gix_hash/
kind.rs

1use std::str::FromStr;
2
3use crate::{oid, Kind, ObjectId};
4
5impl TryFrom<u8> for Kind {
6    type Error = u8;
7
8    fn try_from(value: u8) -> Result<Self, Self::Error> {
9        Ok(match value {
10            1 => Kind::Sha1,
11            unknown => return Err(unknown),
12        })
13    }
14}
15
16impl FromStr for Kind {
17    type Err = String;
18
19    fn from_str(s: &str) -> Result<Self, Self::Err> {
20        Ok(match s {
21            "sha1" | "SHA1" => Kind::Sha1,
22            other => return Err(other.into()),
23        })
24    }
25}
26
27impl std::fmt::Display for Kind {
28    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
29        match self {
30            Kind::Sha1 => f.write_str("SHA1"),
31        }
32    }
33}
34
35impl Kind {
36    /// Returns the shortest hash we support.
37    #[inline]
38    pub const fn shortest() -> Self {
39        Self::Sha1
40    }
41
42    /// Returns the longest hash we support.
43    #[inline]
44    pub const fn longest() -> Self {
45        Self::Sha1
46    }
47
48    /// Returns a buffer suitable to hold the longest possible hash in hex.
49    #[inline]
50    pub const fn hex_buf() -> [u8; Kind::longest().len_in_hex()] {
51        [0u8; Kind::longest().len_in_hex()]
52    }
53
54    /// Returns a buffer suitable to hold the longest possible hash as raw bytes.
55    #[inline]
56    pub const fn buf() -> [u8; Kind::longest().len_in_bytes()] {
57        [0u8; Kind::longest().len_in_bytes()]
58    }
59
60    /// Returns the amount of bytes needed to encode this instance as hexadecimal characters.
61    #[inline]
62    pub const fn len_in_hex(&self) -> usize {
63        match self {
64            Kind::Sha1 => 40,
65        }
66    }
67    /// Returns the amount of bytes taken up by the hash of this instance.
68    #[inline]
69    pub const fn len_in_bytes(&self) -> usize {
70        match self {
71            Kind::Sha1 => 20,
72        }
73    }
74
75    /// Returns the kind of hash that would fit the given `hex_len`, or `None` if there is no fitting hash.
76    /// Note that `0` as `hex_len` up to 40 always yields `Sha1`.
77    #[inline]
78    pub const fn from_hex_len(hex_len: usize) -> Option<Self> {
79        Some(match hex_len {
80            0..=40 => Kind::Sha1,
81            _ => return None,
82        })
83    }
84
85    /// Converts a size in bytes as obtained by `Kind::len_in_bytes()` into the corresponding hash kind, if possible.
86    ///
87    /// **Panics** if the hash length doesn't match a known hash.
88    ///
89    /// NOTE that this method isn't public as it shouldn't be encouraged to assume all hashes have the same length.
90    /// However, if there should be such a thing, our `oid` implementation will have to become an enum and it's pretty breaking
91    /// to the way it's currently being used as auto-dereffing doesn't work anymore. Let's hope it won't happen.
92    // TODO: make 'const' once Rust 1.57 is more readily available in projects using 'gitoxide'.
93    #[inline]
94    pub(crate) fn from_len_in_bytes(bytes: usize) -> Self {
95        match bytes {
96            20 => Kind::Sha1,
97            _ => panic!("BUG: must be called only with valid hash lengths produced by len_in_bytes()"),
98        }
99    }
100
101    /// Create a shared null-id of our hash kind.
102    #[inline]
103    pub fn null_ref(&self) -> &'static oid {
104        match self {
105            Kind::Sha1 => oid::null_sha1(),
106        }
107    }
108
109    /// Create an owned null-id of our hash kind.
110    #[inline]
111    pub const fn null(&self) -> ObjectId {
112        match self {
113            Kind::Sha1 => ObjectId::null_sha1(),
114        }
115    }
116}
gix_hash/kind.rs

gix_hash/
kind.rs
