xorfilter-rs 0.5.1

Xor Filters: Faster and Smaller Than Bloom and Cuckoo Filters
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84

use std::{
    collections::hash_map::DefaultHasher,
    hash::{self, BuildHasher, Hasher},
};

/// Wrapper type for [std::hash::BuildHasherDefault], that uses
/// [DefaultHasher] as the hasher.
#[derive(Clone)]
pub struct BuildHasherDefault {
    hasher: hash::BuildHasherDefault<DefaultHasher>,
}

impl From<BuildHasherDefault> for Vec<u8> {
    fn from(_: BuildHasherDefault) -> Vec<u8> {
        vec![]
    }
}

impl From<Vec<u8>> for BuildHasherDefault {
    fn from(_: Vec<u8>) -> BuildHasherDefault {
        BuildHasherDefault {
            hasher: hash::BuildHasherDefault::<DefaultHasher>::default(),
        }
    }
}

impl BuildHasher for BuildHasherDefault {
    type Hasher = DefaultHasher;

    fn build_hasher(&self) -> Self::Hasher {
        self.hasher.build_hasher()
    }
}

impl Default for BuildHasherDefault {
    fn default() -> Self {
        BuildHasherDefault {
            hasher: hash::BuildHasherDefault::<DefaultHasher>::default(),
        }
    }
}

/// NoHash type skips hashing altogether.
///
/// When a filter is constructed using NoHash as the type parameter then it is upto
/// application to generate the 64-bit hash digest outside this library.
#[derive(Clone)]
pub struct NoHash;

impl From<NoHash> for Vec<u8> {
    fn from(_: NoHash) -> Vec<u8> {
        vec![]
    }
}

impl From<Vec<u8>> for NoHash {
    fn from(_: Vec<u8>) -> NoHash {
        NoHash
    }
}

impl BuildHasher for NoHash {
    type Hasher = NoHash;

    fn build_hasher(&self) -> Self {
        NoHash
    }
}

impl Default for NoHash {
    fn default() -> Self {
        NoHash
    }
}

impl Hasher for NoHash {
    fn write(&mut self, _bytes: &[u8]) {
        panic!("Can't generate hash digest using NoHash")
    }

    fn finish(&self) -> u64 {
        panic!("Can't generate hash digest using NoHash")
    }
}