superbit/simhash/
sim_hasher.rs

1use siphasher::sip::SipHasher;
2use siphasher::sip128::{Hasher128, SipHasher as SipHasher128};
3use std::hash::{Hash, Hasher};
4use xxhash_rust::xxh3::Xxh3;
5
6pub trait SimHasher: Sized {
7    type T;
8    fn hash<U>(&self, item: &U) -> Self::T
9    where
10        Self: Sized,
11        U: Hash;
12}
13
14pub struct SimSipHasher64 {
15    key1: u64,
16    key2: u64,
17}
18
19impl SimSipHasher64 {
20    pub fn new(key1: u64, key2: u64) -> Self {
21        SimSipHasher64 { key1, key2 }
22    }
23}
24
25impl SimHasher for SimSipHasher64 {
26    type T = u64;
27
28    fn hash<U>(&self, item: &U) -> Self::T
29    where
30        Self: Sized,
31        U: Hash,
32    {
33        let mut sip = SipHasher::new_with_keys(self.key1, self.key2);
34        item.hash(&mut sip);
35        sip.finish()
36    }
37}
38
39pub struct SimSipHasher128 {
40    key1: u64,
41    key2: u64,
42}
43
44impl SimSipHasher128 {
45    pub fn new(key1: u64, key2: u64) -> Self {
46        SimSipHasher128 { key1, key2 }
47    }
48}
49
50impl SimHasher for SimSipHasher128 {
51    type T = u128;
52
53    fn hash<U>(&self, item: &U) -> Self::T
54    where
55        Self: Sized,
56        U: Hash,
57    {
58        let mut sip = SipHasher128::new_with_keys(self.key1, self.key2);
59        item.hash(&mut sip);
60        sip.finish128().as_u128()
61    }
62}
63
64pub struct Xxh3Hasher64;
65
66impl Xxh3Hasher64 {
67    #[inline]
68    pub fn new() -> Self {
69        Self
70    }
71}
72
73impl SimHasher for Xxh3Hasher64 {
74    type T = u64;
75
76    #[inline]
77    fn hash<U>(&self, item: &U) -> Self::T
78    where
79        U: Hash,
80    {
81        let mut h = Xxh3::new();
82        item.hash(&mut h);
83        h.finish()
84    }
85}
86
87pub struct Xxh3Hasher128; // no fields
88
89impl Xxh3Hasher128 {
90    pub fn new() -> Self {
91        Self
92    }
93}
94
95impl SimHasher for Xxh3Hasher128 {
96    type T = u128;
97
98    #[inline]
99    fn hash<U>(&self, item: &U) -> Self::T
100    where
101        U: Hash,
102    {
103        let mut h = Xxh3::new(); // default seed = 0
104        item.hash(&mut h);
105        h.digest128() // returns u128 directly (crate ≥ 1.2)
106    }
107}
superbit/simhash/sim_hasher.rs

superbit/simhash/
sim_hasher.rs
