Function addReference

plumbing/object/commit_walker.go:237–290

(
	repoStorer storage.Storer,
	commitIterFunc func(*Commit) CommitIter,
	ref *plumbing.Reference,
	commitsPath *list.List,
	commitsLookup map[plumbing.Hash]*list.Element)

}

func addReference(
	repoStorer storage.Storer,
	commitIterFunc func(*Commit) CommitIter,
	ref *plumbing.Reference,
	commitsPath *list.List,
	commitsLookup map[plumbing.Hash]*list.Element) error {

	_, exists := commitsLookup[ref.Hash()]
	if exists {
		// we already have it - skip the reference.
		return nil
	}

	refCommit, _ := GetCommit(repoStorer, ref.Hash())
	if refCommit == nil {
		// if it's not a commit - skip it.
		return nil
	}

	var (
		refCommits []*Commit
		parent     *list.Element
	)
	// collect all ref commits to add
	commitIter := commitIterFunc(refCommit)
	for c, e := commitIter.Next(); e == nil; {
		parent, exists = commitsLookup[c.Hash]
		if exists {
			break
		}
		refCommits = append(refCommits, c)
		c, e = commitIter.Next()
	}
	commitIter.Close()

	if parent == nil {
		// common parent - not found
		// add all commits to the path from this ref (maybe it's a HEAD and we don't have anything, yet)
		for _, c := range refCommits {
			parent = commitsPath.PushBack(c)
			commitsLookup[c.Hash] = parent
		}
	} else {
		// add ref's commits to the path in reverse order (from the latest)
		for i := len(refCommits) - 1; i >= 0; i-- {
			c := refCommits[i]
			// insert before found common parent
			parent = commitsPath.InsertBefore(c, parent)
			commitsLookup[c.Hash] = parent
		}
	}

	return nil
}

func (it *commitAllIterator) Next() (*Commit, error) {
	if it.currCommit == nil {