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

//! File identifier definition

/// Unique file identifier
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[cfg_attr(feature = "serde", derive(rserde::Serialize, rserde::Deserialize))]
#[cfg_attr(feature = "serde", serde(crate = "rserde"))]
pub struct FileId(u32);

const MAX_VALUE: u32 = 0x7FFFFFFF;
const BUILTIN_BIT: u32 = 0x80000000;

impl FileId {
    /// Create a new file identifier
    ///
    /// # Panics
    ///
    /// panics if raw is greater than 0x7FFFFFFF
    pub fn new(raw: u32) -> Self {
        if raw > MAX_VALUE {
            panic!("file identifier is too large");
        }

        Self(raw)
    }

    /// Create a new file identifier for a built-in string
    ///
    /// # Panics
    ///
    /// panics if raw is greater than 0x7FFFFFFE
    pub fn builtin(raw: u32) -> Self {
        if raw > (MAX_VALUE - 1) {
            panic!("file identifier is too large");
        }

        Self(BUILTIN_BIT | (raw + 1))
    }

    /// Get the number behind this id, regardless of its type
    pub fn number(&self) -> u32 {
        if (self.0 & BUILTIN_BIT) == BUILTIN_BIT {
            let raw = self.0 & !BUILTIN_BIT;
            if raw == 0 {
                raw
            } else {
                raw - 1
            }
        } else {
            self.0
        }
    }
}

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

impl std::fmt::Display for FileId {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        if (self.0 & BUILTIN_BIT) == BUILTIN_BIT {
            let raw = self.0 & !BUILTIN_BIT;

            if raw == 0 {
                write!(f, "internal")
            } else {
                write!(f, "builtin-{}", raw - 1)
            }
        } else {
            write!(f, "{}", self.0)
        }
    }
}

impl From<u32> for FileId {
    fn from(value: u32) -> Self {
        Self(value)
    }
}

impl From<FileId> for u32 {
    fn from(value: FileId) -> Self {
        value.0
    }
}