Add some exceptions.

1 files changed, 7 insertions, 2 deletions

diff --git a/src/vyconf_tree.ml b/src/vyconf_tree.ml
index 449f095..f634d55 100644
--- a/src/vyconf_tree.ml
+++ b/src/vyconf_tree.ml
@@ -1,5 +1,9 @@
 type 'a vyconf_tree = Node of string * 'a * ('a vyconf_tree list)
 
+exception Empty_path
+exception Duplicate_child
+exception Nonexistent_path
+
 let name_of_node (Node (name, _, _)) = name
 
 let children_of_node (Node (_, _, children)) = children
@@ -47,14 +51,15 @@ let replace_child node child =
 
 let rec insert_child default_data node path data =
     match path with
-    | [] -> raise (Failure "Can't insert at empty path")
+    | [] -> raise Empty_path
     | [name] -> insert_immediate_child node name data
     | name :: names ->
         let next_child = find_child node name in
         match next_child with
         | Some next_child' ->
             let new_node = insert_child default_data next_child' names data in
-            replace_child node new_node
+            if names = [] then raise Duplicate_child
+            else replace_child node new_node
         | None ->
             let next_child' = Node (name, default_data, []) in
             let new_node = insert_child default_data next_child' names data in