use std::{convert::TryFrom, str::FromStr}; use crate::{oid, Kind, ObjectId}; impl Default for Kind {    fn default() -> Self {        Kind::Sha1    }} impl TryFrom<u8> for Kind {    type Error = u8;     fn try_from(value: u8) -> Result<Self, Self::Error> {        Ok(match value {            1 => Kind::Sha1,            unknown => return Err(unknown),        })    }} impl FromStr for Kind {    type Err = String;     fn from_str(s: &str) -> Result<Self, Self::Err> {        Ok(match s {            "sha1" | "SHA1" => Kind::Sha1,            other => return Err(other.into()),        })    }} impl std::fmt::Display for Kind {    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {        match self {            Kind::Sha1 => f.write_str("SHA1"),        }    }} impl Kind {    /// Returns the shortest hash we support    #[inline]    pub const fn shortest() -> Self {        Self::Sha1    }     /// Returns the longest hash we support    #[inline]    pub const fn longest() -> Self {        Self::Sha1    }     /// Returns a buffer suitable to hold the longest possible hash in hex.    #[inline]    pub const fn hex_buf() -> [u8; Kind::longest().len_in_hex()] {        [0u8; Kind::longest().len_in_hex()]    }     /// Returns a buffer suitable to hold the longest possible hash as raw bytes.    #[inline]    pub const fn buf() -> [u8; Kind::longest().len_in_bytes()] {        [0u8; Kind::longest().len_in_bytes()]    }     /// Returns the amount of ascii-characters needed to encode this has in hex    #[inline]    pub const fn len_in_hex(&self) -> usize {        match self {            Kind::Sha1 => 40,        }    }    /// Returns the amount of bytes taken up by the hash of the current kind    #[inline]    pub const fn len_in_bytes(&self) -> usize {        match self {            Kind::Sha1 => 20,        }    }     /// Returns the kind of hash that would fit the given `hex_len`, or `None` if there is no fitting hash.    /// Note that 0 as `hex_len` fits always yields Sha1.    #[inline]    pub const fn from_hex_len(hex_len: usize) -> Option<Self> {        Some(match hex_len {            0..=40 => Kind::Sha1,            _ => return None,        })    }     /// Converts a size in bytes as obtained by `Kind::len_in_bytes()` into the corresponding hash kind, if possible.    ///    /// **Panics** if the hash length doesn't match a known hash.    ///    /// NOTE that this method isn't public as it shouldn't be encouraged to assume all hashes have the same length.    /// However, if there should be such a thing, our `oid` implementation will have to become an enum and it's pretty breaking    /// to the way it's currently being used as auto-dereffing doesn't work anymore. Let's hope it won't happen.    // TODO: make 'const' once Rust 1.57 is more readily available in projects using 'gitoxide'.    #[inline]    pub(crate) fn from_len_in_bytes(bytes: usize) -> Self {        match bytes {            20 => Kind::Sha1,            _ => panic!("BUG: must be called only with valid hash lengths produced by len_in_bytes()"),        }    }     /// Create a null-id of our hash kind.    #[inline]    pub fn null_ref(&self) -> &'static oid {        match self {            Kind::Sha1 => oid::null_sha1(),        }    }     /// Create a null-id of our hash kind.    #[inline]    pub const fn null(&self) -> ObjectId {        match self {            Kind::Sha1 => ObjectId::null_sha1(),        }    }}