Give Object and Reference an Onwer accessor

This reduces the need to carry around a pointer to the repository as
well as the objects.

object.go

@@ -22,6 +22,7 @@ type Object interface {
 	Free()
 	Id() *Oid
 	Type() ObjectType
+	Owner() *Repository
 }
 
 type gitObject struct {
@@ -55,6 +56,14 @@ func (o gitObject) Type() ObjectType {
 	return ObjectType(C.git_object_type(o.ptr))
 }
 
+// Owner returns a weak reference to the repository which owns this
+// object
+func (o gitObject) Owner() *Repository {
+	return &Repository{
+		ptr: C.git_object_owner(o.ptr),
+	}
+}
+
 func (o *gitObject) Free() {
 	runtime.SetFinalizer(o, nil)
 	C.git_object_free(o.ptr)

object_test.go

@@ -75,3 +75,29 @@ func TestObjectPoymorphism(t *testing.T) {
 		t.Fatalf("Failed to parse the right revision")
 	}
 }
+
+func checkOwner(t *testing.T, repo *Repository, obj Object) {
+	owner := obj.Owner()
+	if owner == nil {
+		t.Fatal("bad owner")
+	}
+
+	if owner.ptr != repo.ptr {
+		t.Fatalf("bad owner, got %v expected %v\n", owner.ptr, repo.ptr)
+	}
+}
+
+func TestObjectOwner(t *testing.T) {
+	repo := createTestRepo(t)
+	defer os.RemoveAll(repo.Workdir())
+	commitId, treeId := seedTestRepo(t, repo)
+
+	commit, err := repo.LookupCommit(commitId)
+	checkFatal(t, err)
+
+	tree, err := repo.LookupTree(treeId)
+	checkFatal(t, err)
+
+	checkOwner(t, repo, commit)
+	checkOwner(t, repo, tree)
+}

reference.go

@@ -161,6 +161,14 @@ func (v *Reference) Peel(t ObjectType) (Object, error) {
 	return allocObject(cobj), nil
 }
 
+// Owner returns a weak reference to the repository which owns this
+// reference.
+func (v *Reference) Owner() *Repository {
+	return &Repository{
+		ptr: C.git_reference_owner(v.ptr),
+	}
+}
+
 // Cmp compares both references, retursn 0 on equality, otherwise a
 // stable sorting.
 func (v *Reference) Cmp(ref2 *Reference) int {

reference_test.go

@@ -138,6 +138,24 @@ func TestReferenceIterator(t *testing.T) {
 
 }
 
+func TestReferenceOwner(t *testing.T) {
+	repo := createTestRepo(t)
+	defer os.RemoveAll(repo.Workdir())
+	commitId, _ := seedTestRepo(t, repo)
+
+	ref, err := repo.CreateReference("refs/heads/foo", commitId, true, nil, "")
+	checkFatal(t, err)
+
+	owner := ref.Owner()
+	if owner == nil {
+		t.Fatal("nil owner")
+	}
+
+	if owner.ptr != repo.ptr {
+		t.Fatalf("bad ptr, expected %v have %v\n", repo.ptr, owner.ptr)
+	}
+}
+
 func TestUtil(t *testing.T) {
 	repo := createTestRepo(t)
 	defer os.RemoveAll(repo.Workdir())