Made memory.Index implement sql.OrderedIndex

Author: zachmu

memory/index.go

@@ -38,6 +38,7 @@ type Index struct {
 
 var _ sql.Index = (*Index)(nil)
 var _ sql.FilteredIndex = (*Index)(nil)
+var _ sql.OrderedIndex = (*Index)(nil)
 
 func (idx *Index) Database() string                    { return idx.DB }
 func (idx *Index) Driver() string                      { return idx.DriverName }
@@ -232,6 +233,10 @@ func getType(val interface{}) (interface{}, sql.Type) {
 	}
 }
 
+func (idx *Index) Order() sql.IndexOrder {
+	return sql.IndexOrderAsc
+}
+
 func or(expressions ...sql.Expression) sql.Expression {
 	if len(expressions) == 1 {
 		return expressions[0]