1 /// A wrapper struct that implements `Eq` and `Ord` based on the wrapped
2 /// integer modulo 3. Used to test that `Iterator::max` and `Iterator::min`
3 /// return the correct element if some of them are equal.
7 impl PartialEq for Mod3 {
8 fn eq(&self, other: &Self) -> bool {
9 self.0 % 3 == other.0 % 3
15 impl PartialOrd for Mod3 {
16 fn partial_cmp(&self, other: &Self) -> Option<core::cmp::Ordering> {
22 fn cmp(&self, other: &Self) -> core::cmp::Ordering {
23 (self.0 % 3).cmp(&(other.0 % 3))
29 let empty: [isize; 0] = [];
33 assert!(!xs.iter().lt(ys.iter()));
34 assert!(!xs.iter().le(ys.iter()));
35 assert!(xs.iter().gt(ys.iter()));
36 assert!(xs.iter().ge(ys.iter()));
38 assert!(ys.iter().lt(xs.iter()));
39 assert!(ys.iter().le(xs.iter()));
40 assert!(!ys.iter().gt(xs.iter()));
41 assert!(!ys.iter().ge(xs.iter()));
43 assert!(empty.iter().lt(xs.iter()));
44 assert!(empty.iter().le(xs.iter()));
45 assert!(!empty.iter().gt(xs.iter()));
46 assert!(!empty.iter().ge(xs.iter()));
49 let u = [1.0f64, 2.0];
50 let v = [0.0f64 / 0.0, 3.0];
52 assert!(!u.iter().lt(v.iter()));
53 assert!(!u.iter().le(v.iter()));
54 assert!(!u.iter().gt(v.iter()));
55 assert!(!u.iter().ge(v.iter()));
57 let a = [0.0f64 / 0.0];
61 assert!(a.iter().lt(b.iter()) == (a[0] < b[0]));
62 assert!(a.iter().le(b.iter()) == (a[0] <= b[0]));
63 assert!(a.iter().gt(b.iter()) == (a[0] > b[0]));
64 assert!(a.iter().ge(b.iter()) == (a[0] >= b[0]));
66 assert!(c.iter().lt(b.iter()) == (c[0] < b[0]));
67 assert!(c.iter().le(b.iter()) == (c[0] <= b[0]));
68 assert!(c.iter().gt(b.iter()) == (c[0] > b[0]));
69 assert!(c.iter().ge(b.iter()) == (c[0] >= b[0]));
74 use core::cmp::Ordering;
76 let f = |x: i32, y: i32| (x * x).cmp(&y);
77 let xs = || [1, 2, 3, 4].iter().copied();
78 let ys = || [1, 4, 16].iter().copied();
80 assert_eq!(xs().cmp_by(ys(), f), Ordering::Less);
81 assert_eq!(ys().cmp_by(xs(), f), Ordering::Greater);
82 assert_eq!(xs().cmp_by(xs().map(|x| x * x), f), Ordering::Equal);
83 assert_eq!(xs().rev().cmp_by(ys().rev(), f), Ordering::Greater);
84 assert_eq!(xs().cmp_by(ys().rev(), f), Ordering::Less);
85 assert_eq!(xs().cmp_by(ys().take(2), f), Ordering::Greater);
89 fn test_partial_cmp_by() {
90 use core::cmp::Ordering;
92 let f = |x: i32, y: i32| (x * x).partial_cmp(&y);
93 let xs = || [1, 2, 3, 4].iter().copied();
94 let ys = || [1, 4, 16].iter().copied();
96 assert_eq!(xs().partial_cmp_by(ys(), f), Some(Ordering::Less));
97 assert_eq!(ys().partial_cmp_by(xs(), f), Some(Ordering::Greater));
98 assert_eq!(xs().partial_cmp_by(xs().map(|x| x * x), f), Some(Ordering::Equal));
99 assert_eq!(xs().rev().partial_cmp_by(ys().rev(), f), Some(Ordering::Greater));
100 assert_eq!(xs().partial_cmp_by(xs().rev(), f), Some(Ordering::Less));
101 assert_eq!(xs().partial_cmp_by(ys().take(2), f), Some(Ordering::Greater));
103 let f = |x: f64, y: f64| (x * x).partial_cmp(&y);
104 let xs = || [1.0, 2.0, 3.0, 4.0].iter().copied();
105 let ys = || [1.0, 4.0, f64::NAN, 16.0].iter().copied();
107 assert_eq!(xs().partial_cmp_by(ys(), f), None);
108 assert_eq!(ys().partial_cmp_by(xs(), f), Some(Ordering::Greater));
113 let f = |x: i32, y: i32| x * x == y;
114 let xs = || [1, 2, 3, 4].iter().copied();
115 let ys = || [1, 4, 9, 16].iter().copied();
117 assert!(xs().eq_by(ys(), f));
118 assert!(!ys().eq_by(xs(), f));
119 assert!(!xs().eq_by(xs(), f));
120 assert!(!ys().eq_by(ys(), f));
122 assert!(!xs().take(3).eq_by(ys(), f));
123 assert!(!xs().eq_by(ys().take(3), f));
124 assert!(xs().take(3).eq_by(ys().take(3), f));
128 fn test_iterator_nth() {
129 let v: &[_] = &[0, 1, 2, 3, 4];
130 for i in 0..v.len() {
131 assert_eq!(v.iter().nth(i).unwrap(), &v[i]);
133 assert_eq!(v.iter().nth(v.len()), None);
137 fn test_iterator_nth_back() {
138 let v: &[_] = &[0, 1, 2, 3, 4];
139 for i in 0..v.len() {
140 assert_eq!(v.iter().nth_back(i).unwrap(), &v[v.len() - 1 - i]);
142 assert_eq!(v.iter().nth_back(v.len()), None);
146 fn test_iterator_advance_by() {
147 let v: &[_] = &[0, 1, 2, 3, 4];
149 for i in 0..v.len() {
150 let mut iter = v.iter();
151 assert_eq!(iter.advance_by(i), Ok(()));
152 assert_eq!(iter.next().unwrap(), &v[i]);
153 assert_eq!(iter.advance_by(100), Err(v.len() - 1 - i));
156 assert_eq!(v.iter().advance_by(v.len()), Ok(()));
157 assert_eq!(v.iter().advance_by(100), Err(v.len()));
161 fn test_iterator_advance_back_by() {
162 let v: &[_] = &[0, 1, 2, 3, 4];
164 for i in 0..v.len() {
165 let mut iter = v.iter();
166 assert_eq!(iter.advance_back_by(i), Ok(()));
167 assert_eq!(iter.next_back().unwrap(), &v[v.len() - 1 - i]);
168 assert_eq!(iter.advance_back_by(100), Err(v.len() - 1 - i));
171 assert_eq!(v.iter().advance_back_by(v.len()), Ok(()));
172 assert_eq!(v.iter().advance_back_by(100), Err(v.len()));
176 fn test_iterator_rev_advance_back_by() {
177 let v: &[_] = &[0, 1, 2, 3, 4];
179 for i in 0..v.len() {
180 let mut iter = v.iter().rev();
181 assert_eq!(iter.advance_back_by(i), Ok(()));
182 assert_eq!(iter.next_back().unwrap(), &v[i]);
183 assert_eq!(iter.advance_back_by(100), Err(v.len() - 1 - i));
186 assert_eq!(v.iter().rev().advance_back_by(v.len()), Ok(()));
187 assert_eq!(v.iter().rev().advance_back_by(100), Err(v.len()));
191 fn test_iterator_last() {
192 let v: &[_] = &[0, 1, 2, 3, 4];
193 assert_eq!(v.iter().last().unwrap(), &4);
194 assert_eq!(v[..1].iter().last().unwrap(), &0);
198 fn test_iterator_max() {
199 let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
200 assert_eq!(v[..4].iter().cloned().max(), Some(3));
201 assert_eq!(v.iter().cloned().max(), Some(10));
202 assert_eq!(v[..0].iter().cloned().max(), None);
203 assert_eq!(v.iter().cloned().map(Mod3).max().map(|x| x.0), Some(8));
207 fn test_iterator_min() {
208 let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
209 assert_eq!(v[..4].iter().cloned().min(), Some(0));
210 assert_eq!(v.iter().cloned().min(), Some(0));
211 assert_eq!(v[..0].iter().cloned().min(), None);
212 assert_eq!(v.iter().cloned().map(Mod3).min().map(|x| x.0), Some(0));
216 fn test_iterator_size_hint() {
217 let c = (0..).step_by(1);
218 let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
219 let v2 = &[10, 11, 12];
222 assert_eq!((0..).size_hint(), (usize::MAX, None));
223 assert_eq!(c.size_hint(), (usize::MAX, None));
224 assert_eq!(vi.clone().size_hint(), (10, Some(10)));
226 assert_eq!(c.clone().take(5).size_hint(), (5, Some(5)));
227 assert_eq!(c.clone().skip(5).size_hint().1, None);
228 assert_eq!(c.clone().take_while(|_| false).size_hint(), (0, None));
229 assert_eq!(c.clone().map_while(|_| None::<()>).size_hint(), (0, None));
230 assert_eq!(c.clone().skip_while(|_| false).size_hint(), (0, None));
231 assert_eq!(c.clone().enumerate().size_hint(), (usize::MAX, None));
232 assert_eq!(c.clone().chain(vi.clone().cloned()).size_hint(), (usize::MAX, None));
233 assert_eq!(c.clone().zip(vi.clone()).size_hint(), (10, Some(10)));
234 assert_eq!(c.clone().scan(0, |_, _| Some(0)).size_hint(), (0, None));
235 assert_eq!(c.clone().filter(|_| false).size_hint(), (0, None));
236 assert_eq!(c.clone().map(|_| 0).size_hint(), (usize::MAX, None));
237 assert_eq!(c.filter_map(|_| Some(0)).size_hint(), (0, None));
239 assert_eq!(vi.clone().take(5).size_hint(), (5, Some(5)));
240 assert_eq!(vi.clone().take(12).size_hint(), (10, Some(10)));
241 assert_eq!(vi.clone().skip(3).size_hint(), (7, Some(7)));
242 assert_eq!(vi.clone().skip(12).size_hint(), (0, Some(0)));
243 assert_eq!(vi.clone().take_while(|_| false).size_hint(), (0, Some(10)));
244 assert_eq!(vi.clone().map_while(|_| None::<()>).size_hint(), (0, Some(10)));
245 assert_eq!(vi.clone().skip_while(|_| false).size_hint(), (0, Some(10)));
246 assert_eq!(vi.clone().enumerate().size_hint(), (10, Some(10)));
247 assert_eq!(vi.clone().chain(v2).size_hint(), (13, Some(13)));
248 assert_eq!(vi.clone().zip(v2).size_hint(), (3, Some(3)));
249 assert_eq!(vi.clone().scan(0, |_, _| Some(0)).size_hint(), (0, Some(10)));
250 assert_eq!(vi.clone().filter(|_| false).size_hint(), (0, Some(10)));
251 assert_eq!(vi.clone().map(|&i| i + 1).size_hint(), (10, Some(10)));
252 assert_eq!(vi.filter_map(|_| Some(0)).size_hint(), (0, Some(10)));
257 let v: Box<[isize]> = Box::new([1, 2, 3, 4, 5]);
258 assert!(v.iter().all(|&x| x < 10));
259 assert!(!v.iter().all(|&x| x % 2 == 0));
260 assert!(!v.iter().all(|&x| x > 100));
261 assert!(v[..0].iter().all(|_| panic!()));
266 let v: Box<[isize]> = Box::new([1, 2, 3, 4, 5]);
267 assert!(v.iter().any(|&x| x < 10));
268 assert!(v.iter().any(|&x| x % 2 == 0));
269 assert!(!v.iter().any(|&x| x > 100));
270 assert!(!v[..0].iter().any(|_| panic!()));
275 let v: &[isize] = &[1, 3, 9, 27, 103, 14, 11];
276 assert_eq!(*v.iter().find(|&&x| x & 1 == 0).unwrap(), 14);
277 assert_eq!(*v.iter().find(|&&x| x % 3 == 0).unwrap(), 3);
278 assert!(v.iter().find(|&&x| x % 12 == 0).is_none());
283 let xs: &[isize] = &[];
284 assert_eq!(xs.iter().try_find(testfn), Ok(None));
285 let xs: &[isize] = &[1, 2, 3, 4];
286 assert_eq!(xs.iter().try_find(testfn), Ok(Some(&2)));
287 let xs: &[isize] = &[1, 3, 4];
288 assert_eq!(xs.iter().try_find(testfn), Err(()));
290 let xs: &[isize] = &[1, 2, 3, 4, 5, 6, 7];
291 let mut iter = xs.iter();
292 assert_eq!(iter.try_find(testfn), Ok(Some(&2)));
293 assert_eq!(iter.try_find(testfn), Err(()));
294 assert_eq!(iter.next(), Some(&5));
296 fn testfn(x: &&isize) -> Result<bool, ()> {
308 fn test_try_find_api_usability() -> Result<(), Box<dyn std::error::Error>> {
311 let is_my_num = |s: &str, search: i32| -> Result<bool, std::num::ParseIntError> {
312 Ok(s.parse::<i32>()? == search)
315 let val = a.iter().try_find(|&&s| is_my_num(s, 2))?;
316 assert_eq!(val, Some(&"2"));
323 let v = &[1, 3, 9, 27, 103, 14, 11];
324 assert_eq!(v.iter().position(|x| *x & 1 == 0).unwrap(), 5);
325 assert_eq!(v.iter().position(|x| *x % 3 == 0).unwrap(), 1);
326 assert!(v.iter().position(|x| *x % 12 == 0).is_none());
331 let xs = &[1, 2, 2, 1, 5, 9, 0, 2];
332 assert_eq!(xs.iter().filter(|x| **x == 2).count(), 3);
333 assert_eq!(xs.iter().filter(|x| **x == 5).count(), 1);
334 assert_eq!(xs.iter().filter(|x| **x == 95).count(), 0);
338 fn test_max_by_key() {
339 let xs: &[isize] = &[-3, 0, 1, 5, -10];
340 assert_eq!(*xs.iter().max_by_key(|x| x.abs()).unwrap(), -10);
345 let xs: &[isize] = &[-3, 0, 1, 5, -10];
346 assert_eq!(*xs.iter().max_by(|x, y| x.abs().cmp(&y.abs())).unwrap(), -10);
350 fn test_min_by_key() {
351 let xs: &[isize] = &[-3, 0, 1, 5, -10];
352 assert_eq!(*xs.iter().min_by_key(|x| x.abs()).unwrap(), 0);
357 let xs: &[isize] = &[-3, 0, 1, 5, -10];
358 assert_eq!(*xs.iter().min_by(|x, y| x.abs().cmp(&y.abs())).unwrap(), 0);
364 // sum the first five values
365 let partial_sum = xs.by_ref().take(5).fold(0, |a, b| a + b);
366 assert_eq!(partial_sum, 10);
367 assert_eq!(xs.next(), Some(5));
371 fn test_is_sorted() {
372 assert!([1, 2, 2, 9].iter().is_sorted());
373 assert!(![1, 3, 2].iter().is_sorted());
374 assert!([0].iter().is_sorted());
375 assert!(std::iter::empty::<i32>().is_sorted());
376 assert!(![0.0, 1.0, f32::NAN].iter().is_sorted());
377 assert!([-2, -1, 0, 3].iter().is_sorted());
378 assert!(![-2i32, -1, 0, 3].iter().is_sorted_by_key(|n| n.abs()));
379 assert!(!["c", "bb", "aaa"].iter().is_sorted());
380 assert!(["c", "bb", "aaa"].iter().is_sorted_by_key(|s| s.len()));
384 fn test_partition() {
385 fn check(xs: &mut [i32], ref p: impl Fn(&i32) -> bool, expected: usize) {
386 let i = xs.iter_mut().partition_in_place(p);
387 assert_eq!(expected, i);
388 assert!(xs[..i].iter().all(p));
389 assert!(!xs[i..].iter().any(p));
390 assert!(xs.iter().is_partitioned(p));
391 if i == 0 || i == xs.len() {
392 assert!(xs.iter().rev().is_partitioned(p));
394 assert!(!xs.iter().rev().is_partitioned(p));
398 check(&mut [], |_| true, 0);
399 check(&mut [], |_| false, 0);
401 check(&mut [0], |_| true, 1);
402 check(&mut [0], |_| false, 0);
404 check(&mut [-1, 1], |&x| x > 0, 1);
405 check(&mut [-1, 1], |&x| x < 0, 1);
407 let ref mut xs = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
408 check(xs, |_| true, 10);
409 check(xs, |_| false, 0);
410 check(xs, |&x| x % 2 == 0, 5); // evens
411 check(xs, |&x| x % 2 == 1, 5); // odds
412 check(xs, |&x| x % 3 == 0, 4); // multiple of 3
413 check(xs, |&x| x % 4 == 0, 3); // multiple of 4
414 check(xs, |&x| x % 5 == 0, 2); // multiple of 5
415 check(xs, |&x| x < 3, 3); // small
416 check(xs, |&x| x > 6, 3); // large
420 fn test_iterator_rev_advance_by() {
421 let v: &[_] = &[0, 1, 2, 3, 4];
423 for i in 0..v.len() {
424 let mut iter = v.iter().rev();
425 assert_eq!(iter.advance_by(i), Ok(()));
426 assert_eq!(iter.next().unwrap(), &v[v.len() - 1 - i]);
427 assert_eq!(iter.advance_by(100), Err(v.len() - 1 - i));
430 assert_eq!(v.iter().rev().advance_by(v.len()), Ok(()));
431 assert_eq!(v.iter().rev().advance_by(100), Err(v.len()));
436 let xs: &[isize] = &[];
437 assert_eq!(xs.iter().find_map(half_if_even), None);
438 let xs: &[isize] = &[3, 5];
439 assert_eq!(xs.iter().find_map(half_if_even), None);
440 let xs: &[isize] = &[4, 5];
441 assert_eq!(xs.iter().find_map(half_if_even), Some(2));
442 let xs: &[isize] = &[3, 6];
443 assert_eq!(xs.iter().find_map(half_if_even), Some(3));
445 let xs: &[isize] = &[1, 2, 3, 4, 5, 6, 7];
446 let mut iter = xs.iter();
447 assert_eq!(iter.find_map(half_if_even), Some(1));
448 assert_eq!(iter.find_map(half_if_even), Some(2));
449 assert_eq!(iter.find_map(half_if_even), Some(3));
450 assert_eq!(iter.next(), Some(&7));
452 fn half_if_even(x: &isize) -> Option<isize> {
453 if x % 2 == 0 { Some(x / 2) } else { None }
458 fn test_try_reduce() {
459 let v = [1usize, 2, 3, 4, 5];
460 let sum = v.into_iter().try_reduce(|x, y| x.checked_add(y));
461 assert_eq!(sum, Some(Some(15)));
463 let v = [1, 2, 3, 4, 5, usize::MAX];
464 let sum = v.into_iter().try_reduce(|x, y| x.checked_add(y));
465 assert_eq!(sum, None);
467 let v: [usize; 0] = [];
468 let sum = v.into_iter().try_reduce(|x, y| x.checked_add(y));
469 assert_eq!(sum, Some(None));
471 let v = ["1", "2", "3", "4", "5"];
472 let max = v.into_iter().try_reduce(|x, y| {
473 if x.parse::<usize>().ok()? > y.parse::<usize>().ok()? { Some(x) } else { Some(y) }
475 assert_eq!(max, Some(Some("5")));
477 let v = ["1", "2", "3", "4", "5"];
478 let max: Result<Option<_>, <usize as std::str::FromStr>::Err> =
479 v.into_iter().try_reduce(|x, y| {
480 if x.parse::<usize>()? > y.parse::<usize>()? { Ok(x) } else { Ok(y) }
482 assert_eq!(max, Ok(Some("5")));
486 fn test_iterator_len() {
487 let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
488 assert_eq!(v[..4].iter().count(), 4);
489 assert_eq!(v[..10].iter().count(), 10);
490 assert_eq!(v[..0].iter().count(), 0);
495 let a = vec![1, 2, 3, 4, 5];
496 let b: Vec<isize> = a.iter().cloned().collect();
501 fn test_try_collect() {
502 use core::ops::ControlFlow::{Break, Continue};
504 let u = vec![Some(1), Some(2), Some(3)];
505 let v = u.into_iter().try_collect::<Vec<i32>>();
506 assert_eq!(v, Some(vec![1, 2, 3]));
508 let u = vec![Some(1), Some(2), None, Some(3)];
509 let mut it = u.into_iter();
510 let v = it.try_collect::<Vec<i32>>();
512 let v = it.try_collect::<Vec<i32>>();
513 assert_eq!(v, Some(vec![3]));
515 let u: Vec<Result<i32, ()>> = vec![Ok(1), Ok(2), Ok(3)];
516 let v = u.into_iter().try_collect::<Vec<i32>>();
517 assert_eq!(v, Ok(vec![1, 2, 3]));
519 let u = vec![Ok(1), Ok(2), Err(()), Ok(3)];
520 let v = u.into_iter().try_collect::<Vec<i32>>();
521 assert_eq!(v, Err(()));
523 let numbers = vec![1, 2, 3, 4, 5];
524 let all_positive = numbers
527 .map(|n| if n > 0 { Some(n) } else { None })
528 .try_collect::<Vec<i32>>();
529 assert_eq!(all_positive, Some(numbers));
531 let numbers = vec![-2, -1, 0, 1, 2];
533 numbers.into_iter().map(|n| if n > 0 { Some(n) } else { None }).try_collect::<Vec<i32>>();
534 assert_eq!(all_positive, None);
536 let u = [Continue(1), Continue(2), Break(3), Continue(4), Continue(5)];
537 let mut it = u.into_iter();
539 let v = it.try_collect::<Vec<_>>();
540 assert_eq!(v, Break(3));
542 let v = it.try_collect::<Vec<_>>();
543 assert_eq!(v, Continue(vec![4, 5]));
547 fn test_collect_into() {
548 let a = vec![1, 2, 3, 4, 5];
549 let mut b = Vec::new();
550 a.iter().cloned().collect_into(&mut b);
555 fn iter_try_collect_uses_try_fold_not_next() {
556 // This makes sure it picks up optimizations, and doesn't use the `&mut I` impl.
557 struct PanicOnNext<I>(I);
558 impl<I: Iterator> Iterator for PanicOnNext<I> {
560 fn next(&mut self) -> Option<Self::Item> {
561 panic!("Iterator::next should not be called!")
563 fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R
566 F: FnMut(B, Self::Item) -> R,
567 R: std::ops::Try<Output = B>,
569 self.0.try_fold(init, f)
573 let it = (0..10).map(Some);
574 let _ = PanicOnNext(it).try_collect::<Vec<_>>();
575 // validation is just that it didn't panic.
579 fn test_next_chunk() {
581 assert_eq!(it.next_chunk().unwrap(), [0, 1, 2, 3]);
582 assert_eq!(it.next_chunk().unwrap(), []);
583 assert_eq!(it.next_chunk().unwrap(), [4, 5, 6, 7, 8, 9]);
584 assert_eq!(it.next_chunk::<4>().unwrap_err().as_slice(), &[10, 11]);
587 // just tests by whether or not this compiles
588 fn _empty_impl_all_auto_traits<T>() {
589 use std::panic::{RefUnwindSafe, UnwindSafe};
590 fn all_auto_traits<T: Send + Sync + Unpin + UnwindSafe + RefUnwindSafe>() {}
592 all_auto_traits::<std::iter::Empty<T>>();