vendor/gix-hash/src/kind.rs

   1 use std::{convert::TryFrom, str::FromStr};
   2
   3 use crate::{oid, Kind, ObjectId};
   4
   5 impl 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
  16 impl 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
  27 impl 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
  35 impl 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 ascii-characters needed to encode this has in hex.
  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 the current kind.
  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` fits 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 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 a 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 }