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(********************************************************************)
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(* *)
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(* The LustreC compiler toolset / The LustreC Development Team *)
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(* Copyright 2012 - -- ONERA - CNRS - INPT *)
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(* *)
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(* LustreC is free software, distributed WITHOUT ANY WARRANTY *)
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(* under the terms of the GNU Lesser General Public License *)
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(* version 2.1. *)
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(* *)
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(********************************************************************)
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(** Types definitions and a few utility functions on delay types. *)
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(** Delay analysis by type polymorphism instead of constraints *)
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open Utils
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type delay_expr =
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{mutable ddesc: delay_desc;
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did: int}
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and delay_desc =
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| Dvar (* Monomorphic type variable *)
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| Dundef
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| Darrow of delay_expr * delay_expr
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| Dtuple of delay_expr list
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| Dlink of delay_expr (* During unification, make links instead of substitutions *)
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| Dunivar (* Polymorphic type variable *)
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type error =
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| Delay_clash of delay_expr * delay_expr
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exception Unify of delay_expr * delay_expr
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exception Error of Location.t * error
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let new_id = ref (-1)
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let new_delay desc =
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incr new_id; {ddesc = desc; did = !new_id }
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let new_var () =
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new_delay Dvar
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let new_univar () =
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new_delay Dunivar
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let rec repr =
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function
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{ddesc = Dlink i'} ->
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repr i'
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| i -> i
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(** Splits [ty] into the [lhs,rhs] of an arrow type. Expects an arrow type
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(ensured by language syntax) *)
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let split_arrow de =
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match (repr de).ddesc with
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| Darrow (din,dout) -> din,dout
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(* Functions are not first order, I don't think the var case
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needs to be considered here *)
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| _ -> failwith "Internal error: not an arrow type"
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(** Returns the type corresponding to a type list. *)
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let delay_of_delay_list de =
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if (List.length de) > 1 then
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new_delay (Dtuple de)
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else
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List.hd de
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(** [is_polymorphic de] returns true if [de] is polymorphic. *)
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let rec is_polymorphic de =
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match de.ddesc with
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| Dvar -> false
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| Dundef -> false
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| Darrow (de1,de2) -> (is_polymorphic de1) || (is_polymorphic de2)
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| Dtuple dl -> List.exists is_polymorphic dl
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| Dlink d' -> is_polymorphic d'
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| Dunivar -> true
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(* Pretty-print*)
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open Format
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let rec print_delay fmt de =
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match de.ddesc with
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| Dvar ->
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fprintf fmt "'_%s" (name_of_type de.did)
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| Dundef ->
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fprintf fmt "1"
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| Darrow (de1,de2) ->
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fprintf fmt "%a->%a" print_delay de1 print_delay de2
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| Dtuple delist ->
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fprintf fmt "(%a)"
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(Utils.fprintf_list ~sep:"*" print_delay) delist
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| Dlink de ->
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print_delay fmt de
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| Dunivar ->
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fprintf fmt "'%s" (name_of_delay de.did)
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let pp_error fmt = function
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| Delay_clash (de1,de2) ->
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Utils.reset_names ();
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fprintf fmt "Expected delay %a, got delay %a@." print_delay de1 print_delay de2
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