Implement iterator with far too many clones.

src/parser/list.rs

@@ -73,3 +73,25 @@ impl<T: Debug> List<T> {
         }
     }
 }
+
+pub struct NodeIter<T> {
+    position: 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>>;
+
+    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();
+                (return_value, next_position)
+            }
+        };
+        self.position = next_position;
+        Some(return_value)
+    }
+}