Switch to using borrows instead of cloning the Rc during iteration.

src/parser/list.rs

@@ -74,20 +74,19 @@ impl<T: Debug> List<T> {
     }
 }
 
-pub struct NodeIter<T> {
-    position: Option<Rc<Node<T>>>,
+pub struct NodeIter<'a, T> {
+    position: &'a Option<Rc<Node<T>>>,
 }
 
-impl<T> Iterator for NodeIter<T> {
-    // TODO: This would be a lot better if it returned borrows instead of clones of Rc
-    type Item = Rc<Node<T>>;
+impl<'a, T> Iterator for NodeIter<'a, T> {
+    type Item = &'a Rc<Node<T>>;
 
     fn next(&mut self) -> Option<Self::Item> {
         let (return_value, next_position) = match &self.position {
             None => return None,
             Some(rc_node) => {
-                let next_position = rc_node.parent.clone();
-                let return_value = rc_node.clone();
+                let next_position = &rc_node.parent;
+                let return_value = rc_node;
                 (return_value, next_position)
             }
         };