[#420] Using tree service to list object versions

Signed-off-by: Denis Kirillov <denis@nspcc.ru>

api/data/tree.go

@@ -0,0 +1,37 @@
+package data
+
+import (
+	"time"
+
+	oid "github.com/nspcc-dev/neofs-sdk-go/object/id"
+	"github.com/nspcc-dev/neofs-sdk-go/user"
+)
+
+// NodeVersion represent node from tree service.
+type NodeVersion struct {
+	BaseNodeVersion
+	DeleteMarker  *DeleteMarkerInfo
+	IsUnversioned bool
+}
+
+// DeleteMarkerInfo is used to save object info if node in the tree service is delete marker.
+// We need this information because the "delete marker" object is no longer stored in NeoFS.
+type DeleteMarkerInfo struct {
+	FilePath string
+	Created  time.Time
+	Owner    user.ID
+}
+
+// ExtendedObjectInfo contains additional node info to be able to sort versions by timestamp.
+type ExtendedObjectInfo struct {
+	ObjectInfo  *ObjectInfo
+	NodeVersion *NodeVersion
+}
+
+// BaseNodeVersion is minimal node info from tree service.
+// Basically used for "system" object.
+type BaseNodeVersion struct {
+	ID        uint64
+	OID       oid.ID
+	Timestamp uint64
+}