/// Find the [`Job`]s that are associated with the `wanted` commit.

    pub fn find_by_commit(&self, wanted: Oid) -> Result<FindByCommit<'a>, store::Error> {

        FindByCommit::new(self, wanted)

    }

}

/// [`Iterator`] for finding each [`Job`] where the [`Job::oid`] matches the

/// wanted commit. See [`Jobs::find_by_commit`].

pub struct FindByCommit<'a> {

    jobs: Box<dyn Iterator<Item = Result<(ObjectId, Job), cob::store::Error>> + 'a>,

    needle: Oid,

}

impl<'a> FindByCommit<'a> {

    fn new<R>(jobs: &Jobs<'a, R>, needle: Oid) -> Result<Self, cob::store::Error>

    where

        R: ReadRepository + cob::Store<Namespace = NodeId>,

    {

        Ok(Self {

            jobs: Box::new(jobs.all()?),

            needle,

        })

    }

    fn wanted(&self, job: &Job) -> bool {

        self.needle == *job.oid()

    }

}

impl Iterator for FindByCommit<'_> {

    type Item = Result<(JobId, Job), cob::store::Error>;

    fn next(&mut self) -> Option<Self::Item> {

        let job = self.jobs.next()?;

        job.and_then(|(id, job)| {

            if self.wanted(&job) {

                Ok(Some((JobId::from(id), job)))

            } else {

                self.next().transpose()

            }

        })

        .transpose()

    }