use crate::{borrowed, SIZE_OF_SHA1_DIGEST};use bstr::ByteSlice;use quick_error::quick_error;use std::{fmt, io, ops::Deref}; quick_error! {    /// An error returned by [`Digest::from_40_bytes_in_hex()`]    #[derive(Debug)]    #[allow(missing_docs)]    pub enum Error {        HexDecode(err: String) {            display("Failed to hex hash: {}", err)        }    }} /// An owned hash identifying objects, most commonly Sha1#[derive(PartialEq, Eq, Debug, Hash, Ord, PartialOrd, Clone, Copy)]#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]pub struct Digest([u8; SIZE_OF_SHA1_DIGEST]); /// Access and conversionimpl Digest {    /// Returns the kind of hash used in this `Digest`    pub fn kind(&self) -> crate::Kind {        crate::Kind::Sha1    }    /// Return a borrowed version of this instance    pub fn to_borrowed(&self) -> borrowed::Digest<'_> {        borrowed::Digest::from(&self.0)    }    /// Return the raw byte slice representing this hash    pub fn as_slice(&self) -> &[u8] {        self.0.as_ref()    }    /// Return the raw mutable byte slice representing this hash    pub fn as_mut_slice(&mut self) -> &mut [u8] {        self.0.as_mut()    }     /// Write ourselves to `out` in hexadecimal notation    pub fn write_hex_to(&self, mut out: impl io::Write) -> io::Result<()> {        out.write_all(&self.to_sha1_hex())    }} /// Sha1 hash specific methodsimpl Digest {    /// Create an instance from a `buffer` of 40 bytes encoded with hexadecimal notation.    ///    /// Such a buffer can be obtained using [`write_hex_to(buffer)`][Digest::write_hex_to()]    pub fn from_40_bytes_in_hex(buffer: &[u8]) -> Result<Digest, Error> {        use hex::FromHex;        Ok(Digest(            <[u8; 20]>::from_hex(buffer).map_err(|err| Error::HexDecode(err.to_string()))?,        ))    }    /// Returns ourselves as slice of 20 bytes.    ///    /// Panics if this instance is not a sha1 hash.    pub fn sha1(&self) -> &[u8; SIZE_OF_SHA1_DIGEST] {        &self.0    }     /// Return ourselves as array of 40 hexadecimal bytes.    ///    /// Panics if this instance is not a sha1 hash.    pub fn to_sha1_hex(&self) -> [u8; SIZE_OF_SHA1_DIGEST * 2] {        let mut hex_buf = [0u8; 40];        hex::encode_to_slice(self.0, &mut hex_buf).expect("we can count");        hex_buf    }     /// Return ourselves as hexadecimal string with a length of 40 bytes.    ///    /// Panics if this instance is not a sha1 hash.    pub fn to_sha1_hex_string(&self) -> String {        let buf = self.to_sha1_hex();        std::str::from_utf8(&buf).expect("hex is valid UTF-8").to_string()    }     /// Instantiate an Digest from 20 bytes of a Sha1 digest.    pub fn new_sha1(id: [u8; SIZE_OF_SHA1_DIGEST]) -> Self {        Digest(id)    }     /// Instantiate an Digest from a slice 20 borrowed bytes of a Sha1 digest.    ///    /// Panics of the slice doesn't have a length of 20.    pub fn from_20_bytes(b: &[u8]) -> Digest {        let mut id = [0; SIZE_OF_SHA1_DIGEST];        id.copy_from_slice(b);        Digest(id)    }     /// Instantiate an Digest from a borrowed array of 20 bytes of a Sha1 digest.    pub fn from_borrowed_sha1(b: &[u8; SIZE_OF_SHA1_DIGEST]) -> Digest {        let mut id = [0; SIZE_OF_SHA1_DIGEST];        id.copy_from_slice(&b[..]);        Digest(id)    }     /// Returns an Digest representing a Sha1 with whose memory is zeroed.    pub fn null_sha1() -> Digest {        Digest([0u8; 20])    }} impl From<[u8; SIZE_OF_SHA1_DIGEST]> for Digest {    fn from(v: [u8; 20]) -> Self {        Self::new_sha1(v)    }} impl Deref for Digest {    type Target = [u8; SIZE_OF_SHA1_DIGEST];     fn deref(&self) -> &Self::Target {        &self.0    }} impl fmt::Display for Digest {    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {        write!(f, "{}", &self.to_sha1_hex().as_bstr())    }}