OXYGENHUB
# 55e5a16a2b9c oxygen / crates / oxy-core / src / ids.rs
2.6 KiB · Rust · last changed Import the Oxygen specification and the first Rust implementation (root change) 1 month ago source blame history raw
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//! Random 128-bit identifiers: ChangeId, NodeId, WorkspaceId (spec §6.3, §7.1, §12.2).
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use rand::RngCore;
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use std::fmt;
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macro_rules! id128 {
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    ($name:ident, $doc:literal) => {
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        #[doc = $doc]
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        #[derive(Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
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        pub struct $name(pub [u8; 16]);
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        impl $name {
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            pub const ZERO: $name = $name([0; 16]);
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            /// A fresh identifier from the OS CSPRNG.
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            pub fn random() -> $name {
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                let mut b = [0u8; 16];
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                rand::rngs::OsRng.fill_bytes(&mut b);
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                $name(b)
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            }
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            pub fn to_hex(&self) -> String {
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                hex::encode(self.0)
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            }
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            pub fn from_hex(s: &str) -> Option<$name> {
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                let v = hex::decode(s).ok()?;
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                Some($name(v.try_into().ok()?))
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            }
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            pub fn from_slice(b: &[u8]) -> Option<$name> {
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                Some($name(b.try_into().ok()?))
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            }
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            pub fn short(&self, n: usize) -> String {
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                let h = self.to_hex();
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                h[..n.min(h.len())].to_string()
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            }
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            pub fn starts_with_hex(&self, prefix: &str) -> bool {
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                self.to_hex().starts_with(prefix)
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            }
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        }
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        impl fmt::Display for $name {
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            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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                f.write_str(&self.to_hex())
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            }
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        }
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        impl fmt::Debug for $name {
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            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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                write!(f, "{}({})", stringify!($name), self.short(8))
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            }
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        }
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    };
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}
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id128!(ChangeId, "Stable identity of a change across rewrites (spec §6.2).");
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id128!(NodeId, "Stable identity of a file, directory, or symlink across renames (spec §7.1). `NodeId::ZERO` is the root directory.");
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id128!(WorkspaceId, "Identity of a checkout directory (spec §12.2).");
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impl NodeId {
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    pub const ROOT: NodeId = NodeId::ZERO;
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    pub fn is_root(&self) -> bool {
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        self.is_zero()
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    }
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}
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impl ChangeId {
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    pub fn is_zero(&self) -> bool {
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        *self == Self::ZERO
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    }
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}
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impl NodeId {
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    pub fn is_zero(&self) -> bool {
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        *self == Self::ZERO
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    }
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}
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impl WorkspaceId {
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    pub fn is_zero(&self) -> bool {
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        *self == Self::ZERO
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    }
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}
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#[cfg(test)]
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mod tests {
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    use super::*;
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    #[test]
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    fn random_ids_differ_and_round_trip() {
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        let a = ChangeId::random();
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        let b = ChangeId::random();
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        assert_ne!(a, b);
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        assert_eq!(ChangeId::from_hex(&a.to_hex()), Some(a));
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        assert!(NodeId::ROOT.is_root());
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        assert!(!NodeId::random().is_root());
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    }
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}