60 lines
1.6 KiB
OCaml
60 lines
1.6 KiB
OCaml
(**************************************************************************)
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(* *)
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(* Copyright (c) 2014 - 2016. *)
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(* Dynamic Ledger Solutions, Inc. <contact@tezos.com> *)
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(* *)
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(* All rights reserved. No warranty, explicit or implicit, provided. *)
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(* *)
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(**************************************************************************)
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type 'a raw =
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| Empty of int
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| Inited of {
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data : 'a array ;
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mutable pos : int ;
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}
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type 'a t = 'a raw ref
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let create size = ref (Empty size)
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let add r v =
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match !r with
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| Empty size ->
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r := Inited { data = Array.make size v ; pos = 0 }
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| Inited s ->
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s.pos <-
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if s.pos = 2 * Array.length s.data - 1 then
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Array.length s.data
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else
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s.pos + 1 ;
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s.data.(s.pos mod Array.length s.data) <- v
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let add_list r l = List.iter (add r) l
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let last r =
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match !r with
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| Empty _ -> None
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| Inited { data ; pos } -> Some data.(pos mod Array.length data)
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let fold r ~init ~f =
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match !r with
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| Empty _ -> init
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| Inited { data ; pos } ->
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let size = Array.length data in
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let acc = ref init in
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for i = 0 to min pos (size - 1) do
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acc := f !acc data.((pos - i) mod size)
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done ;
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!acc
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let elements t =
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fold t ~init:[] ~f:(fun acc elt -> elt :: acc)
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exception Empty
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let last_exn r =
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match last r with
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| None -> raise Empty
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| Some d -> d
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