(* Title:  interpreter-state for Lucas-Interpretation

   Author: Walther Neuper 190724

   (c) due to copyright terms

*)

signature INTERPRETER_STATE =

sig

  datatype safe = Sundef | Safe | Unsafe | Helpless;

  val safe2str : safe -> string

  type scrstate

  val e_scrstate : scrstate

  val scrstate2str : Rule.subst * Celem.loc_ * term option * term * safe * bool -> string

  datatype T = RrlsState of Rule.rrlsstate | Pstate of scrstate | Uistate

  val istate2str : T -> string

  val istates2str : T option * T option -> string

  val e_istate : T

  val get_act_env : scrstate -> (term * Env.T)

  val get_subst : scrstate -> (Env.T * (term option * term))

  val get_assoc : scrstate -> bool

  val trans_ass: scrstate -> scrstate -> scrstate

  val trans_env_act: scrstate -> scrstate -> scrstate

  val append_path : Celem.loc_ -> scrstate -> scrstate

  val append_path_form: (Celem.loc_ * term) -> scrstate -> scrstate

  val upd_form : term  -> scrstate -> scrstate

  val upd_curr : term option -> scrstate -> scrstate

  val upd_env: Env.T -> scrstate -> scrstate

  val upd_env': term -> scrstate -> scrstate

  val upd_form_env: (term * Env.T) -> scrstate -> scrstate

(*val upd_act_env: (term * Env.T) -> scrstate -> scrstate*)

  val upd_subst: Env.T -> (term * term) -> scrstate -> scrstate

  val upd_subst_true: (term option * term) -> scrstate -> scrstate

  val upd_subst_false: (term option * term) -> scrstate -> scrstate

end

(**)

structure Istate(**): INTERPRETER_STATE(**) =

struct

(**)

datatype safe = Sundef | Safe | Unsafe | Helpless;

fun safe2str Sundef   = "Sundef"

  | safe2str Safe     = "Safe"

  | safe2str Unsafe   = "Unsafe" 

  | safe2str Helpless = "Helpless";

type scrstate =  (* state for script interpreter                       *)

	 Env.T(*stack*)  (* used to instantiate tac for checking associate

		                12.03.noticed: e_ not updated during execution ?!? *)

	 * Celem.loc_  (* location of tac in script                          *)

	 * term option (* FORMal ARGument of curried functions               *)

	 * term        (* ACTual ARGument (value) for execution of Tactic.T

		                updated also after a derivation by 'new_val'       *)

	 * safe        (* estimation of how result will be obtained          *)

	 * bool;       (* true = strongly .., false = weakly associated: 

					          only used during ass_dn/up                         *)

val e_scrstate =

  ([]: Env.T, []:Celem.loc_, SOME Rule.e_term, Rule.e_term, Sundef, false) : scrstate

fun topt2str NONE = "NONE"

  | topt2str (SOME t) = "SOME" ^ Rule.term2str t;

fun scrstate2str (env, loc_, topt, t, safe, bool) = (* for tests only *)

  "(" ^  Env.env2str env ^ ", " ^ Celem.loc_2str loc_ ^ ", " ^ topt2str topt ^ ", \n" ^ 

  Rule.term2str t ^ ", " ^ safe2str safe ^ ", " ^ bool2str bool ^ ")";

(* for handling type T see fun from_pblobj_or_detail', +? *)

datatype T =                 (*interpreter state*)

	  Uistate                       (*undefined in modspec, in '_deriv'ation*)

  | Pstate of scrstate          (*for script interpreter*)

  | RrlsState of Rule.rrlsstate; (*for reverse rewriting*)

val e_istate = (Pstate ([], [], NONE, Rule.e_term, Sundef, false));

fun rta2str (r, (t, a)) = "\n(" ^ Rule.rule2str r ^ ",(" ^ Rule.term2str t ^", " ^ Rule.terms2str a ^ "))";

fun istate2str Uistate = "Uistate"

  | istate2str (Pstate (e, l, to, t, s, b)) =

    "Pstate ("^ Env.subst2str e ^ ",\n " ^ 

    Celem.loc_2str l ^ ", " ^ Rule.termopt2str to ^ ",\n " ^

    Rule.term2str t ^ ", " ^ safe2str s ^ ", " ^ bool2str b ^ ")"

  | istate2str (RrlsState (t, t1, rss, rtas)) = 

    "RrlsState (" ^ Rule.term2str t ^ ", " ^ Rule.term2str t1 ^ ", " ^

    (strs2str o (map (strs2str o (map Rule.rule2str)))) rss ^ ", " ^

    (strs2str o (map rta2str)) rtas ^ ")";

fun istates2str (NONE, NONE) = "(#NONE, #NONE)"  (* for tests only *)

  | istates2str (NONE, SOME ist) = "(#NONE,\n#SOME " ^ istate2str ist ^ ")"

  | istates2str (SOME ist, NONE) = "(#SOME " ^ istate2str ist ^ ",\n #NONE)"

  | istates2str (SOME i1, SOME i2) = "(#SOME " ^ istate2str i1 ^ ",\n #SOME " ^ istate2str i2 ^ ")";

fun get_act_env (env, _, _, act_arg, _, _) = (act_arg, env)

fun get_assoc (_, _, _, _, _, ass) = ass

fun get_subst (env, _, form_arg, act_arg, _, _) = (env, (form_arg, act_arg))

fun trans_ass (_, _, _, _, _, ass) (env, path, form_arg, act_arg, safe, _) = 

  (env, path, form_arg, act_arg, safe, ass)

fun trans_env_act (env, _, _, act_arg, _, _) (_, path, form_arg, _, safe, ass) = 

  (env, path, form_arg, act_arg, safe, ass)

fun append_path path (env, p, form_arg, act_arg, safe, ass) =

  (env, p @ path, form_arg, act_arg, safe, ass)

fun append_path_form (path, form_arg) (env, p, _, act_arg, safe, ass) =

  (env, p @ path, SOME form_arg, act_arg, safe, ass)

fun upd_form form (env, path, _, act_arg, safe, ass) =

  (env, path, SOME form, act_arg, safe, ass)

fun upd_curr form_arg (env, path, _, res, safe, ass) =

  (env, path, form_arg, res, safe, ass)

fun upd_env env (_, path, form_arg, act_arg, safe, ass) =

  (env, path, form_arg, act_arg, safe, ass)

fun upd_env' form (env, path, form_arg, act_arg, safe, ass) =

    (Env.upd_env env (form, act_arg), path, form_arg, act_arg, safe, ass)

fun upd_form_env (form_arg, env) (_, path, _, act_arg, safe, ass) =

  (env, path, SOME form_arg, act_arg, safe, ass)

(*fun upd_act_env (act_arg, env) (_, path, form_arg, _, safe, ass) =

  (env, path, form_arg, act_arg, safe, ass)*)

fun upd_subst env (form_arg, act_arg) (_, path, _, _, safe, ass) =

  (env, path, SOME form_arg, act_arg, safe, ass)

fun upd_subst_true (form_arg, act_arg) (env, path, _, _, safe, _) =

  (env, path, form_arg, act_arg, safe, true)

fun upd_subst_false (form_arg, act_arg) (env, path, _, _, safe, _) =

  (env, path, form_arg, act_arg, safe, false)

end