71 lines
1.8 KiB
OCaml
71 lines
1.8 KiB
OCaml
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(* Copyright 2012 Tony Garnock-Jones <tonygarnockjones@gmail.com>. *)
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(* This file is part of Ocamlmsg. *)
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(* Ocamlmsg is free software: you can redistribute it and/or modify it *)
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(* under the terms of the GNU General Public License as published by the *)
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(* Free Software Foundation, either version 3 of the License, or (at your *)
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(* option) any later version. *)
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(* Ocamlmsg is distributed in the hope that it will be useful, but *)
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(* WITHOUT ANY WARRANTY; without even the implied warranty of *)
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(* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *)
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(* General Public License for more details. *)
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(* You should have received a copy of the GNU General Public License *)
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(* along with Ocamlmsg. If not, see <http://www.gnu.org/licenses/>. *)
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type t = Stream of (unit -> (string * t) option)
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let make f = Stream f
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let run (Stream f) = f ()
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let empty = Stream (fun () -> None)
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let const v = Stream (fun () -> Some (v, empty))
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let rec seq s1 s2 =
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Stream (fun () ->
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match run s1 with
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| None -> run s2
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| Some (v, k) -> Some (v, seq k s2))
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let rec from_list vs =
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Stream (fun () ->
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match vs with
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| [] -> None
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| v :: vs -> Some (v, (from_list vs)))
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let rec map f vs =
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Stream (fun () ->
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match vs with
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| [] -> None
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| v :: vs -> run (seq (f v) (map f vs)))
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let rec from_iter f =
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let cache = ref None in
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Stream (fun () ->
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match !cache with
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| Some v -> v
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| None ->
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let result =
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(match f () with
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| Some str -> Some (str, from_iter f)
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| None -> None)
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in
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cache := Some result;
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result)
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let rec iter f (Stream s_f) =
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match s_f () with
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| None -> ()
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| Some (v, k) -> (f v; iter f k)
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let rec to_list (Stream f) =
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match f () with
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| None -> []
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| Some (v, k) -> v :: to_list k
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let rec to_string s =
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String.concat "" (to_list s)
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