Re: [Libguestfs] [PATCH 1/3] mllib: Add sort_uniq function.

This is copied from supermin. --- mllib/common_utils.ml | 16 ++++++++++++++++ mllib/common_utils.mli | 6 ++++++ 2 files changed, 22 insertions(+) diff --git a/mllib/common_utils.ml b/mllib/common_utils.ml index 13e9256..5fb7183 100644 --- a/mllib/common_utils.ml +++ b/mllib/common_utils.ml @@ -267,6 +267,22 @@ let rec assoc ?(cmp = compare) ~default x = function | (y, y') :: _ when cmp x y = 0 -> y' | _ :: ys -> assoc ~cmp ~default x ys +let uniq ?(cmp = Pervasives.compare) xs = + let rec loop acc = function + | [] -> acc + | [x] -> x :: acc + | x :: (y :: _ as xs) when cmp x y = 0 -> + loop acc xs + | x :: (y :: _ as xs) -> + loop (x :: acc) xs + in + List.rev (loop [] xs) + +let sort_uniq ?(cmp = Pervasives.compare) xs = + let xs = List.sort cmp xs in + let xs = uniq ~cmp xs in + xs + let may f = function | None -> () | Some x -> f x diff --git a/mllib/common_utils.mli b/mllib/common_utils.mli index 44b8c93..68f7988 100644 --- a/mllib/common_utils.mli +++ b/mllib/common_utils.mli @@ -124,6 +124,12 @@ val assoc : ?cmp:('a -> 'a -> int) -> default:'b -> 'a -> ('a * 'b) list -> 'b (** Like {!List.assoc} but with a user-defined comparison function, and instead of raising [Not_found], it returns the [~default] value. *) +val uniq : ?cmp:('a -> 'a -> int) -> 'a list -> 'a list + (** Uniquify a list (the list must be sorted first). *) + +val sort_uniq : ?cmp:('a -> 'a -> int) -> 'a list -> 'a list + (** Sort and uniquify a list. *) + val may : ('a -> unit) -> 'a option -> unit (** [may f (Some x)] runs [f x]. [may f None] does nothing. *)