fix reference shortening

Implemented according to git shorten_unambiguous_ref.
See: https://github.com/git/git/blob/e0aaa1b6532cfce93d87af9bc813fb2e7a7ce9d7/refs.c#L1030

2 files changed, 23 insertions, 18 deletions

diff --git a/plumbing/reference.go b/plumbing/reference.go
index 8fa103e..5d477b9 100644
--- a/plumbing/reference.go
+++ b/plumbing/reference.go
@@ -15,15 +15,16 @@ const (
 	symrefPrefix    = "ref: "
 )
 
-var (
-	refPrefixes = []string{
-		refHeadPrefix,
-		refTagPrefix,
-		refRemotePrefix,
-		refNotePrefix,
-		refPrefix,
-	}
-)
+// refRevParseRules are a set of rules to parse references into short names.
+// These are the same rules as used by git in shorten_unambiguous_ref.
+// See: https://github.com/git/git/blob/e0aaa1b6532cfce93d87af9bc813fb2e7a7ce9d7/refs.c#L417
+var refRevParseRules = []string{
+	"refs/%s",
+	"refs/tags/%s",
+	"refs/heads/%s",
+	"refs/remotes/%s",
+	"refs/remotes/%s/HEAD",
+}
 
 var (
 	ErrReferenceNotFound = errors.New("reference not found")
@@ -60,17 +61,16 @@ func (r ReferenceName) String() string {
 
 // Short returns the short name of a ReferenceName
 func (r ReferenceName) Short() string {
-	return r.removeRefPrefix()
-}
-
-// Instead of hardcoding a number of components, we should remove the prefixes
-// refHeadPrefix, refTagPrefix, refRemotePrefix, refNotePrefix and refPrefix
-func (r ReferenceName) removeRefPrefix() string {
 	s := string(r)
-	for _, prefix := range refPrefixes {
-		s = strings.TrimPrefix(s, prefix)
+	res := s
+	for _, format := range refRevParseRules {
+		_, err := fmt.Sscanf(s, format, &res)
+		if err == nil {
+			continue
+		}
 	}
-	return s
+
+	return res
 }
 
 const (
diff --git a/plumbing/reference_test.go b/plumbing/reference_test.go
index 6a695f4..97c8772 100644
--- a/plumbing/reference_test.go
+++ b/plumbing/reference_test.go
@@ -23,6 +23,11 @@ func (s *ReferenceSuite) TestReferenceNameWithSlash(c *C) {
 	c.Assert(r.Short(), Equals, "origin/feature/AllowSlashes")
 }
 
+func (s *ReferenceSuite) TestReferenceNameNote(c *C) {
+	r := ReferenceName("refs/notes/foo")
+	c.Assert(r.Short(), Equals, "notes/foo")
+}
+
 func (s *ReferenceSuite) TestNewReferenceFromStrings(c *C) {
 	r := NewReferenceFromStrings("refs/heads/v4", "6ecf0ef2c2dffb796033e5a02219af86ec6584e5")
 	c.Assert(r.Type(), Equals, HashReference)