49 lines
1.9 KiB
Rust
49 lines
1.9 KiB
Rust
use core::iter::*;
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#[test]
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fn test_find_map() {
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let xs: &[isize] = &[];
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assert_eq!(xs.iter().find_map(half_if_even), None);
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let xs: &[isize] = &[3, 5];
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assert_eq!(xs.iter().find_map(half_if_even), None);
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let xs: &[isize] = &[4, 5];
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assert_eq!(xs.iter().find_map(half_if_even), Some(2));
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let xs: &[isize] = &[3, 6];
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assert_eq!(xs.iter().find_map(half_if_even), Some(3));
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let xs: &[isize] = &[1, 2, 3, 4, 5, 6, 7];
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let mut iter = xs.iter();
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assert_eq!(iter.find_map(half_if_even), Some(1));
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assert_eq!(iter.find_map(half_if_even), Some(2));
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assert_eq!(iter.find_map(half_if_even), Some(3));
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assert_eq!(iter.next(), Some(&7));
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fn half_if_even(x: &isize) -> Option<isize> {
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if x % 2 == 0 { Some(x / 2) } else { None }
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}
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}
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#[test]
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fn test_map_try_folds() {
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let f = &|acc, x| i32::checked_add(2 * acc, x);
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assert_eq!((0..10).map(|x| x + 3).try_fold(7, f), (3..13).try_fold(7, f));
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assert_eq!((0..10).map(|x| x + 3).try_rfold(7, f), (3..13).try_rfold(7, f));
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let mut iter = (0..40).map(|x| x + 10);
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assert_eq!(iter.try_fold(0, i8::checked_add), None);
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assert_eq!(iter.next(), Some(20));
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assert_eq!(iter.try_rfold(0, i8::checked_add), None);
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assert_eq!(iter.next_back(), Some(46));
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}
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#[test]
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fn test_filter_map_try_folds() {
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let mp = &|x| if 0 <= x && x < 10 { Some(x * 2) } else { None };
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let f = &|acc, x| i32::checked_add(2 * acc, x);
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assert_eq!((-9..20).filter_map(mp).try_fold(7, f), (0..10).map(|x| 2 * x).try_fold(7, f));
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assert_eq!((-9..20).filter_map(mp).try_rfold(7, f), (0..10).map(|x| 2 * x).try_rfold(7, f));
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let mut iter = (0..40).filter_map(|x| if x % 2 == 1 { None } else { Some(x * 2 + 10) });
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assert_eq!(iter.try_fold(0, i8::checked_add), None);
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assert_eq!(iter.next(), Some(38));
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assert_eq!(iter.try_rfold(0, i8::checked_add), None);
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assert_eq!(iter.next_back(), Some(78));
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}
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