use std::collections::BTreeSet; use git_hash::ObjectId; use crate::{    peel,    raw::Reference,    store::{        file,        file::{log, loose::reference::logiter::must_be_io_err},        packed,    },    Target,}; pub trait Sealed {}impl Sealed for crate::Reference {} /// A trait to extend [Reference][crate::Reference] with functionality requiring a [file::Store].pub trait ReferenceExt: Sealed {    /// Obtain a reverse iterator over logs of this reference. See [crate::file::loose::Reference::log_iter_rev()] for details.    fn log_iter_rev<'b>(        &self,        store: &file::Store,        buf: &'b mut [u8],    ) -> std::io::Result<Option<log::iter::Reverse<'b, std::fs::File>>>;     /// Obtain an iterator over logs of this reference. See [crate::file::loose::Reference::log_iter()] for details.    fn log_iter<'a, 'b: 'a>(        &'a self,        store: &file::Store,        buf: &'b mut Vec<u8>,    ) -> std::io::Result<Option<log::iter::Forward<'b>>>;     /// For details, see [Reference::log_exists()].    fn log_exists(&self, store: &file::Store) -> bool;     /// For details, see [Reference::peel_to_id_in_place()].    fn peel_to_id_in_place<E: std::error::Error + Send + Sync + 'static>(        &mut self,        store: &file::Store,        packed: Option<&packed::Buffer>,        find: impl FnMut(git_hash::ObjectId, &mut Vec<u8>) -> Result<Option<(git_object::Kind, &[u8])>, E>,    ) -> Result<ObjectId, peel::to_id::Error>;     /// Follow this symbolic reference one level and return the ref it refers to,    /// possibly providing access to `packed` references for lookup if it contains the referent.    ///    /// Returns `None` if this is not a symbolic reference, hence the leaf of the chain.    fn follow(        &self,        store: &file::Store,        packed: Option<&packed::Buffer>,    ) -> Option<Result<Reference, file::find::existing::Error>>;} impl ReferenceExt for Reference {    fn log_iter_rev<'b>(        &self,        store: &file::Store,        buf: &'b mut [u8],    ) -> std::io::Result<Option<log::iter::Reverse<'b, std::fs::File>>> {        store.reflog_iter_rev(self.name.to_ref(), buf).map_err(must_be_io_err)    }     fn log_iter<'a, 'b: 'a>(        &'a self,        store: &file::Store,        buf: &'b mut Vec<u8>,    ) -> std::io::Result<Option<log::iter::Forward<'b>>> {        store.reflog_iter(self.name.to_ref(), buf).map_err(must_be_io_err)    }     fn log_exists(&self, store: &file::Store) -> bool {        store            .reflog_exists(self.name.to_ref())            .expect("infallible name conversion")    }     fn peel_to_id_in_place<E: std::error::Error + Send + Sync + 'static>(        &mut self,        store: &file::Store,        packed: Option<&packed::Buffer>,        mut find: impl FnMut(git_hash::ObjectId, &mut Vec<u8>) -> Result<Option<(git_object::Kind, &[u8])>, E>,    ) -> Result<ObjectId, peel::to_id::Error> {        match self.peeled {            Some(peeled) => {                self.target = Target::Peeled(peeled.to_owned());                Ok(peeled)            }            None => {                if self.target.kind() == crate::Kind::Symbolic {                    let mut seen = BTreeSet::new();                    let cursor = &mut *self;                    while let Some(next) = cursor.follow(store, packed) {                        let next = next?;                        if seen.contains(&next.name) {                            return Err(peel::to_id::Error::Cycle(store.base.join(cursor.name.to_path())));                        }                        *cursor = next;                        seen.insert(cursor.name.clone());                        const MAX_REF_DEPTH: usize = 5;                        if seen.len() == MAX_REF_DEPTH {                            return Err(peel::to_id::Error::DepthLimitExceeded {                                max_depth: MAX_REF_DEPTH,                            });                        }                    }                };                let mut buf = Vec::new();                let mut oid = self.target.as_id().expect("peeled ref").to_owned();                let peeled_id = loop {                    let (kind, data) = find(oid, &mut buf)                        .map_err(|err| Box::new(err) as Box<dyn std::error::Error + Send + Sync + 'static>)?                        .ok_or_else(|| peel::to_id::Error::NotFound {                            oid,                            name: self.name.0.clone(),                        })?;                    match kind {                        git_object::Kind::Tag => {                            oid = git_object::TagRefIter::from_bytes(data).target_id().ok_or_else(|| {                                peel::to_id::Error::NotFound {                                    oid,                                    name: self.name.0.clone(),                                }                            })?;                        }                        _ => break oid,                    };                };                self.peeled = Some(peeled_id);                self.target = Target::Peeled(peeled_id);                Ok(peeled_id)            }        }    }     fn follow(        &self,        store: &file::Store,        packed: Option<&packed::Buffer>,    ) -> Option<Result<Reference, file::find::existing::Error>> {        match self.peeled {            Some(peeled) => Some(Ok(Reference {                name: self.name.clone(),                target: Target::Peeled(peeled),                peeled: None,            })),            None => match &self.target {                Target::Peeled(_) => None,                Target::Symbolic(full_name) => {                    let path = full_name.to_path();                    match store.find_one_with_verified_input(path.as_ref(), packed) {                        Ok(Some(next)) => Some(Ok(next)),                        Ok(None) => Some(Err(file::find::existing::Error::NotFound(path.into_owned()))),                        Err(err) => Some(Err(file::find::existing::Error::Find(err))),                    }                }            },        }    }}