1use smallvec::{smallvec, SmallVec};
 2use std::iter;
 3
 4#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
 5pub struct Locator(SmallVec<[u8; 4]>);
 6
 7impl Locator {
 8    pub fn min() -> Self {
 9        Self(smallvec![u8::MIN])
10    }
11
12    pub fn max() -> Self {
13        Self(smallvec![u8::MAX])
14    }
15
16    pub fn between(lhs: &Self, rhs: &Self) -> Self {
17        let lhs = lhs.0.iter().copied().chain(iter::repeat(u8::MIN));
18        let rhs = rhs.0.iter().copied().chain(iter::repeat(u8::MAX));
19        let mut location = SmallVec::new();
20        for (lhs, rhs) in lhs.zip(rhs) {
21            let mid = lhs + (rhs.saturating_sub(lhs)) / 2;
22            location.push(mid);
23            if mid > lhs {
24                break;
25            }
26        }
27        Self(location)
28    }
29}
30
31impl Default for Locator {
32    fn default() -> Self {
33        Self::min()
34    }
35}
36
37#[cfg(test)]
38mod tests {
39    use super::*;
40    use rand::prelude::*;
41    use std::mem;
42
43    #[gpui::test(iterations = 100)]
44    fn test_locators(mut rng: StdRng) {
45        let mut lhs = Default::default();
46        let mut rhs = Default::default();
47        while lhs == rhs {
48            lhs = Locator(
49                (0..rng.gen_range(1..=5))
50                    .map(|_| rng.gen_range(0..=100))
51                    .collect(),
52            );
53            rhs = Locator(
54                (0..rng.gen_range(1..=5))
55                    .map(|_| rng.gen_range(0..=100))
56                    .collect(),
57            );
58        }
59
60        if lhs > rhs {
61            mem::swap(&mut lhs, &mut rhs);
62        }
63
64        let middle = Locator::between(&lhs, &rhs);
65        assert!(middle > lhs);
66        assert!(middle < rhs);
67        for ix in 0..middle.0.len() - 1 {
68            assert!(
69                middle.0[ix] == *lhs.0.get(ix).unwrap_or(&0)
70                    || middle.0[ix] == *rhs.0.get(ix).unwrap_or(&0)
71            );
72        }
73    }
74}