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(* Title: Pure/Concurrent/par_exn.ML
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Author: Makarius
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Parallel exceptions as flattened results from acyclic graph of
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evaluations. Interrupt counts as neutral element.
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*)
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signature PAR_EXN =
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sig
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val make: exn list -> exn
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val dest: exn -> (serial * exn) list option
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val release_all: 'a Exn.result list -> 'a list
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val release_first: 'a Exn.result list -> 'a list
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end;
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structure Par_Exn =
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struct
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(* parallel exceptions *)
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exception Par_Exn of (serial * exn) Ord_List.T;
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fun exn_ord ((i, _), (j, _)) = int_ord (j, i);
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fun par_exns (Par_Exn exns) = SOME exns
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| par_exns exn = if Exn.is_interrupt exn then NONE else SOME [(serial (), exn)];
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fun make exns =
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(case map_filter par_exns exns of
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[] => Exn.Interrupt
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| e :: es => Par_Exn (Library.foldl (Ord_List.merge exn_ord) (e, es)));
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fun dest (Par_Exn exns) = SOME (rev exns)
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| dest _ = NONE;
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(* parallel results *)
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fun all_res results = forall (fn Exn.Res _ => true | _ => false) results;
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fun release_all results =
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if all_res results then map Exn.release results
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else raise make (map_filter Exn.get_exn results);
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fun release_first results = release_all results
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handle Par_Exn ((serial, exn) :: _) => reraise exn; (* FIXME preserve serial in location (?!?) *)
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end;
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