1pub trait WordSet: Sized {
2 fn subset(self) -> impl Iterator<Item = Self>;
3}
4
5macro_rules! impl_uint {
6 ( $($ty:ty)* ) => { $(
7 impl WordSet for $ty {
8 fn subset(self) -> impl Iterator<Item = Self> {
9 let n = self;
10 std::iter::successors(Some(0), move |&i| {
11 let d = n ^ i;
12 (d > 0).then(|| {
13 let d_neg = d.wrapping_neg();
14 (i & (d | d_neg)) + (d & d_neg)
15 })
16 })
17 }
18 }
19 )* };
20}
21
22impl_uint! { u8 u16 u32 u64 u128 usize }
23
24#[test]
25fn sanity_check() {
26 assert!(0_usize.subset().eq([0]));
27 eprintln!("{:?}", 0b1101_usize.subset().collect::<Vec<_>>());
28 assert!(
29 0b1101_usize.subset().eq([
30 0b0000, 0b0001, 0b0100, 0b0101, 0b1000, 0b1001, 0b1100, 0b1101
31 ])
32 );
33}