128 lines
3 KiB
OCaml
128 lines
3 KiB
OCaml
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(******************************************************************************
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* Similar to Python's list
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*
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* - mutable
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* - dynamically resized
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* - O(1) read
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* - O(1) write
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* - O(1) append (average case)
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*
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******************************************************************************)
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type 'a vec = {
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mutable length: int;
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mutable capacity: int;
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mutable xs: 'a array;
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}
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(******************************************************************************
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* Constructors
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******************************************************************************)
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let make (size : int) (seed : 'a) : 'a vec = {
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length = size;
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capacity = size;
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xs = Array.make size seed;
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}
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let create () = {
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length = 0;
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capacity = 0;
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xs = [||];
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}
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let from_array (xs : 'a array) : 'a vec = {
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length = Array.length xs;
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capacity = Array.length xs;
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xs = xs;
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}
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let from_list (xs : 'a list) : 'a vec =
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match xs with
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| [] -> create ()
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| y::ys ->
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let result = {
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length = List.length xs;
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capacity = List.length xs;
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xs = Array.make (List.length xs) y;
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} in
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List.iteri (fun i x -> Array.set result.xs i x) xs;
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result
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(******************************************************************************
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* Miscellaneous
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******************************************************************************)
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let append (x : 'a) (v : 'a vec) =
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if v.capacity = 0 then
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begin
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v.length <- 1;
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v.capacity <- 1;
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v.xs <- [|x|];
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end
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else if v.length = v.capacity then
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begin
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(* According to Wikipedia, Python uses 1.25 as the growth factor *)
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let new_cap = v.capacity |> float_of_int |> Float.mul 1.25 |> ceil |> int_of_float in
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let new_xs = Array.make new_cap x in
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Array.iteri (fun i x -> Array.set new_xs i x) v.xs;
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v.capacity <- new_cap;
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v.xs <- new_xs;
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Array.set v.xs v.length x;
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v.length <- v.length + 1;
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end
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else
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begin
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Array.set v.xs v.length x;
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v.length <- v.length + 1;
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end
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let get (i : int) (v : 'a vec) : 'a option =
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if i >= v.length then
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None
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else
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Some v.xs.(i)
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let get_unsafe (i : int) (v : 'a vec) : 'a =
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v.xs.(i)
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let set (i : int) (x : 'a) (v : 'a vec) : unit =
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if i < v.length then
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Array.set v.xs i x
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let length (v : 'a vec) : int =
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v.length
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let update (i : int) (f : 'a -> 'a) (v : 'a vec) : unit =
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match get i v with
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| None -> ()
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| Some x -> set i (f x) v
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let iter (f : 'a -> unit) (v : 'a vec) : unit =
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let n = ref 0 in
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while !n < v.length do
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f v.xs.(!n);
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n := !n + 1;
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done
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let join (sep : string) (v : string vec) : string =
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if length v = 0 then
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""
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else
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let i = ref 1 in
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let result = ref v.xs.(0) in
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while !i < v.length do
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result := !result ^ sep ^ v.xs.(!i);
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i := !i + 1;
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done;
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!result
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let map (f : 'a -> 'b) (v : 'a vec) : 'b vec =
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let result = create () in
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iter (fun x -> append (f x) result) v;
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result
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let append_to (dst : 'a vec) (xs : 'a vec) : unit =
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iter (fun x -> append x dst) xs
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