Add two functions to the Node_list interface (and to the naive implementation):

* pop discards the first element
* append appends the element of the second argument at the end of the first one (in place).

diff --git a/src/naive_node_list.ml b/src/naive_node_list.ml
index b6f0ae4..1b32c47 100644 (file)
--- a/src/naive_node_list.ml
+++ b/src/naive_node_list.ml
@@ -41,9 +41,22 @@ let iter f l =
   loop l.head
 
 
+
+
 let length l = l.length
 let is_empty l = l.head == nil
 
+let pop l =
+  if is_empty l then failwith "pop"
+  else
+    let v = l.head.node in
+    let nhead = l.head.next in
+    l.head <- nhead;
+    if nhead == nil then l.last <- nil;
+    v
+
+
+
 let add n l =
   let ncell = { node = n;
                 next = nil }
@@ -72,6 +85,15 @@ let push_front n l =
     l.length <- l.length + 1;
   end
 
+let append l1 l2 =
+  let len2 = l2.length in
+  if len2 != 0 then begin
+    l1.length <- l1.length + len2;
+    l1.last.next <- l2.head;
+    l1.last <- l2.last;
+  end;
+  l1
+
 let head l = l.head
 let last l = l.last
 let next i = i.next

diff --git a/src/node_list.ml b/src/node_list.ml
index e9bb58a..1856bb8 100644 (file)
--- a/src/node_list.ml
+++ b/src/node_list.ml
@@ -23,6 +23,8 @@ module type S =
     val add : node -> t -> unit
     val push_front : node -> t -> unit
     val push_back : node -> t -> unit
+    val pop : t -> node
+    val append : t -> t -> t
     val iter : (node -> unit) -> t -> unit
     val length : t -> int
     val is_empty : t -> bool