term.go: New function Clone()

term.go

@@ -53,6 +53,25 @@ type term struct {
 	evalFunc evalFuncType
 }
 
+func (s *term) Clone() (d *term) {
+	var children []*term
+	if s.children != nil {
+		children = make([]*term, len(s.children))
+		for i, c := range s.children {
+			children[i] = c.Clone()
+		}
+	}
+	d = &term{
+		tk: *s.tk.Clone(),
+		parent: s.parent,
+		children: children,
+		position: s.position,
+		priority: s.priority,
+		evalFunc: s.evalFunc,
+	}
+	return
+}
+
 func (term *term) String() string {
 	var sb strings.Builder
 	term.toString(&sb)