use std::collections::BTreeSet; use git_hash::ObjectId; use crate::{    packed, peel,    raw::Reference,    store_impl::{file, file::log},    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 {    /// A step towards obtaining forward or reverse iterators on reference logs.    fn log_iter<'a, 's>(&'a self, store: &'s file::Store) -> log::iter::Platform<'a, 's>;     /// 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,        find: impl FnMut(git_hash::ObjectId, &mut Vec<u8>) -> Result<Option<(git_object::Kind, &[u8])>, E>,    ) -> Result<ObjectId, peel::to_id::Error>;     /// For details, see [Reference::peel_to_id_in_place()], with support for a known stable packed buffer.    fn peel_to_id_in_place_packed<E: std::error::Error + Send + Sync + 'static>(        &mut self,        store: &file::Store,        find: impl FnMut(git_hash::ObjectId, &mut Vec<u8>) -> Result<Option<(git_object::Kind, &[u8])>, E>,        packed: Option<&packed::Buffer>,    ) -> Result<ObjectId, peel::to_id::Error>;     /// Follow this symbolic reference one level and return the ref it refers to.    ///    /// Returns `None` if this is not a symbolic reference, hence the leaf of the chain.    fn follow(&self, store: &file::Store) -> Option<Result<Reference, file::find::existing::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_packed(        &self,        store: &file::Store,        packed: Option<&packed::Buffer>,    ) -> Option<Result<Reference, file::find::existing::Error>>;} impl ReferenceExt for Reference {    fn log_iter<'a, 's>(&'a self, store: &'s file::Store) -> log::iter::Platform<'a, 's> {        log::iter::Platform {            store,            name: self.name.as_ref(),            buf: Vec::new(),        }    }     fn log_exists(&self, store: &file::Store) -> bool {        store            .reflog_exists(self.name.as_ref())            .expect("infallible name conversion")    }     fn peel_to_id_in_place<E: std::error::Error + Send + Sync + 'static>(        &mut self,        store: &file::Store,        find: impl FnMut(git_hash::ObjectId, &mut Vec<u8>) -> Result<Option<(git_object::Kind, &[u8])>, E>,    ) -> Result<ObjectId, peel::to_id::Error> {        let packed = store.assure_packed_refs_uptodate().map_err(|err| {            peel::to_id::Error::Follow(file::find::existing::Error::Find(file::find::Error::PackedOpen(err)))        })?;        self.peel_to_id_in_place_packed(store, find, packed.as_deref())    }     fn peel_to_id_in_place_packed<E: std::error::Error + Send + Sync + 'static>(        &mut self,        store: &file::Store,        mut find: impl FnMut(git_hash::ObjectId, &mut Vec<u8>) -> Result<Option<(git_object::Kind, &[u8])>, E>,        packed: Option<&packed::Buffer>,    ) -> 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_packed(store, packed) {                        let next = next?;                        if seen.contains(&next.name) {                            return Err(peel::to_id::Error::Cycle(store.reference_path(cursor.name.as_ref())));                        }                        *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.try_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().map_err(|_err| {                                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) -> Option<Result<Reference, file::find::existing::Error>> {        let packed = match store            .assure_packed_refs_uptodate()            .map_err(|err| file::find::existing::Error::Find(file::find::Error::PackedOpen(err)))        {            Ok(packed) => packed,            Err(err) => return Some(Err(err)),        };        self.follow_packed(store, packed.as_deref())    }     fn follow_packed(        &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) => match store.try_find_packed(full_name.as_ref(), packed) {                    Ok(Some(next)) => Some(Ok(next)),                    Ok(None) => Some(Err(file::find::existing::Error::NotFound(                        full_name.to_path().to_owned(),                    ))),                    Err(err) => Some(Err(file::find::existing::Error::Find(err))),                },            },        }    }}