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62 lines
2 KiB
OCaml
62 lines
2 KiB
OCaml
(*
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Copyright (c) 2014, Simon Cruanes
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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Redistributions of source code must retain the above copyright notice, this
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list of conditions and the following disclaimer. Redistributions in binary
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form must reproduce the above copyright notice, this list of conditions and the
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following disclaimer in the documentation and/or other materials provided with
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the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*)
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(** {1 Interface to Delimcc (Invert control flow)} *)
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type 'a gen = unit -> 'a option
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type 'a res =
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| Start
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| Yield of 'a
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| Stop
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let _ret_none () = None
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let _ret_unit () = ()
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let to_gen seq =
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let p = Delimcc.new_prompt () in
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let _next = ref None in
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ignore (Delimcc.push_prompt p
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(fun () ->
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Delimcc.take_subcont p (fun c () -> _next := Some c; Start);
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seq
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(fun x ->
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Delimcc.take_subcont p (fun c () -> _next := Some c; Yield x)
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);
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_next := None;
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Stop
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));
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(* call next subcont *)
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let rec next () =
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match !_next with
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| None -> None
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| Some f ->
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begin match Delimcc.push_delim_subcont f _ret_unit with
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| Start -> next ()
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| Yield x -> Some x
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| Stop -> None
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end
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in
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next
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