reliq 0.1.0

A portable library of primitive-like constructs.
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
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140

pub trait Key
where
    Self: ::core::fmt::Debug,
    Self: Default,
    Self: Clone,
    Self: Copy,
    Self: Eq,
    Self: ::core::hash::Hash {}

pub trait Val
where
    Self: ::core::fmt::Debug,
    Self: Default,
    Self: Clone,
    Self: Copy {}

pub trait Hasher
where
    Self: Default,
    Self: ::core::hash::Hasher {}

#[derive(Clone)]
pub struct Map<const A: usize, B, C, D = ::core::hash::SipHasher> 
where
    B: Key,
    C: Val,
    D: ::core::hash::Hasher {
    keys: [Option<B>; A],
    vals: [Option<C>; A],
    len: usize,
    hasher: ::core::marker::PhantomData<D>
}

impl<const A: usize, B, C, D> Map<A, B, C, D>
where
    B: Key,
    C: Val,
    D: Hasher {
    pub const fn len(&self) -> usize {
        self.len
    }

    pub const fn cap(&self) -> usize {
        A
    }

    pub const fn is_empty(&self) -> bool {
        self.len == 0
    }

    #[inline]
    pub fn get(&self, key: &B) -> Option<&C> {
        let mut position: usize = self.hash_index(key);
        for _ in 0..A {
            match &self.keys[position] {
                Some(k) if k == key => return self.vals[position].as_ref(),
                None => return None,
                _ => position = (position + 1) % A
            }
        }
        None
    }

    #[inline]
    pub fn insert(&mut self, key: B, data: C) -> Result<(), (B, C)> {
        if self.len >= A {
            return Err((key, data))
        }
        let mut position: usize = self.hash_index(&key);
        for _ in 0..A {
            match &self.keys[position] {
                Some(existing_key) if *existing_key == key => {
                    self.vals[position] = Some(data);
                    return Ok(())
                },
                None => {
                    self.keys[position] = Some(key);
                    self.vals[position] = Some(data);
                    self.len += 1;
                    return Ok(())
                },
                _ => position = (position + 1) % A
            }
        }
        Err((key, data))
    }

    #[inline]
    pub fn remove(&mut self, key: &B) -> Option<C> {
        let mut pos = self.hash_index(key);
        for _ in 0..A {
            match self.keys[pos] {
                Some(k) if k == *key => {
                    let old_val = self.vals[pos].take();
                    self.keys[pos] = None;
                    self.len -= 1;

                    // Reinsert subsequent cluster keys to avoid lookup holes
                    let mut next = (pos + 1) % A;
                    while let Some(k) = self.keys[next] {
                        let val = self.vals[next].take().unwrap();
                        self.keys[next] = None;
                        self.len -= 1;
                        self.insert(k, val).unwrap();
                        next = (next + 1) % A;
                    }
                    return old_val;
                }
                None => return None,
                _ => pos = (pos + 1) % A,
            }
        }
        None
    }

    #[inline]
    fn hash_index(&self, key: &B) -> usize {
        let mut hasher: D = D::default();
        key.hash(&mut hasher);
        (
            hasher.finish() as usize
        ) % A
    }
}

impl<const A: usize, B, C, D> Default for Map<A, B, C, D> 
where
    B: Key,
    C: Val,
    D: Hasher {
    #[inline]
    fn default() -> Self {
        Self {
            keys: [None; A],
            vals: [None; A],
            len: 0,
            hasher: ::core::marker::PhantomData
        }
    }
}