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

use std::marker::PhantomData;
use std::u32::MAX;
use std::hash;
use std::fmt;
use std::cmp::Ordering;

#[derive(Serialize, Deserialize)]
pub struct Id<T> {
    index: u32,
    #[serde(skip)]
    marker: PhantomData<T>,
}

impl<T> Id<T> {
    pub fn invalid() -> Self {
        Self::new(MAX)
    }

    pub fn is_invalid(&self) -> bool {
        self.index == MAX
    }

    pub fn is_valid(&self) -> bool {
        self.index != MAX
    }

    pub fn cast<U>(&self) -> Id<U> {
        Id::new(self.index)
    }

    fn new(index: u32) -> Self {
        Self { index, marker: PhantomData }
    }
}

impl<T> Copy for Id<T> {}

impl<T> Clone for Id<T> {
    fn clone(&self) -> Self {
        *self
    }
}

impl<T> PartialEq for Id<T> {
    fn eq(&self, other: &Self) -> bool {
        self.index == other.index
    }
}

impl<T> Eq for Id<T> {}

impl<T> PartialOrd for Id<T> {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        self.index.partial_cmp(&other.index)
    }
}

impl<T> Ord for Id<T> {
    fn cmp(&self, other: &Self) -> Ordering {
        self.index.cmp(&other.index)
    }
}

impl<T> hash::Hash for Id<T> {
    fn hash<H: hash::Hasher>(&self, hasher: &mut H) {
        self.index.hash(hasher);
    }
}

impl<T> fmt::Debug for Id<T> {
    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        write!(formatter, "Id[{}]", self.index)
    }
}

impl<T> From<usize> for Id<T> {
    fn from(index: usize) -> Self {
        if index >= MAX as usize {
            Self::invalid()
        } else {
            Self::new(index as u32)
        }
    }
}

impl<T> Into<usize> for Id<T> {
    fn into(self) -> usize {
        self.index as usize
    }
}