[#164] sdk/object: Add HasParent method

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/object/raw.go

@@ -148,3 +148,8 @@ func (o *RawObject) CutPayload() *RawObject {
 func (o *RawObject) ResetRelations() {
 	o.resetRelations()
 }
+
+// InitRelations initializes relation field.
+func (o *RawObject) InitRelations() {
+	o.initRelations()
+}

pkg/object/raw_test.go

@@ -275,3 +275,15 @@ func TestRawObject_ResetRelations(t *testing.T) {
 
 	require.Nil(t, obj.GetPreviousID())
 }
+
+func TestRwObject_HasParent(t *testing.T) {
+	obj := NewRaw()
+
+	obj.InitRelations()
+
+	require.True(t, obj.HasParent())
+
+	obj.ResetRelations()
+
+	require.False(t, obj.HasParent())
+}

pkg/object/rw.go

@@ -296,6 +296,12 @@ func (o *rwObject) setParent(v *Object) {
 	})
 }
 
+func (o *rwObject) initRelations() {
+	o.setHeaderField(func(h *object.Header) {
+		h.SetSplit(new(object.SplitHeader))
+	})
+}
+
 func (o *rwObject) resetRelations() {
 	o.setHeaderField(func(h *object.Header) {
 		h.SetSplit(nil)
@@ -340,3 +346,9 @@ func (o *rwObject) cutPayload() *rwObject {
 
 	return (*rwObject)(ov2)
 }
+
+func (o *rwObject) HasParent() bool {
+	return (*object.Object)(o).
+		GetHeader().
+		GetSplit() != nil
+}