106 lines
3 KiB
OCaml
106 lines
3 KiB
OCaml
(**************************************************************************)
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(* *)
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(* Heptagon *)
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(* *)
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(* Author : Marc Pouzet *)
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(* Organization : Demons, LRI, University of Paris-Sud, Orsay *)
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(* *)
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(**************************************************************************)
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open Names
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open Idents
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open Types
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type ct =
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| Ck of ck
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| Cprod of ct list
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and ck =
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| Cbase
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| Cvar of link ref
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| Con of ck * constructor_name * var_ident
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and link =
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| Cindex of int
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| Clink of ck
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exception Unify
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let index = ref 0
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let gen_index () = (incr index; !index)
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(** returns a new clock variable *)
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let new_var () = Cvar { contents = Cindex (gen_index ()); }
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(** returns the canonic (short) representant of a [ck]
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and update it to this value. *)
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let rec ck_repr ck = match ck with
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| Cbase | Con _ | Cvar { contents = Cindex _ } -> ck
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| Cvar (({ contents = Clink ck } as link)) ->
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let ck = ck_repr ck in (link.contents <- Clink ck; ck)
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(** verifies that index is fresh in ck. *)
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let rec occur_check index ck =
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let ck = ck_repr ck in
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match ck with
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| Cbase -> ()
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| Cvar { contents = Cindex n } when index <> n -> ()
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| Con (ck, _, _) -> occur_check index ck
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| _ -> raise Unify
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let rec unify t1 t2 =
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if t1 == t2
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then ()
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else
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(match (t1, t2) with
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| (Ck ck1, Ck ck2) -> unify_ck ck1 ck2
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| (Cprod ct_list1, Cprod ct_list2) ->
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(try List.iter2 unify ct_list1 ct_list2 with | _ -> raise Unify)
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| _ -> raise Unify)
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and unify_ck ck1 ck2 =
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let ck1 = ck_repr ck1 in
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let ck2 = ck_repr ck2 in
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if ck1 == ck2
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then ()
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else
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(match (ck1, ck2) with
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| (Cbase, Cbase) -> ()
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| (Cvar { contents = Cindex n1 }, Cvar { contents = Cindex n2 }) when
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n1 = n2 -> ()
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| (Cvar (({ contents = Cindex n1 } as v)), _) ->
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(occur_check n1 ck2; v.contents <- Clink ck2)
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| (_, Cvar (({ contents = Cindex n2 } as v))) ->
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(occur_check n2 ck1; v.contents <- Clink ck1)
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| (Con (ck1, c1, n1), Con (ck2, c2, n2)) when (c1 = c2) & (n1 = n2) ->
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unify_ck ck1 ck2
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| _ -> raise Unify)
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let rec unify t1 t2 =
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match (t1, t2) with
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| (Ck ck1, Ck ck2) -> unify_ck ck1 ck2
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| (Cprod t1_list, Cprod t2_list) -> unify_list t1_list t2_list
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| _ -> raise Unify
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and unify_list t1_list t2_list =
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try List.iter2 unify t1_list t2_list with | _ -> raise Unify
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let rec skeleton ck = function
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| Tprod ty_list ->
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(match ty_list with
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| [] -> Format.eprintf "Warning, an exp with void type@."; Ck ck
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| _ -> Cprod (List.map (skeleton ck) ty_list))
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| Tarray _ | Tid _ -> Ck ck
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let ckofct = function | Ck ck -> ck_repr ck | Cprod ct_list -> Cbase
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