use std::convert::TryInto; use git_object::bstr::{BStr, BString, ByteSlice}; use crate::{store_impl::packed, FullNameRef, PartialNameRef}; /// packed-refs specific functionalityimpl packed::Buffer {    /// Find a reference with the given `name` and return it.    ///    /// Note that it will look it up verbatim and does not deal with namespaces or special prefixes like    /// `main-worktree/` or `worktrees/<name>/`, as this is left to the caller.    pub fn try_find<'a, Name, E>(&self, name: Name) -> Result<Option<packed::Reference<'_>>, Error>    where        Name: TryInto<&'a PartialNameRef, Error = E>,        Error: From<E>,    {        let name = name.try_into()?;        let mut buf = BString::default();        for inbetween in &["", "tags", "heads", "remotes"] {            let (name, was_absolute) = if name.looks_like_full_name() {                let name = FullNameRef::new_unchecked(name.as_bstr());                let name = match transform_full_name_for_lookup(name) {                    None => return Ok(None),                    Some(name) => name,                };                (name, true)            } else {                let full_name = name.construct_full_name_ref(true, inbetween, &mut buf);                (full_name, false)            };            match self.try_find_full_name(name)? {                Some(r) => return Ok(Some(r)),                None if was_absolute => return Ok(None),                None => continue,            }        }        Ok(None)    }     pub(crate) fn try_find_full_name(&self, name: &FullNameRef) -> Result<Option<packed::Reference<'_>>, Error> {        match self.binary_search_by(name.as_bstr()) {            Ok(line_start) => Ok(Some(                packed::decode::reference::<()>(&self.as_ref()[line_start..])                    .map_err(|_| Error::Parse)?                    .1,            )),            Err((parse_failure, _)) => {                if parse_failure {                    Err(Error::Parse)                } else {                    Ok(None)                }            }        }    }     /// Find a reference with the given `name` and return it.    pub fn find<'a, Name, E>(&self, name: Name) -> Result<packed::Reference<'_>, existing::Error>    where        Name: TryInto<&'a PartialNameRef, Error = E>,        Error: From<E>,    {        match self.try_find(name) {            Ok(Some(r)) => Ok(r),            Ok(None) => Err(existing::Error::NotFound),            Err(err) => Err(existing::Error::Find(err)),        }    }     /// Perform a binary search where `Ok(pos)` is the beginning of the line that matches `name` perfectly and `Err(pos)`    /// is the beginning of the line at which `name` could be inserted to still be in sort order.    pub(in crate::store_impl::packed) fn binary_search_by(&self, full_name: &BStr) -> Result<usize, (bool, usize)> {        let a = self.as_ref();        let search_start_of_record = |ofs: usize| {            a[..ofs]                .rfind(b"\n")                .and_then(|pos| {                    let candidate = pos + 1;                    a.get(candidate).and_then(|b| {                        if *b == b'^' {                            a[..pos].rfind(b"\n").map(|pos| pos + 1)                        } else {                            Some(candidate)                        }                    })                })                .unwrap_or(0)        };        let mut encountered_parse_failure = false;        a.binary_search_by_key(&full_name.as_ref(), |b: &u8| {            let ofs = b as *const u8 as usize - a.as_ptr() as usize;            let line = &a[search_start_of_record(ofs)..];            packed::decode::reference::<()>(line)                .map(|(_rest, r)| r.name.as_bstr().as_ref())                .map_err(|err| {                    encountered_parse_failure = true;                    err                })                .unwrap_or(&[])        })        .map(search_start_of_record)        .map_err(|pos| (encountered_parse_failure, search_start_of_record(pos)))    }} mod error {    use std::convert::Infallible;     /// The error returned by [`find()`][super::packed::Buffer::find()]    #[derive(Debug, thiserror::Error)]    #[allow(missing_docs)]    pub enum Error {        #[error("The ref name or path is not a valid ref name")]        RefnameValidation(#[from] crate::name::Error),        #[error("The reference could not be parsed")]        Parse,    }     impl From<Infallible> for Error {        fn from(_: Infallible) -> Self {            unreachable!("this impl is needed to allow passing a known valid partial path as parameter")        }    }}pub use error::Error; ///pub mod existing {     /// The error returned by [`find_existing()`][super::packed::Buffer::find()]    #[derive(Debug, thiserror::Error)]    #[allow(missing_docs)]    pub enum Error {        #[error("The find operation failed")]        Find(#[from] super::Error),        #[error("The reference did not exist even though that was expected")]        NotFound,    }} pub(crate) fn transform_full_name_for_lookup(name: &FullNameRef) -> Option<&FullNameRef> {    match name.category_and_short_name() {        Some((c, sn)) => {            use crate::Category::*;            Some(match c {                MainRef | LinkedRef { .. } => FullNameRef::new_unchecked(sn),                Tag | RemoteBranch | LocalBranch | Bisect | Rewritten | Note => name,                MainPseudoRef | PseudoRef | LinkedPseudoRef { .. } | WorktreePrivate => return None,            })        }        None => Some(name),    }}