use crate::{    extension::{Link, Signature},    util::split_at_pos,}; /// The signature of the link extension.pub const SIGNATURE: Signature = *b"link"; /// Bitmaps to know which entries to delete or replace, even though details are still unknown.#[derive(Clone)]pub struct Bitmaps {    /// A bitmap to signal which entries to delete, maybe.    pub delete: git_bitmap::ewah::Vec,    /// A bitmap to signal which entries to replace, maybe.    pub replace: git_bitmap::ewah::Vec,} ///pub mod decode {     /// The error returned when decoding link extensions.    #[derive(Debug, thiserror::Error)]    #[allow(missing_docs)]    pub enum Error {        #[error("{0}")]        Corrupt(&'static str),        #[error("{kind} bitmap corrupt")]        BitmapDecode {            err: git_bitmap::ewah::decode::Error,            kind: &'static str,        },    }} pub(crate) fn decode(data: &[u8], object_hash: git_hash::Kind) -> Result<Link, decode::Error> {    let (id, data) = split_at_pos(data, object_hash.len_in_bytes())        .ok_or(decode::Error::Corrupt(            "link extension too short to read share index checksum",        ))        .map(|(id, d)| (git_hash::ObjectId::from(id), d))?;     if data.is_empty() {        return Ok(Link {            shared_index_checksum: id,            bitmaps: None,        });    }     let (delete, data) =        git_bitmap::ewah::decode(data).map_err(|err| decode::Error::BitmapDecode { kind: "delete", err })?;    let (replace, data) =        git_bitmap::ewah::decode(data).map_err(|err| decode::Error::BitmapDecode { kind: "replace", err })?;     if !data.is_empty() {        return Err(decode::Error::Corrupt("garbage trailing link extension"));    }     Ok(Link {        shared_index_checksum: id,        bitmaps: Some(Bitmaps { delete, replace }),    })}