(*  Title:      Pure/Isar/context_rules.ML

    ID:         $Id$

    Author:     Stefan Berghofer and Markus Wenzel, TU Muenchen

Declarations of intro/elim/dest rules in Pure (see also

Provers/classical.ML for a more specialized version of the same idea).

*)

signature CONTEXT_RULES =

sig

  type netpair

  type T

  val netpair_bang: Proof.context -> netpair

  val netpair: Proof.context -> netpair

  val orderlist: ((int * int) * 'a) list -> 'a list

  val find_rules_netpair: bool -> thm list -> term -> netpair -> thm list

  val find_rules: bool -> thm list -> term -> Proof.context -> thm list list

  val print_rules: Proof.context -> unit

  val addSWrapper: ((int -> tactic) -> int -> tactic) -> theory -> theory

  val addWrapper: ((int -> tactic) -> int -> tactic) -> theory -> theory

  val Swrap: Proof.context -> (int -> tactic) -> int -> tactic

  val wrap: Proof.context -> (int -> tactic) -> int -> tactic

  val intro_bang: int option -> attribute

  val elim_bang: int option -> attribute

  val dest_bang: int option -> attribute

  val intro: int option -> attribute

  val elim: int option -> attribute

  val dest: int option -> attribute

  val intro_query: int option -> attribute

  val elim_query: int option -> attribute

  val dest_query: int option -> attribute

  val rule_del: attribute

  val add_args:

    (int option -> attribute) -> (int option -> attribute) -> (int option -> attribute) ->

    Attrib.src -> attribute

end;

structure ContextRules: CONTEXT_RULES =

struct

(** rule declaration contexts **)

(* rule kinds *)

val intro_bangK = (0, false);

val elim_bangK = (0, true);

val introK = (1, false);

val elimK = (1, true);

val intro_queryK = (2, false);

val elim_queryK = (2, true);

val kind_names =

 [(intro_bangK, "safe introduction rules (intro!)"),

  (elim_bangK, "safe elimination rules (elim!)"),

  (introK, "introduction rules (intro)"),

  (elimK, "elimination rules (elim)"),

  (intro_queryK, "extra introduction rules (intro?)"),

  (elim_queryK, "extra elimination rules (elim?)")];

val rule_kinds = map #1 kind_names;

val rule_indexes = distinct (op =) (map #1 rule_kinds);

(* context data *)

type netpair = ((int * int) * (bool * thm)) Net.net * ((int * int) * (bool * thm)) Net.net;

val empty_netpairs: netpair list = replicate (length rule_indexes) (Net.empty, Net.empty);

datatype T = Rules of

 {next: int,

  rules: (int * ((int * bool) * thm)) list,

  netpairs: netpair list,

  wrappers: (((int -> tactic) -> int -> tactic) * stamp) list *

    (((int -> tactic) -> int -> tactic) * stamp) list};

fun make_rules next rules netpairs wrappers =

  Rules {next = next, rules = rules, netpairs = netpairs, wrappers = wrappers};

fun add_rule (i, b) opt_w th (Rules {next, rules, netpairs, wrappers}) =

  let val w = (case opt_w of SOME w => w | NONE => Tactic.subgoals_of_brl (b, th)) in

    make_rules (next - 1) ((w, ((i, b), th)) :: rules)

      (nth_map i (Tactic.insert_tagged_brl ((w, next), (b, th))) netpairs) wrappers

  end;

fun del_rule th (rs as Rules {next, rules, netpairs, wrappers}) =

  let

    fun eq_th (_, (_, th')) = Thm.eq_thm_prop (th, th');

    fun del b netpair = Tactic.delete_tagged_brl (b, th) netpair handle Net.DELETE => netpair;

  in

    if not (exists eq_th rules) then rs

    else make_rules next (filter_out eq_th rules) (map (del false o del true) netpairs) wrappers

  end;

structure Rules = GenericDataFun

(

  type T = T;

  val empty = make_rules ~1 [] empty_netpairs ([], []);

  val extend = I;

  fun merge _ (Rules {rules = rules1, wrappers = (ws1, ws1'), ...},

      Rules {rules = rules2, wrappers = (ws2, ws2'), ...}) =

    let

      val wrappers =

        (Library.merge (eq_snd (op =)) (ws1, ws2), Library.merge (eq_snd (op =)) (ws1', ws2'));

      val rules = Library.merge (fn ((_, (k1, th1)), (_, (k2, th2))) =>

          k1 = k2 andalso Thm.eq_thm_prop (th1, th2)) (rules1, rules2);

      val next = ~ (length rules);

      val netpairs = fold (fn (n, (w, ((i, b), th))) =>

          nth_map i (Tactic.insert_tagged_brl ((w, n), (b, th))))

        (next upto ~1 ~~ rules) empty_netpairs;

    in make_rules (next - 1) rules netpairs wrappers end;

);

fun print_rules ctxt =

  let

    val Rules {rules, ...} = Rules.get (Context.Proof ctxt);

    fun prt_kind (i, b) =

      Pretty.big_list ((the o AList.lookup (op =) kind_names) (i, b) ^ ":")

        (map_filter (fn (_, (k, th)) =>

            if k = (i, b) then SOME (ProofContext.pretty_thm ctxt th) else NONE)

          (sort (int_ord o pairself fst) rules));

  in Pretty.writeln (Pretty.chunks (map prt_kind rule_kinds)) end;

(* access data *)

fun netpairs ctxt = let val Rules {netpairs, ...} = Rules.get (Context.Proof ctxt) in netpairs end;

val netpair_bang = hd o netpairs;

val netpair = hd o tl o netpairs;

(* retrieving rules *)

fun untaglist [] = []

  | untaglist [(k : int * int, x)] = [x]

  | untaglist ((k, x) :: (rest as (k', x') :: _)) =

      if k = k' then untaglist rest

      else x :: untaglist rest;

fun orderlist brls =

  untaglist (sort (prod_ord int_ord int_ord o pairself fst) brls);

fun orderlist_no_weight brls =

  untaglist (sort (int_ord o pairself (snd o fst)) brls);

fun may_unify weighted t net =

  map snd ((if weighted then orderlist else orderlist_no_weight) (Net.unify_term net t));

fun find_erules _ [] = K []

  | find_erules w (fact :: _) = may_unify w (Logic.strip_assums_concl (Thm.prop_of fact));

fun find_irules w goal = may_unify w (Logic.strip_assums_concl goal);

fun find_rules_netpair weighted facts goal (inet, enet) =

  find_erules weighted facts enet @ find_irules weighted goal inet;

fun find_rules weighted facts goals =

  map (find_rules_netpair weighted facts goals) o netpairs;

(* wrappers *)

fun gen_add_wrapper upd w =

  Context.theory_map (Rules.map (fn (rs as Rules {next, rules, netpairs, wrappers}) =>

    make_rules next rules netpairs (upd (fn ws => (w, stamp ()) :: ws) wrappers)));

val addSWrapper = gen_add_wrapper Library.apfst;

val addWrapper = gen_add_wrapper Library.apsnd;

fun gen_wrap which ctxt =

  let val Rules {wrappers, ...} = Rules.get (Context.Proof ctxt)

  in fold_rev fst (which wrappers) end;

val Swrap = gen_wrap #1;

val wrap = gen_wrap #2;

(** attributes **)

(* add and del rules *)

fun rule_del (x, th) =

  (Rules.map (del_rule th o del_rule (Tactic.make_elim th)) x, th);

fun rule_add k view opt_w =

  (fn (x, th) => (Rules.map (add_rule k opt_w (view th)) x, th)) o rule_del;

val intro_bang  = rule_add intro_bangK I;

val elim_bang   = rule_add elim_bangK I;

val dest_bang   = rule_add elim_bangK Tactic.make_elim;

val intro       = rule_add introK I;

val elim        = rule_add elimK I;

val dest        = rule_add elimK Tactic.make_elim;

val intro_query = rule_add intro_queryK I;

val elim_query  = rule_add elim_queryK I;

val dest_query  = rule_add elim_queryK Tactic.make_elim;

val _ = Context.>> (Context.map_theory

  (snd o PureThy.add_thms [(("", Drule.equal_intr_rule), [intro_query NONE])]));

(* concrete syntax *)

fun add_args a b c = Attrib.syntax

  (Scan.lift ((Args.bang >> K a || Args.query >> K c || Scan.succeed b) --

    Scan.option OuterParse.nat) >> (fn (f, n) => f n));

val rule_atts =

 [("intro", add_args intro_bang intro intro_query, "declaration of introduction rule"),

  ("elim", add_args elim_bang elim elim_query, "declaration of elimination rule"),

  ("dest", add_args dest_bang dest dest_query, "declaration of destruction rule"),

  ("rule", Attrib.syntax (Scan.lift Args.del >> K rule_del),

    "remove declaration of intro/elim/dest rule")];

val _ = Context.>> (Context.map_theory (Attrib.add_attributes rule_atts));

end;