create position builder

node/node.go

@@ -2,6 +2,13 @@ package node
 
 // Node interface
 type Node interface {
-	Attributes() map[string]interface{}
-	Walk(v Visitor)
+	Attributes() map[string]interface{} // Attributes returns node attributes as map
+	Walk(v Visitor)                     // Walk traverses nodes
+}
+
+// Visitor interface
+type Visitor interface {
+	EnterNode(node Node) bool              // EnterNode invoked for each node encountered by Walk.
+	GetChildrenVisitor(Key string) Visitor // GetChildrenVisitor returns visitor for children nodes
+	LeaveNode(node Node)                   // LeaveNode invoked after process node
 }

node/visitor.go

@@ -1,7 +0,0 @@
-package node
-
-type Visitor interface {
-	EnterNode(node Node) bool
-	GetChildrenVisitor(Key string) Visitor
-	LeaveNode(node Node)
-}