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

use sanakirja::{Representable, Alignment};
use std;
use bs58;

// Patch Identifiers.
pub const PATCH_ID_SIZE: usize = 8;
pub const ROOT_PATCH_ID: PatchId = PatchId([0; PATCH_ID_SIZE]);
pub const P_ROOT_PATCH_ID: &'static PatchId = &PatchId([0; PATCH_ID_SIZE]);

/// An internal patch identifier, less random than external patch
/// identifiers, but more stable in time, and much smaller.
#[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Hash, Serialize, Deserialize)]
pub struct PatchId([u8; PATCH_ID_SIZE]);

impl std::fmt::Debug for PatchId {
    fn fmt(&self, fmt: &mut std::fmt::Formatter) -> std::fmt::Result {
        write!(fmt, "PatchId({})", self.to_base58())
    }
}

use hex::ToHex;
impl ToHex for PatchId {
    fn to_hex(&self) -> String {
        self.0.to_hex()
    }
}
impl PatchId {
    /// New patch id (initialised to 0).
    pub fn new() -> Self {
        PatchId([0; PATCH_ID_SIZE])
    }
    /// Encode this patch id in base58.
    pub fn to_base58(&self) -> String {
        bs58::encode(&self.0).into_string()
    }
    /// Decode this patch id from its base58 encoding.
    pub fn from_base58(s: &str) -> Option<Self> {
        let mut p = PatchId::new();
        if bs58::decode(s).into(&mut p.0).is_ok() {
            Some(p)
        } else {
            None
        }
    }
}

impl std::ops::Deref for PatchId {
    type Target = [u8];
    fn deref(&self) -> &Self::Target {
        &self.0
    }
}
impl std::ops::DerefMut for PatchId {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.0
    }
}
#[derive(Debug, Clone, Copy)]
pub struct UnsafePatchId(*const PatchId);

impl Representable for UnsafePatchId {
    fn alignment() -> Alignment {
        Alignment::B1
    }
    fn onpage_size(&self) -> u16 {
        std::mem::size_of::<PatchId>() as u16
    }
    unsafe fn write_value(&self, p: *mut u8) {
        trace!("write_value {:?}", p);
        std::ptr::copy(self.0, p as *mut PatchId, 1)
    }
    unsafe fn read_value(p: *const u8) -> Self {
        trace!("read_value {:?}", p);
        UnsafePatchId(p as *const PatchId)
    }
    unsafe fn cmp_value<T>(&self, _: &T, x: Self) -> std::cmp::Ordering {
        let a: &PatchId = &*self.0;
        let b: &PatchId = PatchId::from_unsafe(x);
        a.cmp(b)
    }
    type PageOffsets = std::iter::Empty<u64>;
    fn page_offsets(&self) -> Self::PageOffsets { std::iter::empty() }
}
impl PatchId {
    #[doc(hidden)]
    pub fn to_unsafe(&self) -> UnsafePatchId {
        UnsafePatchId(self)
    }
    #[doc(hidden)]
    pub unsafe fn from_unsafe<'a>(p: UnsafePatchId) -> &'a PatchId {
        &*p.0
    }
}