215 lines
7.0 KiB
Rust
215 lines
7.0 KiB
Rust
use core::assert_eq;
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use super::*;
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use core::iter::*;
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use core::num::NonZeroUsize;
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#[test]
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fn test_iterator_flatten() {
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let xs = [0, 3, 6];
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let ys = [0, 1, 2, 3, 4, 5, 6, 7, 8];
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let it = xs.iter().map(|&x| (x..).step_by(1).take(3)).flatten();
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let mut i = 0;
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for x in it {
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assert_eq!(x, ys[i]);
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i += 1;
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}
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assert_eq!(i, ys.len());
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}
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/// Tests `Flatten::fold` with items already picked off the front and back,
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/// to make sure all parts of the `Flatten` are folded correctly.
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#[test]
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fn test_iterator_flatten_fold() {
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let xs = [0, 3, 6];
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let ys = [1, 2, 3, 4, 5, 6, 7];
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let mut it = xs.iter().map(|&x| x..x + 3).flatten();
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assert_eq!(it.next(), Some(0));
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assert_eq!(it.next_back(), Some(8));
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let i = it.fold(0, |i, x| {
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assert_eq!(x, ys[i]);
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i + 1
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});
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assert_eq!(i, ys.len());
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let mut it = xs.iter().map(|&x| x..x + 3).flatten();
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assert_eq!(it.next(), Some(0));
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assert_eq!(it.next_back(), Some(8));
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let i = it.rfold(ys.len(), |i, x| {
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assert_eq!(x, ys[i - 1]);
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i - 1
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});
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assert_eq!(i, 0);
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}
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#[test]
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fn test_flatten_try_folds() {
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let f = &|acc, x| i32::checked_add(acc * 2 / 3, x);
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let mr = &|x| (5 * x)..(5 * x + 5);
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assert_eq!((0..10).map(mr).flatten().try_fold(7, f), (0..50).try_fold(7, f));
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assert_eq!((0..10).map(mr).flatten().try_rfold(7, f), (0..50).try_rfold(7, f));
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let mut iter = (0..10).map(mr).flatten();
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iter.next();
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iter.next_back(); // have front and back iters in progress
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assert_eq!(iter.try_rfold(7, f), (1..49).try_rfold(7, f));
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let mut iter = (0..10).map(|x| (4 * x)..(4 * x + 4)).flatten();
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assert_eq!(iter.try_fold(0, i8::checked_add), None);
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assert_eq!(iter.next(), Some(17));
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assert_eq!(iter.try_rfold(0, i8::checked_add), None);
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assert_eq!(iter.next_back(), Some(35));
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}
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#[test]
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fn test_flatten_advance_by() {
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let mut it = once(0..10).chain(once(10..30)).chain(once(30..40)).flatten();
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assert_eq!(it.advance_by(5), Ok(()));
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assert_eq!(it.next(), Some(5));
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assert_eq!(it.advance_by(9), Ok(()));
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assert_eq!(it.next(), Some(15));
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assert_eq!(it.advance_back_by(4), Ok(()));
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assert_eq!(it.next_back(), Some(35));
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assert_eq!(it.advance_back_by(9), Ok(()));
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assert_eq!(it.next_back(), Some(25));
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assert_eq!(it.advance_by(usize::MAX), Err(NonZeroUsize::new(usize::MAX - 9).unwrap()));
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assert_eq!(it.advance_back_by(usize::MAX), Err(NonZeroUsize::new(usize::MAX).unwrap()));
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assert_eq!(it.advance_by(0), Ok(()));
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assert_eq!(it.advance_back_by(0), Ok(()));
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assert_eq!(it.size_hint(), (0, Some(0)));
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}
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#[test]
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fn test_flatten_non_fused_outer() {
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let mut iter = NonFused::new(once(0..2)).flatten();
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assert_eq!(iter.next_back(), Some(1));
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assert_eq!(iter.next(), Some(0));
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assert_eq!(iter.next(), None);
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assert_eq!(iter.next(), None);
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let mut iter = NonFused::new(once(0..2)).flatten();
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assert_eq!(iter.next(), Some(0));
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assert_eq!(iter.next_back(), Some(1));
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assert_eq!(iter.next_back(), None);
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assert_eq!(iter.next_back(), None);
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}
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#[test]
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fn test_flatten_non_fused_inner() {
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let mut iter = once(0..1).chain(once(1..3)).flat_map(NonFused::new);
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assert_eq!(iter.next_back(), Some(2));
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assert_eq!(iter.next(), Some(0));
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assert_eq!(iter.next(), Some(1));
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assert_eq!(iter.next(), None);
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assert_eq!(iter.next(), None);
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let mut iter = once(0..1).chain(once(1..3)).flat_map(NonFused::new);
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assert_eq!(iter.next(), Some(0));
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assert_eq!(iter.next_back(), Some(2));
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assert_eq!(iter.next_back(), Some(1));
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assert_eq!(iter.next_back(), None);
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assert_eq!(iter.next_back(), None);
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}
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#[test]
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fn test_double_ended_flatten() {
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let u = [0, 1];
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let v = [5, 6, 7, 8];
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let mut it = u.iter().map(|x| &v[*x..v.len()]).flatten();
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assert_eq!(it.next_back().unwrap(), &8);
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assert_eq!(it.next().unwrap(), &5);
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assert_eq!(it.next_back().unwrap(), &7);
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assert_eq!(it.next_back().unwrap(), &6);
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assert_eq!(it.next_back().unwrap(), &8);
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assert_eq!(it.next().unwrap(), &6);
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assert_eq!(it.next_back().unwrap(), &7);
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assert_eq!(it.next_back(), None);
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assert_eq!(it.next(), None);
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assert_eq!(it.next_back(), None);
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}
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#[test]
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fn test_trusted_len_flatten() {
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fn assert_trusted_len<T: TrustedLen>(_: &T) {}
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let mut iter = IntoIterator::into_iter([[0; 3]; 4]).flatten();
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assert_trusted_len(&iter);
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assert_eq!(iter.size_hint(), (12, Some(12)));
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iter.next();
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assert_eq!(iter.size_hint(), (11, Some(11)));
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iter.next_back();
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assert_eq!(iter.size_hint(), (10, Some(10)));
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let iter = IntoIterator::into_iter([[(); usize::MAX]; 1]).flatten();
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assert_eq!(iter.size_hint(), (usize::MAX, Some(usize::MAX)));
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let iter = IntoIterator::into_iter([[(); usize::MAX]; 2]).flatten();
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assert_eq!(iter.size_hint(), (usize::MAX, None));
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let mut a = [(); 10];
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let mut b = [(); 10];
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let iter = IntoIterator::into_iter([&mut a, &mut b]).flatten();
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assert_trusted_len(&iter);
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assert_eq!(iter.size_hint(), (20, Some(20)));
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core::mem::drop(iter);
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let iter = IntoIterator::into_iter([&a, &b]).flatten();
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assert_trusted_len(&iter);
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assert_eq!(iter.size_hint(), (20, Some(20)));
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let iter = [(), (), ()].iter().flat_map(|_| [(); 1000]);
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assert_trusted_len(&iter);
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assert_eq!(iter.size_hint(), (3000, Some(3000)));
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let iter = [(), ()].iter().flat_map(|_| &a);
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assert_trusted_len(&iter);
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assert_eq!(iter.size_hint(), (20, Some(20)));
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}
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#[test]
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fn test_flatten_count() {
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let mut it = once(0..10).chain(once(10..30)).chain(once(30..40)).flatten();
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assert_eq!(it.clone().count(), 40);
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assert_eq!(it.advance_by(5), Ok(()));
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assert_eq!(it.clone().count(), 35);
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assert_eq!(it.advance_back_by(5), Ok(()));
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assert_eq!(it.clone().count(), 30);
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assert_eq!(it.advance_by(10), Ok(()));
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assert_eq!(it.clone().count(), 20);
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assert_eq!(it.advance_back_by(8), Ok(()));
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assert_eq!(it.clone().count(), 12);
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assert_eq!(it.advance_by(4), Ok(()));
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assert_eq!(it.clone().count(), 8);
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assert_eq!(it.advance_back_by(5), Ok(()));
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assert_eq!(it.clone().count(), 3);
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assert_eq!(it.advance_by(3), Ok(()));
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assert_eq!(it.clone().count(), 0);
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}
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#[test]
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fn test_flatten_last() {
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let mut it = once(0..10).chain(once(10..30)).chain(once(30..40)).flatten();
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assert_eq!(it.clone().last(), Some(39));
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assert_eq!(it.advance_by(5), Ok(())); // 5..40
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assert_eq!(it.clone().last(), Some(39));
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assert_eq!(it.advance_back_by(5), Ok(())); // 5..35
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assert_eq!(it.clone().last(), Some(34));
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assert_eq!(it.advance_by(10), Ok(())); // 15..35
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assert_eq!(it.clone().last(), Some(34));
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assert_eq!(it.advance_back_by(8), Ok(())); // 15..27
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assert_eq!(it.clone().last(), Some(26));
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assert_eq!(it.advance_by(4), Ok(())); // 19..27
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assert_eq!(it.clone().last(), Some(26));
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assert_eq!(it.advance_back_by(5), Ok(())); // 19..22
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assert_eq!(it.clone().last(), Some(21));
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assert_eq!(it.advance_by(3), Ok(())); // 22..22
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assert_eq!(it.clone().last(), None);
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}
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