funclang series4: Fixed insert function in ass9.

funclang-taddeus/series4/ass9.ml

@@ -19,15 +19,32 @@ let rec insert trie key value =
         else if starts_with key k then
             (* Inserted key should be in this node because it starts with
              * the node's key *)
+            let rec walk_nodes = function
+                | [] -> Empty
+                | node::tail ->
+                    match node with
+                    | Empty -> Empty
+                    | Node (k, _, _) ->
+                        if starts_with key k then
+                            Node (k, v, (insert node key value)::children)
+                        else
+                            walk_nodes tail
+            in
+            (* First, check if the new pair should be inserted in one of the
+             * children. If not, prepend it to the children list while moving
+             * all children that are should be inside the new node *)
+            match walk_nodes children with
+            | Empty ->
                 let matches_key = function
                     | Empty -> false
-                | Node (k, _, c) -> starts_with key k
+                    | Node (k, _, _) -> starts_with k key
                 in
-            (* 'move' are the children that are moved to be the children of the
-             * inserted node, 'siblings' are the children that remain in the
-             * current matched node *)
+                (* 'move' are the children that are moved to be the children of
+                 * the inserted node, 'siblings' are the children that remain
+                 * in the current matched node *)
                 let move, siblings = partition matches_key children in
-            Node (k, v, siblings @ [Node (key, value, move)])
+                Node (k, v, (Node (key, value, move))::siblings)
+            | node -> node
         else
             raise (Failure "Inserted key does not start with node key")
 ;;
@@ -68,6 +85,6 @@ let rec matches trie key =
         @ match_nodes children
 ;;
 
-let a = Node ([1;2;3], "a", []);;
+(*let a = Node ([1;2;3], "a", []);;
 let b = Node ([1;3], "b", [a]);;
-let c = Node ([3;4], "c", [b]);;
+let c = Node ([3;4], "c", [b]);;*)