From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:02:58 +0200 Subject: Adding upstream version 1.64.0+dfsg1. Signed-off-by: Daniel Baumann --- library/core/tests/iter/adapters/step_by.rs | 246 ++++++++++++++++++++++++++++ 1 file changed, 246 insertions(+) create mode 100644 library/core/tests/iter/adapters/step_by.rs (limited to 'library/core/tests/iter/adapters/step_by.rs') diff --git a/library/core/tests/iter/adapters/step_by.rs b/library/core/tests/iter/adapters/step_by.rs new file mode 100644 index 000000000..94f2fa8c2 --- /dev/null +++ b/library/core/tests/iter/adapters/step_by.rs @@ -0,0 +1,246 @@ +use core::iter::*; + +#[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 = "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_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)); +} -- cgit v1.2.3