OXYGENHUB
# a405d4c99440 oxygen / crates / oxy-core / src / ids.rs
2.7 KiB · Rust · last changed Unbound hosted repositories adopt the first pusher's id 1 month ago source blame history raw
1 
//! Random 128-bit identifiers: ChangeId, NodeId, WorkspaceId (spec §6.3, §7.1, §12.2).
2
3 
use rand::RngCore;
4 
use std::fmt;
5
6 
macro_rules! id128 {
7 
    ($name:ident, $doc:literal) => {
8 
        #[doc = $doc]
9 
        #[derive(Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
10 
        pub struct $name(pub [u8; 16]);
11
12 
        impl $name {
13 
            pub const ZERO: $name = $name([0; 16]);
14
15 
            /// A fresh identifier from the OS CSPRNG.
16 
            pub fn random() -> $name {
17 
                let mut b = [0u8; 16];
18 
                rand::rngs::OsRng.fill_bytes(&mut b);
19 
                $name(b)
20 
            }
21 
            pub fn to_hex(&self) -> String {
22 
                hex::encode(self.0)
23 
            }
24 
            pub fn from_hex(s: &str) -> Option<$name> {
25 
                let v = hex::decode(s).ok()?;
26 
                Some($name(v.try_into().ok()?))
27 
            }
28 
            pub fn from_slice(b: &[u8]) -> Option<$name> {
29 
                Some($name(b.try_into().ok()?))
30 
            }
31 
            pub fn short(&self, n: usize) -> String {
32 
                let h = self.to_hex();
33 
                h[..n.min(h.len())].to_string()
34 
            }
35 
            pub fn starts_with_hex(&self, prefix: &str) -> bool {
36 
                self.to_hex().starts_with(prefix)
37 
            }
38 
        }
39
40 
        impl fmt::Display for $name {
41 
            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
42 
                f.write_str(&self.to_hex())
43 
            }
44 
        }
45 
        impl fmt::Debug for $name {
46 
            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
47 
                write!(f, "{}({})", stringify!($name), self.short(8))
48 
            }
49 
        }
50 
    };
51 
}
52
53 
id128!(
54 
    ChangeId,
55 
    "Stable identity of a change across rewrites (spec §6.2)."
56 
);
57 
id128!(NodeId, "Stable identity of a file, directory, or symlink across renames (spec §7.1). `NodeId::ZERO` is the root directory.");
58 
id128!(
59 
    WorkspaceId,
60 
    "Identity of a checkout directory (spec §12.2)."
61 
);
62
63 
impl NodeId {
64 
    pub const ROOT: NodeId = NodeId::ZERO;
65 
    pub fn is_root(&self) -> bool {
66 
        self.is_zero()
67 
    }
68 
}
69
70 
impl ChangeId {
71 
    pub fn is_zero(&self) -> bool {
72 
        *self == Self::ZERO
73 
    }
74 
}
75 
impl NodeId {
76 
    pub fn is_zero(&self) -> bool {
77 
        *self == Self::ZERO
78 
    }
79 
}
80 
impl WorkspaceId {
81 
    pub fn is_zero(&self) -> bool {
82 
        *self == Self::ZERO
83 
    }
84 
}
85
86 
#[cfg(test)]
87 
mod tests {
88 
    use super::*;
89
90 
    #[test]
91 
    fn random_ids_differ_and_round_trip() {
92 
        let a = ChangeId::random();
93 
        let b = ChangeId::random();
94 
        assert_ne!(a, b);
95 
        assert_eq!(ChangeId::from_hex(&a.to_hex()), Some(a));
96 
        assert!(NodeId::ROOT.is_root());
97 
        assert!(!NodeId::random().is_root());
98 
    }
99 
}