4 fn test_iterator_skip_while() {
5 let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19];
6 let ys = [15, 16, 17, 19];
7 let it = xs.iter().skip_while(|&x| *x < 15);
10 assert_eq!(*x, ys[i]);
13 assert_eq!(i, ys.len());
17 fn test_iterator_skip_while_fold() {
18 let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19];
19 let ys = [15, 16, 17, 19];
20 let it = xs.iter().skip_while(|&x| *x < 15);
21 let i = it.fold(0, |i, &x| {
25 assert_eq!(i, ys.len());
27 let mut it = xs.iter().skip_while(|&x| *x < 15);
28 assert_eq!(it.next(), Some(&ys[0])); // process skips before folding
29 let i = it.fold(1, |i, &x| {
33 assert_eq!(i, ys.len());
37 fn test_skip_while_try_fold() {
38 let f = &|acc, x| i32::checked_add(2 * acc, x);
39 fn p(&x: &i32) -> bool {
42 assert_eq!((1..20).skip_while(p).try_fold(7, f), (6..20).try_fold(7, f));
43 let mut iter = (1..20).skip_while(p);
44 assert_eq!(iter.nth(5), Some(11));
45 assert_eq!(iter.try_fold(7, f), (12..20).try_fold(7, f));
47 let mut iter = (0..50).skip_while(|&x| (x % 20) < 15);
48 assert_eq!(iter.try_fold(0, i8::checked_add), None);
49 assert_eq!(iter.next(), Some(23));