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Diffstat (limited to 'compiler/rustc_data_structures/src/svh.rs')
-rw-r--r-- | compiler/rustc_data_structures/src/svh.rs | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/compiler/rustc_data_structures/src/svh.rs b/compiler/rustc_data_structures/src/svh.rs new file mode 100644 index 000000000..61654b9e8 --- /dev/null +++ b/compiler/rustc_data_structures/src/svh.rs @@ -0,0 +1,69 @@ +//! Calculation and management of a Strict Version Hash for crates +//! +//! The SVH is used for incremental compilation to track when HIR +//! nodes have changed between compilations, and also to detect +//! mismatches where we have two versions of the same crate that were +//! compiled from distinct sources. + +use rustc_serialize::{Decodable, Decoder, Encodable, Encoder}; +use std::fmt; +use std::hash::{Hash, Hasher}; + +use crate::stable_hasher; + +#[derive(Copy, Clone, PartialEq, Eq, Debug)] +pub struct Svh { + hash: u64, +} + +impl Svh { + /// Creates a new `Svh` given the hash. If you actually want to + /// compute the SVH from some HIR, you want the `calculate_svh` + /// function found in `rustc_incremental`. + pub fn new(hash: u64) -> Svh { + Svh { hash } + } + + pub fn as_u64(&self) -> u64 { + self.hash + } + + pub fn to_string(&self) -> String { + format!("{:016x}", self.hash) + } +} + +impl Hash for Svh { + fn hash<H>(&self, state: &mut H) + where + H: Hasher, + { + self.hash.to_le().hash(state); + } +} + +impl fmt::Display for Svh { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.pad(&self.to_string()) + } +} + +impl<S: Encoder> Encodable<S> for Svh { + fn encode(&self, s: &mut S) { + s.emit_u64(self.as_u64().to_le()); + } +} + +impl<D: Decoder> Decodable<D> for Svh { + fn decode(d: &mut D) -> Svh { + Svh::new(u64::from_le(d.read_u64())) + } +} + +impl<T> stable_hasher::HashStable<T> for Svh { + #[inline] + fn hash_stable(&self, ctx: &mut T, hasher: &mut stable_hasher::StableHasher) { + let Svh { hash } = *self; + hash.hash_stable(ctx, hasher); + } +} |