0, 0, 1, 1, 1]); + assert_eq!(&ys, &[0, 0, 0, 1]); + + let mut xs = [0; 6]; + let mut ys = [0; 4]; + + { + let mut it = xs.iter_mut().map(|x| *x += 1).zip(ys.iter_mut().map(|y| *y += 1)); + (&mut it).take(5).count(); + it.next_back(); + } + assert_eq!(&xs, &[1, 1, 1, 1, 1, 1]); + assert_eq!(&ys, &[1, 1, 1, 1]); +} + +#[test] +fn test_zip_nested_sideffectful() { + let mut xs = [0; 6]; + let ys = [0; 4]; + + { + // test that it has the side effect nested inside enumerate + let it = xs.iter_mut().map(|x| *x = 1).enumerate().zip(&ys); + it.count(); + } + assert_eq!(&xs, &[1, 1, 1, 1, 1, 0]); +} + +#[test] +fn test_zip_nth_back_side_effects_exhausted() { + let mut a = Vec::new(); + let mut b = Vec::new(); + let mut iter = [1, 2, 3, 4, 5, 6] + .iter() + .cloned() + .map(|n| { + a.push(n); + n * 10 + }) + .zip([2, 3, 4].iter().cloned().map(|n| { + b.push(n * 100); + n * 1000 + })); + + iter.next(); + iter.next(); + iter.next(); + iter.next(); + assert_eq!(iter.nth_back(0), None); + assert_eq!(a, vec![1, 2, 3, 4, 6, 5]); + assert_eq!(b, vec![200, 300, 400]); +} + +#[test] +fn test_iterator_step_by() { + // Identity + let mut it = (0..).step_by(1).take(3); + assert_eq!(it.next(), Some(0)); + assert_eq!(it.next(), Some(1)); + assert_eq!(it.next(), Some(2)); + assert_eq!(it.next(), None); + + let mut it = (0..).step_by(3).take(4); + assert_eq!(it.next(), Some(0)); + assert_eq!(it.next(), Some(3)); + assert_eq!(it.next(), Some(6)); + assert_eq!(it.next(), Some(9)); + assert_eq!(it.next(), None); + + let mut it = (0..3).step_by(1); + assert_eq!(it.next_back(), Some(2)); + assert_eq!(it.next_back(), Some(1)); + assert_eq!(it.next_back(), Some(0)); + assert_eq!(it.next_back(), None); + + let mut it = (0..11).step_by(3); + assert_eq!(it.next_back(), Some(9)); + assert_eq!(it.next_back(), Some(6)); + assert_eq!(it.next_back(), Some(3)); + assert_eq!(it.next_back(), Some(0)); + assert_eq!(it.next_back(), None); +} + +#[test] +fn test_iterator_step_by_nth() { + let mut it = (0..16).step_by(5); + assert_eq!(it.nth(0), Some(0)); + assert_eq!(it.nth(0), Some(5)); + assert_eq!(it.nth(0), Some(10)); + assert_eq!(it.nth(0), Some(15)); + assert_eq!(it.nth(0), None); + + let it = (0..18).step_by(5); + assert_eq!(it.clone().nth(0), Some(0)); + assert_eq!(it.clone().nth(1), Some(5)); + assert_eq!(it.clone().nth(2), Some(10)); + assert_eq!(it.clone().nth(3), Some(15)); + assert_eq!(it.clone().nth(4), None); + assert_eq!(it.clone().nth(42), None); +} + +#[test] +fn test_iterator_step_by_nth_overflow() { + #[cfg(target_pointer_width = "8")] + type Bigger = u16; + #[cfg(target_pointer_width = "16")] + type Bigger = u32; + #[cfg(target_pointer_width = "32")] + type Bigger = u64; + #[cfg(target_pointer_width = "64")] + type Bigger = u128; + + #[derive(Clone)] + struct Test(Bigger); + impl Iterator for &mut Test { + type Item = i32; + fn next(&mut self) -> Option { + Some(21) + } + fn nth(&mut self, n: usize) -> Option { + self.0 += n as Bigger + 1; + Some(42) + } + } + + let mut it = Test(0); + let root = usize::MAX >> (usize::BITS / 2); + let n = root + 20; + (&mut it).step_by(n).nth(n); + assert_eq!(it.0, n as Bigger * n as Bigger); + + // large step + let mut it = Test(0); + (&mut it).step_by(usize::MAX).nth(5); + assert_eq!(it.0, (usize::MAX as Bigger) * 5); + + // n + 1 overflows + let mut it = Test(0); + (&mut it).step_by(2).nth(usize::MAX); + assert_eq!(it.0, (usize::MAX as Bigger) * 2); + + // n + 1 overflows + let mut it = Test(0); + (&mut it).step_by(1).nth(usize::MAX); + assert_eq!(it.0, (usize::MAX as Bigger) * 1); +} + +#[test] +fn test_iterator_step_by_nth_try_fold() { + let mut it = (0..).step_by(10); + assert_eq!(it.try_fold(0, i8::checked_add), None); + assert_eq!(it.next(), Some(60)); + assert_eq!(it.try_fold(0, i8::checked_add), None); + assert_eq!(it.next(), Some(90)); + + let mut it = (100..).step_by(10); + assert_eq!(it.try_fold(50, i8::checked_add), None); + assert_eq!(it.next(), Some(110)); + + let mut it = (100..=100).step_by(10); + assert_eq!(it.next(), Some(100)); + assert_eq!(it.try_fold(0, i8::checked_add), Some(0)); +} + +#[test] +fn test_iterator_step_by_nth_back() { + let mut it = (0..16).step_by(5); + assert_eq!(it.nth_back(0), Some(15)); + assert_eq!(it.nth_back(0), Some(10)); + assert_eq!(it.nth_back(0), Some(5)); + assert_eq!(it.nth_back(0), Some(0)); + assert_eq!(it.nth_back(0), None); + + let mut it = (0..16).step_by(5); + assert_eq!(it.next(), Some(0)); // to set `first_take` to `false` + assert_eq!(it.nth_back(0), Some(15)); + assert_eq!(it.nth_back(0), Some(10)); + assert_eq!(it.nth_back(0), Some(5)); + assert_eq!(it.nth_back(0), None); + + let it = || (0..18).step_by(5); + assert_eq!(it().nth_back(0), Some(15)); + assert_eq!(it().nth_back(1), Some(10)); + assert_eq!(it().nth_back(2), Some(5)); + assert_eq!(it().nth_back(3), Some(0)); + assert_eq!(it().nth_back(4), None); + assert_eq!(it().nth_back(42), None); +} + +#[test] +fn test_iterator_step_by_nth_try_rfold() { + let mut it = (0..100).step_by(10); + assert_eq!(it.try_rfold(0, i8::checked_add), None); + assert_eq!(it.next_back(), Some(70)); + assert_eq!(it.next(), Some(0)); + assert_eq!(it.try_rfold(0, i8::checked_add), None); + assert_eq!(it.next_back(), Some(30)); + + let mut it = (0..100).step_by(10); + assert_eq!(it.try_rfold(50, i8::checked_add), None); + assert_eq!(it.next_back(), Some(80)); + + let mut it = (100..=100).step_by(10); + assert_eq!(it.next_back(), Some(100)); + assert_eq!(it.try_fold(0, i8::checked_add), Some(0)); +} + +#[test] +#[should_panic] +fn test_iterator_step_by_zero() { + let mut it = (0..).step_by(0); + it.next(); +} + +#[test] +fn test_iterator_step_by_size_hint() { + struct StubSizeHint(usize, Option); + impl Iterator for StubSizeHint { + type Item = (); + fn next(&mut self) -> Option<()> { + self.0 -= 1; + if let Some(ref mut upper) = self.1 { + *upper -= 1; + } + Some(()) + } + fn size_hint(&self) -> (usize, Option) { + (self.0, self.1) + } + } + + // The two checks in each case are needed because the logic + // is different before the first call to `next()`. + + let mut it = StubSizeHint(10, Some(10)).step_by(1); + assert_eq!(it.size_hint(), (10, Some(10))); + it.next(); + assert_eq!(it.size_hint(), (9, Some(9))); + + // exact multiple + let mut it = StubSizeHint(10, Some(10)).step_by(3); + assert_eq!(it.size_hint(), (4, Some(4))); + it.next(); + assert_eq!(it.size_hint(), (3, Some(3))); + + // larger base range, but not enough to get another element + let mut it = StubSizeHint(12, Some(12)).step_by(3); + assert_eq!(it.size_hint(), (4, Some(4))); + it.next(); + assert_eq!(it.size_hint(), (3, Some(3))); + + // smaller base range, so fewer resulting elements + let mut it = StubSizeHint(9, Some(9)).step_by(3); + assert_eq!(it.size_hint(), (3, Some(3))); + it.next(); + assert_eq!(it.size_hint(), (2, Some(2))); + + // infinite upper bound + let mut it = StubSizeHint(usize::MAX, None).step_by(1); + assert_eq!(it.size_hint(), (usize::MAX, None)); + it.next(); + assert_eq!(it.size_hint(), (usize::MAX - 1, None)); + + // still infinite with larger step + let mut it = StubSizeHint(7, None).step_by(3); + assert_eq!(it.size_hint(), (3, None)); + it.next(); + assert_eq!(it.size_hint(), (2, None)); + + // propagates ExactSizeIterator + let a = [1, 2, 3, 4, 5]; + let it = a.iter().step_by(2); + assert_eq!(it.len(), 3); + + // Cannot be TrustedLen as a step greater than one makes an iterator + // with (usize::MAX, None) no longer meet the safety requirements + trait TrustedLenCheck { + fn test(self) -> bool; + } + impl TrustedLenCheck for T { + default fn test(self) -> bool { + false + } + } + impl TrustedLenCheck for T { + fn test(self) -> bool { + true + } + } + assert!(TrustedLenCheck::test(a.iter())); + assert!(!TrustedLenCheck::test(a.iter().step_by(1))); +} + +#[test] +fn test_filter_map() { + let it = (0..).step_by(1).take(10).filter_map(|x| if x % 2 == 0 { Some(x * x) } else { None }); + assert_eq!(it.collect::>(), [0 * 0, 2 * 2, 4 * 4, 6 * 6, 8 * 8]); +} + +#[test] +fn test_filter_map_fold() { + let xs = [0, 1, 2, 3, 4, 5, 6, 7, 8]; + let ys = [0 * 0, 2 * 2, 4 * 4, 6 * 6, 8 * 8]; + let it = xs.iter().filter_map(|&x| if x % 2 == 0 { Some(x * x) } else { None }); + let i = it.fold(0, |i, x| { + assert_eq!(x, ys[i]); + i + 1 + }); + assert_eq!(i, ys.len()); + + let it = xs.iter().filter_map(|&x| if x % 2 == 0 { Some(x * x) } else { None }); + let i = it.rfold(ys.len(), |i, x| { + assert_eq!(x, ys[i - 1]); + i - 1 + }); + assert_eq!(i, 0); +} + +#[test] +fn test_iterator_enumerate() { + let xs = [0, 1, 2, 3, 4, 5]; + let it = xs.iter().enumerate(); + for (i, &x) in it { + assert_eq!(i, x); + } +} + +#[test] +fn test_iterator_enumerate_nth() { + let xs = [0, 1, 2, 3, 4, 5]; + for (i, &x) in xs.iter().enumerate() { + assert_eq!(i, x); + } + + let mut it = xs.iter().enumerate(); + while let Some((i, &x)) = it.nth(0) { + assert_eq!(i, x); + } + + let mut it = xs.iter().enumerate(); + while let Some((i, &x)) = it.nth(1) { + assert_eq!(i, x); + } + + let (i, &x) = xs.iter().enumerate().nth(3).unwrap(); + assert_eq!(i, x); + assert_eq!(i, 3); +} + +#[test] +fn test_iterator_enumerate_nth_back() { + let xs = [0, 1, 2, 3, 4, 5]; + let mut it = xs.iter().enumerate(); + while let Some((i, &x)) = it.nth_back(0) { + assert_eq!(i, x); + } + + let mut it = xs.iter().enumerate(); + while let Some((i, &x)) = it.nth_back(1) { + assert_eq!(i, x); + } + + let (i, &x) = xs.iter().enumerate().nth_back(3).unwrap(); + assert_eq!(i, x); + assert_eq!(i, 2); +} + +#[test] +fn test_iterator_enumerate_count() { + let xs = [0, 1, 2, 3, 4, 5]; + assert_eq!(xs.iter().enumerate().count(), 6); +} + +#[test] +fn test_iterator_enumerate_fold() { + let xs = [0, 1, 2, 3, 4, 5]; + let mut it = xs.iter().enumerate(); + // steal a couple to get an interesting offset + assert_eq!(it.next(), Some((0, &0))); + assert_eq!(it.next(), Some((1, &1))); + let i = it.fold(2, |i, (j, &x)| { + assert_eq!(i, j); + assert_eq!(x, xs[j]); + i + 1 + }); + assert_eq!(i, xs.len()); + + let mut it = xs.iter().enumerate(); + assert_eq!(it.next(), Some((0, &0))); + let i = it.rfold(xs.len() - 1, |i, (j, &x)| { + assert_eq!(i, j); + assert_eq!(x, xs[j]); + i - 1 + }); + assert_eq!(i, 0); +} + +#[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_iterator_peekable() { + let xs = vec![0, 1, 2, 3, 4, 5]; + + let mut it = xs.iter().cloned().peekable(); + assert_eq!(it.len(), 6); + assert_eq!(it.peek().unwrap(), &0); + assert_eq!(it.len(), 6); + assert_eq!(it.next().unwrap(), 0); + assert_eq!(it.len(), 5); + assert_eq!(it.next().unwrap(), 1); + assert_eq!(it.len(), 4); + assert_eq!(it.next().unwrap(), 2); + assert_eq!(it.len(), 3); + assert_eq!(it.peek().unwrap(), &3); + assert_eq!(it.len(), 3); + assert_eq!(it.peek().unwrap(), &3); + assert_eq!(it.len(), 3); + assert_eq!(it.next().unwrap(), 3); + assert_eq!(it.len(), 2); + assert_eq!(it.next().unwrap(), 4); + assert_eq!(it.len(), 1); + assert_eq!(it.peek().unwrap(), &5); + assert_eq!(it.len(), 1); + assert_eq!(it.next().unwrap(), 5); + assert_eq!(it.len(), 0); + assert!(it.peek().is_none()); + assert_eq!(it.len(), 0); + assert!(it.next().is_none()); + assert_eq!(it.len(), 0); + + let mut it = xs.iter().cloned().peekable(); + assert_eq!(it.len(), 6); + assert_eq!(it.peek().unwrap(), &0); + assert_eq!(it.len(), 6); + assert_eq!(it.next_back().unwrap(), 5); + assert_eq!(it.len(), 5); + assert_eq!(it.next_back().unwrap(), 4); + assert_eq!(it.len(), 4); + assert_eq!(it.next_back().unwrap(), 3); + assert_eq!(it.len(), 3); + assert_eq!(it.peek().unwrap(), &0); + assert_eq!(it.len(), 3); + assert_eq!(it.peek().unwrap(), &0); + assert_eq!(it.len(), 3); + assert_eq!(it.next_back().unwrap(), 2); + assert_eq!(it.len(), 2); + assert_eq!(it.next_back().unwrap(), 1); + assert_eq!(it.len(), 1); + assert_eq!(it.peek().unwrap(), &0); + assert_eq!(it.len(), 1); + assert_eq!(it.next_back().unwrap(), 0); + assert_eq!(it.len(), 0); + assert!(it.peek().is_none()); + assert_eq!(it.len(), 0); + assert!(it.next_back().is_none()); + assert_eq!(it.len(), 0); +} + +#[test] +fn test_iterator_peekable_count() { + let xs = [0, 1, 2, 3, 4, 5]; + let ys = [10]; + let zs: [i32; 0] = []; + + assert_eq!(xs.iter().peekable().count(), 6); + + let mut it = xs.iter().peekable(); + assert_eq!(it.peek(), Some(&&0)); + assert_eq!(it.count(), 6); + + assert_eq!(ys.iter().peekable().count(), 1); + + let mut it = ys.iter().peekable(); + assert_eq!(it.peek(), Some(&&10)); + assert_eq!(it.count(), 1); + + assert_eq!(zs.iter().peekable().count(), 0); + + let mut it = zs.iter().peekable(); + assert_eq!(it.peek(), None); +} + +#[test] +fn test_iterator_peekable_nth() { + let xs = [0, 1, 2, 3, 4, 5]; + let mut it = xs.iter().peekable(); + + assert_eq!(it.peek(), Some(&&0)); + assert_eq!(it.nth(0), Some(&0)); + assert_eq!(it.peek(), Some(&&1)); + assert_eq!(it.nth(1), Some(&2)); + assert_eq!(it.peek(), Some(&&3)); + assert_eq!(it.nth(2), Some(&5)); + assert_eq!(it.next(), None); +} + +#[test] +fn test_iterator_peekable_last() { + let xs = [0, 1, 2, 3, 4, 5]; + let ys = [0]; + + let mut it = xs.iter().peekable(); + assert_eq!(it.peek(), Some(&&0)); + assert_eq!(it.last(), Some(&5)); + + let mut it = ys.iter().peekable(); + assert_eq!(it.peek(), Some(&&0)); + assert_eq!(it.last(), Some(&0)); + + let mut it = ys.iter().peekable(); + assert_eq!(it.next(), Some(&0)); + assert_eq!(it.peek(), None); + assert_eq!(it.last(), None); +} + +#[test] +fn test_iterator_peekable_fold() { + let xs = [0, 1, 2, 3, 4, 5]; + let mut it = xs.iter().peekable(); + assert_eq!(it.peek(), Some(&&0)); + let i = it.fold(0, |i, &x| { + assert_eq!(x, xs[i]); + i + 1 + }); + assert_eq!(i, xs.len()); +} + +#[test] +fn test_iterator_peekable_rfold() { + let xs = [0, 1, 2, 3, 4, 5]; + let mut it = xs.iter().peekable(); + assert_eq!(it.peek(), Some(&&0)); + let i = it.rfold(0, |i, &x| { + assert_eq!(x, xs[xs.len() - 1 - i]); + i + 1 + }); + assert_eq!(i, xs.len()); +} + +#[test] +fn test_iterator_peekable_next_if_eq() { + // first, try on references + let xs = vec!["Heart", "of", "Gold"]; + let mut it = xs.into_iter().peekable(); + // try before `peek()` + assert_eq!(it.next_if_eq(&"trillian"), None); + assert_eq!(it.next_if_eq(&"Heart"), Some("Heart")); + // try after peek() + assert_eq!(it.peek(), Some(&"of")); + assert_eq!(it.next_if_eq(&"of"), Some("of")); + assert_eq!(it.next_if_eq(&"zaphod"), None); + // make sure `next()` still behaves + assert_eq!(it.next(), Some("Gold")); + + // make sure comparison works for owned values + let xs = vec![String::from("Ludicrous"), "speed".into()]; + let mut it = xs.into_iter().peekable(); + // make sure basic functionality works + assert_eq!(it.next_if_eq("Ludicrous"), Some("Ludicrous".into())); + assert_eq!(it.next_if_eq("speed"), Some("speed".into())); + assert_eq!(it.next_if_eq(""), None); +} + +#[test] +fn test_iterator_peekable_mut() { + let mut it = vec![1, 2, 3].into_iter().peekable(); + if let Some(p) = it.peek_mut() { + if *p == 1 { + *p = 5; + } + } + assert_eq!(it.collect::>(), vec![5, 2, 3]); +} + +/// This is an iterator that follows the Iterator contract, +/// but it is not fused. After having returned None once, it will start +/// producing elements if .next() is called again. +pub struct CycleIter<'a, T> { + index: usize, + data: &'a [T], +} + +pub fn cycle(data: &[T]) -> CycleIter<'_, T> { + CycleIter { index: 0, data } +} + +impl<'a, T> Iterator for CycleIter<'a, T> { + type Item = &'a T; + fn next(&mut self) -> Option { + let elt = self.data.get(self.index); + self.index += 1; + self.index %= 1 + self.data.len(); + elt + } +} + +#[test] +fn test_iterator_peekable_remember_peek_none_1() { + // Check that the loop using .peek() terminates + let data = [1, 2, 3]; + let mut iter = cycle(&data).peekable(); + + let mut n = 0; + while let Some(_) = iter.next() { + let is_the_last = iter.peek().is_none(); + assert_eq!(is_the_last, n == data.len() - 1); + n += 1; + if n > data.len() { + break; + } + } + assert_eq!(n, data.len()); +} + +#[test] +fn test_iterator_peekable_remember_peek_none_2() { + let data = [0]; + let mut iter = cycle(&data).peekable(); + iter.next(); + assert_eq!(iter.peek(), None); + assert_eq!(iter.last(), None); +} + +#[test] +fn test_iterator_peekable_remember_peek_none_3() { + let data = [0]; + let mut iter = cycle(&data).peekable(); + iter.peek(); + assert_eq!(iter.nth(0), Some(&0)); + + let mut iter = cycle(&data).peekable(); + iter.next(); + assert_eq!(iter.peek(), None); + assert_eq!(iter.nth(0), None); +} + +#[test] +fn test_iterator_take_while() { + let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19]; + let ys = [0, 1, 2, 3, 5, 13]; + let it = xs.iter().take_while(|&x| *x < 15); + let mut i = 0; + for x in it { + assert_eq!(*x, ys[i]); + i += 1; + } + assert_eq!(i, ys.len()); +} + +#[test] +fn test_iterator_skip_while() { + let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19]; + let ys = [15, 16, 17, 19]; + let it = xs.iter().skip_while(|&x| *x < 15); + let mut i = 0; + for x in it { + assert_eq!(*x, ys[i]); + i += 1; + } + assert_eq!(i, ys.len()); +} + +#[test] +fn test_iterator_skip_while_fold() { + let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19]; + let ys = [15, 16, 17, 19]; + let it = xs.iter().skip_while(|&x| *x < 15); + let i = it.fold(0, |i, &x| { + assert_eq!(x, ys[i]); + i + 1 + }); + assert_eq!(i, ys.len()); + + let mut it = xs.iter().skip_while(|&x| *x < 15); + assert_eq!(it.next(), Some(&ys[0])); // process skips before folding + let i = it.fold(1, |i, &x| { + assert_eq!(x, ys[i]); + i + 1 + }); + assert_eq!(i, ys.len()); +} + +#[test] +fn test_iterator_skip() { + let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19, 20, 30]; + let ys = [13, 15, 16, 17, 19, 20, 30]; + let mut it = xs.iter().skip(5); + let mut i = 0; + while let Some(&x) = it.next() { + assert_eq!(x, ys[i]); + i += 1; + assert_eq!(it.len(), xs.len() - 5 - i); + } + assert_eq!(i, ys.len()); + assert_eq!(it.len(), 0); +} + +#[test] +fn test_iterator_skip_doubleended() { + let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19, 20, 30]; + let mut it = xs.iter().rev().skip(5); + assert_eq!(it.next(), Some(&15)); + assert_eq!(it.by_ref().rev().next(), Some(&0)); + assert_eq!(it.next(), Some(&13)); + assert_eq!(it.by_ref().rev().next(), Some(&1)); + assert_eq!(it.next(), Some(&5)); + assert_eq!(it.by_ref().rev().next(), Some(&2)); + assert_eq!(it.next(), Some(&3)); + assert_eq!(it.next(), None); + let mut it = xs.iter().rev().skip(5).rev(); + assert_eq!(it.next(), Some(&0)); + assert_eq!(it.rev().next(), Some(&15)); + let mut it_base = xs.iter(); + { + let mut it = it_base.by_ref().skip(5).rev(); + assert_eq!(it.next(), Some(&30)); + assert_eq!(it.next(), Some(&20)); + assert_eq!(it.next(), Some(&19)); + assert_eq!(it.next(), Some(&17)); + assert_eq!(it.next(), Some(&16)); + assert_eq!(it.next(), Some(&15)); + assert_eq!(it.next(), Some(&13)); + assert_eq!(it.next(), None); + } + // make sure the skipped parts have not been consumed + assert_eq!(it_base.next(), Some(&0)); + assert_eq!(it_base.next(), Some(&1)); + assert_eq!(it_base.next(), Some(&2)); + assert_eq!(it_base.next(), Some(&3)); + assert_eq!(it_base.next(), Some(&5)); + assert_eq!(it_base.next(), None); + let it = xs.iter().skip(5).rev(); + assert_eq!(it.last(), Some(&13)); +} + +#[test] +fn test_iterator_skip_nth() { + let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19, 20, 30]; + + let mut it = xs.iter().skip(0); + assert_eq!(it.nth(0), Some(&0)); + assert_eq!(it.nth(1), Some(&2)); + + let mut it = xs.iter().skip(5); + assert_eq!(it.nth(0), Some(&13)); + assert_eq!(it.nth(1), Some(&16)); + + let mut it = xs.iter().skip(12); + assert_eq!(it.nth(0), None); +} + +#[test] +fn test_iterator_skip_count() { + let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19, 20, 30]; + + assert_eq!(xs.iter().skip(0).count(), 12); + assert_eq!(xs.iter().skip(1).count(), 11); + assert_eq!(xs.iter().skip(11).count(), 1); + assert_eq!(xs.iter().skip(12).count(), 0); + assert_eq!(xs.iter().skip(13).count(), 0); +} + +#[test] +fn test_iterator_skip_last() { + let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19, 20, 30]; + + assert_eq!(xs.iter().skip(0).last(), Some(&30)); + assert_eq!(xs.iter().skip(1).last(), Some(&30)); + assert_eq!(xs.iter().skip(11).last(), Some(&30)); + assert_eq!(xs.iter().skip(12).last(), None); + assert_eq!(xs.iter().skip(13).last(), None); + + let mut it = xs.iter().skip(5); + assert_eq!(it.next(), Some(&13)); + assert_eq!(it.last(), Some(&30)); +} + +#[test] +fn test_iterator_skip_fold() { + let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19, 20, 30]; + let ys = [13, 15, 16, 17, 19, 20, 30]; + + let it = xs.iter().skip(5); + let i = it.fold(0, |i, &x| { + assert_eq!(x, ys[i]); + i + 1 + }); + assert_eq!(i, ys.len()); + + let mut it = xs.iter().skip(5); + assert_eq!(it.next(), Some(&ys[0])); // process skips before folding + let i = it.fold(1, |i, &x| { + assert_eq!(x, ys[i]); + i + 1 + }); + assert_eq!(i, ys.len()); + + let it = xs.iter().skip(5); + let i = it.rfold(ys.len(), |i, &x| { + let i = i - 1; + assert_eq!(x, ys[i]); + i + }); + assert_eq!(i, 0); + + let mut it = xs.iter().skip(5); + assert_eq!(it.next(), Some(&ys[0])); // process skips before folding + let i = it.rfold(ys.len(), |i, &x| { + let i = i - 1; + assert_eq!(x, ys[i]); + i + }); + assert_eq!(i, 1); +} + +#[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_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_iterator_scan() { + // test the type inference + fn add(old: &mut isize, new: &usize) -> Option { + *old += *new as isize; + Some(*old as f64) + } + let xs = [0, 1, 2, 3, 4]; + let ys = [0f64, 1.0, 3.0, 6.0, 10.0]; + + let it = xs.iter().scan(0, add); + let mut i = 0; + for x in it { + assert_eq!(x, ys[i]); + i += 1; + } + assert_eq!(i, ys.len()); +} + +#[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_iterator_flatten() { + let xs = [0, 3, 6]; + let ys = [0, 1, 2, 3, 4, 5, 6, 7, 8]; + let it = xs.iter().map(|&x| (x..).step_by(1).take(3)).flatten(); + let mut i = 0; + for x in it { + assert_eq!(x, ys[i]); + i += 1; + } + assert_eq!(i, ys.len()); +} + +/// Tests `Flatten::fold` with items already picked off the front and back, +/// to make sure all parts of the `Flatten` are folded correctly. +#[test] +fn test_iterator_flatten_fold() { + let xs = [0, 3, 6]; + let ys = [1, 2, 3, 4, 5, 6, 7]; + let mut it = xs.iter().map(|&x| x..x + 3).flatten(); + 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().map(|&x| x..x + 3).flatten(); + 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_inspect() { + let xs = [1, 2, 3, 4]; + let mut n = 0; + + let ys = xs.iter().cloned().inspect(|_| n += 1).collect::>(); + + assert_eq!(n, xs.len()); + assert_eq!(&xs[..], &ys[..]); +} + +#[test] +fn test_inspect_fold() { + let xs = [1, 2, 3, 4]; + let mut n = 0; + { + let it = xs.iter().inspect(|_| n += 1); + let i = it.fold(0, |i, &x| { + assert_eq!(x, xs[i]); + i + 1 + }); + assert_eq!(i, xs.len()); + } + assert_eq!(n, xs.len()); + + let mut n = 0; + { + let it = xs.iter().inspect(|_| n += 1); + let i = it.rfold(xs.len(), |i, &x| { + assert_eq!(x, xs[i - 1]); + i - 1 + }); + assert_eq!(i, 0); + } + assert_eq!(n, xs.len()); +} + +#[test] +fn test_cycle() { + let cycle_len = 3; + let it = (0..).step_by(1).take(cycle_len).cycle(); + assert_eq!(it.size_hint(), (usize::MAX, None)); + for (i, x) in it.take(100).enumerate() { + assert_eq!(i % cycle_len, x); + } + + let mut it = (0..).step_by(1).take(0).cycle(); + assert_eq!(it.size_hint(), (0, Some(0))); + assert_eq!(it.next(), None); + + assert_eq!(empty::().cycle().fold(0, |acc, x| acc + x), 0); + + assert_eq!(once(1).cycle().skip(1).take(4).fold(0, |acc, x| acc + x), 4); + + assert_eq!((0..10).cycle().take(5).sum::(), 10); + assert_eq!((0..10).cycle().take(15).sum::(), 55); + assert_eq!((0..10).cycle().take(25).sum::(), 100); + + let mut iter = (0..10).cycle(); + iter.nth(14); + assert_eq!(iter.take(8).sum::(), 38); + + let mut iter = (0..10).cycle(); + iter.nth(9); + assert_eq!(iter.take(3).sum::(), 3); +} + +#[test] +fn test_iterator_nth() { + let v: &[_] = &[0, 1, 2, 3, 4]; + for i in 0..v.len() { + assert_eq!(v.iter().nth(i).unwrap(), &v[i]); + } + assert_eq!(v.iter().nth(v.len()), None); +} + +#[test] +fn test_iterator_nth_back() { + let v: &[_] = &[0, 1, 2, 3, 4]; + for i in 0..v.len() { + assert_eq!(v.iter().nth_back(i).unwrap(), &v[v.len() - 1 - i]); + } + assert_eq!(v.iter().nth_back(v.len()), None); +} + +#[test] +fn test_iterator_rev_nth_back() { + let v: &[_] = &[0, 1, 2, 3, 4]; + for i in 0..v.len() { + assert_eq!(v.iter().rev().nth_back(i).unwrap(), &v[i]); + } + assert_eq!(v.iter().rev().nth_back(v.len()), None); +} + +#[test] +fn test_iterator_rev_nth() { + let v: &[_] = &[0, 1, 2, 3, 4]; + for i in 0..v.len() { + assert_eq!(v.iter().rev().nth(i).unwrap(), &v[v.len() - 1 - i]); + } + assert_eq!(v.iter().rev().nth(v.len()), None); +} + +#[test] +fn test_iterator_advance_by() { + let v: &[_] = &[0, 1, 2, 3, 4]; + + for i in 0..v.len() { + let mut iter = v.iter(); + assert_eq!(iter.advance_by(i), Ok(())); + assert_eq!(iter.next().unwrap(), &v[i]); + assert_eq!(iter.advance_by(100), Err(v.len() - 1 - i)); + } + + assert_eq!(v.iter().advance_by(v.len()), Ok(())); + assert_eq!(v.iter().advance_by(100), Err(v.len())); +} + +#[test] +fn test_iterator_advance_back_by() { + let v: &[_] = &[0, 1, 2, 3, 4]; + + for i in 0..v.len() { + let mut iter = v.iter(); + assert_eq!(iter.advance_back_by(i), Ok(())); + assert_eq!(iter.next_back().unwrap(), &v[v.len() - 1 - i]); + assert_eq!(iter.advance_back_by(100), Err(v.len() - 1 - i)); + } + + assert_eq!(v.iter().advance_back_by(v.len()), Ok(())); + assert_eq!(v.iter().advance_back_by(100), Err(v.len())); +} + +#[test] +fn test_iterator_rev_advance_by() { + let v: &[_] = &[0, 1, 2, 3, 4]; + + for i in 0..v.len() { + let mut iter = v.iter().rev(); + assert_eq!(iter.advance_by(i), Ok(())); + assert_eq!(iter.next().unwrap(), &v[v.len() - 1 - i]); + assert_eq!(iter.advance_by(100), Err(v.len() - 1 - i)); + } + + assert_eq!(v.iter().rev().advance_by(v.len()), Ok(())); + assert_eq!(v.iter().rev().advance_by(100), Err(v.len())); +} + +#[test] +fn test_iterator_rev_advance_back_by() { + let v: &[_] = &[0, 1, 2, 3, 4]; + + for i in 0..v.len() { + let mut iter = v.iter().rev(); + assert_eq!(iter.advance_back_by(i), Ok(())); + assert_eq!(iter.next_back().unwrap(), &v[i]); + assert_eq!(iter.advance_back_by(100), Err(v.len() - 1 - i)); + } + + assert_eq!(v.iter().rev().advance_back_by(v.len()), Ok(())); + assert_eq!(v.iter().rev().advance_back_by(100), Err(v.len())); +} + +#[test] +fn test_iterator_last() { + let v: &[_] = &[0, 1, 2, 3, 4]; + assert_eq!(v.iter().last().unwrap(), &4); + assert_eq!(v[..1].iter().last().unwrap(), &0); +} + +#[test] +fn test_iterator_len() { + let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; + assert_eq!(v[..4].iter().count(), 4); + assert_eq!(v[..10].iter().count(), 10); + assert_eq!(v[..0].iter().count(), 0); +} + +#[test] +fn test_iterator_sum() { + let v: &[i32] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; + assert_eq!(v[..4].iter().cloned().sum::(), 6); + assert_eq!(v.iter().cloned().sum::(), 55); + assert_eq!(v[..0].iter().cloned().sum::(), 0); +} + +#[test] +fn test_iterator_sum_result() { + let v: &[Result] = &[Ok(1), Ok(2), Ok(3), Ok(4)]; + assert_eq!(v.iter().cloned().sum::>(), Ok(10)); + let v: &[Result] = &[Ok(1), Err(()), Ok(3), Ok(4)]; + assert_eq!(v.iter().cloned().sum::>(), Err(())); + + #[derive(PartialEq, Debug)] + struct S(Result); + + impl Sum> for S { + fn sum>>(mut iter: I) -> Self { + // takes the sum by repeatedly calling `next` on `iter`, + // thus testing that repeated calls to `ResultShunt::try_fold` + // produce the expected results + Self(iter.by_ref().sum()) + } + } + + let v: &[Result] = &[Ok(1), Ok(2), Ok(3), Ok(4)]; + assert_eq!(v.iter().cloned().sum::(), S(Ok(10))); + let v: &[Result] = &[Ok(1), Err(()), Ok(3), Ok(4)]; + assert_eq!(v.iter().cloned().sum::(), S(Err(()))); +} + +#[test] +fn test_iterator_sum_option() { + let v: &[Option] = &[Some(1), Some(2), Some(3), Some(4)]; + assert_eq!(v.iter().cloned().sum::>(), Some(10)); + let v: &[Option] = &[Some(1), None, Some(3), Some(4)]; + assert_eq!(v.iter().cloned().sum::>(), None); +} + +#[test] +fn test_iterator_product() { + let v: &[i32] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; + assert_eq!(v[..4].iter().cloned().product::(), 0); + assert_eq!(v[1..5].iter().cloned().product::(), 24); + assert_eq!(v[..0].iter().cloned().product::(), 1); +} + +#[test] +fn test_iterator_product_result() { + let v: &[Result] = &[Ok(1), Ok(2), Ok(3), Ok(4)]; + assert_eq!(v.iter().cloned().product::>(), Ok(24)); + let v: &[Result] = &[Ok(1), Err(()), Ok(3), Ok(4)]; + assert_eq!(v.iter().cloned().product::>(), Err(())); +} + +/// A wrapper struct that implements `Eq` and `Ord` based on the wrapped +/// integer modulo 3. Used to test that `Iterator::max` and `Iterator::min` +/// return the correct element if some of them are equal. +#[derive(Debug)] +struct Mod3(i32); + +impl PartialEq for Mod3 { + fn eq(&self, other: &Self) -> bool { + self.0 % 3 == other.0 % 3 + } +} + +impl Eq for Mod3 {} + +impl PartialOrd for Mod3 { + fn partial_cmp(&self, other: &Self) -> Option { + Some(self.cmp(other)) + } +} + +impl Ord for Mod3 { + fn cmp(&self, other: &Self) -> core::cmp::Ordering { + (self.0 % 3).cmp(&(other.0 % 3)) + } +} + +#[test] +fn test_iterator_product_option() { + let v: &[Option] = &[Some(1), Some(2), Some(3), Some(4)]; + assert_eq!(v.iter().cloned().product::>(), Some(24)); + let v: &[Option] = &[Some(1), None, Some(3), Some(4)]; + assert_eq!(v.iter().cloned().product::>(), None); +} + +#[test] +fn test_iterator_max() { + let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; + assert_eq!(v[..4].iter().cloned().max(), Some(3)); + assert_eq!(v.iter().cloned().max(), Some(10)); + assert_eq!(v[..0].iter().cloned().max(), None); + assert_eq!(v.iter().cloned().map(Mod3).max().map(|x| x.0), Some(8)); +} + +#[test] +fn test_iterator_min() { + let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; + assert_eq!(v[..4].iter().cloned().min(), Some(0)); + assert_eq!(v.iter().cloned().min(), Some(0)); + assert_eq!(v[..0].iter().cloned().min(), None); + assert_eq!(v.iter().cloned().map(Mod3).min().map(|x| x.0), Some(0)); +} + +#[test] +fn test_iterator_size_hint() { + let c = (0..).step_by(1); + let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]; + let v2 = &[10, 11, 12]; + let vi = v.iter(); + + assert_eq!((0..).size_hint(), (usize::MAX, None)); + assert_eq!(c.size_hint(), (usize::MAX, None)); + assert_eq!(vi.clone().size_hint(), (10, Some(10))); + + assert_eq!(c.clone().take(5).size_hint(), (5, Some(5))); + assert_eq!(c.clone().skip(5).size_hint().1, None); + assert_eq!(c.clone().take_while(|_| false).size_hint(), (0, None)); + assert_eq!(c.clone().map_while(|_| None::<()>).size_hint(), (0, None)); + assert_eq!(c.clone().skip_while(|_| false).size_hint(), (0, None)); + assert_eq!(c.clone().enumerate().size_hint(), (usize::MAX, None)); + assert_eq!(c.clone().chain(vi.clone().cloned()).size_hint(), (usize::MAX, None)); + assert_eq!(c.clone().zip(vi.clone()).size_hint(), (10, Some(10))); + assert_eq!(c.clone().scan(0, |_, _| Some(0)).size_hint(), (0, None)); + assert_eq!(c.clone().filter(|_| false).size_hint(), (0, None)); + assert_eq!(c.clone().map(|_| 0).size_hint(), (usize::MAX, None)); + assert_eq!(c.filter_map(|_| Some(0)).size_hint(), (0, None)); + + assert_eq!(vi.clone().take(5).size_hint(), (5, Some(5))); + assert_eq!(vi.clone().take(12).size_hint(), (10, Some(10))); + assert_eq!(vi.clone().skip(3).size_hint(), (7, Some(7))); + assert_eq!(vi.clone().skip(12).size_hint(), (0, Some(0))); + assert_eq!(vi.clone().take_while(|_| false).size_hint(), (0, Some(10))); + assert_eq!(vi.clone().map_while(|_| None::<()>).size_hint(), (0, Some(10))); + assert_eq!(vi.clone().skip_while(|_| false).size_hint(), (0, Some(10))); + assert_eq!(vi.clone().enumerate().size_hint(), (10, Some(10))); + assert_eq!(vi.clone().chain(v2).size_hint(), (13, Some(13))); + assert_eq!(vi.clone().zip(v2).size_hint(), (3, Some(3))); + assert_eq!(vi.clone().scan(0, |_, _| Some(0)).size_hint(), (0, Some(10))); + assert_eq!(vi.clone().filter(|_| false).size_hint(), (0, Some(10))); + assert_eq!(vi.clone().map(|&i| i + 1).size_hint(), (10, Some(10))); + assert_eq!(vi.filter_map(|_| Some(0)).size_hint(), (0, Some(10))); +} + +#[test] +fn test_collect() { + let a = vec![1, 2, 3, 4, 5]; + let b: Vec = a.iter().cloned().collect(); + assert!(a == b); +} + +#[test] +fn test_all() { + let v: Box<[isize]> = Box::new([1, 2, 3, 4, 5]); + assert!(v.iter().all(|&x| x < 10)); + assert!(!v.iter().all(|&x| x % 2 == 0)); + assert!(!v.iter().all(|&x| x > 100)); + assert!(v[..0].iter().all(|_| panic!())); +} + +#[test] +fn test_any() { + let v: Box<[isize]> = Box::new([1, 2, 3, 4, 5]); + assert!(v.iter().any(|&x| x < 10)); + assert!(v.iter().any(|&x| x % 2 == 0)); + assert!(!v.iter().any(|&x| x > 100)); + assert!(!v[..0].iter().any(|_| panic!())); +} + +#[test] +fn test_at_least() { + let vec = vec![1, 2, 3, 4, 5]; + assert!(vec.iter().at_least(0, |i| i % 2 == 0)); + assert!(vec.iter().at_least(1, |i| i % 2 == 0)); + assert!(vec.iter().at_least(2, |i| i % 2 == 0)); + assert!(!vec.iter().at_least(3, |i| i % 2 == 0)); + assert!(vec.iter().at_least(0, |&i| i > 100)); + assert!(vec.iter().at_least(5, |&i| i < 100)); + + assert!(!&vec[..0].iter().at_least(0, |_| panic!())); +} + +#[test] +fn test_at_most() { + let vec = vec![1, 2, 3, 4, 5]; + assert!(vec.iter().at_most(0, |&i| i > 100)); + assert!(vec.iter().at_most(5, |&i| i < 100)); + assert!(vec.iter().at_most(3, |i| i % 2 == 0)); + assert!(vec.iter().at_most(2, |i| i % 2 == 0)); + assert!(!vec.iter().at_most(1, |i| i % 2 == 0)); + assert!(!vec.iter().at_most(0, |i| i % 2 == 0)); + + assert!(&vec[..0].iter().at_most(0, |_| panic!())); +} + +#[test] +fn test_find() { + let v: &[isize] = &[1, 3, 9, 27, 103, 14, 11]; + assert_eq!(*v.iter().find(|&&x| x & 1 == 0).unwrap(), 14); + assert_eq!(*v.iter().find(|&&x| x % 3 == 0).unwrap(), 3); + assert!(v.iter().find(|&&x| x % 12 == 0).is_none()); +} + +#[test] +fn test_find_map() { + let xs: &[isize] = &[]; + assert_eq!(xs.iter().find_map(half_if_even), None); + let xs: &[isize] = &[3, 5]; + assert_eq!(xs.iter().find_map(half_if_even), None); + let xs: &[isize] = &[4, 5]; + assert_eq!(xs.iter().find_map(half_if_even), Some(2)); + let xs: &[isize] = &[3, 6]; + assert_eq!(xs.iter().find_map(half_if_even), Some(3)); + + let xs: &[isize] = &[1, 2, 3, 4, 5, 6, 7]; + let mut iter = xs.iter(); + assert_eq!(iter.find_map(half_if_even), Some(1)); + assert_eq!(iter.find_map(half_if_even), Some(2)); + assert_eq!(iter.find_map(half_if_even), Some(3)); + assert_eq!(iter.next(), Some(&7)); + + fn half_if_even(x: &isize) -> Option { + if x % 2 == 0 { Some(x / 2) } else { None } + } +} + +#[test] +fn test_try_find() { + let xs: &[isize] = &[]; + assert_eq!(xs.iter().try_find(testfn), Ok(None)); + let xs: &[isize] = &[1, 2, 3, 4]; + assert_eq!(xs.iter().try_find(testfn), Ok(Some(&2))); + let xs: &[isize] = &[1, 3, 4]; + assert_eq!(xs.iter().try_find(testfn), Err(())); + + let xs: &[isize] = &[1, 2, 3, 4, 5, 6, 7]; + let mut iter = xs.iter(); + assert_eq!(iter.try_find(testfn), Ok(Some(&2))); + assert_eq!(iter.try_find(testfn), Err(())); + assert_eq!(iter.next(), Some(&5)); + + fn testfn(x: &&isize) -> Result { + if **x == 2 { + return Ok(true); + } + if **x == 4 { + return Err(()); + } + Ok(false) + } +} + +#[test] +fn test_try_find_api_usability() -> Result<(), Box> { + let a = ["1", "2"]; + + let is_my_num = |s: &str, search: i32| -> Result { + Ok(s.parse::()? == search) + }; + + let val = a.iter().try_find(|&&s| is_my_num(s, 2))?; + assert_eq!(val, Some(&"2")); + + Ok(()) +} + +#[test] +fn test_position() { + let v = &[1, 3, 9, 27, 103, 14, 11]; + assert_eq!(v.iter().position(|x| *x & 1 == 0).unwrap(), 5); + assert_eq!(v.iter().position(|x| *x % 3 == 0).unwrap(), 1); + assert!(v.iter().position(|x| *x % 12 == 0).is_none()); +} + +#[test] +fn test_count() { + let xs = &[1, 2, 2, 1, 5, 9, 0, 2]; + assert_eq!(xs.iter().filter(|x| **x == 2).count(), 3); + assert_eq!(xs.iter().filter(|x| **x == 5).count(), 1); + assert_eq!(xs.iter().filter(|x| **x == 95).count(), 0); +} + +#[test] +fn test_max_by_key() { + let xs: &[isize] = &[-3, 0, 1, 5, -10]; + assert_eq!(*xs.iter().max_by_key(|x| x.abs()).unwrap(), -10); +} + +#[test] +fn test_max_by() { + let xs: &[isize] = &[-3, 0, 1, 5, -10]; + assert_eq!(*xs.iter().max_by(|x, y| x.abs().cmp(&y.abs())).unwrap(), -10); +} + +#[test] +fn test_min_by_key() { + let xs: &[isize] = &[-3, 0, 1, 5, -10]; + assert_eq!(*xs.iter().min_by_key(|x| x.abs()).unwrap(), 0); +} + +#[test] +fn test_min_by() { + let xs: &[isize] = &[-3, 0, 1, 5, -10]; + assert_eq!(*xs.iter().min_by(|x, y| x.abs().cmp(&y.abs())).unwrap(), 0); +} + +#[test] +fn test_by_ref() { + let mut xs = 0..10; + // sum the first five values + let partial_sum = xs.by_ref().take(5).fold(0, |a, b| a + b); + assert_eq!(partial_sum, 10); + assert_eq!(xs.next(), Some(5)); +} + +#[test] +fn test_rev() { + let xs = [2, 4, 6, 8, 10, 12, 14, 16]; + let mut it = xs.iter(); + it.next(); + it.next(); + assert!(it.rev().cloned().collect::>() == vec![16, 14, 12, 10, 8, 6]); +} + +#[test] +fn test_copied() { + let xs = [2, 4, 6, 8]; + + let mut it = xs.iter().copied(); + assert_eq!(it.len(), 4); + assert_eq!(it.next(), Some(2)); + assert_eq!(it.len(), 3); + assert_eq!(it.next(), Some(4)); + assert_eq!(it.len(), 2); + assert_eq!(it.next_back(), Some(8)); + assert_eq!(it.len(), 1); + assert_eq!(it.next_back(), Some(6)); + assert_eq!(it.len(), 0); + assert_eq!(it.next_back(), None); +} + +#[test] +fn test_cloned() { + let xs = [2, 4, 6, 8]; + + let mut it = xs.iter().cloned(); + assert_eq!(it.len(), 4); + assert_eq!(it.next(), Some(2)); + assert_eq!(it.len(), 3); + assert_eq!(it.next(), Some(4)); + assert_eq!(it.len(), 2); + assert_eq!(it.next_back(), Some(8)); + assert_eq!(it.len(), 1); + assert_eq!(it.next_back(), Some(6)); + assert_eq!(it.len(), 0); + assert_eq!(it.next_back(), None); +} + +#[test] +fn test_cloned_side_effects() { + let mut count = 0; + { + let iter = [1, 2, 3] + .iter() + .map(|x| { + count += 1; + x + }) + .cloned() + .zip(&[1]); + for _ in iter {} + } + assert_eq!(count, 2); +} + +#[test] +fn test_double_ended_map() { + let xs = [1, 2, 3, 4, 5, 6]; + let mut it = xs.iter().map(|&x| x * -1); + assert_eq!(it.next(), Some(-1)); + assert_eq!(it.next(), Some(-2)); + assert_eq!(it.next_back(), Some(-6)); + assert_eq!(it.next_back(), Some(-5)); + assert_eq!(it.next(), Some(-3)); + assert_eq!(it.next_back(), Some(-4)); + assert_eq!(it.next(), None); +} + +#[test] +fn test_double_ended_enumerate() { + let xs = [1, 2, 3, 4, 5, 6]; + let mut it = xs.iter().cloned().enumerate(); + assert_eq!(it.next(), Some((0, 1))); + assert_eq!(it.next(), Some((1, 2))); + assert_eq!(it.next_back(), Some((5, 6))); + assert_eq!(it.next_back(), Some((4, 5))); + assert_eq!(it.next_back(), Some((3, 4))); + assert_eq!(it.next_back(), Some((2, 3))); + assert_eq!(it.next(), None); +} + +#[test] +fn test_double_ended_zip() { + let xs = [1, 2, 3, 4, 5, 6]; + let ys = [1, 2, 3, 7]; + let a = xs.iter().cloned(); + let b = ys.iter().cloned(); + let mut it = a.zip(b); + assert_eq!(it.next(), Some((1, 1))); + assert_eq!(it.next(), Some((2, 2))); + assert_eq!(it.next_back(), Some((4, 7))); + assert_eq!(it.next_back(), Some((3, 3))); + assert_eq!(it.next(), None); +} + +#[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); +} + +#[test] +fn test_double_ended_filter_map() { + let xs = [1, 2, 3, 4, 5, 6]; + let mut it = xs.iter().filter_map(|&x| if x & 1 == 0 { Some(x * 2) } else { None }); + assert_eq!(it.next_back().unwrap(), 12); + assert_eq!(it.next_back().unwrap(), 8); + assert_eq!(it.next().unwrap(), 4); + assert_eq!(it.next_back(), None); +} + +#[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 { + if self.0 { + Some(99) + } else { + self.0 = true; + None + } + } + } + + impl DoubleEndedIterator for CrazyIterator { + fn next_back(&mut self) -> Option { + self.next() + } + } + + assert_eq!(CrazyIterator::new().chain(0..10).rev().last(), Some(0)); + assert!((0..10).chain(CrazyIterator::new()).rev().any(|i| i == 0)); +} + +#[test] +fn test_rposition() { + fn f(xy: &(isize, char)) -> bool { + let (_x, y) = *xy; + y == 'b' + } + fn g(xy: &(isize, char)) -> bool { + let (_x, y) = *xy; + y == 'd' + } + let v = [(0, 'a'), (1, 'b'), (2, 'c'), (3, 'b')]; + + assert_eq!(v.iter().rposition(f), Some(3)); + assert!(v.iter().rposition(g).is_none()); +} + +#[test] +fn test_rev_rposition() { + let v = [0, 0, 1, 1]; + assert_eq!(v.iter().rev().rposition(|&x| x == 1), Some(1)); +} + +#[test] +#[should_panic] +fn test_rposition_panic() { + let v: [(Box<_>, Box<_>); 4] = [(box 0, box 0), (box 0, box 0), (box 0, box 0), (box 0, box 0)]; + let mut i = 0; + v.iter().rposition(|_elt| { + if i == 2 { + panic!() + } + i += 1; + false + }); +} + +#[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); +} + +#[test] +fn test_double_ended_flatten() { + let u = [0, 1]; + let v = [5, 6, 7, 8]; + let mut it = u.iter().map(|x| &v[*x..v.len()]).flatten(); + 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); +} + +#[test] +fn test_double_ended_range() { + assert_eq!((11..14).rev().collect::>(), [13, 12, 11]); + for _ in (10..0).rev() { + panic!("unreachable"); + } + + assert_eq!((11..14).rev().collect::>(), [13, 12, 11]); + for _ in (10..0).rev() { + panic!("unreachable"); + } +} + +#[test] +fn test_range() { + assert_eq!((0..5).collect::>(), [0, 1, 2, 3, 4]); + assert_eq!((-10..-1).collect::>(), [-10, -9, -8, -7, -6, -5, -4, -3, -2]); + assert_eq!((0..5).rev().collect::>(), [4, 3, 2, 1, 0]); + assert_eq!((200..-5).count(), 0); + assert_eq!((200..-5).rev().count(), 0); + assert_eq!((200..200).count(), 0); + assert_eq!((200..200).rev().count(), 0); + + assert_eq!((0..100).size_hint(), (100, Some(100))); + // this test is only meaningful when sizeof usize < sizeof u64 + assert_eq!((usize::MAX - 1..usize::MAX).size_hint(), (1, Some(1))); + assert_eq!((-10..-1).size_hint(), (9, Some(9))); + assert_eq!((-1..-10).size_hint(), (0, Some(0))); + + assert_eq!((-70..58).size_hint(), (128, Some(128))); + assert_eq!((-128..127).size_hint(), (255, Some(255))); + assert_eq!( + (-2..isize::MAX).size_hint(), + (isize::MAX as usize + 2, Some(isize::MAX as usize + 2)) + ); +} + +#[test] +fn test_char_range() { + use std::char; + // Miri is too slow + let from = if cfg!(miri) { char::from_u32(0xD800 - 10).unwrap() } else { '\0' }; + let to = if cfg!(miri) { char::from_u32(0xDFFF + 10).unwrap() } else { char::MAX }; + assert!((from..=to).eq((from as u32..=to as u32).filter_map(char::from_u32))); + assert!((from..=to).rev().eq((from as u32..=to as u32).filter_map(char::from_u32).rev())); + + assert_eq!(('\u{D7FF}'..='\u{E000}').count(), 2); + assert_eq!(('\u{D7FF}'..='\u{E000}').size_hint(), (2, Some(2))); + assert_eq!(('\u{D7FF}'..'\u{E000}').count(), 1); + assert_eq!(('\u{D7FF}'..'\u{E000}').size_hint(), (1, Some(1))); +} + +#[test] +fn test_range_exhaustion() { + let mut r = 10..10; + assert!(r.is_empty()); + assert_eq!(r.next(), None); + assert_eq!(r.next_back(), None); + assert_eq!(r, 10..10); + + let mut r = 10..12; + assert_eq!(r.next(), Some(10)); + assert_eq!(r.next(), Some(11)); + assert!(r.is_empty()); + assert_eq!(r, 12..12); + assert_eq!(r.next(), None); + + let mut r = 10..12; + assert_eq!(r.next_back(), Some(11)); + assert_eq!(r.next_back(), Some(10)); + assert!(r.is_empty()); + assert_eq!(r, 10..10); + assert_eq!(r.next_back(), None); + + let mut r = 100..10; + assert!(r.is_empty()); + assert_eq!(r.next(), None); + assert_eq!(r.next_back(), None); + assert_eq!(r, 100..10); +} + +#[test] +fn test_range_inclusive_exhaustion() { + let mut r = 10..=10; + assert_eq!(r.next(), Some(10)); + assert!(r.is_empty()); + assert_eq!(r.next(), None); + assert_eq!(r.next(), None); + + assert_eq!(*r.start(), 10); + assert_eq!(*r.end(), 10); + assert_ne!(r, 10..=10); + + let mut r = 10..=10; + assert_eq!(r.next_back(), Some(10)); + assert!(r.is_empty()); + assert_eq!(r.next_back(), None); + + assert_eq!(*r.start(), 10); + assert_eq!(*r.end(), 10); + assert_ne!(r, 10..=10); + + let mut r = 10..=12; + assert_eq!(r.next(), Some(10)); + assert_eq!(r.next(), Some(11)); + assert_eq!(r.next(), Some(12)); + assert!(r.is_empty()); + assert_eq!(r.next(), None); + + let mut r = 10..=12; + assert_eq!(r.next_back(), Some(12)); + assert_eq!(r.next_back(), Some(11)); + assert_eq!(r.next_back(), Some(10)); + assert!(r.is_empty()); + assert_eq!(r.next_back(), None); + + let mut r = 10..=12; + assert_eq!(r.nth(2), Some(12)); + assert!(r.is_empty()); + assert_eq!(r.next(), None); + + let mut r = 10..=12; + assert_eq!(r.nth(5), None); + assert!(r.is_empty()); + assert_eq!(r.next(), None); + + let mut r = 100..=10; + assert_eq!(r.next(), None); + assert!(r.is_empty()); + assert_eq!(r.next(), None); + assert_eq!(r.next(), None); + assert_eq!(r, 100..=10); + + let mut r = 100..=10; + assert_eq!(r.next_back(), None); + assert!(r.is_empty()); + assert_eq!(r.next_back(), None); + assert_eq!(r.next_back(), None); + assert_eq!(r, 100..=10); +} + +#[test] +fn test_range_nth() { + assert_eq!((10..15).nth(0), Some(10)); + assert_eq!((10..15).nth(1), Some(11)); + assert_eq!((10..15).nth(4), Some(14)); + assert_eq!((10..15).nth(5), None); + + let mut r = 10..20; + assert_eq!(r.nth(2), Some(12)); + assert_eq!(r, 13..20); + assert_eq!(r.nth(2), Some(15)); + assert_eq!(r, 16..20); + assert_eq!(r.nth(10), None); + assert_eq!(r, 20..20); +} + +#[test] +fn test_range_nth_back() { + assert_eq!((10..15).nth_back(0), Some(14)); + assert_eq!((10..15).nth_back(1), Some(13)); + assert_eq!((10..15).nth_back(4), Some(10)); + assert_eq!((10..15).nth_back(5), None); + assert_eq!((-120..80_i8).nth_back(199), Some(-120)); + + let mut r = 10..20; + assert_eq!(r.nth_back(2), Some(17)); + assert_eq!(r, 10..17); + assert_eq!(r.nth_back(2), Some(14)); + assert_eq!(r, 10..14); + assert_eq!(r.nth_back(10), None); + assert_eq!(r, 10..10); +} + +#[test] +fn test_range_from_nth() { + assert_eq!((10..).nth(0), Some(10)); + assert_eq!((10..).nth(1), Some(11)); + assert_eq!((10..).nth(4), Some(14)); + + let mut r = 10..; + assert_eq!(r.nth(2), Some(12)); + assert_eq!(r, 13..); + assert_eq!(r.nth(2), Some(15)); + assert_eq!(r, 16..); + assert_eq!(r.nth(10), Some(26)); + assert_eq!(r, 27..); + + assert_eq!((0..).size_hint(), (usize::MAX, None)); +} + +fn is_trusted_len(_: I) {} + +#[test] +fn test_range_from_take() { + let mut it = (0..).take(3); + assert_eq!(it.next(), Some(0)); + assert_eq!(it.next(), Some(1)); + assert_eq!(it.next(), Some(2)); + assert_eq!(it.next(), None); + is_trusted_len((0..).take(3)); + assert_eq!((0..).take(3).size_hint(), (3, Some(3))); + assert_eq!((0..).take(0).size_hint(), (0, Some(0))); + assert_eq!((0..).take(usize::MAX).size_hint(), (usize::MAX, Some(usize::MAX))); +} + +#[test] +fn test_range_from_take_collect() { + let v: Vec<_> = (0..).take(3).collect(); + assert_eq!(v, vec![0, 1, 2]); +} + +#[test] +fn test_range_inclusive_nth() { + assert_eq!((10..=15).nth(0), Some(10)); + assert_eq!((10..=15).nth(1), Some(11)); + assert_eq!((10..=15).nth(5), Some(15)); + assert_eq!((10..=15).nth(6), None); + + let mut exhausted_via_next = 10_u8..=20; + while exhausted_via_next.next().is_some() {} + + let mut r = 10_u8..=20; + assert_eq!(r.nth(2), Some(12)); + assert_eq!(r, 13..=20); + assert_eq!(r.nth(2), Some(15)); + assert_eq!(r, 16..=20); + assert_eq!(r.is_empty(), false); + assert_eq!(ExactSizeIterator::is_empty(&r), false); + assert_eq!(r.nth(10), None); + assert_eq!(r.is_empty(), true); + assert_eq!(r, exhausted_via_next); + assert_eq!(ExactSizeIterator::is_empty(&r), true); +} + +#[test] +fn test_range_inclusive_nth_back() { + assert_eq!((10..=15).nth_back(0), Some(15)); + assert_eq!((10..=15).nth_back(1), Some(14)); + assert_eq!((10..=15).nth_back(5), Some(10)); + assert_eq!((10..=15).nth_back(6), None); + assert_eq!((-120..=80_i8).nth_back(200), Some(-120)); + + let mut exhausted_via_next_back = 10_u8..=20; + while exhausted_via_next_back.next_back().is_some() {} + + let mut r = 10_u8..=20; + assert_eq!(r.nth_back(2), Some(18)); + assert_eq!(r, 10..=17); + assert_eq!(r.nth_back(2), Some(15)); + assert_eq!(r, 10..=14); + assert_eq!(r.is_empty(), false); + assert_eq!(ExactSizeIterator::is_empty(&r), false); + assert_eq!(r.nth_back(10), None); + assert_eq!(r.is_empty(), true); + assert_eq!(r, exhausted_via_next_back); + assert_eq!(ExactSizeIterator::is_empty(&r), true); +} + +#[test] +fn test_range_len() { + assert_eq!((0..10_u8).len(), 10); + assert_eq!((9..10_u8).len(), 1); + assert_eq!((10..10_u8).len(), 0); + assert_eq!((11..10_u8).len(), 0); + assert_eq!((100..10_u8).len(), 0); +} + +#[test] +fn test_range_inclusive_len() { + assert_eq!((0..=10_u8).len(), 11); + assert_eq!((9..=10_u8).len(), 2); + assert_eq!((10..=10_u8).len(), 1); + assert_eq!((11..=10_u8).len(), 0); + assert_eq!((100..=10_u8).len(), 0); +} + +#[test] +fn test_range_step() { + #![allow(deprecated)] + + assert_eq!((0..20).step_by(5).collect::>(), [0, 5, 10, 15]); + assert_eq!((1..21).rev().step_by(5).collect::>(), [20, 15, 10, 5]); + assert_eq!((1..21).rev().step_by(6).collect::>(), [20, 14, 8, 2]); + assert_eq!((200..255).step_by(50).collect::>(), [200, 250]); + assert_eq!((200..-5).step_by(1).collect::>(), []); + assert_eq!((200..200).step_by(1).collect::>(), []); + + assert_eq!((0..20).step_by(1).size_hint(), (20, Some(20))); + assert_eq!((0..20).step_by(21).size_hint(), (1, Some(1))); + assert_eq!((0..20).step_by(5).size_hint(), (4, Some(4))); + assert_eq!((1..21).rev().step_by(5).size_hint(), (4, Some(4))); + assert_eq!((1..21).rev().step_by(6).size_hint(), (4, Some(4))); + assert_eq!((20..-5).step_by(1).size_hint(), (0, Some(0))); + assert_eq!((20..20).step_by(1).size_hint(), (0, Some(0))); + assert_eq!((i8::MIN..i8::MAX).step_by(-(i8::MIN as i32) as usize).size_hint(), (2, Some(2))); + assert_eq!((i16::MIN..i16::MAX).step_by(i16::MAX as usize).size_hint(), (3, Some(3))); + assert_eq!((isize::MIN..isize::MAX).step_by(1).size_hint(), (usize::MAX, Some(usize::MAX))); +} + +#[test] +fn test_step_by_skip() { + assert_eq!((0..640).step_by(128).skip(1).collect::>(), [128, 256, 384, 512]); + assert_eq!((0..=50).step_by(10).nth(3), Some(30)); + assert_eq!((200..=255u8).step_by(10).nth(3), Some(230)); +} + +#[test] +fn test_range_inclusive_step() { + assert_eq!((0..=50).step_by(10).collect::>(), [0, 10, 20, 30, 40, 50]); + assert_eq!((0..=5).step_by(1).collect::>(), [0, 1, 2, 3, 4, 5]); + assert_eq!((200..=255u8).step_by(10).collect::>(), [200, 210, 220, 230, 240, 250]); + assert_eq!((250..=255u8).step_by(1).collect::>(), [250, 251, 252, 253, 254, 255]); +} + +#[test] +fn test_range_last_max() { + assert_eq!((0..20).last(), Some(19)); + assert_eq!((-20..0).last(), Some(-1)); + assert_eq!((5..5).last(), None); + + assert_eq!((0..20).max(), Some(19)); + assert_eq!((-20..0).max(), Some(-1)); + assert_eq!((5..5).max(), None); +} + +#[test] +fn test_range_inclusive_last_max() { + assert_eq!((0..=20).last(), Some(20)); + assert_eq!((-20..=0).last(), Some(0)); + assert_eq!((5..=5).last(), Some(5)); + let mut r = 10..=10; + r.next(); + assert_eq!(r.last(), None); + + assert_eq!((0..=20).max(), Some(20)); + assert_eq!((-20..=0).max(), Some(0)); + assert_eq!((5..=5).max(), Some(5)); + let mut r = 10..=10; + r.next(); + assert_eq!(r.max(), None); +} + +#[test] +fn test_range_min() { + assert_eq!((0..20).min(), Some(0)); + assert_eq!((-20..0).min(), Some(-20)); + assert_eq!((5..5).min(), None); +} + +#[test] +fn test_range_inclusive_min() { + assert_eq!((0..=20).min(), Some(0)); + assert_eq!((-20..=0).min(), Some(-20)); + assert_eq!((5..=5).min(), Some(5)); + let mut r = 10..=10; + r.next(); + assert_eq!(r.min(), None); +} + +#[test] +fn test_range_inclusive_folds() { + assert_eq!((1..=10).sum::(), 55); + assert_eq!((1..=10).rev().sum::(), 55); + + let mut it = 44..=50; + assert_eq!(it.try_fold(0, i8::checked_add), None); + assert_eq!(it, 47..=50); + assert_eq!(it.try_fold(0, i8::checked_add), None); + assert_eq!(it, 50..=50); + assert_eq!(it.try_fold(0, i8::checked_add), Some(50)); + assert!(it.is_empty()); + assert_eq!(it.try_fold(0, i8::checked_add), Some(0)); + assert!(it.is_empty()); + + let mut it = 40..=47; + assert_eq!(it.try_rfold(0, i8::checked_add), None); + assert_eq!(it, 40..=44); + assert_eq!(it.try_rfold(0, i8::checked_add), None); + assert_eq!(it, 40..=41); + assert_eq!(it.try_rfold(0, i8::checked_add), Some(81)); + assert!(it.is_empty()); + assert_eq!(it.try_rfold(0, i8::checked_add), Some(0)); + assert!(it.is_empty()); + + let mut it = 10..=20; + assert_eq!(it.try_fold(0, |a, b| Some(a + b)), Some(165)); + assert!(it.is_empty()); + assert_eq!(it.try_fold(0, |a, b| Some(a + b)), Some(0)); + assert!(it.is_empty()); + + let mut it = 10..=20; + assert_eq!(it.try_rfold(0, |a, b| Some(a + b)), Some(165)); + assert!(it.is_empty()); + assert_eq!(it.try_rfold(0, |a, b| Some(a + b)), Some(0)); + assert!(it.is_empty()); +} + +#[test] +fn test_range_size_hint() { + assert_eq!((0..0usize).size_hint(), (0, Some(0))); + assert_eq!((0..100usize).size_hint(), (100, Some(100))); + assert_eq!((0..usize::MAX).size_hint(), (usize::MAX, Some(usize::MAX))); + + let umax = u128::try_from(usize::MAX).unwrap(); + assert_eq!((0..0u128).size_hint(), (0, Some(0))); + assert_eq!((0..100u128).size_hint(), (100, Some(100))); + assert_eq!((0..umax).size_hint(), (usize::MAX, Some(usize::MAX))); + assert_eq!((0..umax + 1).size_hint(), (usize::MAX, None)); + + assert_eq!((0..0isize).size_hint(), (0, Some(0))); + assert_eq!((-100..100isize).size_hint(), (200, Some(200))); + assert_eq!((isize::MIN..isize::MAX).size_hint(), (usize::MAX, Some(usize::MAX))); + + let imin = i128::try_from(isize::MIN).unwrap(); + let imax = i128::try_from(isize::MAX).unwrap(); + assert_eq!((0..0i128).size_hint(), (0, Some(0))); + assert_eq!((-100..100i128).size_hint(), (200, Some(200))); + assert_eq!((imin..imax).size_hint(), (usize::MAX, Some(usize::MAX))); + assert_eq!((imin..imax + 1).size_hint(), (usize::MAX, None)); +} + +#[test] +fn test_range_inclusive_size_hint() { + assert_eq!((1..=0usize).size_hint(), (0, Some(0))); + assert_eq!((0..=0usize).size_hint(), (1, Some(1))); + assert_eq!((0..=100usize).size_hint(), (101, Some(101))); + assert_eq!((0..=usize::MAX - 1).size_hint(), (usize::MAX, Some(usize::MAX))); + assert_eq!((0..=usize::MAX).size_hint(), (usize::MAX, None)); + + let umax = u128::try_from(usize::MAX).unwrap(); + assert_eq!((1..=0u128).size_hint(), (0, Some(0))); + assert_eq!((0..=0u128).size_hint(), (1, Some(1))); + assert_eq!((0..=100u128).size_hint(), (101, Some(101))); + assert_eq!((0..=umax - 1).size_hint(), (usize::MAX, Some(usize::MAX))); + assert_eq!((0..=umax).size_hint(), (usize::MAX, None)); + assert_eq!((0..=umax + 1).size_hint(), (usize::MAX, None)); + + assert_eq!((0..=-1isize).size_hint(), (0, Some(0))); + assert_eq!((0..=0isize).size_hint(), (1, Some(1))); + assert_eq!((-100..=100isize).size_hint(), (201, Some(201))); + assert_eq!((isize::MIN..=isize::MAX - 1).size_hint(), (usize::MAX, Some(usize::MAX))); + assert_eq!((isize::MIN..=isize::MAX).size_hint(), (usize::MAX, None)); + + let imin = i128::try_from(isize::MIN).unwrap(); + let imax = i128::try_from(isize::MAX).unwrap(); + assert_eq!((0..=-1i128).size_hint(), (0, Some(0))); + assert_eq!((0..=0i128).size_hint(), (1, Some(1))); + assert_eq!((-100..=100i128).size_hint(), (201, Some(201))); + assert_eq!((imin..=imax - 1).size_hint(), (usize::MAX, Some(usize::MAX))); + assert_eq!((imin..=imax).size_hint(), (usize::MAX, None)); + assert_eq!((imin..=imax + 1).size_hint(), (usize::MAX, None)); +} + +#[test] +fn test_repeat() { + let mut it = repeat(42); + assert_eq!(it.next(), Some(42)); + assert_eq!(it.next(), Some(42)); + assert_eq!(it.next(), Some(42)); + assert_eq!(repeat(42).size_hint(), (usize::MAX, None)); +} + +#[test] +fn test_repeat_take() { + let mut it = repeat(42).take(3); + assert_eq!(it.next(), Some(42)); + assert_eq!(it.next(), Some(42)); + assert_eq!(it.next(), Some(42)); + assert_eq!(it.next(), None); + is_trusted_len(repeat(42).take(3)); + assert_eq!(repeat(42).take(3).size_hint(), (3, Some(3))); + assert_eq!(repeat(42).take(0).size_hint(), (0, Some(0))); + assert_eq!(repeat(42).take(usize::MAX).size_hint(), (usize::MAX, Some(usize::MAX))); +} + +#[test] +fn test_repeat_take_collect() { + let v: Vec<_> = repeat(42).take(3).collect(); + assert_eq!(v, vec![42, 42, 42]); +} + +#[test] +fn test_repeat_with() { + #[derive(PartialEq, Debug)] + struct NotClone(usize); + let mut it = repeat_with(|| NotClone(42)); + assert_eq!(it.next(), Some(NotClone(42))); + assert_eq!(it.next(), Some(NotClone(42))); + assert_eq!(it.next(), Some(NotClone(42))); + assert_eq!(repeat_with(|| NotClone(42)).size_hint(), (usize::MAX, None)); +} + +#[test] +fn test_repeat_with_take() { + let mut it = repeat_with(|| 42).take(3); + assert_eq!(it.next(), Some(42)); + assert_eq!(it.next(), Some(42)); + assert_eq!(it.next(), Some(42)); + assert_eq!(it.next(), None); + is_trusted_len(repeat_with(|| 42).take(3)); + assert_eq!(repeat_with(|| 42).take(3).size_hint(), (3, Some(3))); + assert_eq!(repeat_with(|| 42).take(0).size_hint(), (0, Some(0))); + assert_eq!(repeat_with(|| 42).take(usize::MAX).size_hint(), (usize::MAX, Some(usize::MAX))); +} + +#[test] +fn test_repeat_with_take_collect() { + let mut curr = 1; + let v: Vec<_> = repeat_with(|| { + let tmp = curr; + curr *= 2; + tmp + }) + .take(5) + .collect(); + assert_eq!(v, vec![1, 2, 4, 8, 16]); +} + +#[test] +fn test_successors() { + let mut powers_of_10 = successors(Some(1_u16), |n| n.checked_mul(10)); + assert_eq!(powers_of_10.by_ref().collect::>(), &[1, 10, 100, 1_000, 10_000]); + assert_eq!(powers_of_10.next(), None); + + let mut empty = successors(None::, |_| unimplemented!()); + assert_eq!(empty.next(), None); + assert_eq!(empty.next(), None); +} + +#[test] +fn test_fuse() { + let mut it = 0..3; + assert_eq!(it.len(), 3); + assert_eq!(it.next(), Some(0)); + assert_eq!(it.len(), 2); + assert_eq!(it.next(), Some(1)); + assert_eq!(it.len(), 1); + assert_eq!(it.next(), Some(2)); + assert_eq!(it.len(), 0); + assert_eq!(it.next(), None); + assert_eq!(it.len(), 0); + assert_eq!(it.next(), None); + assert_eq!(it.len(), 0); + assert_eq!(it.next(), None); + assert_eq!(it.len(), 0); +} + +#[test] +fn test_fuse_nth() { + let xs = [0, 1, 2]; + let mut it = xs.iter(); + + assert_eq!(it.len(), 3); + assert_eq!(it.nth(2), Some(&2)); + assert_eq!(it.len(), 0); + assert_eq!(it.nth(2), None); + assert_eq!(it.len(), 0); +} + +#[test] +fn test_fuse_last() { + let xs = [0, 1, 2]; + let it = xs.iter(); + + assert_eq!(it.len(), 3); + assert_eq!(it.last(), Some(&2)); +} + +#[test] +fn test_fuse_count() { + let xs = [0, 1, 2]; + let it = xs.iter(); + + assert_eq!(it.len(), 3); + assert_eq!(it.count(), 3); + // Can't check len now because count consumes. +} + +#[test] +fn test_fuse_fold() { + let xs = [0, 1, 2]; + let it = xs.iter(); // `FusedIterator` + let i = it.fuse().fold(0, |i, &x| { + assert_eq!(x, xs[i]); + i + 1 + }); + assert_eq!(i, xs.len()); + + let it = xs.iter(); // `FusedIterator` + let i = it.fuse().rfold(xs.len(), |i, &x| { + assert_eq!(x, xs[i - 1]); + i - 1 + }); + assert_eq!(i, 0); + + let it = xs.iter().scan((), |_, &x| Some(x)); // `!FusedIterator` + let i = it.fuse().fold(0, |i, x| { + assert_eq!(x, xs[i]); + i + 1 + }); + assert_eq!(i, xs.len()); +} + +#[test] +fn test_once() { + let mut it = once(42); + assert_eq!(it.next(), Some(42)); + assert_eq!(it.next(), None); +} + +#[test] +fn test_once_with() { + let count = Cell::new(0); + let mut it = once_with(|| { + count.set(count.get() + 1); + 42 + }); + + assert_eq!(count.get(), 0); + assert_eq!(it.next(), Some(42)); + assert_eq!(count.get(), 1); + assert_eq!(it.next(), None); + assert_eq!(count.get(), 1); + assert_eq!(it.next(), None); + assert_eq!(count.get(), 1); +} + +#[test] +fn test_empty() { + let mut it = empty::(); + assert_eq!(it.next(), 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_steps_between() { + assert_eq!(Step::steps_between(&20_u8, &200_u8), Some(180_usize)); + assert_eq!(Step::steps_between(&-20_i8, &80_i8), Some(100_usize)); + assert_eq!(Step::steps_between(&-120_i8, &80_i8), Some(200_usize)); + assert_eq!(Step::steps_between(&20_u32, &4_000_100_u32), Some(4_000_080_usize)); + assert_eq!(Step::steps_between(&-20_i32, &80_i32), Some(100_usize)); + assert_eq!(Step::steps_between(&-2_000_030_i32, &2_000_050_i32), Some(4_000_080_usize)); + + // Skip u64/i64 to avoid differences with 32-bit vs 64-bit platforms + + assert_eq!(Step::steps_between(&20_u128, &200_u128), Some(180_usize)); + assert_eq!(Step::steps_between(&-20_i128, &80_i128), Some(100_usize)); + if cfg!(target_pointer_width = "64") { + assert_eq!(Step::steps_between(&10_u128, &0x1_0000_0000_0000_0009_u128), Some(usize::MAX)); + } + assert_eq!(Step::steps_between(&10_u128, &0x1_0000_0000_0000_000a_u128), None); + assert_eq!(Step::steps_between(&10_i128, &0x1_0000_0000_0000_000a_i128), None); + assert_eq!( + Step::steps_between(&-0x1_0000_0000_0000_0000_i128, &0x1_0000_0000_0000_0000_i128,), + None, + ); +} + +#[test] +fn test_step_forward() { + assert_eq!(Step::forward_checked(55_u8, 200_usize), Some(255_u8)); + assert_eq!(Step::forward_checked(252_u8, 200_usize), None); + assert_eq!(Step::forward_checked(0_u8, 256_usize), None); + assert_eq!(Step::forward_checked(-110_i8, 200_usize), Some(90_i8)); + assert_eq!(Step::forward_checked(-110_i8, 248_usize), None); + assert_eq!(Step::forward_checked(-126_i8, 256_usize), None); + + assert_eq!(Step::forward_checked(35_u16, 100_usize), Some(135_u16)); + assert_eq!(Step::forward_checked(35_u16, 65500_usize), Some(u16::MAX)); + assert_eq!(Step::forward_checked(36_u16, 65500_usize), None); + assert_eq!(Step::forward_checked(-110_i16, 200_usize), Some(90_i16)); + assert_eq!(Step::forward_checked(-20_030_i16, 50_050_usize), Some(30_020_i16)); + assert_eq!(Step::forward_checked(-10_i16, 40_000_usize), None); + assert_eq!(Step::forward_checked(-10_i16, 70_000_usize), None); + + assert_eq!(Step::forward_checked(10_u128, 70_000_usize), Some(70_010_u128)); + assert_eq!(Step::forward_checked(10_i128, 70_030_usize), Some(70_040_i128)); + assert_eq!( + Step::forward_checked(0xffff_ffff_ffff_ffff__ffff_ffff_ffff_ff00_u128, 0xff_usize), + Some(u128::MAX), + ); + assert_eq!( + Step::forward_checked(0xffff_ffff_ffff_ffff__ffff_ffff_ffff_ff00_u128, 0x100_usize), + None + ); + assert_eq!( + Step::forward_checked(0x7fff_ffff_ffff_ffff__ffff_ffff_ffff_ff00_i128, 0xff_usize), + Some(i128::MAX), + ); + assert_eq!( + Step::forward_checked(0x7fff_ffff_ffff_ffff__ffff_ffff_ffff_ff00_i128, 0x100_usize), + None + ); +} + +#[test] +fn test_step_backward() { + assert_eq!(Step::backward_checked(255_u8, 200_usize), Some(55_u8)); + assert_eq!(Step::backward_checked(100_u8, 200_usize), None); + assert_eq!(Step::backward_checked(255_u8, 256_usize), None); + assert_eq!(Step::backward_checked(90_i8, 200_usize), Some(-110_i8)); + assert_eq!(Step::backward_checked(110_i8, 248_usize), None); + assert_eq!(Step::backward_checked(127_i8, 256_usize), None); + + assert_eq!(Step::backward_checked(135_u16, 100_usize), Some(35_u16)); + assert_eq!(Step::backward_checked(u16::MAX, 65500_usize), Some(35_u16)); + assert_eq!(Step::backward_checked(10_u16, 11_usize), None); + assert_eq!(Step::backward_checked(90_i16, 200_usize), Some(-110_i16)); + assert_eq!(Step::backward_checked(30_020_i16, 50_050_usize), Some(-20_030_i16)); + assert_eq!(Step::backward_checked(-10_i16, 40_000_usize), None); + assert_eq!(Step::backward_checked(-10_i16, 70_000_usize), None); + + assert_eq!(Step::backward_checked(70_010_u128, 70_000_usize), Some(10_u128)); + assert_eq!(Step::backward_checked(70_020_i128, 70_030_usize), Some(-10_i128)); + assert_eq!(Step::backward_checked(10_u128, 7_usize), Some(3_u128)); + assert_eq!(Step::backward_checked(10_u128, 11_usize), None); + assert_eq!( + Step::backward_checked(-0x7fff_ffff_ffff_ffff__ffff_ffff_ffff_ff00_i128, 0x100_usize), + Some(i128::MIN) + ); +} + +#[test] +fn test_rev_try_folds() { + let f = &|acc, x| i32::checked_add(2 * acc, x); + assert_eq!((1..10).rev().try_fold(7, f), (1..10).try_rfold(7, f)); + assert_eq!((1..10).rev().try_rfold(7, f), (1..10).try_fold(7, f)); + + let a = [10, 20, 30, 40, 100, 60, 70, 80, 90]; + let mut iter = a.iter().rev(); + assert_eq!(iter.try_fold(0_i8, |acc, &x| acc.checked_add(x)), None); + assert_eq!(iter.next(), Some(&70)); + let mut iter = a.iter().rev(); + assert_eq!(iter.try_rfold(0_i8, |acc, &x| acc.checked_add(x)), None); + assert_eq!(iter.next_back(), Some(&60)); +} + +#[test] +fn test_cloned_try_folds() { + let a = [1, 2, 3, 4, 5, 6, 7, 8, 9]; + let f = &|acc, x| i32::checked_add(2 * acc, x); + let f_ref = &|acc, &x| i32::checked_add(2 * acc, x); + assert_eq!(a.iter().cloned().try_fold(7, f), a.iter().try_fold(7, f_ref)); + assert_eq!(a.iter().cloned().try_rfold(7, f), a.iter().try_rfold(7, f_ref)); + + let a = [10, 20, 30, 40, 100, 60, 70, 80, 90]; + let mut iter = a.iter().cloned(); + assert_eq!(iter.try_fold(0_i8, |acc, x| acc.checked_add(x)), None); + assert_eq!(iter.next(), Some(60)); + let mut iter = a.iter().cloned(); + assert_eq!(iter.try_rfold(0_i8, |acc, x| acc.checked_add(x)), None); + assert_eq!(iter.next_back(), Some(70)); +} + +#[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_map_try_folds() { + let f = &|acc, x| i32::checked_add(2 * acc, x); + assert_eq!((0..10).map(|x| x + 3).try_fold(7, f), (3..13).try_fold(7, f)); + assert_eq!((0..10).map(|x| x + 3).try_rfold(7, f), (3..13).try_rfold(7, f)); + + let mut iter = (0..40).map(|x| x + 10); + 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(46)); +} + +#[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_filter_map_try_folds() { + let mp = &|x| if 0 <= x && x < 10 { Some(x * 2) } else { None }; + let f = &|acc, x| i32::checked_add(2 * acc, x); + assert_eq!((-9..20).filter_map(mp).try_fold(7, f), (0..10).map(|x| 2 * x).try_fold(7, f)); + assert_eq!((-9..20).filter_map(mp).try_rfold(7, f), (0..10).map(|x| 2 * x).try_rfold(7, f)); + + let mut iter = (0..40).filter_map(|x| if x % 2 == 1 { None } else { Some(x * 2 + 10) }); + assert_eq!(iter.try_fold(0, i8::checked_add), None); + assert_eq!(iter.next(), Some(38)); + assert_eq!(iter.try_rfold(0, i8::checked_add), None); + assert_eq!(iter.next_back(), Some(78)); +} + +#[test] +fn test_enumerate_try_folds() { + let f = &|acc, (i, x)| usize::checked_add(2 * acc, x / (i + 1) + i); + assert_eq!((9..18).enumerate().try_fold(7, f), (0..9).map(|i| (i, i + 9)).try_fold(7, f)); + assert_eq!((9..18).enumerate().try_rfold(7, f), (0..9).map(|i| (i, i + 9)).try_rfold(7, f)); + + let mut iter = (100..200).enumerate(); + let f = &|acc, (i, x)| u8::checked_add(acc, u8::checked_div(x, i as u8 + 1)?); + assert_eq!(iter.try_fold(0, f), None); + assert_eq!(iter.next(), Some((7, 107))); + assert_eq!(iter.try_rfold(0, f), None); + assert_eq!(iter.next_back(), Some((11, 111))); +} + +#[test] +fn test_peek_try_folds() { + let f = &|acc, x| i32::checked_add(2 * acc, x); + + assert_eq!((1..20).peekable().try_fold(7, f), (1..20).try_fold(7, f)); + assert_eq!((1..20).peekable().try_rfold(7, f), (1..20).try_rfold(7, f)); + + let mut iter = (1..20).peekable(); + assert_eq!(iter.peek(), Some(&1)); + assert_eq!(iter.try_fold(7, f), (1..20).try_fold(7, f)); + + let mut iter = (1..20).peekable(); + assert_eq!(iter.peek(), Some(&1)); + assert_eq!(iter.try_rfold(7, f), (1..20).try_rfold(7, f)); + + let mut iter = [100, 20, 30, 40, 50, 60, 70].iter().cloned().peekable(); + assert_eq!(iter.peek(), Some(&100)); + assert_eq!(iter.try_fold(0, i8::checked_add), None); + assert_eq!(iter.peek(), Some(&40)); + + let mut iter = [100, 20, 30, 40, 50, 60, 70].iter().cloned().peekable(); + assert_eq!(iter.peek(), Some(&100)); + assert_eq!(iter.try_rfold(0, i8::checked_add), None); + assert_eq!(iter.peek(), Some(&100)); + assert_eq!(iter.next_back(), Some(50)); + + let mut iter = (2..5).peekable(); + assert_eq!(iter.peek(), Some(&2)); + assert_eq!(iter.try_for_each(Err), Err(2)); + assert_eq!(iter.peek(), Some(&3)); + assert_eq!(iter.try_for_each(Err), Err(3)); + assert_eq!(iter.peek(), Some(&4)); + assert_eq!(iter.try_for_each(Err), Err(4)); + assert_eq!(iter.peek(), None); + assert_eq!(iter.try_for_each(Err), Ok(())); + + let mut iter = (2..5).peekable(); + assert_eq!(iter.peek(), Some(&2)); + assert_eq!(iter.try_rfold((), |(), x| Err(x)), Err(4)); + assert_eq!(iter.peek(), Some(&2)); + assert_eq!(iter.try_rfold((), |(), x| Err(x)), Err(3)); + assert_eq!(iter.peek(), Some(&2)); + assert_eq!(iter.try_rfold((), |(), x| Err(x)), Err(2)); + assert_eq!(iter.peek(), None); + assert_eq!(iter.try_rfold((), |(), x| Err(x)), Ok(())); +} + +#[test] +fn test_skip_while_try_fold() { + let f = &|acc, x| i32::checked_add(2 * acc, x); + fn p(&x: &i32) -> bool { + (x % 10) <= 5 + } + assert_eq!((1..20).skip_while(p).try_fold(7, f), (6..20).try_fold(7, f)); + let mut iter = (1..20).skip_while(p); + assert_eq!(iter.nth(5), Some(11)); + assert_eq!(iter.try_fold(7, f), (12..20).try_fold(7, f)); + + let mut iter = (0..50).skip_while(|&x| (x % 20) < 15); + assert_eq!(iter.try_fold(0, i8::checked_add), None); + assert_eq!(iter.next(), Some(23)); +} + +#[test] +fn test_take_while_folds() { + let f = &|acc, x| i32::checked_add(2 * acc, x); + assert_eq!((1..20).take_while(|&x| x != 10).try_fold(7, f), (1..10).try_fold(7, f)); + let mut iter = (1..20).take_while(|&x| x != 10); + assert_eq!(iter.try_fold(0, |x, y| Some(x + y)), Some((1..10).sum())); + assert_eq!(iter.next(), None, "flag should be set"); + let iter = (1..20).take_while(|&x| x != 10); + assert_eq!(iter.fold(0, |x, y| x + y), (1..10).sum()); + + let mut iter = (10..50).take_while(|&x| x != 40); + assert_eq!(iter.try_fold(0, i8::checked_add), None); + assert_eq!(iter.next(), Some(20)); +} + +#[test] +fn test_skip_try_folds() { + let f = &|acc, x| i32::checked_add(2 * acc, x); + assert_eq!((1..20).skip(9).try_fold(7, f), (10..20).try_fold(7, f)); + assert_eq!((1..20).skip(9).try_rfold(7, f), (10..20).try_rfold(7, f)); + + let mut iter = (0..30).skip(10); + 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)); +} + +#[test] +fn test_skip_nth_back() { + let xs = [0, 1, 2, 3, 4, 5]; + let mut it = xs.iter().skip(2); + assert_eq!(it.nth_back(0), Some(&5)); + assert_eq!(it.nth_back(1), Some(&3)); + assert_eq!(it.nth_back(0), Some(&2)); + assert_eq!(it.nth_back(0), None); + + let ys = [2, 3, 4, 5]; + let mut ity = ys.iter(); + let mut it = xs.iter().skip(2); + assert_eq!(it.nth_back(1), ity.nth_back(1)); + assert_eq!(it.clone().nth(0), ity.clone().nth(0)); + assert_eq!(it.nth_back(0), ity.nth_back(0)); + assert_eq!(it.clone().nth(0), ity.clone().nth(0)); + assert_eq!(it.nth_back(0), ity.nth_back(0)); + assert_eq!(it.clone().nth(0), ity.clone().nth(0)); + assert_eq!(it.nth_back(0), ity.nth_back(0)); + assert_eq!(it.clone().nth(0), ity.clone().nth(0)); + + let mut it = xs.iter().skip(2); + assert_eq!(it.nth_back(4), None); + assert_eq!(it.nth_back(0), None); + + let mut it = xs.iter(); + it.by_ref().skip(2).nth_back(3); + assert_eq!(it.next_back(), Some(&1)); + + let mut it = xs.iter(); + it.by_ref().skip(2).nth_back(10); + assert_eq!(it.next_back(), Some(&1)); +} + +#[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_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_flatten_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).map(mr).flatten().try_fold(7, f), (0..50).try_fold(7, f)); + assert_eq!((0..10).map(mr).flatten().try_rfold(7, f), (0..50).try_rfold(7, f)); + let mut iter = (0..10).map(mr).flatten(); + 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).map(|x| (4 * x)..(4 * x + 4)).flatten(); + 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_functor_laws() { + // identity: + fn identity(x: T) -> T { + x + } + assert_eq!((0..10).map(identity).sum::(), (0..10).sum()); + + // composition: + fn f(x: usize) -> usize { + x + 3 + } + fn g(x: usize) -> usize { + x * 2 + } + fn h(x: usize) -> usize { + g(f(x)) + } + assert_eq!((0..10).map(f).map(g).sum::(), (0..10).map(h).sum()); +} + +#[test] +fn test_monad_laws_left_identity() { + fn f(x: usize) -> impl Iterator { + (0..10).map(move |y| x * y) + } + assert_eq!(once(42).flat_map(f.clone()).sum::(), f(42).sum()); +} + +#[test] +fn test_monad_laws_right_identity() { + assert_eq!((0..10).flat_map(|x| once(x)).sum::(), (0..10).sum()); +} + +#[test] +fn test_monad_laws_associativity() { + fn f(x: usize) -> impl Iterator { + 0..x + } + fn g(x: usize) -> impl Iterator { + (0..x).rev() + } + assert_eq!( + (0..10).flat_map(f).flat_map(g).sum::(), + (0..10).flat_map(|x| f(x).flat_map(g)).sum::() + ); +} + +#[test] +fn test_is_sorted() { + assert!([1, 2, 2, 9].iter().is_sorted()); + assert!(![1, 3, 2].iter().is_sorted()); + assert!([0].iter().is_sorted()); + assert!(std::iter::empty::().is_sorted()); + assert!(![0.0, 1.0, f32::NAN].iter().is_sorted()); + assert!([-2, -1, 0, 3].iter().is_sorted()); + assert!(![-2i32, -1, 0, 3].iter().is_sorted_by_key(|n| n.abs())); + assert!(!["c", "bb", "aaa"].iter().is_sorted()); + assert!(["c", "bb", "aaa"].iter().is_sorted_by_key(|s| s.len())); +} + +#[test] +fn test_partition() { + fn check(xs: &mut [i32], ref p: impl Fn(&i32) -> bool, expected: usize) { + let i = xs.iter_mut().partition_in_place(p); + assert_eq!(expected, i); + assert!(xs[..i].iter().all(p)); + assert!(!xs[i..].iter().any(p)); + assert!(xs.iter().is_partitioned(p)); + if i == 0 || i == xs.len() { + assert!(xs.iter().rev().is_partitioned(p)); + } else { + assert!(!xs.iter().rev().is_partitioned(p)); + } + } + + check(&mut [], |_| true, 0); + check(&mut [], |_| false, 0); + + check(&mut [0], |_| true, 1); + check(&mut [0], |_| false, 0); + + check(&mut [-1, 1], |&x| x > 0, 1); + check(&mut [-1, 1], |&x| x < 0, 1); + + let ref mut xs = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]; + check(xs, |_| true, 10); + check(xs, |_| false, 0); + check(xs, |&x| x % 2 == 0, 5); // evens + check(xs, |&x| x % 2 == 1, 5); // odds + check(xs, |&x| x % 3 == 0, 4); // multiple of 3 + check(xs, |&x| x % 4 == 0, 3); // multiple of 4 + check(xs, |&x| x % 5 == 0, 2); // multiple of 5 + check(xs, |&x| x < 3, 3); // small + check(xs, |&x| x > 6, 3); // large +} + +/// An iterator that panics whenever `next` or next_back` is called +/// after `None` has already been returned. This does not violate +/// `Iterator`'s contract. Used to test that iterator adaptors don't +/// poll their inner iterators after exhausting them. +struct NonFused { + iter: I, + done: bool, +} + +impl NonFused { + fn new(iter: I) -> Self { + Self { iter, done: false } + } +} + +impl Iterator for NonFused +where + I: Iterator, +{ + type Item = I::Item; + + fn next(&mut self) -> Option { + assert!(!self.done, "this iterator has already returned None"); + self.iter.next().or_else(|| { + self.done = true; + None + }) + } +} + +impl DoubleEndedIterator for NonFused +where + I: DoubleEndedIterator, +{ + fn next_back(&mut self) -> Option { + assert!(!self.done, "this iterator has already returned None"); + self.iter.next_back().or_else(|| { + self.done = true; + None + }) + } +} + +#[test] +fn test_peekable_non_fused() { + let mut iter = NonFused::new(empty::()).peekable(); + + assert_eq!(iter.peek(), None); + assert_eq!(iter.next_back(), None); +} + +#[test] +fn test_flatten_non_fused_outer() { + let mut iter = NonFused::new(once(0..2)).flatten(); + + assert_eq!(iter.next_back(), Some(1)); + assert_eq!(iter.next(), Some(0)); + assert_eq!(iter.next(), None); +} + +#[test] +fn test_flatten_non_fused_inner() { + let mut iter = once(0..1).chain(once(1..3)).flat_map(NonFused::new); + + assert_eq!(iter.next_back(), Some(2)); + assert_eq!(iter.next(), Some(0)); + assert_eq!(iter.next(), Some(1)); + assert_eq!(iter.next(), None); +} + +#[test] +pub fn extend_for_unit() { + let mut x = 0; + { + let iter = (0..5).map(|_| { + x += 1; + }); + ().extend(iter); + } + assert_eq!(x, 5); +} + +#[test] +fn test_intersperse() { + let xs = ["a", "", "b", "c"]; + let v: Vec<&str> = xs.iter().map(|x| x.clone()).intersperse(", ").collect(); + let text: String = v.concat(); + assert_eq!(text, "a, , b, c".to_string()); + + let ys = [0, 1, 2, 3]; + let mut it = ys[..0].iter().map(|x| *x).intersperse(1); + assert!(it.next() == None); +} + +#[test] +fn test_intersperse_size_hint() { + let xs = ["a", "", "b", "c"]; + let mut iter = xs.iter().map(|x| x.clone()).intersperse(", "); + assert_eq!(iter.size_hint(), (7, Some(7))); + + assert_eq!(iter.next(), Some("a")); + assert_eq!(iter.size_hint(), (6, Some(6))); + assert_eq!(iter.next(), Some(", ")); + assert_eq!(iter.size_hint(), (5, Some(5))); + + assert_eq!([].iter().intersperse(&()).size_hint(), (0, Some(0))); +} + +#[test] +fn test_fold_specialization_intersperse() { + let mut iter = (1..2).intersperse(0); + iter.clone().for_each(|x| assert_eq!(Some(x), iter.next())); + + let mut iter = (1..3).intersperse(0); + iter.clone().for_each(|x| assert_eq!(Some(x), iter.next())); + + let mut iter = (1..4).intersperse(0); + iter.clone().for_each(|x| assert_eq!(Some(x), iter.next())); +} + +#[test] +fn test_try_fold_specialization_intersperse_ok() { + let mut iter = (1..2).intersperse(0); + iter.clone().try_for_each(|x| { + assert_eq!(Some(x), iter.next()); + Some(()) + }); + + let mut iter = (1..3).intersperse(0); + iter.clone().try_for_each(|x| { + assert_eq!(Some(x), iter.next()); + Some(()) + }); + + let mut iter = (1..4).intersperse(0); + iter.clone().try_for_each(|x| { + assert_eq!(Some(x), iter.next()); + Some(()) + }); +} + +#[test] +fn test_try_fold_specialization_intersperse_err() { + let orig_iter = ["a", "b"].iter().copied().intersperse("-"); + + // Abort after the first item. + let mut iter = orig_iter.clone(); + iter.try_for_each(|_| None::<()>); + assert_eq!(iter.next(), Some("-")); + assert_eq!(iter.next(), Some("b")); + assert_eq!(iter.next(), None); + + // Abort after the second item. + let mut iter = orig_iter.clone(); + iter.try_for_each(|item| if item == "-" { None } else { Some(()) }); + assert_eq!(iter.next(), Some("b")); + assert_eq!(iter.next(), None); + + // Abort after the third item. + let mut iter = orig_iter.clone(); + iter.try_for_each(|item| if item == "b" { None } else { Some(()) }); + assert_eq!(iter.next(), None); +} From ed688ec46effc5cd905711a7fbcc1278d3d66556 Mon Sep 17 00:00:00 2001 From: Folyd Date: Sat, 9 Jan 2021 22:10:23 +0800 Subject: [PATCH 2/8] Add iter_at_least and iter_at_most feature flags --- library/core/src/iter/traits/iterator.rs | 4 ++-- library/core/tests/lib.rs | 2 ++ 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs index 30993c636e781..c84ef917a0d60 100644 --- a/library/core/src/iter/traits/iterator.rs +++ b/library/core/src/iter/traits/iterator.rs @@ -2310,7 +2310,7 @@ pub trait Iterator { /// assert_eq!(iter.next(), Some(&2)); /// ``` #[inline] - #[unstable(feature = "at_least", reason = "new API", issue = "none")] + #[unstable(feature = "iter_at_least", reason = "new API", issue = "none")] fn at_least(&mut self, n: usize, f: F) -> bool where Self: Sized, @@ -2379,7 +2379,7 @@ pub trait Iterator { /// assert_eq!(iter.next(), Some(&3)); /// ``` #[inline] - #[unstable(feature = "at_most", reason = "new API", issue = "none")] + #[unstable(feature = "iter_at_most", reason = "new API", issue = "none")] fn at_most(&mut self, n: usize, f: F) -> bool where Self: Sized, diff --git a/library/core/tests/lib.rs b/library/core/tests/lib.rs index b7a406c30e91b..8fbe88b5a0e3d 100644 --- a/library/core/tests/lib.rs +++ b/library/core/tests/lib.rs @@ -77,6 +77,8 @@ #![feature(integer_atomics)] #![feature(slice_group_by)] #![feature(trusted_random_access)] +#![feature(iter_at_least)] +#![feature(iter_at_most)] #![deny(unsafe_op_in_unsafe_fn)] extern crate test; From b9e47c5793f7d431efe50cfcded2e6964c70587e Mon Sep 17 00:00:00 2001 From: Folyd Date: Mon, 11 Jan 2021 00:12:31 +0800 Subject: [PATCH 3/8] Cargo fmt --- library/core/src/iter/traits/iterator.rs | 24 ++++++++---------------- 1 file changed, 8 insertions(+), 16 deletions(-) diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs index c84ef917a0d60..f72406b02a921 100644 --- a/library/core/src/iter/traits/iterator.rs +++ b/library/core/src/iter/traits/iterator.rs @@ -2312,9 +2312,9 @@ pub trait Iterator { #[inline] #[unstable(feature = "iter_at_least", reason = "new API", issue = "none")] fn at_least(&mut self, n: usize, f: F) -> bool - where - Self: Sized, - F: FnMut(Self::Item) -> bool, + where + Self: Sized, + F: FnMut(Self::Item) -> bool, { #[inline] fn check( @@ -2324,11 +2324,7 @@ pub trait Iterator { move |mut i, x| { i += f(x) as usize; - if i < n { - ControlFlow::Continue(i) - } else { - ControlFlow::Break(i) - } + if i < n { ControlFlow::Continue(i) } else { ControlFlow::Break(i) } } } @@ -2381,9 +2377,9 @@ pub trait Iterator { #[inline] #[unstable(feature = "iter_at_most", reason = "new API", issue = "none")] fn at_most(&mut self, n: usize, f: F) -> bool - where - Self: Sized, - F: FnMut(Self::Item) -> bool, + where + Self: Sized, + F: FnMut(Self::Item) -> bool, { #[inline] fn check( @@ -2393,11 +2389,7 @@ pub trait Iterator { move |mut i, x| { i += f(x) as usize; - if i <= n { - ControlFlow::Continue(i) - } else { - ControlFlow::Break(i) - } + if i <= n { ControlFlow::Continue(i) } else { ControlFlow::Break(i) } } } From ff1cfbe3b7f1b7ce4fd60b312bdd4e3599d3db9c Mon Sep 17 00:00:00 2001 From: Folyd Date: Mon, 11 Jan 2021 12:41:33 +0800 Subject: [PATCH 4/8] Add iter_at_least and iter_at_most feature flags to core/lib.rs --- library/core/src/lib.rs | 2 ++ 1 file changed, 2 insertions(+) diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs index 263c6c9cf0f26..c57953d266dd6 100644 --- a/library/core/src/lib.rs +++ b/library/core/src/lib.rs @@ -165,6 +165,8 @@ #![feature(no_niche)] // rust-lang/rust#68303 #![feature(unsafe_block_in_unsafe_fn)] #![feature(int_error_matching)] +#![feature(iter_at_least)] +#![feature(iter_at_most)] #![deny(unsafe_op_in_unsafe_fn)] #[prelude_import] From 71c87ef1793507decf7f52e0de0ab2ed841360e8 Mon Sep 17 00:00:00 2001 From: Folyd Date: Mon, 11 Jan 2021 23:04:50 +0800 Subject: [PATCH 5/8] Add feature flag to docs test --- library/core/src/iter/traits/iterator.rs | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs index f72406b02a921..a88294a795107 100644 --- a/library/core/src/iter/traits/iterator.rs +++ b/library/core/src/iter/traits/iterator.rs @@ -2284,6 +2284,8 @@ pub trait Iterator { /// Basic usage: /// /// ``` + /// #![feature(iter_at_least)] + /// /// let a = [1, 2, 3]; /// /// assert!(a.iter().at_least(1, |&x| x > 0)); @@ -2294,6 +2296,8 @@ pub trait Iterator { /// Stopping at the `n`th `true`: /// /// ``` + /// #![feature(iter_at_least)] + /// /// let a = vec![1, 2, 3, 4, 5]; /// /// let mut iter = a.iter(); @@ -2349,6 +2353,8 @@ pub trait Iterator { /// Basic usage: /// /// ``` + /// #![feature(iter_at_most)] + /// /// let a = [1, 2, 3]; /// /// assert!(a.iter().at_most(1, |&x| x > 3)); @@ -2359,6 +2365,8 @@ pub trait Iterator { /// Stopping at the `n + 1`th `true`: /// /// ``` + /// #![feature(iter_at_most)] + /// /// let a = vec![1, 2, 3, 4, 5]; /// /// let mut iter = a.iter(); From 5951055f6627a482042e67d8e79cc2ef55000a70 Mon Sep 17 00:00:00 2001 From: Folyd Date: Mon, 11 Jan 2021 23:25:40 +0800 Subject: [PATCH 6/8] Remove redundant feature flags --- library/core/src/lib.rs | 2 -- 1 file changed, 2 deletions(-) diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs index c57953d266dd6..263c6c9cf0f26 100644 --- a/library/core/src/lib.rs +++ b/library/core/src/lib.rs @@ -165,8 +165,6 @@ #![feature(no_niche)] // rust-lang/rust#68303 #![feature(unsafe_block_in_unsafe_fn)] #![feature(int_error_matching)] -#![feature(iter_at_least)] -#![feature(iter_at_most)] #![deny(unsafe_op_in_unsafe_fn)] #[prelude_import] From 7fb280a5a0f195da108dcd7312ac414ea0fc0b4f Mon Sep 17 00:00:00 2001 From: Folyd Date: Wed, 13 Jan 2021 00:34:36 +0800 Subject: [PATCH 7/8] Fix docs test --- library/core/src/iter/traits/iterator.rs | 22 ++++++++-------------- 1 file changed, 8 insertions(+), 14 deletions(-) diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs index a88294a795107..078a9a2fe2179 100644 --- a/library/core/src/iter/traits/iterator.rs +++ b/library/core/src/iter/traits/iterator.rs @@ -2289,7 +2289,6 @@ pub trait Iterator { /// let a = [1, 2, 3]; /// /// assert!(a.iter().at_least(1, |&x| x > 0)); - /// /// assert!(!a.iter().at_least(1, |&x| x > 5)); /// ``` /// @@ -2300,12 +2299,10 @@ pub trait Iterator { /// /// let a = vec![1, 2, 3, 4, 5]; /// - /// let mut iter = a.iter(); - /// - /// assert!(iter.at_least(0, |&x| x % 2 == 0)); - /// assert!(iter.at_least(1, |&x| x % 2 == 0)); - /// assert!(iter.at_least(2, |&x| x % 2 == 0)); - /// assert!(!iter.at_least(3, |&x| x % 2 == 0)); + /// assert!(a.iter().at_least(0, |&x| x % 2 == 0)); + /// assert!(a.iter().at_least(1, |&x| x % 2 == 0)); + /// assert!(a.iter().at_least(2, |&x| x % 2 == 0)); + /// assert!(!a.iter().at_least(3, |&x| x % 2 == 0)); /// /// // we can still use `iter`, as there are more elements. /// let a = [1, 2, 3]; @@ -2358,7 +2355,6 @@ pub trait Iterator { /// let a = [1, 2, 3]; /// /// assert!(a.iter().at_most(1, |&x| x > 3)); - /// /// assert!(!a.iter().at_most(1, |&x| x > 0)); /// ``` /// @@ -2369,12 +2365,10 @@ pub trait Iterator { /// /// let a = vec![1, 2, 3, 4, 5]; /// - /// let mut iter = a.iter(); - /// - /// assert!(iter.at_least(0, |&x| x % 2 == 0)); - /// assert!(iter.at_least(1, |&x| x % 2 == 0)); - /// assert!(iter.at_least(2, |&x| x % 2 == 0)); - /// assert!(!iter.at_least(3, |&x| x % 2 == 0)); + /// assert!(!a.iter().at_most(0, |&x| x % 2 == 0)); + /// assert!(!a.iter().at_most(1, |&x| x % 2 == 0)); + /// assert!(a.iter().at_most(2, |&x| x % 2 == 0)); + /// assert!(a.iter().at_most(3, |&x| x % 2 == 0)); /// /// // we can still use `iter`, as there are more elements. /// let a = [1, 1, 3]; From f1764bdb0dd48ec1e2d5d8fee0a0d04fff0c3757 Mon Sep 17 00:00:00 2001 From: Folyd Date: Sat, 30 Jan 2021 14:36:14 +0800 Subject: [PATCH 8/8] Move at_least/at_most testcases to new iter module --- library/core/tests/iter.rs | 3615 -------------------- library/core/tests/iter/traits/iterator.rs | 26 + 2 files changed, 26 insertions(+), 3615 deletions(-) delete mode 100644 library/core/tests/iter.rs diff --git a/library/core/tests/iter.rs b/library/core/tests/iter.rs deleted file mode 100644 index 8fde885259af8..0000000000000 --- a/library/core/tests/iter.rs +++ /dev/null @@ -1,3615 +0,0 @@ -// ignore-tidy-filelength - -use core::cell::Cell; -use core::convert::TryFrom; -use core::iter::*; - -/// An iterator wrapper that panics whenever `next` or `next_back` is called -/// after `None` has been returned. -struct Unfuse { - iter: I, - exhausted: bool, -} - -fn unfuse(iter: I) -> Unfuse { - Unfuse { iter: iter.into_iter(), exhausted: false } -} - -impl Iterator for Unfuse -where - I: Iterator, -{ - type Item = I::Item; - - fn next(&mut self) -> Option { - assert!(!self.exhausted); - let next = self.iter.next(); - self.exhausted = next.is_none(); - next - } -} - -impl DoubleEndedIterator for Unfuse -where - I: DoubleEndedIterator, -{ - fn next_back(&mut self) -> Option { - assert!(!self.exhausted); - let next = self.iter.next_back(); - self.exhausted = next.is_none(); - next - } -} - -#[test] -fn test_lt() { - let empty: [isize; 0] = []; - let xs = [1, 2, 3]; - let ys = [1, 2, 0]; - - assert!(!xs.iter().lt(ys.iter())); - assert!(!xs.iter().le(ys.iter())); - assert!(xs.iter().gt(ys.iter())); - assert!(xs.iter().ge(ys.iter())); - - assert!(ys.iter().lt(xs.iter())); - assert!(ys.iter().le(xs.iter())); - assert!(!ys.iter().gt(xs.iter())); - assert!(!ys.iter().ge(xs.iter())); - - assert!(empty.iter().lt(xs.iter())); - assert!(empty.iter().le(xs.iter())); - assert!(!empty.iter().gt(xs.iter())); - assert!(!empty.iter().ge(xs.iter())); - - // Sequence with NaN - let u = [1.0f64, 2.0]; - let v = [0.0f64 / 0.0, 3.0]; - - assert!(!u.iter().lt(v.iter())); - assert!(!u.iter().le(v.iter())); - assert!(!u.iter().gt(v.iter())); - assert!(!u.iter().ge(v.iter())); - - let a = [0.0f64 / 0.0]; - let b = [1.0f64]; - let c = [2.0f64]; - - assert!(a.iter().lt(b.iter()) == (a[0] < b[0])); - assert!(a.iter().le(b.iter()) == (a[0] <= b[0])); - assert!(a.iter().gt(b.iter()) == (a[0] > b[0])); - assert!(a.iter().ge(b.iter()) == (a[0] >= b[0])); - - assert!(c.iter().lt(b.iter()) == (c[0] < b[0])); - assert!(c.iter().le(b.iter()) == (c[0] <= b[0])); - assert!(c.iter().gt(b.iter()) == (c[0] > b[0])); - assert!(c.iter().ge(b.iter()) == (c[0] >= b[0])); -} - -#[test] -fn test_multi_iter() { - let xs = [1, 2, 3, 4]; - let ys = [4, 3, 2, 1]; - assert!(xs.iter().eq(ys.iter().rev())); - assert!(xs.iter().lt(xs.iter().skip(2))); -} - -#[test] -fn test_cmp_by() { - use core::cmp::Ordering; - - let f = |x: i32, y: i32| (x * x).cmp(&y); - let xs = || [1, 2, 3, 4].iter().copied(); - let ys = || [1, 4, 16].iter().copied(); - - assert_eq!(xs().cmp_by(ys(), f), Ordering::Less); - assert_eq!(ys().cmp_by(xs(), f), Ordering::Greater); - assert_eq!(xs().cmp_by(xs().map(|x| x * x), f), Ordering::Equal); - assert_eq!(xs().rev().cmp_by(ys().rev(), f), Ordering::Greater); - assert_eq!(xs().cmp_by(ys().rev(), f), Ordering::Less); - assert_eq!(xs().cmp_by(ys().take(2), f), Ordering::Greater); -} - -#[test] -fn test_partial_cmp_by() { - use core::cmp::Ordering; - - let f = |x: i32, y: i32| (x * x).partial_cmp(&y); - let xs = || [1, 2, 3, 4].iter().copied(); - let ys = || [1, 4, 16].iter().copied(); - - assert_eq!(xs().partial_cmp_by(ys(), f), Some(Ordering::Less)); - assert_eq!(ys().partial_cmp_by(xs(), f), Some(Ordering::Greater)); - assert_eq!(xs().partial_cmp_by(xs().map(|x| x * x), f), Some(Ordering::Equal)); - assert_eq!(xs().rev().partial_cmp_by(ys().rev(), f), Some(Ordering::Greater)); - assert_eq!(xs().partial_cmp_by(xs().rev(), f), Some(Ordering::Less)); - assert_eq!(xs().partial_cmp_by(ys().take(2), f), Some(Ordering::Greater)); - - let f = |x: f64, y: f64| (x * x).partial_cmp(&y); - let xs = || [1.0, 2.0, 3.0, 4.0].iter().copied(); - let ys = || [1.0, 4.0, f64::NAN, 16.0].iter().copied(); - - assert_eq!(xs().partial_cmp_by(ys(), f), None); - assert_eq!(ys().partial_cmp_by(xs(), f), Some(Ordering::Greater)); -} - -#[test] -fn test_eq_by() { - let f = |x: i32, y: i32| x * x == y; - let xs = || [1, 2, 3, 4].iter().copied(); - let ys = || [1, 4, 9, 16].iter().copied(); - - assert!(xs().eq_by(ys(), f)); - assert!(!ys().eq_by(xs(), f)); - assert!(!xs().eq_by(xs(), f)); - assert!(!ys().eq_by(ys(), f)); - - assert!(!xs().take(3).eq_by(ys(), f)); - assert!(!xs().eq_by(ys().take(3), f)); - assert!(xs().take(3).eq_by(ys().take(3), f)); -} - -#[test] -fn test_counter_from_iter() { - let it = (0..).step_by(5).take(10); - let xs: Vec = FromIterator::from_iter(it); - assert_eq!(xs, [0, 5, 10, 15, 20, 25, 30, 35, 40, 45]); -} - -#[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(xs).chain(unfuse(ys)); - iter.advance_by(i).unwrap(); - assert_eq!(iter.next(), Some(&xs[i])); - assert_eq!(iter.advance_by(100), Err(len - i - 1)); - } - - for i in 0..ys.len() { - let mut iter = unfuse(xs).chain(unfuse(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)); - } - - let mut iter = xs.iter().chain(ys); - iter.advance_by(len).unwrap(); - assert_eq!(iter.next(), None); - - let mut iter = xs.iter().chain(ys); - assert_eq!(iter.advance_by(len + 1), Err(len)); - } - - 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(xs).chain(unfuse(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)); - } - - for i in 0..xs.len() { - let mut iter = unfuse(xs).chain(unfuse(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)); - } - - let mut iter = xs.iter().chain(ys); - iter.advance_back_by(len).unwrap(); - assert_eq!(iter.next_back(), None); - - let mut iter = xs.iter().chain(ys); - assert_eq!(iter.advance_back_by(len + 1), Err(len)); - } - - 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); -} - -struct Toggle { - is_empty: bool, -} - -impl Iterator for Toggle { - type Item = (); - - // alternates between `None` and `Some(())` - fn next(&mut self) -> Option { - if self.is_empty { - self.is_empty = false; - None - } else { - self.is_empty = true; - Some(()) - } - } - - fn size_hint(&self) -> (usize, Option) { - if self.is_empty { (0, Some(0)) } else { (1, Some(1)) } - } -} - -impl DoubleEndedIterator for Toggle { - fn next_back(&mut self) -> Option { - self.next() - } -} - -#[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 }); - iter.next().unwrap_none(); - iter.next().unwrap(); - iter.next().unwrap_none(); - - let mut iter = Toggle { is_empty: true }.chain(NonFused::new(empty())); - iter.next_back().unwrap_none(); - iter.next_back().unwrap(); - iter.next_back().unwrap_none(); -} - -#[test] -fn test_zip_nth() { - let xs = [0, 1, 2, 4, 5]; - let ys = [10, 11, 12]; - - let mut it = xs.iter().zip(&ys); - assert_eq!(it.nth(0), Some((&0, &10))); - assert_eq!(it.nth(1), Some((&2, &12))); - assert_eq!(it.nth(0), None); - - let mut it = xs.iter().zip(&ys); - assert_eq!(it.nth(3), None); - - let mut it = ys.iter().zip(&xs); - assert_eq!(it.nth(3), None); -} - -#[test] -fn test_zip_nth_side_effects() { - let mut a = Vec::new(); - let mut b = Vec::new(); - let value = [1, 2, 3, 4, 5, 6] - .iter() - .cloned() - .map(|n| { - a.push(n); - n * 10 - }) - .zip([2, 3, 4, 5, 6, 7, 8].iter().cloned().map(|n| { - b.push(n * 100); - n * 1000 - })) - .skip(1) - .nth(3); - assert_eq!(value, Some((50, 6000))); - assert_eq!(a, vec![1, 2, 3, 4, 5]); - assert_eq!(b, vec![200, 300, 400, 500, 600]); -} - -#[test] -fn test_zip_next_back_side_effects() { - let mut a = Vec::new(); - let mut b = Vec::new(); - let mut iter = [1, 2, 3, 4, 5, 6] - .iter() - .cloned() - .map(|n| { - a.push(n); - n * 10 - }) - .zip([2, 3, 4, 5, 6, 7, 8].iter().cloned().map(|n| { - b.push(n * 100); - n * 1000 - })); - - // The second iterator is one item longer, so `next_back` is called on it - // one more time. - assert_eq!(iter.next_back(), Some((60, 7000))); - assert_eq!(iter.next_back(), Some((50, 6000))); - assert_eq!(iter.next_back(), Some((40, 5000))); - assert_eq!(iter.next_back(), Some((30, 4000))); - assert_eq!(a, vec![6, 5, 4, 3]); - assert_eq!(b, vec![800, 700, 600, 500, 400]); -} - -#[test] -fn test_zip_nth_back_side_effects() { - let mut a = Vec::new(); - let mut b = Vec::new(); - let value = [1, 2, 3, 4, 5, 6] - .iter() - .cloned() - .map(|n| { - a.push(n); - n * 10 - }) - .zip([2, 3, 4, 5, 6, 7, 8].iter().cloned().map(|n| { - b.push(n * 100); - n * 1000 - })) - .nth_back(3); - assert_eq!(value, Some((30, 4000))); - assert_eq!(a, vec![6, 5, 4, 3]); - assert_eq!(b, vec![800, 700, 600, 500, 400]); -} - -#[test] -fn test_zip_next_back_side_effects_exhausted() { - let mut a = Vec::new(); - let mut b = Vec::new(); - let mut iter = [1, 2, 3, 4, 5, 6] - .iter() - .cloned() - .map(|n| { - a.push(n); - n * 10 - }) - .zip([2, 3, 4].iter().cloned().map(|n| { - b.push(n * 100); - n * 1000 - })); - - iter.next(); - iter.next(); - iter.next(); - iter.next(); - assert_eq!(iter.next_back(), None); - assert_eq!(a, vec![1, 2, 3, 4, 6, 5]); - assert_eq!(b, vec![200, 300, 400]); -} - -#[derive(Debug)] -struct CountClone(Cell); - -fn count_clone() -> CountClone { - CountClone(Cell::new(0)) -} - -impl PartialEq for CountClone { - fn eq(&self, rhs: &i32) -> bool { - self.0.get() == *rhs - } -} - -impl Clone for CountClone { - fn clone(&self) -> Self { - let ret = CountClone(self.0.clone()); - let n = self.0.get(); - self.0.set(n + 1); - ret - } -} - -#[test] -fn test_zip_cloned_sideffectful() { - let xs = [count_clone(), count_clone(), count_clone(), count_clone()]; - let ys = [count_clone(), count_clone()]; - - for _ in xs.iter().cloned().zip(ys.iter().cloned()) {} - - assert_eq!(&xs, &[1, 1, 1, 0][..]); - assert_eq!(&ys, &[1, 1][..]); - - let xs = [count_clone(), count_clone()]; - let ys = [count_clone(), count_clone(), count_clone(), count_clone()]; - - for _ in xs.iter().cloned().zip(ys.iter().cloned()) {} - - assert_eq!(&xs, &[1, 1][..]); - assert_eq!(&ys, &[1, 1, 0, 0][..]); -} - -#[test] -fn test_zip_map_sideffectful() { - let mut xs = [0; 6]; - let mut ys = [0; 4]; - - for _ in xs.iter_mut().map(|x| *x += 1).zip(ys.iter_mut().map(|y| *y += 1)) {} - - assert_eq!(&xs, &[1, 1, 1, 1, 1, 0]); - assert_eq!(&ys, &[1, 1, 1, 1]); - - let mut xs = [0; 4]; - let mut ys = [0; 6]; - - for _ in xs.iter_mut().map(|x| *x += 1).zip(ys.iter_mut().map(|y| *y += 1)) {} - - assert_eq!(&xs, &[1, 1, 1, 1]); - assert_eq!(&ys, &[1, 1, 1, 1, 0, 0]); -} - -#[test] -fn test_zip_map_rev_sideffectful() { - let mut xs = [0; 6]; - let mut ys = [0; 4]; - - { - let mut it = xs.iter_mut().map(|x| *x += 1).zip(ys.iter_mut().map(|y| *y += 1)); - it.next_back(); - } - assert_eq!(&xs, &[0, 0, 0, 1, 1, 1]); - assert_eq!(&ys, &[0, 0, 0, 1]); - - let mut xs = [0; 6]; - let mut ys = [0; 4]; - - { - let mut it = xs.iter_mut().map(|x| *x += 1).zip(ys.iter_mut().map(|y| *y += 1)); - (&mut it).take(5).count(); - it.next_back(); - } - assert_eq!(&xs, &[1, 1, 1, 1, 1, 1]); - assert_eq!(&ys, &[1, 1, 1, 1]); -} - -#[test] -fn test_zip_nested_sideffectful() { - let mut xs = [0; 6]; - let ys = [0; 4]; - - { - // test that it has the side effect nested inside enumerate - let it = xs.iter_mut().map(|x| *x = 1).enumerate().zip(&ys); - it.count(); - } - assert_eq!(&xs, &[1, 1, 1, 1, 1, 0]); -} - -#[test] -fn test_zip_nth_back_side_effects_exhausted() { - let mut a = Vec::new(); - let mut b = Vec::new(); - let mut iter = [1, 2, 3, 4, 5, 6] - .iter() - .cloned() - .map(|n| { - a.push(n); - n * 10 - }) - .zip([2, 3, 4].iter().cloned().map(|n| { - b.push(n * 100); - n * 1000 - })); - - iter.next(); - iter.next(); - iter.next(); - iter.next(); - assert_eq!(iter.nth_back(0), None); - assert_eq!(a, vec![1, 2, 3, 4, 6, 5]); - assert_eq!(b, vec![200, 300, 400]); -} - -#[test] -fn test_iterator_step_by() { - // Identity - let mut it = (0..).step_by(1).take(3); - assert_eq!(it.next(), Some(0)); - assert_eq!(it.next(), Some(1)); - assert_eq!(it.next(), Some(2)); - assert_eq!(it.next(), None); - - let mut it = (0..).step_by(3).take(4); - assert_eq!(it.next(), Some(0)); - assert_eq!(it.next(), Some(3)); - assert_eq!(it.next(), Some(6)); - assert_eq!(it.next(), Some(9)); - assert_eq!(it.next(), None); - - let mut it = (0..3).step_by(1); - assert_eq!(it.next_back(), Some(2)); - assert_eq!(it.next_back(), Some(1)); - assert_eq!(it.next_back(), Some(0)); - assert_eq!(it.next_back(), None); - - let mut it = (0..11).step_by(3); - assert_eq!(it.next_back(), Some(9)); - assert_eq!(it.next_back(), Some(6)); - assert_eq!(it.next_back(), Some(3)); - assert_eq!(it.next_back(), Some(0)); - assert_eq!(it.next_back(), None); -} - -#[test] -fn test_iterator_step_by_nth() { - let mut it = (0..16).step_by(5); - assert_eq!(it.nth(0), Some(0)); - assert_eq!(it.nth(0), Some(5)); - assert_eq!(it.nth(0), Some(10)); - assert_eq!(it.nth(0), Some(15)); - assert_eq!(it.nth(0), None); - - let it = (0..18).step_by(5); - assert_eq!(it.clone().nth(0), Some(0)); - assert_eq!(it.clone().nth(1), Some(5)); - assert_eq!(it.clone().nth(2), Some(10)); - assert_eq!(it.clone().nth(3), Some(15)); - assert_eq!(it.clone().nth(4), None); - assert_eq!(it.clone().nth(42), None); -} - -#[test] -fn test_iterator_step_by_nth_overflow() { - #[cfg(target_pointer_width = "8")] - type Bigger = u16; - #[cfg(target_pointer_width = "16")] - type Bigger = u32; - #[cfg(target_pointer_width = "32")] - type Bigger = u64; - #[cfg(target_pointer_width = "64")] - type Bigger = u128; - - #[derive(Clone)] - struct Test(Bigger); - impl Iterator for &mut Test { - type Item = i32; - fn next(&mut self) -> Option { - Some(21) - } - fn nth(&mut self, n: usize) -> Option { - self.0 += n as Bigger + 1; - Some(42) - } - } - - let mut it = Test(0); - let root = usize::MAX >> (usize::BITS / 2); - let n = root + 20; - (&mut it).step_by(n).nth(n); - assert_eq!(it.0, n as Bigger * n as Bigger); - - // large step - let mut it = Test(0); - (&mut it).step_by(usize::MAX).nth(5); - assert_eq!(it.0, (usize::MAX as Bigger) * 5); - - // n + 1 overflows - let mut it = Test(0); - (&mut it).step_by(2).nth(usize::MAX); - assert_eq!(it.0, (usize::MAX as Bigger) * 2); - - // n + 1 overflows - let mut it = Test(0); - (&mut it).step_by(1).nth(usize::MAX); - assert_eq!(it.0, (usize::MAX as Bigger) * 1); -} - -#[test] -fn test_iterator_step_by_nth_try_fold() { - let mut it = (0..).step_by(10); - assert_eq!(it.try_fold(0, i8::checked_add), None); - assert_eq!(it.next(), Some(60)); - assert_eq!(it.try_fold(0, i8::checked_add), None); - assert_eq!(it.next(), Some(90)); - - let mut it = (100..).step_by(10); - assert_eq!(it.try_fold(50, i8::checked_add), None); - assert_eq!(it.next(), Some(110)); - - let mut it = (100..=100).step_by(10); - assert_eq!(it.next(), Some(100)); - assert_eq!(it.try_fold(0, i8::checked_add), Some(0)); -} - -#[test] -fn test_iterator_step_by_nth_back() { - let mut it = (0..16).step_by(5); - assert_eq!(it.nth_back(0), Some(15)); - assert_eq!(it.nth_back(0), Some(10)); - assert_eq!(it.nth_back(0), Some(5)); - assert_eq!(it.nth_back(0), Some(0)); - assert_eq!(it.nth_back(0), None); - - let mut it = (0..16).step_by(5); - assert_eq!(it.next(), Some(0)); // to set `first_take` to `false` - assert_eq!(it.nth_back(0), Some(15)); - assert_eq!(it.nth_back(0), Some(10)); - assert_eq!(it.nth_back(0), Some(5)); - assert_eq!(it.nth_back(0), None); - - let it = || (0..18).step_by(5); - assert_eq!(it().nth_back(0), Some(15)); - assert_eq!(it().nth_back(1), Some(10)); - assert_eq!(it().nth_back(2), Some(5)); - assert_eq!(it().nth_back(3), Some(0)); - assert_eq!(it().nth_back(4), None); - assert_eq!(it().nth_back(42), None); -} - -#[test] -fn test_iterator_step_by_nth_try_rfold() { - let mut it = (0..100).step_by(10); - assert_eq!(it.try_rfold(0, i8::checked_add), None); - assert_eq!(it.next_back(), Some(70)); - assert_eq!(it.next(), Some(0)); - assert_eq!(it.try_rfold(0, i8::checked_add), None); - assert_eq!(it.next_back(), Some(30)); - - let mut it = (0..100).step_by(10); - assert_eq!(it.try_rfold(50, i8::checked_add), None); - assert_eq!(it.next_back(), Some(80)); - - let mut it = (100..=100).step_by(10); - assert_eq!(it.next_back(), Some(100)); - assert_eq!(it.try_fold(0, i8::checked_add), Some(0)); -} - -#[test] -#[should_panic] -fn test_iterator_step_by_zero() { - let mut it = (0..).step_by(0); - it.next(); -} - -#[test] -fn test_iterator_step_by_size_hint() { - struct StubSizeHint(usize, Option); - impl Iterator for StubSizeHint { - type Item = (); - fn next(&mut self) -> Option<()> { - self.0 -= 1; - if let Some(ref mut upper) = self.1 { - *upper -= 1; - } - Some(()) - } - fn size_hint(&self) -> (usize, Option) { - (self.0, self.1) - } - } - - // The two checks in each case are needed because the logic - // is different before the first call to `next()`. - - let mut it = StubSizeHint(10, Some(10)).step_by(1); - assert_eq!(it.size_hint(), (10, Some(10))); - it.next(); - assert_eq!(it.size_hint(), (9, Some(9))); - - // exact multiple - let mut it = StubSizeHint(10, Some(10)).step_by(3); - assert_eq!(it.size_hint(), (4, Some(4))); - it.next(); - assert_eq!(it.size_hint(), (3, Some(3))); - - // larger base range, but not enough to get another element - let mut it = StubSizeHint(12, Some(12)).step_by(3); - assert_eq!(it.size_hint(), (4, Some(4))); - it.next(); - assert_eq!(it.size_hint(), (3, Some(3))); - - // smaller base range, so fewer resulting elements - let mut it = StubSizeHint(9, Some(9)).step_by(3); - assert_eq!(it.size_hint(), (3, Some(3))); - it.next(); - assert_eq!(it.size_hint(), (2, Some(2))); - - // infinite upper bound - let mut it = StubSizeHint(usize::MAX, None).step_by(1); - assert_eq!(it.size_hint(), (usize::MAX, None)); - it.next(); - assert_eq!(it.size_hint(), (usize::MAX - 1, None)); - - // still infinite with larger step - let mut it = StubSizeHint(7, None).step_by(3); - assert_eq!(it.size_hint(), (3, None)); - it.next(); - assert_eq!(it.size_hint(), (2, None)); - - // propagates ExactSizeIterator - let a = [1, 2, 3, 4, 5]; - let it = a.iter().step_by(2); - assert_eq!(it.len(), 3); - - // Cannot be TrustedLen as a step greater than one makes an iterator - // with (usize::MAX, None) no longer meet the safety requirements - trait TrustedLenCheck { - fn test(self) -> bool; - } - impl TrustedLenCheck for T { - default fn test(self) -> bool { - false - } - } - impl TrustedLenCheck for T { - fn test(self) -> bool { - true - } - } - assert!(TrustedLenCheck::test(a.iter())); - assert!(!TrustedLenCheck::test(a.iter().step_by(1))); -} - -#[test] -fn test_filter_map() { - let it = (0..).step_by(1).take(10).filter_map(|x| if x % 2 == 0 { Some(x * x) } else { None }); - assert_eq!(it.collect::>(), [0 * 0, 2 * 2, 4 * 4, 6 * 6, 8 * 8]); -} - -#[test] -fn test_filter_map_fold() { - let xs = [0, 1, 2, 3, 4, 5, 6, 7, 8]; - let ys = [0 * 0, 2 * 2, 4 * 4, 6 * 6, 8 * 8]; - let it = xs.iter().filter_map(|&x| if x % 2 == 0 { Some(x * x) } else { None }); - let i = it.fold(0, |i, x| { - assert_eq!(x, ys[i]); - i + 1 - }); - assert_eq!(i, ys.len()); - - let it = xs.iter().filter_map(|&x| if x % 2 == 0 { Some(x * x) } else { None }); - let i = it.rfold(ys.len(), |i, x| { - assert_eq!(x, ys[i - 1]); - i - 1 - }); - assert_eq!(i, 0); -} - -#[test] -fn test_iterator_enumerate() { - let xs = [0, 1, 2, 3, 4, 5]; - let it = xs.iter().enumerate(); - for (i, &x) in it { - assert_eq!(i, x); - } -} - -#[test] -fn test_iterator_enumerate_nth() { - let xs = [0, 1, 2, 3, 4, 5]; - for (i, &x) in xs.iter().enumerate() { - assert_eq!(i, x); - } - - let mut it = xs.iter().enumerate(); - while let Some((i, &x)) = it.nth(0) { - assert_eq!(i, x); - } - - let mut it = xs.iter().enumerate(); - while let Some((i, &x)) = it.nth(1) { - assert_eq!(i, x); - } - - let (i, &x) = xs.iter().enumerate().nth(3).unwrap(); - assert_eq!(i, x); - assert_eq!(i, 3); -} - -#[test] -fn test_iterator_enumerate_nth_back() { - let xs = [0, 1, 2, 3, 4, 5]; - let mut it = xs.iter().enumerate(); - while let Some((i, &x)) = it.nth_back(0) { - assert_eq!(i, x); - } - - let mut it = xs.iter().enumerate(); - while let Some((i, &x)) = it.nth_back(1) { - assert_eq!(i, x); - } - - let (i, &x) = xs.iter().enumerate().nth_back(3).unwrap(); - assert_eq!(i, x); - assert_eq!(i, 2); -} - -#[test] -fn test_iterator_enumerate_count() { - let xs = [0, 1, 2, 3, 4, 5]; - assert_eq!(xs.iter().enumerate().count(), 6); -} - -#[test] -fn test_iterator_enumerate_fold() { - let xs = [0, 1, 2, 3, 4, 5]; - let mut it = xs.iter().enumerate(); - // steal a couple to get an interesting offset - assert_eq!(it.next(), Some((0, &0))); - assert_eq!(it.next(), Some((1, &1))); - let i = it.fold(2, |i, (j, &x)| { - assert_eq!(i, j); - assert_eq!(x, xs[j]); - i + 1 - }); - assert_eq!(i, xs.len()); - - let mut it = xs.iter().enumerate(); - assert_eq!(it.next(), Some((0, &0))); - let i = it.rfold(xs.len() - 1, |i, (j, &x)| { - assert_eq!(i, j); - assert_eq!(x, xs[j]); - i - 1 - }); - assert_eq!(i, 0); -} - -#[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_iterator_peekable() { - let xs = vec![0, 1, 2, 3, 4, 5]; - - let mut it = xs.iter().cloned().peekable(); - assert_eq!(it.len(), 6); - assert_eq!(it.peek().unwrap(), &0); - assert_eq!(it.len(), 6); - assert_eq!(it.next().unwrap(), 0); - assert_eq!(it.len(), 5); - assert_eq!(it.next().unwrap(), 1); - assert_eq!(it.len(), 4); - assert_eq!(it.next().unwrap(), 2); - assert_eq!(it.len(), 3); - assert_eq!(it.peek().unwrap(), &3); - assert_eq!(it.len(), 3); - assert_eq!(it.peek().unwrap(), &3); - assert_eq!(it.len(), 3); - assert_eq!(it.next().unwrap(), 3); - assert_eq!(it.len(), 2); - assert_eq!(it.next().unwrap(), 4); - assert_eq!(it.len(), 1); - assert_eq!(it.peek().unwrap(), &5); - assert_eq!(it.len(), 1); - assert_eq!(it.next().unwrap(), 5); - assert_eq!(it.len(), 0); - assert!(it.peek().is_none()); - assert_eq!(it.len(), 0); - assert!(it.next().is_none()); - assert_eq!(it.len(), 0); - - let mut it = xs.iter().cloned().peekable(); - assert_eq!(it.len(), 6); - assert_eq!(it.peek().unwrap(), &0); - assert_eq!(it.len(), 6); - assert_eq!(it.next_back().unwrap(), 5); - assert_eq!(it.len(), 5); - assert_eq!(it.next_back().unwrap(), 4); - assert_eq!(it.len(), 4); - assert_eq!(it.next_back().unwrap(), 3); - assert_eq!(it.len(), 3); - assert_eq!(it.peek().unwrap(), &0); - assert_eq!(it.len(), 3); - assert_eq!(it.peek().unwrap(), &0); - assert_eq!(it.len(), 3); - assert_eq!(it.next_back().unwrap(), 2); - assert_eq!(it.len(), 2); - assert_eq!(it.next_back().unwrap(), 1); - assert_eq!(it.len(), 1); - assert_eq!(it.peek().unwrap(), &0); - assert_eq!(it.len(), 1); - assert_eq!(it.next_back().unwrap(), 0); - assert_eq!(it.len(), 0); - assert!(it.peek().is_none()); - assert_eq!(it.len(), 0); - assert!(it.next_back().is_none()); - assert_eq!(it.len(), 0); -} - -#[test] -fn test_iterator_peekable_count() { - let xs = [0, 1, 2, 3, 4, 5]; - let ys = [10]; - let zs: [i32; 0] = []; - - assert_eq!(xs.iter().peekable().count(), 6); - - let mut it = xs.iter().peekable(); - assert_eq!(it.peek(), Some(&&0)); - assert_eq!(it.count(), 6); - - assert_eq!(ys.iter().peekable().count(), 1); - - let mut it = ys.iter().peekable(); - assert_eq!(it.peek(), Some(&&10)); - assert_eq!(it.count(), 1); - - assert_eq!(zs.iter().peekable().count(), 0); - - let mut it = zs.iter().peekable(); - assert_eq!(it.peek(), None); -} - -#[test] -fn test_iterator_peekable_nth() { - let xs = [0, 1, 2, 3, 4, 5]; - let mut it = xs.iter().peekable(); - - assert_eq!(it.peek(), Some(&&0)); - assert_eq!(it.nth(0), Some(&0)); - assert_eq!(it.peek(), Some(&&1)); - assert_eq!(it.nth(1), Some(&2)); - assert_eq!(it.peek(), Some(&&3)); - assert_eq!(it.nth(2), Some(&5)); - assert_eq!(it.next(), None); -} - -#[test] -fn test_iterator_peekable_last() { - let xs = [0, 1, 2, 3, 4, 5]; - let ys = [0]; - - let mut it = xs.iter().peekable(); - assert_eq!(it.peek(), Some(&&0)); - assert_eq!(it.last(), Some(&5)); - - let mut it = ys.iter().peekable(); - assert_eq!(it.peek(), Some(&&0)); - assert_eq!(it.last(), Some(&0)); - - let mut it = ys.iter().peekable(); - assert_eq!(it.next(), Some(&0)); - assert_eq!(it.peek(), None); - assert_eq!(it.last(), None); -} - -#[test] -fn test_iterator_peekable_fold() { - let xs = [0, 1, 2, 3, 4, 5]; - let mut it = xs.iter().peekable(); - assert_eq!(it.peek(), Some(&&0)); - let i = it.fold(0, |i, &x| { - assert_eq!(x, xs[i]); - i + 1 - }); - assert_eq!(i, xs.len()); -} - -#[test] -fn test_iterator_peekable_rfold() { - let xs = [0, 1, 2, 3, 4, 5]; - let mut it = xs.iter().peekable(); - assert_eq!(it.peek(), Some(&&0)); - let i = it.rfold(0, |i, &x| { - assert_eq!(x, xs[xs.len() - 1 - i]); - i + 1 - }); - assert_eq!(i, xs.len()); -} - -#[test] -fn test_iterator_peekable_next_if_eq() { - // first, try on references - let xs = vec!["Heart", "of", "Gold"]; - let mut it = xs.into_iter().peekable(); - // try before `peek()` - assert_eq!(it.next_if_eq(&"trillian"), None); - assert_eq!(it.next_if_eq(&"Heart"), Some("Heart")); - // try after peek() - assert_eq!(it.peek(), Some(&"of")); - assert_eq!(it.next_if_eq(&"of"), Some("of")); - assert_eq!(it.next_if_eq(&"zaphod"), None); - // make sure `next()` still behaves - assert_eq!(it.next(), Some("Gold")); - - // make sure comparison works for owned values - let xs = vec![String::from("Ludicrous"), "speed".into()]; - let mut it = xs.into_iter().peekable(); - // make sure basic functionality works - assert_eq!(it.next_if_eq("Ludicrous"), Some("Ludicrous".into())); - assert_eq!(it.next_if_eq("speed"), Some("speed".into())); - assert_eq!(it.next_if_eq(""), None); -} - -#[test] -fn test_iterator_peekable_mut() { - let mut it = vec![1, 2, 3].into_iter().peekable(); - if let Some(p) = it.peek_mut() { - if *p == 1 { - *p = 5; - } - } - assert_eq!(it.collect::>(), vec![5, 2, 3]); -} - -/// This is an iterator that follows the Iterator contract, -/// but it is not fused. After having returned None once, it will start -/// producing elements if .next() is called again. -pub struct CycleIter<'a, T> { - index: usize, - data: &'a [T], -} - -pub fn cycle(data: &[T]) -> CycleIter<'_, T> { - CycleIter { index: 0, data } -} - -impl<'a, T> Iterator for CycleIter<'a, T> { - type Item = &'a T; - fn next(&mut self) -> Option { - let elt = self.data.get(self.index); - self.index += 1; - self.index %= 1 + self.data.len(); - elt - } -} - -#[test] -fn test_iterator_peekable_remember_peek_none_1() { - // Check that the loop using .peek() terminates - let data = [1, 2, 3]; - let mut iter = cycle(&data).peekable(); - - let mut n = 0; - while let Some(_) = iter.next() { - let is_the_last = iter.peek().is_none(); - assert_eq!(is_the_last, n == data.len() - 1); - n += 1; - if n > data.len() { - break; - } - } - assert_eq!(n, data.len()); -} - -#[test] -fn test_iterator_peekable_remember_peek_none_2() { - let data = [0]; - let mut iter = cycle(&data).peekable(); - iter.next(); - assert_eq!(iter.peek(), None); - assert_eq!(iter.last(), None); -} - -#[test] -fn test_iterator_peekable_remember_peek_none_3() { - let data = [0]; - let mut iter = cycle(&data).peekable(); - iter.peek(); - assert_eq!(iter.nth(0), Some(&0)); - - let mut iter = cycle(&data).peekable(); - iter.next(); - assert_eq!(iter.peek(), None); - assert_eq!(iter.nth(0), None); -} - -#[test] -fn test_iterator_take_while() { - let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19]; - let ys = [0, 1, 2, 3, 5, 13]; - let it = xs.iter().take_while(|&x| *x < 15); - let mut i = 0; - for x in it { - assert_eq!(*x, ys[i]); - i += 1; - } - assert_eq!(i, ys.len()); -} - -#[test] -fn test_iterator_skip_while() { - let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19]; - let ys = [15, 16, 17, 19]; - let it = xs.iter().skip_while(|&x| *x < 15); - let mut i = 0; - for x in it { - assert_eq!(*x, ys[i]); - i += 1; - } - assert_eq!(i, ys.len()); -} - -#[test] -fn test_iterator_skip_while_fold() { - let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19]; - let ys = [15, 16, 17, 19]; - let it = xs.iter().skip_while(|&x| *x < 15); - let i = it.fold(0, |i, &x| { - assert_eq!(x, ys[i]); - i + 1 - }); - assert_eq!(i, ys.len()); - - let mut it = xs.iter().skip_while(|&x| *x < 15); - assert_eq!(it.next(), Some(&ys[0])); // process skips before folding - let i = it.fold(1, |i, &x| { - assert_eq!(x, ys[i]); - i + 1 - }); - assert_eq!(i, ys.len()); -} - -#[test] -fn test_iterator_skip() { - let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19, 20, 30]; - let ys = [13, 15, 16, 17, 19, 20, 30]; - let mut it = xs.iter().skip(5); - let mut i = 0; - while let Some(&x) = it.next() { - assert_eq!(x, ys[i]); - i += 1; - assert_eq!(it.len(), xs.len() - 5 - i); - } - assert_eq!(i, ys.len()); - assert_eq!(it.len(), 0); -} - -#[test] -fn test_iterator_skip_doubleended() { - let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19, 20, 30]; - let mut it = xs.iter().rev().skip(5); - assert_eq!(it.next(), Some(&15)); - assert_eq!(it.by_ref().rev().next(), Some(&0)); - assert_eq!(it.next(), Some(&13)); - assert_eq!(it.by_ref().rev().next(), Some(&1)); - assert_eq!(it.next(), Some(&5)); - assert_eq!(it.by_ref().rev().next(), Some(&2)); - assert_eq!(it.next(), Some(&3)); - assert_eq!(it.next(), None); - let mut it = xs.iter().rev().skip(5).rev(); - assert_eq!(it.next(), Some(&0)); - assert_eq!(it.rev().next(), Some(&15)); - let mut it_base = xs.iter(); - { - let mut it = it_base.by_ref().skip(5).rev(); - assert_eq!(it.next(), Some(&30)); - assert_eq!(it.next(), Some(&20)); - assert_eq!(it.next(), Some(&19)); - assert_eq!(it.next(), Some(&17)); - assert_eq!(it.next(), Some(&16)); - assert_eq!(it.next(), Some(&15)); - assert_eq!(it.next(), Some(&13)); - assert_eq!(it.next(), None); - } - // make sure the skipped parts have not been consumed - assert_eq!(it_base.next(), Some(&0)); - assert_eq!(it_base.next(), Some(&1)); - assert_eq!(it_base.next(), Some(&2)); - assert_eq!(it_base.next(), Some(&3)); - assert_eq!(it_base.next(), Some(&5)); - assert_eq!(it_base.next(), None); - let it = xs.iter().skip(5).rev(); - assert_eq!(it.last(), Some(&13)); -} - -#[test] -fn test_iterator_skip_nth() { - let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19, 20, 30]; - - let mut it = xs.iter().skip(0); - assert_eq!(it.nth(0), Some(&0)); - assert_eq!(it.nth(1), Some(&2)); - - let mut it = xs.iter().skip(5); - assert_eq!(it.nth(0), Some(&13)); - assert_eq!(it.nth(1), Some(&16)); - - let mut it = xs.iter().skip(12); - assert_eq!(it.nth(0), None); -} - -#[test] -fn test_iterator_skip_count() { - let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19, 20, 30]; - - assert_eq!(xs.iter().skip(0).count(), 12); - assert_eq!(xs.iter().skip(1).count(), 11); - assert_eq!(xs.iter().skip(11).count(), 1); - assert_eq!(xs.iter().skip(12).count(), 0); - assert_eq!(xs.iter().skip(13).count(), 0); -} - -#[test] -fn test_iterator_skip_last() { - let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19, 20, 30]; - - assert_eq!(xs.iter().skip(0).last(), Some(&30)); - assert_eq!(xs.iter().skip(1).last(), Some(&30)); - assert_eq!(xs.iter().skip(11).last(), Some(&30)); - assert_eq!(xs.iter().skip(12).last(), None); - assert_eq!(xs.iter().skip(13).last(), None); - - let mut it = xs.iter().skip(5); - assert_eq!(it.next(), Some(&13)); - assert_eq!(it.last(), Some(&30)); -} - -#[test] -fn test_iterator_skip_fold() { - let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19, 20, 30]; - let ys = [13, 15, 16, 17, 19, 20, 30]; - - let it = xs.iter().skip(5); - let i = it.fold(0, |i, &x| { - assert_eq!(x, ys[i]); - i + 1 - }); - assert_eq!(i, ys.len()); - - let mut it = xs.iter().skip(5); - assert_eq!(it.next(), Some(&ys[0])); // process skips before folding - let i = it.fold(1, |i, &x| { - assert_eq!(x, ys[i]); - i + 1 - }); - assert_eq!(i, ys.len()); - - let it = xs.iter().skip(5); - let i = it.rfold(ys.len(), |i, &x| { - let i = i - 1; - assert_eq!(x, ys[i]); - i - }); - assert_eq!(i, 0); - - let mut it = xs.iter().skip(5); - assert_eq!(it.next(), Some(&ys[0])); // process skips before folding - let i = it.rfold(ys.len(), |i, &x| { - let i = i - 1; - assert_eq!(x, ys[i]); - i - }); - assert_eq!(i, 1); -} - -#[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_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_iterator_scan() { - // test the type inference - fn add(old: &mut isize, new: &usize) -> Option { - *old += *new as isize; - Some(*old as f64) - } - let xs = [0, 1, 2, 3, 4]; - let ys = [0f64, 1.0, 3.0, 6.0, 10.0]; - - let it = xs.iter().scan(0, add); - let mut i = 0; - for x in it { - assert_eq!(x, ys[i]); - i += 1; - } - assert_eq!(i, ys.len()); -} - -#[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_iterator_flatten() { - let xs = [0, 3, 6]; - let ys = [0, 1, 2, 3, 4, 5, 6, 7, 8]; - let it = xs.iter().map(|&x| (x..).step_by(1).take(3)).flatten(); - let mut i = 0; - for x in it { - assert_eq!(x, ys[i]); - i += 1; - } - assert_eq!(i, ys.len()); -} - -/// Tests `Flatten::fold` with items already picked off the front and back, -/// to make sure all parts of the `Flatten` are folded correctly. -#[test] -fn test_iterator_flatten_fold() { - let xs = [0, 3, 6]; - let ys = [1, 2, 3, 4, 5, 6, 7]; - let mut it = xs.iter().map(|&x| x..x + 3).flatten(); - 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().map(|&x| x..x + 3).flatten(); - 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_inspect() { - let xs = [1, 2, 3, 4]; - let mut n = 0; - - let ys = xs.iter().cloned().inspect(|_| n += 1).collect::>(); - - assert_eq!(n, xs.len()); - assert_eq!(&xs[..], &ys[..]); -} - -#[test] -fn test_inspect_fold() { - let xs = [1, 2, 3, 4]; - let mut n = 0; - { - let it = xs.iter().inspect(|_| n += 1); - let i = it.fold(0, |i, &x| { - assert_eq!(x, xs[i]); - i + 1 - }); - assert_eq!(i, xs.len()); - } - assert_eq!(n, xs.len()); - - let mut n = 0; - { - let it = xs.iter().inspect(|_| n += 1); - let i = it.rfold(xs.len(), |i, &x| { - assert_eq!(x, xs[i - 1]); - i - 1 - }); - assert_eq!(i, 0); - } - assert_eq!(n, xs.len()); -} - -#[test] -fn test_cycle() { - let cycle_len = 3; - let it = (0..).step_by(1).take(cycle_len).cycle(); - assert_eq!(it.size_hint(), (usize::MAX, None)); - for (i, x) in it.take(100).enumerate() { - assert_eq!(i % cycle_len, x); - } - - let mut it = (0..).step_by(1).take(0).cycle(); - assert_eq!(it.size_hint(), (0, Some(0))); - assert_eq!(it.next(), None); - - assert_eq!(empty::().cycle().fold(0, |acc, x| acc + x), 0); - - assert_eq!(once(1).cycle().skip(1).take(4).fold(0, |acc, x| acc + x), 4); - - assert_eq!((0..10).cycle().take(5).sum::(), 10); - assert_eq!((0..10).cycle().take(15).sum::(), 55); - assert_eq!((0..10).cycle().take(25).sum::(), 100); - - let mut iter = (0..10).cycle(); - iter.nth(14); - assert_eq!(iter.take(8).sum::(), 38); - - let mut iter = (0..10).cycle(); - iter.nth(9); - assert_eq!(iter.take(3).sum::(), 3); -} - -#[test] -fn test_iterator_nth() { - let v: &[_] = &[0, 1, 2, 3, 4]; - for i in 0..v.len() { - assert_eq!(v.iter().nth(i).unwrap(), &v[i]); - } - assert_eq!(v.iter().nth(v.len()), None); -} - -#[test] -fn test_iterator_nth_back() { - let v: &[_] = &[0, 1, 2, 3, 4]; - for i in 0..v.len() { - assert_eq!(v.iter().nth_back(i).unwrap(), &v[v.len() - 1 - i]); - } - assert_eq!(v.iter().nth_back(v.len()), None); -} - -#[test] -fn test_iterator_rev_nth_back() { - let v: &[_] = &[0, 1, 2, 3, 4]; - for i in 0..v.len() { - assert_eq!(v.iter().rev().nth_back(i).unwrap(), &v[i]); - } - assert_eq!(v.iter().rev().nth_back(v.len()), None); -} - -#[test] -fn test_iterator_rev_nth() { - let v: &[_] = &[0, 1, 2, 3, 4]; - for i in 0..v.len() { - assert_eq!(v.iter().rev().nth(i).unwrap(), &v[v.len() - 1 - i]); - } - assert_eq!(v.iter().rev().nth(v.len()), None); -} - -#[test] -fn test_iterator_advance_by() { - let v: &[_] = &[0, 1, 2, 3, 4]; - - for i in 0..v.len() { - let mut iter = v.iter(); - assert_eq!(iter.advance_by(i), Ok(())); - assert_eq!(iter.next().unwrap(), &v[i]); - assert_eq!(iter.advance_by(100), Err(v.len() - 1 - i)); - } - - assert_eq!(v.iter().advance_by(v.len()), Ok(())); - assert_eq!(v.iter().advance_by(100), Err(v.len())); -} - -#[test] -fn test_iterator_advance_back_by() { - let v: &[_] = &[0, 1, 2, 3, 4]; - - for i in 0..v.len() { - let mut iter = v.iter(); - assert_eq!(iter.advance_back_by(i), Ok(())); - assert_eq!(iter.next_back().unwrap(), &v[v.len() - 1 - i]); - assert_eq!(iter.advance_back_by(100), Err(v.len() - 1 - i)); - } - - assert_eq!(v.iter().advance_back_by(v.len()), Ok(())); - assert_eq!(v.iter().advance_back_by(100), Err(v.len())); -} - -#[test] -fn test_iterator_rev_advance_by() { - let v: &[_] = &[0, 1, 2, 3, 4]; - - for i in 0..v.len() { - let mut iter = v.iter().rev(); - assert_eq!(iter.advance_by(i), Ok(())); - assert_eq!(iter.next().unwrap(), &v[v.len() - 1 - i]); - assert_eq!(iter.advance_by(100), Err(v.len() - 1 - i)); - } - - assert_eq!(v.iter().rev().advance_by(v.len()), Ok(())); - assert_eq!(v.iter().rev().advance_by(100), Err(v.len())); -} - -#[test] -fn test_iterator_rev_advance_back_by() { - let v: &[_] = &[0, 1, 2, 3, 4]; - - for i in 0..v.len() { - let mut iter = v.iter().rev(); - assert_eq!(iter.advance_back_by(i), Ok(())); - assert_eq!(iter.next_back().unwrap(), &v[i]); - assert_eq!(iter.advance_back_by(100), Err(v.len() - 1 - i)); - } - - assert_eq!(v.iter().rev().advance_back_by(v.len()), Ok(())); - assert_eq!(v.iter().rev().advance_back_by(100), Err(v.len())); -} - -#[test] -fn test_iterator_last() { - let v: &[_] = &[0, 1, 2, 3, 4]; - assert_eq!(v.iter().last().unwrap(), &4); - assert_eq!(v[..1].iter().last().unwrap(), &0); -} - -#[test] -fn test_iterator_len() { - let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; - assert_eq!(v[..4].iter().count(), 4); - assert_eq!(v[..10].iter().count(), 10); - assert_eq!(v[..0].iter().count(), 0); -} - -#[test] -fn test_iterator_sum() { - let v: &[i32] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; - assert_eq!(v[..4].iter().cloned().sum::(), 6); - assert_eq!(v.iter().cloned().sum::(), 55); - assert_eq!(v[..0].iter().cloned().sum::(), 0); -} - -#[test] -fn test_iterator_sum_result() { - let v: &[Result] = &[Ok(1), Ok(2), Ok(3), Ok(4)]; - assert_eq!(v.iter().cloned().sum::>(), Ok(10)); - let v: &[Result] = &[Ok(1), Err(()), Ok(3), Ok(4)]; - assert_eq!(v.iter().cloned().sum::>(), Err(())); - - #[derive(PartialEq, Debug)] - struct S(Result); - - impl Sum> for S { - fn sum>>(mut iter: I) -> Self { - // takes the sum by repeatedly calling `next` on `iter`, - // thus testing that repeated calls to `ResultShunt::try_fold` - // produce the expected results - Self(iter.by_ref().sum()) - } - } - - let v: &[Result] = &[Ok(1), Ok(2), Ok(3), Ok(4)]; - assert_eq!(v.iter().cloned().sum::(), S(Ok(10))); - let v: &[Result] = &[Ok(1), Err(()), Ok(3), Ok(4)]; - assert_eq!(v.iter().cloned().sum::(), S(Err(()))); -} - -#[test] -fn test_iterator_sum_option() { - let v: &[Option] = &[Some(1), Some(2), Some(3), Some(4)]; - assert_eq!(v.iter().cloned().sum::>(), Some(10)); - let v: &[Option] = &[Some(1), None, Some(3), Some(4)]; - assert_eq!(v.iter().cloned().sum::>(), None); -} - -#[test] -fn test_iterator_product() { - let v: &[i32] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; - assert_eq!(v[..4].iter().cloned().product::(), 0); - assert_eq!(v[1..5].iter().cloned().product::(), 24); - assert_eq!(v[..0].iter().cloned().product::(), 1); -} - -#[test] -fn test_iterator_product_result() { - let v: &[Result] = &[Ok(1), Ok(2), Ok(3), Ok(4)]; - assert_eq!(v.iter().cloned().product::>(), Ok(24)); - let v: &[Result] = &[Ok(1), Err(()), Ok(3), Ok(4)]; - assert_eq!(v.iter().cloned().product::>(), Err(())); -} - -/// A wrapper struct that implements `Eq` and `Ord` based on the wrapped -/// integer modulo 3. Used to test that `Iterator::max` and `Iterator::min` -/// return the correct element if some of them are equal. -#[derive(Debug)] -struct Mod3(i32); - -impl PartialEq for Mod3 { - fn eq(&self, other: &Self) -> bool { - self.0 % 3 == other.0 % 3 - } -} - -impl Eq for Mod3 {} - -impl PartialOrd for Mod3 { - fn partial_cmp(&self, other: &Self) -> Option { - Some(self.cmp(other)) - } -} - -impl Ord for Mod3 { - fn cmp(&self, other: &Self) -> core::cmp::Ordering { - (self.0 % 3).cmp(&(other.0 % 3)) - } -} - -#[test] -fn test_iterator_product_option() { - let v: &[Option] = &[Some(1), Some(2), Some(3), Some(4)]; - assert_eq!(v.iter().cloned().product::>(), Some(24)); - let v: &[Option] = &[Some(1), None, Some(3), Some(4)]; - assert_eq!(v.iter().cloned().product::>(), None); -} - -#[test] -fn test_iterator_max() { - let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; - assert_eq!(v[..4].iter().cloned().max(), Some(3)); - assert_eq!(v.iter().cloned().max(), Some(10)); - assert_eq!(v[..0].iter().cloned().max(), None); - assert_eq!(v.iter().cloned().map(Mod3).max().map(|x| x.0), Some(8)); -} - -#[test] -fn test_iterator_min() { - let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; - assert_eq!(v[..4].iter().cloned().min(), Some(0)); - assert_eq!(v.iter().cloned().min(), Some(0)); - assert_eq!(v[..0].iter().cloned().min(), None); - assert_eq!(v.iter().cloned().map(Mod3).min().map(|x| x.0), Some(0)); -} - -#[test] -fn test_iterator_size_hint() { - let c = (0..).step_by(1); - let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]; - let v2 = &[10, 11, 12]; - let vi = v.iter(); - - assert_eq!((0..).size_hint(), (usize::MAX, None)); - assert_eq!(c.size_hint(), (usize::MAX, None)); - assert_eq!(vi.clone().size_hint(), (10, Some(10))); - - assert_eq!(c.clone().take(5).size_hint(), (5, Some(5))); - assert_eq!(c.clone().skip(5).size_hint().1, None); - assert_eq!(c.clone().take_while(|_| false).size_hint(), (0, None)); - assert_eq!(c.clone().map_while(|_| None::<()>).size_hint(), (0, None)); - assert_eq!(c.clone().skip_while(|_| false).size_hint(), (0, None)); - assert_eq!(c.clone().enumerate().size_hint(), (usize::MAX, None)); - assert_eq!(c.clone().chain(vi.clone().cloned()).size_hint(), (usize::MAX, None)); - assert_eq!(c.clone().zip(vi.clone()).size_hint(), (10, Some(10))); - assert_eq!(c.clone().scan(0, |_, _| Some(0)).size_hint(), (0, None)); - assert_eq!(c.clone().filter(|_| false).size_hint(), (0, None)); - assert_eq!(c.clone().map(|_| 0).size_hint(), (usize::MAX, None)); - assert_eq!(c.filter_map(|_| Some(0)).size_hint(), (0, None)); - - assert_eq!(vi.clone().take(5).size_hint(), (5, Some(5))); - assert_eq!(vi.clone().take(12).size_hint(), (10, Some(10))); - assert_eq!(vi.clone().skip(3).size_hint(), (7, Some(7))); - assert_eq!(vi.clone().skip(12).size_hint(), (0, Some(0))); - assert_eq!(vi.clone().take_while(|_| false).size_hint(), (0, Some(10))); - assert_eq!(vi.clone().map_while(|_| None::<()>).size_hint(), (0, Some(10))); - assert_eq!(vi.clone().skip_while(|_| false).size_hint(), (0, Some(10))); - assert_eq!(vi.clone().enumerate().size_hint(), (10, Some(10))); - assert_eq!(vi.clone().chain(v2).size_hint(), (13, Some(13))); - assert_eq!(vi.clone().zip(v2).size_hint(), (3, Some(3))); - assert_eq!(vi.clone().scan(0, |_, _| Some(0)).size_hint(), (0, Some(10))); - assert_eq!(vi.clone().filter(|_| false).size_hint(), (0, Some(10))); - assert_eq!(vi.clone().map(|&i| i + 1).size_hint(), (10, Some(10))); - assert_eq!(vi.filter_map(|_| Some(0)).size_hint(), (0, Some(10))); -} - -#[test] -fn test_collect() { - let a = vec![1, 2, 3, 4, 5]; - let b: Vec = a.iter().cloned().collect(); - assert!(a == b); -} - -#[test] -fn test_all() { - let v: Box<[isize]> = Box::new([1, 2, 3, 4, 5]); - assert!(v.iter().all(|&x| x < 10)); - assert!(!v.iter().all(|&x| x % 2 == 0)); - assert!(!v.iter().all(|&x| x > 100)); - assert!(v[..0].iter().all(|_| panic!())); -} - -#[test] -fn test_any() { - let v: Box<[isize]> = Box::new([1, 2, 3, 4, 5]); - assert!(v.iter().any(|&x| x < 10)); - assert!(v.iter().any(|&x| x % 2 == 0)); - assert!(!v.iter().any(|&x| x > 100)); - assert!(!v[..0].iter().any(|_| panic!())); -} - -#[test] -fn test_at_least() { - let vec = vec![1, 2, 3, 4, 5]; - assert!(vec.iter().at_least(0, |i| i % 2 == 0)); - assert!(vec.iter().at_least(1, |i| i % 2 == 0)); - assert!(vec.iter().at_least(2, |i| i % 2 == 0)); - assert!(!vec.iter().at_least(3, |i| i % 2 == 0)); - assert!(vec.iter().at_least(0, |&i| i > 100)); - assert!(vec.iter().at_least(5, |&i| i < 100)); - - assert!(!&vec[..0].iter().at_least(0, |_| panic!())); -} - -#[test] -fn test_at_most() { - let vec = vec![1, 2, 3, 4, 5]; - assert!(vec.iter().at_most(0, |&i| i > 100)); - assert!(vec.iter().at_most(5, |&i| i < 100)); - assert!(vec.iter().at_most(3, |i| i % 2 == 0)); - assert!(vec.iter().at_most(2, |i| i % 2 == 0)); - assert!(!vec.iter().at_most(1, |i| i % 2 == 0)); - assert!(!vec.iter().at_most(0, |i| i % 2 == 0)); - - assert!(&vec[..0].iter().at_most(0, |_| panic!())); -} - -#[test] -fn test_find() { - let v: &[isize] = &[1, 3, 9, 27, 103, 14, 11]; - assert_eq!(*v.iter().find(|&&x| x & 1 == 0).unwrap(), 14); - assert_eq!(*v.iter().find(|&&x| x % 3 == 0).unwrap(), 3); - assert!(v.iter().find(|&&x| x % 12 == 0).is_none()); -} - -#[test] -fn test_find_map() { - let xs: &[isize] = &[]; - assert_eq!(xs.iter().find_map(half_if_even), None); - let xs: &[isize] = &[3, 5]; - assert_eq!(xs.iter().find_map(half_if_even), None); - let xs: &[isize] = &[4, 5]; - assert_eq!(xs.iter().find_map(half_if_even), Some(2)); - let xs: &[isize] = &[3, 6]; - assert_eq!(xs.iter().find_map(half_if_even), Some(3)); - - let xs: &[isize] = &[1, 2, 3, 4, 5, 6, 7]; - let mut iter = xs.iter(); - assert_eq!(iter.find_map(half_if_even), Some(1)); - assert_eq!(iter.find_map(half_if_even), Some(2)); - assert_eq!(iter.find_map(half_if_even), Some(3)); - assert_eq!(iter.next(), Some(&7)); - - fn half_if_even(x: &isize) -> Option { - if x % 2 == 0 { Some(x / 2) } else { None } - } -} - -#[test] -fn test_try_find() { - let xs: &[isize] = &[]; - assert_eq!(xs.iter().try_find(testfn), Ok(None)); - let xs: &[isize] = &[1, 2, 3, 4]; - assert_eq!(xs.iter().try_find(testfn), Ok(Some(&2))); - let xs: &[isize] = &[1, 3, 4]; - assert_eq!(xs.iter().try_find(testfn), Err(())); - - let xs: &[isize] = &[1, 2, 3, 4, 5, 6, 7]; - let mut iter = xs.iter(); - assert_eq!(iter.try_find(testfn), Ok(Some(&2))); - assert_eq!(iter.try_find(testfn), Err(())); - assert_eq!(iter.next(), Some(&5)); - - fn testfn(x: &&isize) -> Result { - if **x == 2 { - return Ok(true); - } - if **x == 4 { - return Err(()); - } - Ok(false) - } -} - -#[test] -fn test_try_find_api_usability() -> Result<(), Box> { - let a = ["1", "2"]; - - let is_my_num = |s: &str, search: i32| -> Result { - Ok(s.parse::()? == search) - }; - - let val = a.iter().try_find(|&&s| is_my_num(s, 2))?; - assert_eq!(val, Some(&"2")); - - Ok(()) -} - -#[test] -fn test_position() { - let v = &[1, 3, 9, 27, 103, 14, 11]; - assert_eq!(v.iter().position(|x| *x & 1 == 0).unwrap(), 5); - assert_eq!(v.iter().position(|x| *x % 3 == 0).unwrap(), 1); - assert!(v.iter().position(|x| *x % 12 == 0).is_none()); -} - -#[test] -fn test_count() { - let xs = &[1, 2, 2, 1, 5, 9, 0, 2]; - assert_eq!(xs.iter().filter(|x| **x == 2).count(), 3); - assert_eq!(xs.iter().filter(|x| **x == 5).count(), 1); - assert_eq!(xs.iter().filter(|x| **x == 95).count(), 0); -} - -#[test] -fn test_max_by_key() { - let xs: &[isize] = &[-3, 0, 1, 5, -10]; - assert_eq!(*xs.iter().max_by_key(|x| x.abs()).unwrap(), -10); -} - -#[test] -fn test_max_by() { - let xs: &[isize] = &[-3, 0, 1, 5, -10]; - assert_eq!(*xs.iter().max_by(|x, y| x.abs().cmp(&y.abs())).unwrap(), -10); -} - -#[test] -fn test_min_by_key() { - let xs: &[isize] = &[-3, 0, 1, 5, -10]; - assert_eq!(*xs.iter().min_by_key(|x| x.abs()).unwrap(), 0); -} - -#[test] -fn test_min_by() { - let xs: &[isize] = &[-3, 0, 1, 5, -10]; - assert_eq!(*xs.iter().min_by(|x, y| x.abs().cmp(&y.abs())).unwrap(), 0); -} - -#[test] -fn test_by_ref() { - let mut xs = 0..10; - // sum the first five values - let partial_sum = xs.by_ref().take(5).fold(0, |a, b| a + b); - assert_eq!(partial_sum, 10); - assert_eq!(xs.next(), Some(5)); -} - -#[test] -fn test_rev() { - let xs = [2, 4, 6, 8, 10, 12, 14, 16]; - let mut it = xs.iter(); - it.next(); - it.next(); - assert!(it.rev().cloned().collect::>() == vec![16, 14, 12, 10, 8, 6]); -} - -#[test] -fn test_copied() { - let xs = [2, 4, 6, 8]; - - let mut it = xs.iter().copied(); - assert_eq!(it.len(), 4); - assert_eq!(it.next(), Some(2)); - assert_eq!(it.len(), 3); - assert_eq!(it.next(), Some(4)); - assert_eq!(it.len(), 2); - assert_eq!(it.next_back(), Some(8)); - assert_eq!(it.len(), 1); - assert_eq!(it.next_back(), Some(6)); - assert_eq!(it.len(), 0); - assert_eq!(it.next_back(), None); -} - -#[test] -fn test_cloned() { - let xs = [2, 4, 6, 8]; - - let mut it = xs.iter().cloned(); - assert_eq!(it.len(), 4); - assert_eq!(it.next(), Some(2)); - assert_eq!(it.len(), 3); - assert_eq!(it.next(), Some(4)); - assert_eq!(it.len(), 2); - assert_eq!(it.next_back(), Some(8)); - assert_eq!(it.len(), 1); - assert_eq!(it.next_back(), Some(6)); - assert_eq!(it.len(), 0); - assert_eq!(it.next_back(), None); -} - -#[test] -fn test_cloned_side_effects() { - let mut count = 0; - { - let iter = [1, 2, 3] - .iter() - .map(|x| { - count += 1; - x - }) - .cloned() - .zip(&[1]); - for _ in iter {} - } - assert_eq!(count, 2); -} - -#[test] -fn test_double_ended_map() { - let xs = [1, 2, 3, 4, 5, 6]; - let mut it = xs.iter().map(|&x| x * -1); - assert_eq!(it.next(), Some(-1)); - assert_eq!(it.next(), Some(-2)); - assert_eq!(it.next_back(), Some(-6)); - assert_eq!(it.next_back(), Some(-5)); - assert_eq!(it.next(), Some(-3)); - assert_eq!(it.next_back(), Some(-4)); - assert_eq!(it.next(), None); -} - -#[test] -fn test_double_ended_enumerate() { - let xs = [1, 2, 3, 4, 5, 6]; - let mut it = xs.iter().cloned().enumerate(); - assert_eq!(it.next(), Some((0, 1))); - assert_eq!(it.next(), Some((1, 2))); - assert_eq!(it.next_back(), Some((5, 6))); - assert_eq!(it.next_back(), Some((4, 5))); - assert_eq!(it.next_back(), Some((3, 4))); - assert_eq!(it.next_back(), Some((2, 3))); - assert_eq!(it.next(), None); -} - -#[test] -fn test_double_ended_zip() { - let xs = [1, 2, 3, 4, 5, 6]; - let ys = [1, 2, 3, 7]; - let a = xs.iter().cloned(); - let b = ys.iter().cloned(); - let mut it = a.zip(b); - assert_eq!(it.next(), Some((1, 1))); - assert_eq!(it.next(), Some((2, 2))); - assert_eq!(it.next_back(), Some((4, 7))); - assert_eq!(it.next_back(), Some((3, 3))); - assert_eq!(it.next(), None); -} - -#[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); -} - -#[test] -fn test_double_ended_filter_map() { - let xs = [1, 2, 3, 4, 5, 6]; - let mut it = xs.iter().filter_map(|&x| if x & 1 == 0 { Some(x * 2) } else { None }); - assert_eq!(it.next_back().unwrap(), 12); - assert_eq!(it.next_back().unwrap(), 8); - assert_eq!(it.next().unwrap(), 4); - assert_eq!(it.next_back(), None); -} - -#[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 { - if self.0 { - Some(99) - } else { - self.0 = true; - None - } - } - } - - impl DoubleEndedIterator for CrazyIterator { - fn next_back(&mut self) -> Option { - self.next() - } - } - - assert_eq!(CrazyIterator::new().chain(0..10).rev().last(), Some(0)); - assert!((0..10).chain(CrazyIterator::new()).rev().any(|i| i == 0)); -} - -#[test] -fn test_rposition() { - fn f(xy: &(isize, char)) -> bool { - let (_x, y) = *xy; - y == 'b' - } - fn g(xy: &(isize, char)) -> bool { - let (_x, y) = *xy; - y == 'd' - } - let v = [(0, 'a'), (1, 'b'), (2, 'c'), (3, 'b')]; - - assert_eq!(v.iter().rposition(f), Some(3)); - assert!(v.iter().rposition(g).is_none()); -} - -#[test] -fn test_rev_rposition() { - let v = [0, 0, 1, 1]; - assert_eq!(v.iter().rev().rposition(|&x| x == 1), Some(1)); -} - -#[test] -#[should_panic] -fn test_rposition_panic() { - let v: [(Box<_>, Box<_>); 4] = [(box 0, box 0), (box 0, box 0), (box 0, box 0), (box 0, box 0)]; - let mut i = 0; - v.iter().rposition(|_elt| { - if i == 2 { - panic!() - } - i += 1; - false - }); -} - -#[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); -} - -#[test] -fn test_double_ended_flatten() { - let u = [0, 1]; - let v = [5, 6, 7, 8]; - let mut it = u.iter().map(|x| &v[*x..v.len()]).flatten(); - 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); -} - -#[test] -fn test_double_ended_range() { - assert_eq!((11..14).rev().collect::>(), [13, 12, 11]); - for _ in (10..0).rev() { - panic!("unreachable"); - } - - assert_eq!((11..14).rev().collect::>(), [13, 12, 11]); - for _ in (10..0).rev() { - panic!("unreachable"); - } -} - -#[test] -fn test_range() { - assert_eq!((0..5).collect::>(), [0, 1, 2, 3, 4]); - assert_eq!((-10..-1).collect::>(), [-10, -9, -8, -7, -6, -5, -4, -3, -2]); - assert_eq!((0..5).rev().collect::>(), [4, 3, 2, 1, 0]); - assert_eq!((200..-5).count(), 0); - assert_eq!((200..-5).rev().count(), 0); - assert_eq!((200..200).count(), 0); - assert_eq!((200..200).rev().count(), 0); - - assert_eq!((0..100).size_hint(), (100, Some(100))); - // this test is only meaningful when sizeof usize < sizeof u64 - assert_eq!((usize::MAX - 1..usize::MAX).size_hint(), (1, Some(1))); - assert_eq!((-10..-1).size_hint(), (9, Some(9))); - assert_eq!((-1..-10).size_hint(), (0, Some(0))); - - assert_eq!((-70..58).size_hint(), (128, Some(128))); - assert_eq!((-128..127).size_hint(), (255, Some(255))); - assert_eq!( - (-2..isize::MAX).size_hint(), - (isize::MAX as usize + 2, Some(isize::MAX as usize + 2)) - ); -} - -#[test] -fn test_char_range() { - use std::char; - // Miri is too slow - let from = if cfg!(miri) { char::from_u32(0xD800 - 10).unwrap() } else { '\0' }; - let to = if cfg!(miri) { char::from_u32(0xDFFF + 10).unwrap() } else { char::MAX }; - assert!((from..=to).eq((from as u32..=to as u32).filter_map(char::from_u32))); - assert!((from..=to).rev().eq((from as u32..=to as u32).filter_map(char::from_u32).rev())); - - assert_eq!(('\u{D7FF}'..='\u{E000}').count(), 2); - assert_eq!(('\u{D7FF}'..='\u{E000}').size_hint(), (2, Some(2))); - assert_eq!(('\u{D7FF}'..'\u{E000}').count(), 1); - assert_eq!(('\u{D7FF}'..'\u{E000}').size_hint(), (1, Some(1))); -} - -#[test] -fn test_range_exhaustion() { - let mut r = 10..10; - assert!(r.is_empty()); - assert_eq!(r.next(), None); - assert_eq!(r.next_back(), None); - assert_eq!(r, 10..10); - - let mut r = 10..12; - assert_eq!(r.next(), Some(10)); - assert_eq!(r.next(), Some(11)); - assert!(r.is_empty()); - assert_eq!(r, 12..12); - assert_eq!(r.next(), None); - - let mut r = 10..12; - assert_eq!(r.next_back(), Some(11)); - assert_eq!(r.next_back(), Some(10)); - assert!(r.is_empty()); - assert_eq!(r, 10..10); - assert_eq!(r.next_back(), None); - - let mut r = 100..10; - assert!(r.is_empty()); - assert_eq!(r.next(), None); - assert_eq!(r.next_back(), None); - assert_eq!(r, 100..10); -} - -#[test] -fn test_range_inclusive_exhaustion() { - let mut r = 10..=10; - assert_eq!(r.next(), Some(10)); - assert!(r.is_empty()); - assert_eq!(r.next(), None); - assert_eq!(r.next(), None); - - assert_eq!(*r.start(), 10); - assert_eq!(*r.end(), 10); - assert_ne!(r, 10..=10); - - let mut r = 10..=10; - assert_eq!(r.next_back(), Some(10)); - assert!(r.is_empty()); - assert_eq!(r.next_back(), None); - - assert_eq!(*r.start(), 10); - assert_eq!(*r.end(), 10); - assert_ne!(r, 10..=10); - - let mut r = 10..=12; - assert_eq!(r.next(), Some(10)); - assert_eq!(r.next(), Some(11)); - assert_eq!(r.next(), Some(12)); - assert!(r.is_empty()); - assert_eq!(r.next(), None); - - let mut r = 10..=12; - assert_eq!(r.next_back(), Some(12)); - assert_eq!(r.next_back(), Some(11)); - assert_eq!(r.next_back(), Some(10)); - assert!(r.is_empty()); - assert_eq!(r.next_back(), None); - - let mut r = 10..=12; - assert_eq!(r.nth(2), Some(12)); - assert!(r.is_empty()); - assert_eq!(r.next(), None); - - let mut r = 10..=12; - assert_eq!(r.nth(5), None); - assert!(r.is_empty()); - assert_eq!(r.next(), None); - - let mut r = 100..=10; - assert_eq!(r.next(), None); - assert!(r.is_empty()); - assert_eq!(r.next(), None); - assert_eq!(r.next(), None); - assert_eq!(r, 100..=10); - - let mut r = 100..=10; - assert_eq!(r.next_back(), None); - assert!(r.is_empty()); - assert_eq!(r.next_back(), None); - assert_eq!(r.next_back(), None); - assert_eq!(r, 100..=10); -} - -#[test] -fn test_range_nth() { - assert_eq!((10..15).nth(0), Some(10)); - assert_eq!((10..15).nth(1), Some(11)); - assert_eq!((10..15).nth(4), Some(14)); - assert_eq!((10..15).nth(5), None); - - let mut r = 10..20; - assert_eq!(r.nth(2), Some(12)); - assert_eq!(r, 13..20); - assert_eq!(r.nth(2), Some(15)); - assert_eq!(r, 16..20); - assert_eq!(r.nth(10), None); - assert_eq!(r, 20..20); -} - -#[test] -fn test_range_nth_back() { - assert_eq!((10..15).nth_back(0), Some(14)); - assert_eq!((10..15).nth_back(1), Some(13)); - assert_eq!((10..15).nth_back(4), Some(10)); - assert_eq!((10..15).nth_back(5), None); - assert_eq!((-120..80_i8).nth_back(199), Some(-120)); - - let mut r = 10..20; - assert_eq!(r.nth_back(2), Some(17)); - assert_eq!(r, 10..17); - assert_eq!(r.nth_back(2), Some(14)); - assert_eq!(r, 10..14); - assert_eq!(r.nth_back(10), None); - assert_eq!(r, 10..10); -} - -#[test] -fn test_range_from_nth() { - assert_eq!((10..).nth(0), Some(10)); - assert_eq!((10..).nth(1), Some(11)); - assert_eq!((10..).nth(4), Some(14)); - - let mut r = 10..; - assert_eq!(r.nth(2), Some(12)); - assert_eq!(r, 13..); - assert_eq!(r.nth(2), Some(15)); - assert_eq!(r, 16..); - assert_eq!(r.nth(10), Some(26)); - assert_eq!(r, 27..); - - assert_eq!((0..).size_hint(), (usize::MAX, None)); -} - -fn is_trusted_len(_: I) {} - -#[test] -fn test_range_from_take() { - let mut it = (0..).take(3); - assert_eq!(it.next(), Some(0)); - assert_eq!(it.next(), Some(1)); - assert_eq!(it.next(), Some(2)); - assert_eq!(it.next(), None); - is_trusted_len((0..).take(3)); - assert_eq!((0..).take(3).size_hint(), (3, Some(3))); - assert_eq!((0..).take(0).size_hint(), (0, Some(0))); - assert_eq!((0..).take(usize::MAX).size_hint(), (usize::MAX, Some(usize::MAX))); -} - -#[test] -fn test_range_from_take_collect() { - let v: Vec<_> = (0..).take(3).collect(); - assert_eq!(v, vec![0, 1, 2]); -} - -#[test] -fn test_range_inclusive_nth() { - assert_eq!((10..=15).nth(0), Some(10)); - assert_eq!((10..=15).nth(1), Some(11)); - assert_eq!((10..=15).nth(5), Some(15)); - assert_eq!((10..=15).nth(6), None); - - let mut exhausted_via_next = 10_u8..=20; - while exhausted_via_next.next().is_some() {} - - let mut r = 10_u8..=20; - assert_eq!(r.nth(2), Some(12)); - assert_eq!(r, 13..=20); - assert_eq!(r.nth(2), Some(15)); - assert_eq!(r, 16..=20); - assert_eq!(r.is_empty(), false); - assert_eq!(ExactSizeIterator::is_empty(&r), false); - assert_eq!(r.nth(10), None); - assert_eq!(r.is_empty(), true); - assert_eq!(r, exhausted_via_next); - assert_eq!(ExactSizeIterator::is_empty(&r), true); -} - -#[test] -fn test_range_inclusive_nth_back() { - assert_eq!((10..=15).nth_back(0), Some(15)); - assert_eq!((10..=15).nth_back(1), Some(14)); - assert_eq!((10..=15).nth_back(5), Some(10)); - assert_eq!((10..=15).nth_back(6), None); - assert_eq!((-120..=80_i8).nth_back(200), Some(-120)); - - let mut exhausted_via_next_back = 10_u8..=20; - while exhausted_via_next_back.next_back().is_some() {} - - let mut r = 10_u8..=20; - assert_eq!(r.nth_back(2), Some(18)); - assert_eq!(r, 10..=17); - assert_eq!(r.nth_back(2), Some(15)); - assert_eq!(r, 10..=14); - assert_eq!(r.is_empty(), false); - assert_eq!(ExactSizeIterator::is_empty(&r), false); - assert_eq!(r.nth_back(10), None); - assert_eq!(r.is_empty(), true); - assert_eq!(r, exhausted_via_next_back); - assert_eq!(ExactSizeIterator::is_empty(&r), true); -} - -#[test] -fn test_range_len() { - assert_eq!((0..10_u8).len(), 10); - assert_eq!((9..10_u8).len(), 1); - assert_eq!((10..10_u8).len(), 0); - assert_eq!((11..10_u8).len(), 0); - assert_eq!((100..10_u8).len(), 0); -} - -#[test] -fn test_range_inclusive_len() { - assert_eq!((0..=10_u8).len(), 11); - assert_eq!((9..=10_u8).len(), 2); - assert_eq!((10..=10_u8).len(), 1); - assert_eq!((11..=10_u8).len(), 0); - assert_eq!((100..=10_u8).len(), 0); -} - -#[test] -fn test_range_step() { - #![allow(deprecated)] - - assert_eq!((0..20).step_by(5).collect::>(), [0, 5, 10, 15]); - assert_eq!((1..21).rev().step_by(5).collect::>(), [20, 15, 10, 5]); - assert_eq!((1..21).rev().step_by(6).collect::>(), [20, 14, 8, 2]); - assert_eq!((200..255).step_by(50).collect::>(), [200, 250]); - assert_eq!((200..-5).step_by(1).collect::>(), []); - assert_eq!((200..200).step_by(1).collect::>(), []); - - assert_eq!((0..20).step_by(1).size_hint(), (20, Some(20))); - assert_eq!((0..20).step_by(21).size_hint(), (1, Some(1))); - assert_eq!((0..20).step_by(5).size_hint(), (4, Some(4))); - assert_eq!((1..21).rev().step_by(5).size_hint(), (4, Some(4))); - assert_eq!((1..21).rev().step_by(6).size_hint(), (4, Some(4))); - assert_eq!((20..-5).step_by(1).size_hint(), (0, Some(0))); - assert_eq!((20..20).step_by(1).size_hint(), (0, Some(0))); - assert_eq!((i8::MIN..i8::MAX).step_by(-(i8::MIN as i32) as usize).size_hint(), (2, Some(2))); - assert_eq!((i16::MIN..i16::MAX).step_by(i16::MAX as usize).size_hint(), (3, Some(3))); - assert_eq!((isize::MIN..isize::MAX).step_by(1).size_hint(), (usize::MAX, Some(usize::MAX))); -} - -#[test] -fn test_step_by_skip() { - assert_eq!((0..640).step_by(128).skip(1).collect::>(), [128, 256, 384, 512]); - assert_eq!((0..=50).step_by(10).nth(3), Some(30)); - assert_eq!((200..=255u8).step_by(10).nth(3), Some(230)); -} - -#[test] -fn test_range_inclusive_step() { - assert_eq!((0..=50).step_by(10).collect::>(), [0, 10, 20, 30, 40, 50]); - assert_eq!((0..=5).step_by(1).collect::>(), [0, 1, 2, 3, 4, 5]); - assert_eq!((200..=255u8).step_by(10).collect::>(), [200, 210, 220, 230, 240, 250]); - assert_eq!((250..=255u8).step_by(1).collect::>(), [250, 251, 252, 253, 254, 255]); -} - -#[test] -fn test_range_last_max() { - assert_eq!((0..20).last(), Some(19)); - assert_eq!((-20..0).last(), Some(-1)); - assert_eq!((5..5).last(), None); - - assert_eq!((0..20).max(), Some(19)); - assert_eq!((-20..0).max(), Some(-1)); - assert_eq!((5..5).max(), None); -} - -#[test] -fn test_range_inclusive_last_max() { - assert_eq!((0..=20).last(), Some(20)); - assert_eq!((-20..=0).last(), Some(0)); - assert_eq!((5..=5).last(), Some(5)); - let mut r = 10..=10; - r.next(); - assert_eq!(r.last(), None); - - assert_eq!((0..=20).max(), Some(20)); - assert_eq!((-20..=0).max(), Some(0)); - assert_eq!((5..=5).max(), Some(5)); - let mut r = 10..=10; - r.next(); - assert_eq!(r.max(), None); -} - -#[test] -fn test_range_min() { - assert_eq!((0..20).min(), Some(0)); - assert_eq!((-20..0).min(), Some(-20)); - assert_eq!((5..5).min(), None); -} - -#[test] -fn test_range_inclusive_min() { - assert_eq!((0..=20).min(), Some(0)); - assert_eq!((-20..=0).min(), Some(-20)); - assert_eq!((5..=5).min(), Some(5)); - let mut r = 10..=10; - r.next(); - assert_eq!(r.min(), None); -} - -#[test] -fn test_range_inclusive_folds() { - assert_eq!((1..=10).sum::(), 55); - assert_eq!((1..=10).rev().sum::(), 55); - - let mut it = 44..=50; - assert_eq!(it.try_fold(0, i8::checked_add), None); - assert_eq!(it, 47..=50); - assert_eq!(it.try_fold(0, i8::checked_add), None); - assert_eq!(it, 50..=50); - assert_eq!(it.try_fold(0, i8::checked_add), Some(50)); - assert!(it.is_empty()); - assert_eq!(it.try_fold(0, i8::checked_add), Some(0)); - assert!(it.is_empty()); - - let mut it = 40..=47; - assert_eq!(it.try_rfold(0, i8::checked_add), None); - assert_eq!(it, 40..=44); - assert_eq!(it.try_rfold(0, i8::checked_add), None); - assert_eq!(it, 40..=41); - assert_eq!(it.try_rfold(0, i8::checked_add), Some(81)); - assert!(it.is_empty()); - assert_eq!(it.try_rfold(0, i8::checked_add), Some(0)); - assert!(it.is_empty()); - - let mut it = 10..=20; - assert_eq!(it.try_fold(0, |a, b| Some(a + b)), Some(165)); - assert!(it.is_empty()); - assert_eq!(it.try_fold(0, |a, b| Some(a + b)), Some(0)); - assert!(it.is_empty()); - - let mut it = 10..=20; - assert_eq!(it.try_rfold(0, |a, b| Some(a + b)), Some(165)); - assert!(it.is_empty()); - assert_eq!(it.try_rfold(0, |a, b| Some(a + b)), Some(0)); - assert!(it.is_empty()); -} - -#[test] -fn test_range_size_hint() { - assert_eq!((0..0usize).size_hint(), (0, Some(0))); - assert_eq!((0..100usize).size_hint(), (100, Some(100))); - assert_eq!((0..usize::MAX).size_hint(), (usize::MAX, Some(usize::MAX))); - - let umax = u128::try_from(usize::MAX).unwrap(); - assert_eq!((0..0u128).size_hint(), (0, Some(0))); - assert_eq!((0..100u128).size_hint(), (100, Some(100))); - assert_eq!((0..umax).size_hint(), (usize::MAX, Some(usize::MAX))); - assert_eq!((0..umax + 1).size_hint(), (usize::MAX, None)); - - assert_eq!((0..0isize).size_hint(), (0, Some(0))); - assert_eq!((-100..100isize).size_hint(), (200, Some(200))); - assert_eq!((isize::MIN..isize::MAX).size_hint(), (usize::MAX, Some(usize::MAX))); - - let imin = i128::try_from(isize::MIN).unwrap(); - let imax = i128::try_from(isize::MAX).unwrap(); - assert_eq!((0..0i128).size_hint(), (0, Some(0))); - assert_eq!((-100..100i128).size_hint(), (200, Some(200))); - assert_eq!((imin..imax).size_hint(), (usize::MAX, Some(usize::MAX))); - assert_eq!((imin..imax + 1).size_hint(), (usize::MAX, None)); -} - -#[test] -fn test_range_inclusive_size_hint() { - assert_eq!((1..=0usize).size_hint(), (0, Some(0))); - assert_eq!((0..=0usize).size_hint(), (1, Some(1))); - assert_eq!((0..=100usize).size_hint(), (101, Some(101))); - assert_eq!((0..=usize::MAX - 1).size_hint(), (usize::MAX, Some(usize::MAX))); - assert_eq!((0..=usize::MAX).size_hint(), (usize::MAX, None)); - - let umax = u128::try_from(usize::MAX).unwrap(); - assert_eq!((1..=0u128).size_hint(), (0, Some(0))); - assert_eq!((0..=0u128).size_hint(), (1, Some(1))); - assert_eq!((0..=100u128).size_hint(), (101, Some(101))); - assert_eq!((0..=umax - 1).size_hint(), (usize::MAX, Some(usize::MAX))); - assert_eq!((0..=umax).size_hint(), (usize::MAX, None)); - assert_eq!((0..=umax + 1).size_hint(), (usize::MAX, None)); - - assert_eq!((0..=-1isize).size_hint(), (0, Some(0))); - assert_eq!((0..=0isize).size_hint(), (1, Some(1))); - assert_eq!((-100..=100isize).size_hint(), (201, Some(201))); - assert_eq!((isize::MIN..=isize::MAX - 1).size_hint(), (usize::MAX, Some(usize::MAX))); - assert_eq!((isize::MIN..=isize::MAX).size_hint(), (usize::MAX, None)); - - let imin = i128::try_from(isize::MIN).unwrap(); - let imax = i128::try_from(isize::MAX).unwrap(); - assert_eq!((0..=-1i128).size_hint(), (0, Some(0))); - assert_eq!((0..=0i128).size_hint(), (1, Some(1))); - assert_eq!((-100..=100i128).size_hint(), (201, Some(201))); - assert_eq!((imin..=imax - 1).size_hint(), (usize::MAX, Some(usize::MAX))); - assert_eq!((imin..=imax).size_hint(), (usize::MAX, None)); - assert_eq!((imin..=imax + 1).size_hint(), (usize::MAX, None)); -} - -#[test] -fn test_repeat() { - let mut it = repeat(42); - assert_eq!(it.next(), Some(42)); - assert_eq!(it.next(), Some(42)); - assert_eq!(it.next(), Some(42)); - assert_eq!(repeat(42).size_hint(), (usize::MAX, None)); -} - -#[test] -fn test_repeat_take() { - let mut it = repeat(42).take(3); - assert_eq!(it.next(), Some(42)); - assert_eq!(it.next(), Some(42)); - assert_eq!(it.next(), Some(42)); - assert_eq!(it.next(), None); - is_trusted_len(repeat(42).take(3)); - assert_eq!(repeat(42).take(3).size_hint(), (3, Some(3))); - assert_eq!(repeat(42).take(0).size_hint(), (0, Some(0))); - assert_eq!(repeat(42).take(usize::MAX).size_hint(), (usize::MAX, Some(usize::MAX))); -} - -#[test] -fn test_repeat_take_collect() { - let v: Vec<_> = repeat(42).take(3).collect(); - assert_eq!(v, vec![42, 42, 42]); -} - -#[test] -fn test_repeat_with() { - #[derive(PartialEq, Debug)] - struct NotClone(usize); - let mut it = repeat_with(|| NotClone(42)); - assert_eq!(it.next(), Some(NotClone(42))); - assert_eq!(it.next(), Some(NotClone(42))); - assert_eq!(it.next(), Some(NotClone(42))); - assert_eq!(repeat_with(|| NotClone(42)).size_hint(), (usize::MAX, None)); -} - -#[test] -fn test_repeat_with_take() { - let mut it = repeat_with(|| 42).take(3); - assert_eq!(it.next(), Some(42)); - assert_eq!(it.next(), Some(42)); - assert_eq!(it.next(), Some(42)); - assert_eq!(it.next(), None); - is_trusted_len(repeat_with(|| 42).take(3)); - assert_eq!(repeat_with(|| 42).take(3).size_hint(), (3, Some(3))); - assert_eq!(repeat_with(|| 42).take(0).size_hint(), (0, Some(0))); - assert_eq!(repeat_with(|| 42).take(usize::MAX).size_hint(), (usize::MAX, Some(usize::MAX))); -} - -#[test] -fn test_repeat_with_take_collect() { - let mut curr = 1; - let v: Vec<_> = repeat_with(|| { - let tmp = curr; - curr *= 2; - tmp - }) - .take(5) - .collect(); - assert_eq!(v, vec![1, 2, 4, 8, 16]); -} - -#[test] -fn test_successors() { - let mut powers_of_10 = successors(Some(1_u16), |n| n.checked_mul(10)); - assert_eq!(powers_of_10.by_ref().collect::>(), &[1, 10, 100, 1_000, 10_000]); - assert_eq!(powers_of_10.next(), None); - - let mut empty = successors(None::, |_| unimplemented!()); - assert_eq!(empty.next(), None); - assert_eq!(empty.next(), None); -} - -#[test] -fn test_fuse() { - let mut it = 0..3; - assert_eq!(it.len(), 3); - assert_eq!(it.next(), Some(0)); - assert_eq!(it.len(), 2); - assert_eq!(it.next(), Some(1)); - assert_eq!(it.len(), 1); - assert_eq!(it.next(), Some(2)); - assert_eq!(it.len(), 0); - assert_eq!(it.next(), None); - assert_eq!(it.len(), 0); - assert_eq!(it.next(), None); - assert_eq!(it.len(), 0); - assert_eq!(it.next(), None); - assert_eq!(it.len(), 0); -} - -#[test] -fn test_fuse_nth() { - let xs = [0, 1, 2]; - let mut it = xs.iter(); - - assert_eq!(it.len(), 3); - assert_eq!(it.nth(2), Some(&2)); - assert_eq!(it.len(), 0); - assert_eq!(it.nth(2), None); - assert_eq!(it.len(), 0); -} - -#[test] -fn test_fuse_last() { - let xs = [0, 1, 2]; - let it = xs.iter(); - - assert_eq!(it.len(), 3); - assert_eq!(it.last(), Some(&2)); -} - -#[test] -fn test_fuse_count() { - let xs = [0, 1, 2]; - let it = xs.iter(); - - assert_eq!(it.len(), 3); - assert_eq!(it.count(), 3); - // Can't check len now because count consumes. -} - -#[test] -fn test_fuse_fold() { - let xs = [0, 1, 2]; - let it = xs.iter(); // `FusedIterator` - let i = it.fuse().fold(0, |i, &x| { - assert_eq!(x, xs[i]); - i + 1 - }); - assert_eq!(i, xs.len()); - - let it = xs.iter(); // `FusedIterator` - let i = it.fuse().rfold(xs.len(), |i, &x| { - assert_eq!(x, xs[i - 1]); - i - 1 - }); - assert_eq!(i, 0); - - let it = xs.iter().scan((), |_, &x| Some(x)); // `!FusedIterator` - let i = it.fuse().fold(0, |i, x| { - assert_eq!(x, xs[i]); - i + 1 - }); - assert_eq!(i, xs.len()); -} - -#[test] -fn test_once() { - let mut it = once(42); - assert_eq!(it.next(), Some(42)); - assert_eq!(it.next(), None); -} - -#[test] -fn test_once_with() { - let count = Cell::new(0); - let mut it = once_with(|| { - count.set(count.get() + 1); - 42 - }); - - assert_eq!(count.get(), 0); - assert_eq!(it.next(), Some(42)); - assert_eq!(count.get(), 1); - assert_eq!(it.next(), None); - assert_eq!(count.get(), 1); - assert_eq!(it.next(), None); - assert_eq!(count.get(), 1); -} - -#[test] -fn test_empty() { - let mut it = empty::(); - assert_eq!(it.next(), 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_steps_between() { - assert_eq!(Step::steps_between(&20_u8, &200_u8), Some(180_usize)); - assert_eq!(Step::steps_between(&-20_i8, &80_i8), Some(100_usize)); - assert_eq!(Step::steps_between(&-120_i8, &80_i8), Some(200_usize)); - assert_eq!(Step::steps_between(&20_u32, &4_000_100_u32), Some(4_000_080_usize)); - assert_eq!(Step::steps_between(&-20_i32, &80_i32), Some(100_usize)); - assert_eq!(Step::steps_between(&-2_000_030_i32, &2_000_050_i32), Some(4_000_080_usize)); - - // Skip u64/i64 to avoid differences with 32-bit vs 64-bit platforms - - assert_eq!(Step::steps_between(&20_u128, &200_u128), Some(180_usize)); - assert_eq!(Step::steps_between(&-20_i128, &80_i128), Some(100_usize)); - if cfg!(target_pointer_width = "64") { - assert_eq!(Step::steps_between(&10_u128, &0x1_0000_0000_0000_0009_u128), Some(usize::MAX)); - } - assert_eq!(Step::steps_between(&10_u128, &0x1_0000_0000_0000_000a_u128), None); - assert_eq!(Step::steps_between(&10_i128, &0x1_0000_0000_0000_000a_i128), None); - assert_eq!( - Step::steps_between(&-0x1_0000_0000_0000_0000_i128, &0x1_0000_0000_0000_0000_i128,), - None, - ); -} - -#[test] -fn test_step_forward() { - assert_eq!(Step::forward_checked(55_u8, 200_usize), Some(255_u8)); - assert_eq!(Step::forward_checked(252_u8, 200_usize), None); - assert_eq!(Step::forward_checked(0_u8, 256_usize), None); - assert_eq!(Step::forward_checked(-110_i8, 200_usize), Some(90_i8)); - assert_eq!(Step::forward_checked(-110_i8, 248_usize), None); - assert_eq!(Step::forward_checked(-126_i8, 256_usize), None); - - assert_eq!(Step::forward_checked(35_u16, 100_usize), Some(135_u16)); - assert_eq!(Step::forward_checked(35_u16, 65500_usize), Some(u16::MAX)); - assert_eq!(Step::forward_checked(36_u16, 65500_usize), None); - assert_eq!(Step::forward_checked(-110_i16, 200_usize), Some(90_i16)); - assert_eq!(Step::forward_checked(-20_030_i16, 50_050_usize), Some(30_020_i16)); - assert_eq!(Step::forward_checked(-10_i16, 40_000_usize), None); - assert_eq!(Step::forward_checked(-10_i16, 70_000_usize), None); - - assert_eq!(Step::forward_checked(10_u128, 70_000_usize), Some(70_010_u128)); - assert_eq!(Step::forward_checked(10_i128, 70_030_usize), Some(70_040_i128)); - assert_eq!( - Step::forward_checked(0xffff_ffff_ffff_ffff__ffff_ffff_ffff_ff00_u128, 0xff_usize), - Some(u128::MAX), - ); - assert_eq!( - Step::forward_checked(0xffff_ffff_ffff_ffff__ffff_ffff_ffff_ff00_u128, 0x100_usize), - None - ); - assert_eq!( - Step::forward_checked(0x7fff_ffff_ffff_ffff__ffff_ffff_ffff_ff00_i128, 0xff_usize), - Some(i128::MAX), - ); - assert_eq!( - Step::forward_checked(0x7fff_ffff_ffff_ffff__ffff_ffff_ffff_ff00_i128, 0x100_usize), - None - ); -} - -#[test] -fn test_step_backward() { - assert_eq!(Step::backward_checked(255_u8, 200_usize), Some(55_u8)); - assert_eq!(Step::backward_checked(100_u8, 200_usize), None); - assert_eq!(Step::backward_checked(255_u8, 256_usize), None); - assert_eq!(Step::backward_checked(90_i8, 200_usize), Some(-110_i8)); - assert_eq!(Step::backward_checked(110_i8, 248_usize), None); - assert_eq!(Step::backward_checked(127_i8, 256_usize), None); - - assert_eq!(Step::backward_checked(135_u16, 100_usize), Some(35_u16)); - assert_eq!(Step::backward_checked(u16::MAX, 65500_usize), Some(35_u16)); - assert_eq!(Step::backward_checked(10_u16, 11_usize), None); - assert_eq!(Step::backward_checked(90_i16, 200_usize), Some(-110_i16)); - assert_eq!(Step::backward_checked(30_020_i16, 50_050_usize), Some(-20_030_i16)); - assert_eq!(Step::backward_checked(-10_i16, 40_000_usize), None); - assert_eq!(Step::backward_checked(-10_i16, 70_000_usize), None); - - assert_eq!(Step::backward_checked(70_010_u128, 70_000_usize), Some(10_u128)); - assert_eq!(Step::backward_checked(70_020_i128, 70_030_usize), Some(-10_i128)); - assert_eq!(Step::backward_checked(10_u128, 7_usize), Some(3_u128)); - assert_eq!(Step::backward_checked(10_u128, 11_usize), None); - assert_eq!( - Step::backward_checked(-0x7fff_ffff_ffff_ffff__ffff_ffff_ffff_ff00_i128, 0x100_usize), - Some(i128::MIN) - ); -} - -#[test] -fn test_rev_try_folds() { - let f = &|acc, x| i32::checked_add(2 * acc, x); - assert_eq!((1..10).rev().try_fold(7, f), (1..10).try_rfold(7, f)); - assert_eq!((1..10).rev().try_rfold(7, f), (1..10).try_fold(7, f)); - - let a = [10, 20, 30, 40, 100, 60, 70, 80, 90]; - let mut iter = a.iter().rev(); - assert_eq!(iter.try_fold(0_i8, |acc, &x| acc.checked_add(x)), None); - assert_eq!(iter.next(), Some(&70)); - let mut iter = a.iter().rev(); - assert_eq!(iter.try_rfold(0_i8, |acc, &x| acc.checked_add(x)), None); - assert_eq!(iter.next_back(), Some(&60)); -} - -#[test] -fn test_cloned_try_folds() { - let a = [1, 2, 3, 4, 5, 6, 7, 8, 9]; - let f = &|acc, x| i32::checked_add(2 * acc, x); - let f_ref = &|acc, &x| i32::checked_add(2 * acc, x); - assert_eq!(a.iter().cloned().try_fold(7, f), a.iter().try_fold(7, f_ref)); - assert_eq!(a.iter().cloned().try_rfold(7, f), a.iter().try_rfold(7, f_ref)); - - let a = [10, 20, 30, 40, 100, 60, 70, 80, 90]; - let mut iter = a.iter().cloned(); - assert_eq!(iter.try_fold(0_i8, |acc, x| acc.checked_add(x)), None); - assert_eq!(iter.next(), Some(60)); - let mut iter = a.iter().cloned(); - assert_eq!(iter.try_rfold(0_i8, |acc, x| acc.checked_add(x)), None); - assert_eq!(iter.next_back(), Some(70)); -} - -#[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_map_try_folds() { - let f = &|acc, x| i32::checked_add(2 * acc, x); - assert_eq!((0..10).map(|x| x + 3).try_fold(7, f), (3..13).try_fold(7, f)); - assert_eq!((0..10).map(|x| x + 3).try_rfold(7, f), (3..13).try_rfold(7, f)); - - let mut iter = (0..40).map(|x| x + 10); - 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(46)); -} - -#[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_filter_map_try_folds() { - let mp = &|x| if 0 <= x && x < 10 { Some(x * 2) } else { None }; - let f = &|acc, x| i32::checked_add(2 * acc, x); - assert_eq!((-9..20).filter_map(mp).try_fold(7, f), (0..10).map(|x| 2 * x).try_fold(7, f)); - assert_eq!((-9..20).filter_map(mp).try_rfold(7, f), (0..10).map(|x| 2 * x).try_rfold(7, f)); - - let mut iter = (0..40).filter_map(|x| if x % 2 == 1 { None } else { Some(x * 2 + 10) }); - assert_eq!(iter.try_fold(0, i8::checked_add), None); - assert_eq!(iter.next(), Some(38)); - assert_eq!(iter.try_rfold(0, i8::checked_add), None); - assert_eq!(iter.next_back(), Some(78)); -} - -#[test] -fn test_enumerate_try_folds() { - let f = &|acc, (i, x)| usize::checked_add(2 * acc, x / (i + 1) + i); - assert_eq!((9..18).enumerate().try_fold(7, f), (0..9).map(|i| (i, i + 9)).try_fold(7, f)); - assert_eq!((9..18).enumerate().try_rfold(7, f), (0..9).map(|i| (i, i + 9)).try_rfold(7, f)); - - let mut iter = (100..200).enumerate(); - let f = &|acc, (i, x)| u8::checked_add(acc, u8::checked_div(x, i as u8 + 1)?); - assert_eq!(iter.try_fold(0, f), None); - assert_eq!(iter.next(), Some((7, 107))); - assert_eq!(iter.try_rfold(0, f), None); - assert_eq!(iter.next_back(), Some((11, 111))); -} - -#[test] -fn test_peek_try_folds() { - let f = &|acc, x| i32::checked_add(2 * acc, x); - - assert_eq!((1..20).peekable().try_fold(7, f), (1..20).try_fold(7, f)); - assert_eq!((1..20).peekable().try_rfold(7, f), (1..20).try_rfold(7, f)); - - let mut iter = (1..20).peekable(); - assert_eq!(iter.peek(), Some(&1)); - assert_eq!(iter.try_fold(7, f), (1..20).try_fold(7, f)); - - let mut iter = (1..20).peekable(); - assert_eq!(iter.peek(), Some(&1)); - assert_eq!(iter.try_rfold(7, f), (1..20).try_rfold(7, f)); - - let mut iter = [100, 20, 30, 40, 50, 60, 70].iter().cloned().peekable(); - assert_eq!(iter.peek(), Some(&100)); - assert_eq!(iter.try_fold(0, i8::checked_add), None); - assert_eq!(iter.peek(), Some(&40)); - - let mut iter = [100, 20, 30, 40, 50, 60, 70].iter().cloned().peekable(); - assert_eq!(iter.peek(), Some(&100)); - assert_eq!(iter.try_rfold(0, i8::checked_add), None); - assert_eq!(iter.peek(), Some(&100)); - assert_eq!(iter.next_back(), Some(50)); - - let mut iter = (2..5).peekable(); - assert_eq!(iter.peek(), Some(&2)); - assert_eq!(iter.try_for_each(Err), Err(2)); - assert_eq!(iter.peek(), Some(&3)); - assert_eq!(iter.try_for_each(Err), Err(3)); - assert_eq!(iter.peek(), Some(&4)); - assert_eq!(iter.try_for_each(Err), Err(4)); - assert_eq!(iter.peek(), None); - assert_eq!(iter.try_for_each(Err), Ok(())); - - let mut iter = (2..5).peekable(); - assert_eq!(iter.peek(), Some(&2)); - assert_eq!(iter.try_rfold((), |(), x| Err(x)), Err(4)); - assert_eq!(iter.peek(), Some(&2)); - assert_eq!(iter.try_rfold((), |(), x| Err(x)), Err(3)); - assert_eq!(iter.peek(), Some(&2)); - assert_eq!(iter.try_rfold((), |(), x| Err(x)), Err(2)); - assert_eq!(iter.peek(), None); - assert_eq!(iter.try_rfold((), |(), x| Err(x)), Ok(())); -} - -#[test] -fn test_skip_while_try_fold() { - let f = &|acc, x| i32::checked_add(2 * acc, x); - fn p(&x: &i32) -> bool { - (x % 10) <= 5 - } - assert_eq!((1..20).skip_while(p).try_fold(7, f), (6..20).try_fold(7, f)); - let mut iter = (1..20).skip_while(p); - assert_eq!(iter.nth(5), Some(11)); - assert_eq!(iter.try_fold(7, f), (12..20).try_fold(7, f)); - - let mut iter = (0..50).skip_while(|&x| (x % 20) < 15); - assert_eq!(iter.try_fold(0, i8::checked_add), None); - assert_eq!(iter.next(), Some(23)); -} - -#[test] -fn test_take_while_folds() { - let f = &|acc, x| i32::checked_add(2 * acc, x); - assert_eq!((1..20).take_while(|&x| x != 10).try_fold(7, f), (1..10).try_fold(7, f)); - let mut iter = (1..20).take_while(|&x| x != 10); - assert_eq!(iter.try_fold(0, |x, y| Some(x + y)), Some((1..10).sum())); - assert_eq!(iter.next(), None, "flag should be set"); - let iter = (1..20).take_while(|&x| x != 10); - assert_eq!(iter.fold(0, |x, y| x + y), (1..10).sum()); - - let mut iter = (10..50).take_while(|&x| x != 40); - assert_eq!(iter.try_fold(0, i8::checked_add), None); - assert_eq!(iter.next(), Some(20)); -} - -#[test] -fn test_skip_try_folds() { - let f = &|acc, x| i32::checked_add(2 * acc, x); - assert_eq!((1..20).skip(9).try_fold(7, f), (10..20).try_fold(7, f)); - assert_eq!((1..20).skip(9).try_rfold(7, f), (10..20).try_rfold(7, f)); - - let mut iter = (0..30).skip(10); - 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)); -} - -#[test] -fn test_skip_nth_back() { - let xs = [0, 1, 2, 3, 4, 5]; - let mut it = xs.iter().skip(2); - assert_eq!(it.nth_back(0), Some(&5)); - assert_eq!(it.nth_back(1), Some(&3)); - assert_eq!(it.nth_back(0), Some(&2)); - assert_eq!(it.nth_back(0), None); - - let ys = [2, 3, 4, 5]; - let mut ity = ys.iter(); - let mut it = xs.iter().skip(2); - assert_eq!(it.nth_back(1), ity.nth_back(1)); - assert_eq!(it.clone().nth(0), ity.clone().nth(0)); - assert_eq!(it.nth_back(0), ity.nth_back(0)); - assert_eq!(it.clone().nth(0), ity.clone().nth(0)); - assert_eq!(it.nth_back(0), ity.nth_back(0)); - assert_eq!(it.clone().nth(0), ity.clone().nth(0)); - assert_eq!(it.nth_back(0), ity.nth_back(0)); - assert_eq!(it.clone().nth(0), ity.clone().nth(0)); - - let mut it = xs.iter().skip(2); - assert_eq!(it.nth_back(4), None); - assert_eq!(it.nth_back(0), None); - - let mut it = xs.iter(); - it.by_ref().skip(2).nth_back(3); - assert_eq!(it.next_back(), Some(&1)); - - let mut it = xs.iter(); - it.by_ref().skip(2).nth_back(10); - assert_eq!(it.next_back(), Some(&1)); -} - -#[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_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_flatten_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).map(mr).flatten().try_fold(7, f), (0..50).try_fold(7, f)); - assert_eq!((0..10).map(mr).flatten().try_rfold(7, f), (0..50).try_rfold(7, f)); - let mut iter = (0..10).map(mr).flatten(); - 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).map(|x| (4 * x)..(4 * x + 4)).flatten(); - 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_functor_laws() { - // identity: - fn identity(x: T) -> T { - x - } - assert_eq!((0..10).map(identity).sum::(), (0..10).sum()); - - // composition: - fn f(x: usize) -> usize { - x + 3 - } - fn g(x: usize) -> usize { - x * 2 - } - fn h(x: usize) -> usize { - g(f(x)) - } - assert_eq!((0..10).map(f).map(g).sum::(), (0..10).map(h).sum()); -} - -#[test] -fn test_monad_laws_left_identity() { - fn f(x: usize) -> impl Iterator { - (0..10).map(move |y| x * y) - } - assert_eq!(once(42).flat_map(f.clone()).sum::(), f(42).sum()); -} - -#[test] -fn test_monad_laws_right_identity() { - assert_eq!((0..10).flat_map(|x| once(x)).sum::(), (0..10).sum()); -} - -#[test] -fn test_monad_laws_associativity() { - fn f(x: usize) -> impl Iterator { - 0..x - } - fn g(x: usize) -> impl Iterator { - (0..x).rev() - } - assert_eq!( - (0..10).flat_map(f).flat_map(g).sum::(), - (0..10).flat_map(|x| f(x).flat_map(g)).sum::() - ); -} - -#[test] -fn test_is_sorted() { - assert!([1, 2, 2, 9].iter().is_sorted()); - assert!(![1, 3, 2].iter().is_sorted()); - assert!([0].iter().is_sorted()); - assert!(std::iter::empty::().is_sorted()); - assert!(![0.0, 1.0, f32::NAN].iter().is_sorted()); - assert!([-2, -1, 0, 3].iter().is_sorted()); - assert!(![-2i32, -1, 0, 3].iter().is_sorted_by_key(|n| n.abs())); - assert!(!["c", "bb", "aaa"].iter().is_sorted()); - assert!(["c", "bb", "aaa"].iter().is_sorted_by_key(|s| s.len())); -} - -#[test] -fn test_partition() { - fn check(xs: &mut [i32], ref p: impl Fn(&i32) -> bool, expected: usize) { - let i = xs.iter_mut().partition_in_place(p); - assert_eq!(expected, i); - assert!(xs[..i].iter().all(p)); - assert!(!xs[i..].iter().any(p)); - assert!(xs.iter().is_partitioned(p)); - if i == 0 || i == xs.len() { - assert!(xs.iter().rev().is_partitioned(p)); - } else { - assert!(!xs.iter().rev().is_partitioned(p)); - } - } - - check(&mut [], |_| true, 0); - check(&mut [], |_| false, 0); - - check(&mut [0], |_| true, 1); - check(&mut [0], |_| false, 0); - - check(&mut [-1, 1], |&x| x > 0, 1); - check(&mut [-1, 1], |&x| x < 0, 1); - - let ref mut xs = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]; - check(xs, |_| true, 10); - check(xs, |_| false, 0); - check(xs, |&x| x % 2 == 0, 5); // evens - check(xs, |&x| x % 2 == 1, 5); // odds - check(xs, |&x| x % 3 == 0, 4); // multiple of 3 - check(xs, |&x| x % 4 == 0, 3); // multiple of 4 - check(xs, |&x| x % 5 == 0, 2); // multiple of 5 - check(xs, |&x| x < 3, 3); // small - check(xs, |&x| x > 6, 3); // large -} - -/// An iterator that panics whenever `next` or next_back` is called -/// after `None` has already been returned. This does not violate -/// `Iterator`'s contract. Used to test that iterator adaptors don't -/// poll their inner iterators after exhausting them. -struct NonFused { - iter: I, - done: bool, -} - -impl NonFused { - fn new(iter: I) -> Self { - Self { iter, done: false } - } -} - -impl Iterator for NonFused -where - I: Iterator, -{ - type Item = I::Item; - - fn next(&mut self) -> Option { - assert!(!self.done, "this iterator has already returned None"); - self.iter.next().or_else(|| { - self.done = true; - None - }) - } -} - -impl DoubleEndedIterator for NonFused -where - I: DoubleEndedIterator, -{ - fn next_back(&mut self) -> Option { - assert!(!self.done, "this iterator has already returned None"); - self.iter.next_back().or_else(|| { - self.done = true; - None - }) - } -} - -#[test] -fn test_peekable_non_fused() { - let mut iter = NonFused::new(empty::()).peekable(); - - assert_eq!(iter.peek(), None); - assert_eq!(iter.next_back(), None); -} - -#[test] -fn test_flatten_non_fused_outer() { - let mut iter = NonFused::new(once(0..2)).flatten(); - - assert_eq!(iter.next_back(), Some(1)); - assert_eq!(iter.next(), Some(0)); - assert_eq!(iter.next(), None); -} - -#[test] -fn test_flatten_non_fused_inner() { - let mut iter = once(0..1).chain(once(1..3)).flat_map(NonFused::new); - - assert_eq!(iter.next_back(), Some(2)); - assert_eq!(iter.next(), Some(0)); - assert_eq!(iter.next(), Some(1)); - assert_eq!(iter.next(), None); -} - -#[test] -pub fn extend_for_unit() { - let mut x = 0; - { - let iter = (0..5).map(|_| { - x += 1; - }); - ().extend(iter); - } - assert_eq!(x, 5); -} - -#[test] -fn test_intersperse() { - let xs = ["a", "", "b", "c"]; - let v: Vec<&str> = xs.iter().map(|x| x.clone()).intersperse(", ").collect(); - let text: String = v.concat(); - assert_eq!(text, "a, , b, c".to_string()); - - let ys = [0, 1, 2, 3]; - let mut it = ys[..0].iter().map(|x| *x).intersperse(1); - assert!(it.next() == None); -} - -#[test] -fn test_intersperse_size_hint() { - let xs = ["a", "", "b", "c"]; - let mut iter = xs.iter().map(|x| x.clone()).intersperse(", "); - assert_eq!(iter.size_hint(), (7, Some(7))); - - assert_eq!(iter.next(), Some("a")); - assert_eq!(iter.size_hint(), (6, Some(6))); - assert_eq!(iter.next(), Some(", ")); - assert_eq!(iter.size_hint(), (5, Some(5))); - - assert_eq!([].iter().intersperse(&()).size_hint(), (0, Some(0))); -} - -#[test] -fn test_fold_specialization_intersperse() { - let mut iter = (1..2).intersperse(0); - iter.clone().for_each(|x| assert_eq!(Some(x), iter.next())); - - let mut iter = (1..3).intersperse(0); - iter.clone().for_each(|x| assert_eq!(Some(x), iter.next())); - - let mut iter = (1..4).intersperse(0); - iter.clone().for_each(|x| assert_eq!(Some(x), iter.next())); -} - -#[test] -fn test_try_fold_specialization_intersperse_ok() { - let mut iter = (1..2).intersperse(0); - iter.clone().try_for_each(|x| { - assert_eq!(Some(x), iter.next()); - Some(()) - }); - - let mut iter = (1..3).intersperse(0); - iter.clone().try_for_each(|x| { - assert_eq!(Some(x), iter.next()); - Some(()) - }); - - let mut iter = (1..4).intersperse(0); - iter.clone().try_for_each(|x| { - assert_eq!(Some(x), iter.next()); - Some(()) - }); -} - -#[test] -fn test_try_fold_specialization_intersperse_err() { - let orig_iter = ["a", "b"].iter().copied().intersperse("-"); - - // Abort after the first item. - let mut iter = orig_iter.clone(); - iter.try_for_each(|_| None::<()>); - assert_eq!(iter.next(), Some("-")); - assert_eq!(iter.next(), Some("b")); - assert_eq!(iter.next(), None); - - // Abort after the second item. - let mut iter = orig_iter.clone(); - iter.try_for_each(|item| if item == "-" { None } else { Some(()) }); - assert_eq!(iter.next(), Some("b")); - assert_eq!(iter.next(), None); - - // Abort after the third item. - let mut iter = orig_iter.clone(); - iter.try_for_each(|item| if item == "b" { None } else { Some(()) }); - assert_eq!(iter.next(), None); -} diff --git a/library/core/tests/iter/traits/iterator.rs b/library/core/tests/iter/traits/iterator.rs index 422e389e38017..ffc5d17498cf3 100644 --- a/library/core/tests/iter/traits/iterator.rs +++ b/library/core/tests/iter/traits/iterator.rs @@ -270,6 +270,32 @@ fn test_any() { assert!(!v[..0].iter().any(|_| panic!())); } +#[test] +fn test_at_least() { + let vec = vec![1, 2, 3, 4, 5]; + assert!(vec.iter().at_least(0, |i| i % 2 == 0)); + assert!(vec.iter().at_least(1, |i| i % 2 == 0)); + assert!(vec.iter().at_least(2, |i| i % 2 == 0)); + assert!(!vec.iter().at_least(3, |i| i % 2 == 0)); + assert!(vec.iter().at_least(0, |&i| i > 100)); + assert!(vec.iter().at_least(5, |&i| i < 100)); + + assert!(!&vec[..0].iter().at_least(0, |_| panic!())); +} + +#[test] +fn test_at_most() { + let vec = vec![1, 2, 3, 4, 5]; + assert!(vec.iter().at_most(0, |&i| i > 100)); + assert!(vec.iter().at_most(5, |&i| i < 100)); + assert!(vec.iter().at_most(3, |i| i % 2 == 0)); + assert!(vec.iter().at_most(2, |i| i % 2 == 0)); + assert!(!vec.iter().at_most(1, |i| i % 2 == 0)); + assert!(!vec.iter().at_most(0, |i| i % 2 == 0)); + + assert!(&vec[..0].iter().at_most(0, |_| panic!())); +} + #[test] fn test_find() { let v: &[isize] = &[1, 3, 9, 27, 103, 14, 11];