Make tree insert position-aware.

Make insertion at the beginning default behaviour.
Implement insertion at the end.

3 files changed, 23 insertions, 10 deletions

diff --git a/src/vytree.ml b/src/vytree.ml
index ed5efd2..93d3d71 100644
--- a/src/vytree.ml
+++ b/src/vytree.ml
@@ -4,7 +4,7 @@ type 'a	t = {
     children: 'a t list
 }
 
-type position = Before of string | After of string | Default
+type position = Before of string | After of string | End | Default
 
 type node_type = Leaf | Tag | Other
 
@@ -21,10 +21,14 @@ let name_of_node node = node.name
 let data_of_node node = node.data
 let children_of_node node = node.children
 
-let insert_immediate node name data =
+let insert_immediate ?(position=Default) node name data =
     let new_node = make data name in
-    let children' = new_node :: node.children in
-    { node with children = children' }
+    let children' =
+        match position with
+        | Default -> new_node :: node.children
+        | End -> node.children @ [new_node]
+        | _ -> assert false
+    in { node with children = children' }
 
 let delete_immediate node name =
     let children' = Vylist.remove (fun x -> x.name = name) node.children in
@@ -60,13 +64,13 @@ let rec do_with_child fn node path =
         let new_node = do_with_child fn next_child names in
         replace node new_node
 
-let rec insert node path data =
+let rec insert ?(position=Default) node path data =
     match path with
     | [] -> raise Empty_path
     | [name] ->
        (let last_child = find node name in
         match last_child with
-        | None -> insert_immediate node name data
+        | None -> insert_immediate ~position:position node name data
         | (Some _) -> raise Duplicate_child)
     | name :: names ->
         let next_child = find node name in
diff --git a/src/vytree.mli b/src/vytree.mli
index 4b52727..e912922 100644
--- a/src/vytree.mli
+++ b/src/vytree.mli
@@ -5,7 +5,7 @@ exception Duplicate_child
 exception Nonexistent_path
 exception Insert_error of string
 
-type position = Before of string | After of string | Default
+type position = Before of string | After of string | End | Default
 
 type node_type = Leaf | Tag | Other
 
@@ -19,7 +19,7 @@ val children_of_node : 'a t -> 'a t list
 val find : 'a t -> string -> 'a t option
 val find_or_fail : 'a t -> string -> 'a t
 
-val insert : 'a t -> string list -> 'a -> 'a t
+val insert : ?position:position -> 'a t -> string list -> 'a -> 'a t
 
 val delete : 'a t -> string list -> 'a t
 
diff --git a/test/vytree_test.ml b/test/vytree_test.ml
index 24a6d1e..86a6269 100644
--- a/test/vytree_test.ml
+++ b/test/vytree_test.ml
@@ -21,8 +21,8 @@ let test_insert_immediate_child test_ctxt =
     assert_equal (children_of_node node')
                  [make () "foo"]
 
-(* Inserting one child after another adds it to the
-   end of the children list *)
+(* Inserting one child after another works.
+   The default behaviour is to insert new items at the beginning.  *)
 let test_insert_multiple_children test_ctxt =
     let node = make () "root" in
     let node' = insert node ["foo"] () in
@@ -47,6 +47,14 @@ let test_insert_duplicate_child test_ctxt =
     let node = insert node ["foo"] () in
     assert_raises Duplicate_child (fun () -> insert node ["foo"] ())
 
+(* Inserting a child at the end works *)
+let test_insert_multiple_children_end test_ctxt =
+    let node = make () "root" in
+    let node = insert node ["foo"] () in
+    let node = insert ~position:End node ["bar"] () in
+    assert_equal (children_of_node node)
+                 [make () "foo"; make () "bar"]
+
 (* list_children correctly returns a list of children names *)
 let test_list_children test_ctxt =
     let node = make () "root" in
@@ -126,6 +134,7 @@ let suite =
         "test_insert_multiple_children" >:: test_insert_multiple_children;
         "test_insert_multi_level" >:: test_insert_multi_level;
         "test_insert_duplicate_child" >:: test_insert_duplicate_child;
+        "test_insert_multiple_children_end" >:: test_insert_multiple_children_end;
         "test_list_children" >:: test_list_children;
         "test_delete_immediate_child" >:: test_delete_immediate_child;
         "test_delete_multi_level" >:: test_delete_multi_level;