1 // Copyright 2016 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use rustc_serialize::{Encodable, Decodable, Encoder, Decoder};
12 use rustc_data_structures::stable_hasher;
16 #[derive(Eq, PartialEq, Ord, PartialOrd, Hash, Debug, Clone, Copy)]
17 pub struct Fingerprint(u64, u64);
21 pub fn zero() -> Fingerprint {
26 pub fn from_smaller_hash(hash: u64) -> Fingerprint {
27 Fingerprint(hash, hash)
31 pub fn to_smaller_hash(&self) -> u64 {
35 pub fn to_hex(&self) -> String {
36 format!("{:x}{:x}", self.0, self.1)
40 impl Encodable for Fingerprint {
42 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
43 s.emit_u64(self.0.to_le())?;
44 s.emit_u64(self.1.to_le())
48 impl Decodable for Fingerprint {
50 fn decode<D: Decoder>(d: &mut D) -> Result<Fingerprint, D::Error> {
51 let _0 = u64::from_le(d.read_u64()?);
52 let _1 = u64::from_le(d.read_u64()?);
53 Ok(Fingerprint(_0, _1))
57 impl ::std::fmt::Display for Fingerprint {
58 fn fmt(&self, formatter: &mut ::std::fmt::Formatter) -> Result<(), ::std::fmt::Error> {
59 write!(formatter, "{:x}-{:x}", self.0, self.1)
63 impl stable_hasher::StableHasherResult for Fingerprint {
64 fn finish(mut hasher: stable_hasher::StableHasher<Self>) -> Self {
65 let hash_bytes: &[u8] = hasher.finalize();
67 assert!(hash_bytes.len() >= mem::size_of::<u64>() * 2);
68 let hash_bytes: &[u64] = unsafe {
69 slice::from_raw_parts(hash_bytes.as_ptr() as *const u64, 2)
72 // The bytes returned bytes the Blake2B hasher are always little-endian.
73 Fingerprint(u64::from_le(hash_bytes[0]), u64::from_le(hash_bytes[1]))
77 impl<CTX> stable_hasher::HashStable<CTX> for Fingerprint {
79 fn hash_stable<W: stable_hasher::StableHasherResult>(&self,
81 hasher: &mut stable_hasher::StableHasher<W>) {
82 ::std::hash::Hash::hash(self, hasher);