~williewillus/persistent

d09352e5b4f64a8ec16434e9c9250c287b933927 — Vincent Lee 1 year, 3 days ago b27a1a2
Early bits of popping
2 files changed, 22 insertions(+), 0 deletions(-)

M lib/vector.ml
M lib/vector.mli
M lib/vector.ml => lib/vector.ml +18 -0
@@ 207,6 207,24 @@ let update (t : 'a t) (i : int) (value : 'a) : 'a t =
    in
    { t with root = rebuild t.root t.height }

let pop_opt (t : 'a t) : 'a t option =
  match t.count with
  | 0 -> None
  | 1 -> Some (empty ())
  | count ->
     (* TODO: handle tree traversal, tail promotion *)
     if (count - 1) >= (tail_offset t) then
       (* Shrink tail *)
       let tail = Array.sub t.tail 0 (Array.length t.tail - 1) in
       Some { t with tail; count = t.count - 1 }
     else
       Some t

let pop (t : 'a t) : 'a t =
  match pop_opt t with
  | Some t -> t
  | None -> invalid_arg "Popping empty vector"

let of_seq (xs : 'a Seq.t) : 'a t =
  Seq.fold_left append (empty ()) xs


M lib/vector.mli => lib/vector.mli +4 -0
@@ 17,6 17,10 @@ val append : 'a t -> 'a -> 'a t

val update : 'a t -> int -> 'a -> 'a t

val pop_opt : 'a t -> 'a t option

val pop : 'a t -> 'a t

val of_seq : 'a Seq.t -> 'a t

val to_seq : 'a t -> 'a Seq.t