use crate::SHA1_SIZE;use bstr::ByteSlice;use std::convert::{TryFrom, TryInto};use std::fmt; /// A borrowed reference to a hash identifying objects#[derive(PartialEq, Eq, Debug, Hash, Ord, PartialOrd, Clone, Copy)]#[cfg_attr(feature = "serde1", derive(serde::Serialize))]pub struct Id<'a>(&'a [u8; SHA1_SIZE]); /// Accessimpl<'a> Id<'a> {    /// The kind of hash used for this Id    pub fn kind(&self) -> crate::HashKind {        crate::HashKind::Sha1    }    /// The first byte of the hash, commonly used to partition a set of `Id`s    pub fn first_byte(&self) -> u8 {        self.0[0]    }} /// Sha1 specific methodsimpl<'a> Id<'a> {    /// Returns an array with a hexadecimal encoded version of the Sha1 hash this `Id` represents.    ///    /// **Panics** if this is not a Sha1 hash, as identifiable by [`Id::kind()`].    pub fn to_sha1_hex(&self) -> [u8; SHA1_SIZE * 2] {        let mut buf = [0u8; SHA1_SIZE * 2];        hex::encode_to_slice(self.0, &mut buf).expect("to count correctly");        buf    }     /// Returns the bytes making up the Sha1.    ///    /// **Panics** if this is not a Sha1 hash, as identifiable by [`Id::kind()`].    pub fn sha1(&self) -> &[u8; SHA1_SIZE] {        self.0    }     /// Returns a Sha1 Id with all bytes being initialized to zero.    pub fn null_sha1() -> Self {        Id(&[0u8; SHA1_SIZE])    }} impl<'a> From<&'a [u8; SHA1_SIZE]> for Id<'a> {    fn from(v: &'a [u8; SHA1_SIZE]) -> Self {        Id(v)    }} impl<'a> TryFrom<&'a [u8]> for Id<'a> {    type Error = std::array::TryFromSliceError;     fn try_from(value: &'a [u8]) -> Result<Self, Self::Error> {        Ok(Id(value.try_into()?))    }} impl fmt::Display for Id<'_> {    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {        write!(f, "{}", &self.to_sha1_hex().as_bstr())    }} /// Manually created from a version that uses a slice, and we forcefully try to convert it into a borrowed array of the desired size/// Could be improved by fitting this into serde/// Unfortunately the serde::Deserialize derive wouldn't work for borrowed arrays.#[cfg(feature = "serde1")]impl<'de: 'a, 'a> serde::Deserialize<'de> for Id<'a> {    fn deserialize<D>(deserializer: D) -> Result<Self, <D as serde::Deserializer<'de>>::Error>    where        D: serde::Deserializer<'de>,    {        struct __Visitor<'de: 'a, 'a> {            marker: serde::export::PhantomData<Id<'a>>,            lifetime: serde::export::PhantomData<&'de ()>,        }        impl<'de: 'a, 'a> serde::de::Visitor<'de> for __Visitor<'de, 'a> {            type Value = Id<'a>;            fn expecting(&self, __formatter: &mut serde::export::Formatter<'_>) -> serde::export::fmt::Result {                serde::export::Formatter::write_str(__formatter, "tuple struct Id")            }            #[inline]            fn visit_newtype_struct<__E>(self, __e: __E) -> serde::export::Result<Self::Value, __E::Error>            where                __E: serde::Deserializer<'de>,            {                let __field0: &'a [u8] = match <&'a [u8] as serde::Deserialize>::deserialize(__e) {                    serde::export::Ok(__val) => __val,                    serde::export::Err(__err) => {                        return serde::export::Err(__err);                    }                };                serde::export::Ok(Id(__field0.try_into().expect("exactly 20 bytes")))            }            #[inline]            fn visit_seq<__A>(self, mut __seq: __A) -> serde::export::Result<Self::Value, __A::Error>            where                __A: serde::de::SeqAccess<'de>,            {                let __field0 = match match serde::de::SeqAccess::next_element::<&'a [u8]>(&mut __seq) {                    serde::export::Ok(__val) => __val,                    serde::export::Err(__err) => {                        return serde::export::Err(__err);                    }                } {                    serde::export::Some(__value) => __value,                    serde::export::None => {                        return serde::export::Err(serde::de::Error::invalid_length(                            0usize,                            &"tuple struct Id with 1 element",                        ));                    }                };                serde::export::Ok(Id(__field0.try_into().expect("exactly 20 bytes")))            }        }        serde::Deserializer::deserialize_newtype_struct(            deserializer,            "Id",            __Visitor {                marker: serde::export::PhantomData::<Id<'a>>,                lifetime: serde::export::PhantomData,            },        )    }}