use std::convert::TryInto; use git_hash::{oid, ObjectId};use git_odb::{Find, FindExt};use git_ref::{    transaction::{LogChange, PreviousValue, RefLog},    FullName,}; use crate::{commit, ext::ObjectIdExt, object, tag, Id, Object, Reference}; /// Methods related to object creation.impl crate::Repository {    /// Find the object with `id` in the object database or return an error if it could not be found.    ///    /// There are various legitimate reasons for an object to not be present, which is why    /// [`try_find_object(…)`][crate::Repository::try_find_object()] might be preferable instead.    ///    /// # Important    ///    /// As a shared buffer is written to back the object data, the returned `ObjectRef` will prevent other    /// `find_object()` operations from succeeding while alive.    /// To bypass this limit, clone this `sync::Handle` instance.    ///    /// # Performance Note    ///    /// In order to get the kind of the object, is must be fully decoded from storage if it is packed with deltas.    /// Loose object could be partially decoded, even though that's not implemented.    pub fn find_object(&self, id: impl Into<ObjectId>) -> Result<Object<'_>, object::find::existing::OdbError> {        let id = id.into();        let mut buf = self.free_buf();        let kind = self.objects.find(&id, &mut buf)?.kind;        Ok(Object::from_data(id, kind, buf, self))    }     /// Try to find the object with `id` or return `None` it it wasn't found.    ///    /// # Important    ///    /// As a shared buffer is written to back the object data, the returned `ObjectRef` will prevent other    /// `try_find_object()` operations from succeeding while alive.    /// To bypass this limit, clone this `sync::Handle` instance.    pub fn try_find_object(&self, id: impl Into<ObjectId>) -> Result<Option<Object<'_>>, object::find::OdbError> {        let state = self;        let id = id.into();         let mut buf = state.free_buf();        match self.objects.try_find(&id, &mut buf)? {            Some(obj) => {                let kind = obj.kind;                drop(obj);                Ok(Some(Object::from_data(id, kind, buf, self)))            }            None => Ok(None),        }    }     /// Write the given object into the object database and return its object id.    pub fn write_object(&self, object: impl git_object::WriteTo) -> Result<Id<'_>, object::write::Error> {        use git_odb::Write;         let state = self;        state            .objects            .write(object)            .map(|oid| oid.attach(self))            .map_err(Into::into)    }     /// Create a tag reference named `name` (without `refs/tags/` prefix) pointing to a newly created tag object    /// which in turn points to `target` and return the newly created reference.    ///    /// It will be created with `constraint` which is most commonly to [only create it][PreviousValue::MustNotExist]    /// or to [force overwriting a possibly existing tag](PreviousValue::Any).    pub fn tag(        &self,        name: impl AsRef<str>,        target: impl AsRef<oid>,        target_kind: git_object::Kind,        tagger: Option<git_actor::SignatureRef<'_>>,        message: impl AsRef<str>,        constraint: PreviousValue,    ) -> Result<Reference<'_>, tag::Error> {        // NOTE: This could be more efficient if we use a TagRef instead.        let tag = git_object::Tag {            target: target.as_ref().into(),            target_kind,            name: name.as_ref().into(),            tagger: tagger.map(|t| t.to_owned()),            message: message.as_ref().into(),            pgp_signature: None,        };        let tag_id = self.write_object(&tag)?;        self.tag_reference(name, tag_id, constraint).map_err(Into::into)    }     /// Create a new commit object with `author`, `committer` and `message` referring to `tree` with `parents`, and point `reference`    /// to it. The commit is written without message encoding field, which can be assumed to be UTF-8.    ///    /// `reference` will be created if it doesn't exist, and can be `"HEAD"` to automatically write-through to the symbolic reference    /// that `HEAD` points to if it is not detached. For this reason, detached head states cannot be created unless the `HEAD` is detached    /// already. The reflog will be written as canonical git would do, like `<operation> (<detail>): <summary>`.    ///    /// The first parent id in `parents` is expected to be the current target of `reference` and the operation will fail if it is not.    /// If there is no parent, the `reference` is expected to not exist yet.    ///    /// The method fails immediately if a `reference` lock can't be acquired.    pub fn commit<Name, E>(        &self,        reference: Name,        author: git_actor::SignatureRef<'_>,        committer: git_actor::SignatureRef<'_>,        message: impl AsRef<str>,        tree: impl Into<ObjectId>,        parents: impl IntoIterator<Item = impl Into<ObjectId>>,    ) -> Result<Id<'_>, commit::Error>    where        Name: TryInto<FullName, Error = E>,        commit::Error: From<E>,    {        use git_ref::{            transaction::{Change, RefEdit},            Target,        };         // TODO: possibly use CommitRef to save a few allocations (but will have to allocate for object ids anyway.        //       This can be made vastly more efficient though if we wanted to, so we lie in the API        let reference = reference.try_into()?;        let commit = git_object::Commit {            message: message.as_ref().into(),            tree: tree.into(),            author: author.to_owned(),            committer: committer.to_owned(),            encoding: None,            parents: parents.into_iter().map(|id| id.into()).collect(),            extra_headers: Default::default(),        };         let commit_id = self.write_object(&commit)?;        self.edit_reference(            RefEdit {                change: Change::Update {                    log: LogChange {                        mode: RefLog::AndReference,                        force_create_reflog: false,                        message: crate::reference::log::message(                            "commit",                            commit.message.as_ref(),                            commit.parents.len(),                        ),                    },                    expected: match commit.parents.get(0).map(|p| Target::Peeled(*p)) {                        Some(previous) => {                            if reference.as_bstr() == "HEAD" {                                PreviousValue::MustExistAndMatch(previous)                            } else {                                PreviousValue::ExistingMustMatch(previous)                            }                        }                        None => PreviousValue::MustNotExist,                    },                    new: Target::Peeled(commit_id.inner),                },                name: reference,                deref: true,            },            git_lock::acquire::Fail::Immediately,            Some(&commit.committer),        )?;        Ok(commit_id)    }}