(*  Title:      HOL/Tools/Nitpick/nitpick.ML

    Author:     Jasmin Blanchette, TU Muenchen

    Copyright   2008, 2009, 2010

Finite model generation for HOL formulas using Kodkod.

*)

signature NITPICK =

sig

  type styp = Nitpick_Util.styp

  type term_postprocessor = Nitpick_Model.term_postprocessor

  type params = {

    cards_assigns: (typ option * int list) list,

    maxes_assigns: (styp option * int list) list,

    iters_assigns: (styp option * int list) list,

    bitss: int list,

    bisim_depths: int list,

    boxes: (typ option * bool option) list,

    finitizes: (typ option * bool option) list,

    monos: (typ option * bool option) list,

    stds: (typ option * bool) list,

    wfs: (styp option * bool option) list,

    sat_solver: string,

    blocking: bool,

    falsify: bool,

    debug: bool,

    verbose: bool,

    overlord: bool,

    user_axioms: bool option,

    assms: bool,

    merge_type_vars: bool,

    binary_ints: bool option,

    destroy_constrs: bool,

    specialize: bool,

    skolemize: bool,

    star_linear_preds: bool,

    uncurry: bool,

    fast_descrs: bool,

    peephole_optim: bool,

    timeout: Time.time option,

    tac_timeout: Time.time option,

    sym_break: int,

    sharing_depth: int,

    flatten_props: bool,

    max_threads: int,

    show_skolems: bool,

    show_datatypes: bool,

    show_consts: bool,

    evals: term list,

    formats: (term option * int list) list,

    max_potential: int,

    max_genuine: int,

    check_potential: bool,

    check_genuine: bool,

    batch_size: int,

    expect: string}

  val register_frac_type : string -> (string * string) list -> theory -> theory

  val unregister_frac_type : string -> theory -> theory

  val register_codatatype : typ -> string -> styp list -> theory -> theory

  val unregister_codatatype : typ -> theory -> theory

  val register_term_postprocessor :

    typ -> term_postprocessor -> theory -> theory

  val unregister_term_postprocessor : typ -> theory -> theory

  val pick_nits_in_term :

    Proof.state -> params -> bool -> int -> int -> int -> (term * term) list

    -> term list -> term -> string * Proof.state

  val pick_nits_in_subgoal :

    Proof.state -> params -> bool -> int -> int -> string * Proof.state

end;

structure Nitpick : NITPICK =

struct

open Nitpick_Util

open Nitpick_HOL

open Nitpick_Preproc

open Nitpick_Mono

open Nitpick_Scope

open Nitpick_Peephole

open Nitpick_Rep

open Nitpick_Nut

open Nitpick_Kodkod

open Nitpick_Model

structure KK = Kodkod

type params = {

  cards_assigns: (typ option * int list) list,

  maxes_assigns: (styp option * int list) list,

  iters_assigns: (styp option * int list) list,

  bitss: int list,

  bisim_depths: int list,

  boxes: (typ option * bool option) list,

  finitizes: (typ option * bool option) list,

  monos: (typ option * bool option) list,

  stds: (typ option * bool) list,

  wfs: (styp option * bool option) list,

  sat_solver: string,

  blocking: bool,

  falsify: bool,

  debug: bool,

  verbose: bool,

  overlord: bool,

  user_axioms: bool option,

  assms: bool,

  merge_type_vars: bool,

  binary_ints: bool option,

  destroy_constrs: bool,

  specialize: bool,

  skolemize: bool,

  star_linear_preds: bool,

  uncurry: bool,

  fast_descrs: bool,

  peephole_optim: bool,

  timeout: Time.time option,

  tac_timeout: Time.time option,

  sym_break: int,

  sharing_depth: int,

  flatten_props: bool,

  max_threads: int,

  show_skolems: bool,

  show_datatypes: bool,

  show_consts: bool,

  evals: term list,

  formats: (term option * int list) list,

  max_potential: int,

  max_genuine: int,

  check_potential: bool,

  check_genuine: bool,

  batch_size: int,

  expect: string}

type problem_extension = {

  free_names: nut list,

  sel_names: nut list,

  nonsel_names: nut list,

  rel_table: nut NameTable.table,

  unsound: bool,

  scope: scope}

type rich_problem = KK.problem * problem_extension

(* Proof.context -> string -> term list -> Pretty.T list *)

fun pretties_for_formulas _ _ [] = []

  | pretties_for_formulas ctxt s ts =

    [Pretty.str (s ^ plural_s_for_list ts ^ ":"),

     Pretty.indent indent_size (Pretty.chunks

         (map2 (fn j => fn t =>

                   Pretty.block [t |> shorten_names_in_term

                                   |> Syntax.pretty_term ctxt,

                                 Pretty.str (if j = 1 then "." else ";")])

               (length ts downto 1) ts))]

(* unit -> string *)

fun install_java_message () =

  "Nitpick requires a Java 1.5 virtual machine called \"java\"."

(* unit -> string *)

fun install_kodkodi_message () =

  "Nitpick requires the external Java program Kodkodi. To install it, download \

  \the package from Isabelle's web page and add the \"kodkodi-x.y.z\" \

  \directory's full path to \"" ^

  Path.implode (Path.expand (Path.appends

      (Path.variable "ISABELLE_HOME_USER" ::

       map Path.basic ["etc", "components"]))) ^ "\"."

val max_unsound_delay_ms = 200

val max_unsound_delay_percent = 2

(* Time.time option -> int *)

fun unsound_delay_for_timeout NONE = max_unsound_delay_ms

  | unsound_delay_for_timeout (SOME timeout) =

    Int.max (0, Int.min (max_unsound_delay_ms,

                         Time.toMilliseconds timeout

                         * max_unsound_delay_percent div 100))

(* Time.time option -> bool *)

fun passed_deadline NONE = false

  | passed_deadline (SOME time) = Time.compare (Time.now (), time) <> LESS

(* ('a * bool option) list -> bool *)

fun none_true assigns = forall (not_equal (SOME true) o snd) assigns

val syntactic_sorts =

  @{sort "{default,zero,one,plus,minus,uminus,times,inverse,abs,sgn,ord,eq}"} @

  @{sort number}

(* typ -> bool *)

fun has_tfree_syntactic_sort (TFree (_, S as _ :: _)) =

    subset (op =) (S, syntactic_sorts)

  | has_tfree_syntactic_sort _ = false

(* term -> bool *)

val has_syntactic_sorts = exists_type (exists_subtype has_tfree_syntactic_sort)

(* (unit -> string) -> Pretty.T *)

fun plazy f = Pretty.blk (0, pstrs (f ()))

(* Time.time -> Proof.state -> params -> bool -> int -> int -> int

   -> (term * term) list -> term list -> term -> string * Proof.state *)

fun pick_them_nits_in_term deadline state (params : params) auto i n step

                           subst orig_assm_ts orig_t =

  let

    val timer = Timer.startRealTimer ()

    val thy = Proof.theory_of state

    val ctxt = Proof.context_of state

(* FIXME: reintroduce code before new release:

    val nitpick_thy = ThyInfo.get_theory "Nitpick"

    val _ = Theory.subthy (nitpick_thy, thy) orelse

            error "You must import the theory \"Nitpick\" to use Nitpick"

*)

    val {cards_assigns, maxes_assigns, iters_assigns, bitss, bisim_depths,

         boxes, finitizes, monos, stds, wfs, sat_solver, falsify, debug,

         verbose, overlord, user_axioms, assms, merge_type_vars, binary_ints,

         destroy_constrs, specialize, skolemize, star_linear_preds, uncurry,

         fast_descrs, peephole_optim, tac_timeout, sym_break, sharing_depth,

         flatten_props, max_threads, show_skolems, show_datatypes, show_consts,

         evals, formats, max_potential, max_genuine, check_potential,

         check_genuine, batch_size, ...} =

      params

    val state_ref = Unsynchronized.ref state

    (* Pretty.T -> unit *)

    val pprint =

      if auto then

        Unsynchronized.change state_ref o Proof.goal_message o K

        o Pretty.chunks o cons (Pretty.str "") o single

        o Pretty.mark Markup.hilite

      else

        priority o Pretty.string_of

    (* (unit -> Pretty.T) -> unit *)

    fun pprint_m f = () |> not auto ? pprint o f

    fun pprint_v f = () |> verbose ? pprint o f

    fun pprint_d f = () |> debug ? pprint o f

    (* string -> unit *)

    val print = pprint o curry Pretty.blk 0 o pstrs

    (* (unit -> string) -> unit *)

    val print_m = pprint_m o K o plazy

    val print_v = pprint_v o K o plazy

    (* unit -> unit *)

    fun check_deadline () =

      if debug andalso passed_deadline deadline then raise TimeLimit.TimeOut

      else ()

    (* unit -> 'a *)

    fun do_interrupted () =

      if passed_deadline deadline then raise TimeLimit.TimeOut

      else raise Interrupt

    val orig_assm_ts = if assms orelse auto then orig_assm_ts else []

    val _ =

      if step = 0 then

        print_m (fn () => "Nitpicking formula...")

      else

        pprint_m (fn () => Pretty.chunks (

            pretties_for_formulas ctxt ("Nitpicking " ^

                (if i <> 1 orelse n <> 1 then

                   "subgoal " ^ string_of_int i ^ " of " ^ string_of_int n

                 else

                   "goal")) [Logic.list_implies (orig_assm_ts, orig_t)]))

    val neg_t = if falsify then Logic.mk_implies (orig_t, @{prop False})

                else orig_t

    val assms_t = Logic.mk_conjunction_list (neg_t :: orig_assm_ts)

    val (assms_t, evals) =

      assms_t :: evals |> merge_type_vars ? merge_type_vars_in_terms

                       |> pairf hd tl

    val original_max_potential = max_potential

    val original_max_genuine = max_genuine

(*

    val _ = priority ("*** " ^ Syntax.string_of_term ctxt orig_t)

    val _ = List.app (fn t => priority ("*** " ^ Syntax.string_of_term ctxt t))

                     orig_assm_ts

*)

    val max_bisim_depth = fold Integer.max bisim_depths ~1

    val case_names = case_const_names thy stds

    val (defs, built_in_nondefs, user_nondefs) = all_axioms_of thy subst

    val def_table = const_def_table ctxt subst defs

    val nondef_table = const_nondef_table (built_in_nondefs @ user_nondefs)

    val simp_table = Unsynchronized.ref (const_simp_table ctxt subst)

    val psimp_table = const_psimp_table ctxt subst

    val choice_spec_table = const_choice_spec_table ctxt subst

    val user_nondefs =

      user_nondefs |> filter_out (is_choice_spec_axiom thy choice_spec_table)

    val intro_table = inductive_intro_table ctxt subst def_table

    val ground_thm_table = ground_theorem_table thy

    val ersatz_table = ersatz_table thy

    val (hol_ctxt as {wf_cache, ...}) =

      {thy = thy, ctxt = ctxt, max_bisim_depth = max_bisim_depth, boxes = boxes,

       stds = stds, wfs = wfs, user_axioms = user_axioms, debug = debug,

       binary_ints = binary_ints, destroy_constrs = destroy_constrs,

       specialize = specialize, skolemize = skolemize,

       star_linear_preds = star_linear_preds, uncurry = uncurry,

       fast_descrs = fast_descrs, tac_timeout = tac_timeout, evals = evals,

       case_names = case_names, def_table = def_table,

       nondef_table = nondef_table, user_nondefs = user_nondefs,

       simp_table = simp_table, psimp_table = psimp_table,

       choice_spec_table = choice_spec_table, intro_table = intro_table,

       ground_thm_table = ground_thm_table, ersatz_table = ersatz_table,

       skolems = Unsynchronized.ref [], special_funs = Unsynchronized.ref [],

       unrolled_preds = Unsynchronized.ref [], wf_cache = Unsynchronized.ref [],

       constr_cache = Unsynchronized.ref []}

    val frees = Term.add_frees assms_t []

    val _ = null (Term.add_tvars assms_t []) orelse

            raise NOT_SUPPORTED "schematic type variables"

    val (nondef_ts, def_ts, got_all_mono_user_axioms, no_poly_user_axioms,

         binarize) = preprocess_term hol_ctxt finitizes monos assms_t

    val got_all_user_axioms =

      got_all_mono_user_axioms andalso no_poly_user_axioms

    (* styp * (bool * bool) -> unit *)

    fun print_wf (x, (gfp, wf)) =

      pprint (Pretty.blk (0,

          pstrs ("The " ^ (if gfp then "co" else "") ^ "inductive predicate \"")

          @ Syntax.pretty_term ctxt (Const x) ::

          pstrs (if wf then

                   "\" was proved well-founded. Nitpick can compute it \

                   \efficiently."

                 else

                   "\" could not be proved well-founded. Nitpick might need to \

                   \unroll it.")))

    val _ = if verbose then List.app print_wf (!wf_cache) else ()

    val _ =

      pprint_d (fn () => Pretty.chunks

          (pretties_for_formulas ctxt "Preprocessed formula" [hd nondef_ts] @

           pretties_for_formulas ctxt "Relevant definitional axiom" def_ts @

           pretties_for_formulas ctxt "Relevant nondefinitional axiom"

                                 (tl nondef_ts)))

    val _ = List.app (ignore o Term.type_of) (nondef_ts @ def_ts)

            handle TYPE (_, Ts, ts) =>

                   raise TYPE ("Nitpick.pick_them_nits_in_term", Ts, ts)

    val nondef_us = map (nut_from_term hol_ctxt Eq) nondef_ts

    val def_us = map (nut_from_term hol_ctxt DefEq) def_ts

    val (free_names, const_names) =

      fold add_free_and_const_names (nondef_us @ def_us) ([], [])

    val (sel_names, nonsel_names) =

      List.partition (is_sel o nickname_of) const_names

    val sound_finitizes =

      none_true (filter_out (fn (SOME (Type (@{type_name fun}, _)), _) => true

                          | _ => false) finitizes)

    val standard = forall snd stds

(*

    val _ = List.app (priority o string_for_nut ctxt) (nondef_us @ def_us)

*)

    val unique_scope = forall (curry (op =) 1 o length o snd) cards_assigns

    (* typ list -> string -> string *)

    fun monotonicity_message Ts extra =

      let val ss = map (quote o string_for_type ctxt) Ts in

        "The type" ^ plural_s_for_list ss ^ " " ^

        space_implode " " (Sledgehammer_Util.serial_commas "and" ss) ^ " " ^

        (if none_true monos then

           "passed the monotonicity test"

         else

           (if length ss = 1 then "is" else "are") ^ " considered monotonic") ^

        ". " ^ extra

      end

    (* typ -> bool *)

    fun is_type_fundamentally_monotonic T =

      (is_datatype thy stds T andalso not (is_quot_type thy T) andalso

       (not (is_pure_typedef thy T) orelse is_univ_typedef thy T)) orelse

      is_number_type thy T orelse is_bit_type T

    fun is_type_actually_monotonic T =

      formulas_monotonic hol_ctxt binarize T (nondef_ts, def_ts)

    fun is_type_kind_of_monotonic T =

      case triple_lookup (type_match thy) monos T of

        SOME (SOME false) => false

      | _ => is_type_actually_monotonic T

    fun is_type_monotonic T =

      unique_scope orelse

      case triple_lookup (type_match thy) monos T of

        SOME (SOME b) => b

      | _ => is_type_fundamentally_monotonic T orelse

             is_type_actually_monotonic T

    fun is_shallow_datatype_finitizable (T as Type (@{type_name fin_fun}, _)) =

        is_type_kind_of_monotonic T

      | is_shallow_datatype_finitizable (T as Type (@{type_name fun_box}, _)) =

        is_type_kind_of_monotonic T

      | is_shallow_datatype_finitizable T =

        case triple_lookup (type_match thy) finitizes T of

          SOME (SOME b) => b

        | _ => is_type_kind_of_monotonic T

    fun is_datatype_deep T =

      not standard orelse T = nat_T orelse is_word_type T orelse

      exists (curry (op =) T o domain_type o type_of) sel_names

    val all_Ts = ground_types_in_terms hol_ctxt binarize (nondef_ts @ def_ts)

                 |> sort Term_Ord.typ_ord

    val _ = if verbose andalso binary_ints = SOME true andalso

               exists (member (op =) [nat_T, int_T]) all_Ts then

              print_v (K "The option \"binary_ints\" will be ignored because \

                         \of the presence of rationals, reals, \"Suc\", \

                         \\"gcd\", or \"lcm\" in the problem or because of the \

                         \\"non_std\" option.")

            else

              ()

    val (mono_Ts, nonmono_Ts) = List.partition is_type_monotonic all_Ts

    val _ =

      if verbose andalso not unique_scope then

        case filter_out is_type_fundamentally_monotonic mono_Ts of

          [] => ()

        | interesting_mono_Ts =>

          print_v (K (monotonicity_message interesting_mono_Ts

                         "Nitpick might be able to skip some scopes."))

      else

        ()

    val (deep_dataTs, shallow_dataTs) =

      all_Ts |> filter (is_datatype thy stds) |> List.partition is_datatype_deep

    val finitizable_dataTs =

      shallow_dataTs |> filter_out (is_finite_type hol_ctxt)

                     |> filter is_shallow_datatype_finitizable

    val _ =

      if verbose andalso not (null finitizable_dataTs) then

        print_v (K (monotonicity_message finitizable_dataTs

                        "Nitpick can use a more precise finite encoding."))

      else

        ()

    (* This detection code is an ugly hack. Fortunately, it is used only to

       provide a hint to the user. *)

    (* string * (Rule_Cases.T * bool) -> bool *)

    fun is_struct_induct_step (name, (Rule_Cases.Case {fixes, assumes, ...}, _)) =

      not (null fixes) andalso

      exists (String.isSuffix ".hyps" o fst) assumes andalso

      exists (exists (curry (op =) name o shortest_name o fst)

              o datatype_constrs hol_ctxt) deep_dataTs

    val likely_in_struct_induct_step =

      exists is_struct_induct_step (ProofContext.cases_of ctxt)

    val _ = if standard andalso likely_in_struct_induct_step then

              pprint_m (fn () => Pretty.blk (0,

                  pstrs "Hint: To check that the induction hypothesis is \

                        \general enough, try this command: " @

                  [Pretty.mark Markup.sendback (Pretty.blk (0,

                       pstrs ("nitpick [non_std, show_all]")))] @ pstrs "."))

            else

              ()

(*

    val _ = priority "Monotonic types:"

    val _ = List.app (priority o string_for_type ctxt) mono_Ts

    val _ = priority "Nonmonotonic types:"

    val _ = List.app (priority o string_for_type ctxt) nonmono_Ts

*)

    val need_incremental = Int.max (max_potential, max_genuine) >= 2

    val effective_sat_solver =

      if sat_solver <> "smart" then

        if need_incremental andalso

           not (member (op =) (Kodkod_SAT.configured_sat_solvers true)

                       sat_solver) then

          (print_m (K ("An incremental SAT solver is required: \"SAT4J\" will \

                       \be used instead of " ^ quote sat_solver ^ "."));

           "SAT4J")

        else

          sat_solver

      else

        Kodkod_SAT.smart_sat_solver_name need_incremental

    val _ =

      if sat_solver = "smart" then

        print_v (fn () => "Using SAT solver " ^ quote effective_sat_solver ^

                          ". The following" ^

                          (if need_incremental then " incremental " else " ") ^

                          "solvers are configured: " ^

                          commas (map quote (Kodkod_SAT.configured_sat_solvers

                                                       need_incremental)) ^ ".")

      else

        ()

    val too_big_scopes = Unsynchronized.ref []

    (* bool -> scope -> rich_problem option *)

    fun problem_for_scope unsound

            (scope as {card_assigns, bits, bisim_depth, datatypes, ofs, ...}) =

      let

        val _ = not (exists (fn other => scope_less_eq other scope)

                            (!too_big_scopes)) orelse

                raise TOO_LARGE ("Nitpick.pick_them_nits_in_term.\

                                 \problem_for_scope", "too large scope")

(*

        val _ = priority "Offsets:"

        val _ = List.app (fn (T, j0) =>

                             priority (string_for_type ctxt T ^ " = " ^

                                       string_of_int j0))

                         (Typtab.dest ofs)

*)

        val all_exact = forall (is_exact_type datatypes true) all_Ts

        (* nut list -> rep NameTable.table -> nut list * rep NameTable.table *)

        val repify_consts = choose_reps_for_consts scope all_exact

        val main_j0 = offset_of_type ofs bool_T

        val (nat_card, nat_j0) = spec_of_type scope nat_T

        val (int_card, int_j0) = spec_of_type scope int_T

        val _ = (nat_j0 = main_j0 andalso int_j0 = main_j0) orelse

                raise BAD ("Nitpick.pick_them_nits_in_term.problem_for_scope",

                           "bad offsets")

        val kk = kodkod_constrs peephole_optim nat_card int_card main_j0

        val (free_names, rep_table) =

          choose_reps_for_free_vars scope free_names NameTable.empty

        val (sel_names, rep_table) = choose_reps_for_all_sels scope rep_table

        val (nonsel_names, rep_table) = repify_consts nonsel_names rep_table

        val min_highest_arity =

          NameTable.fold (curry Int.max o arity_of_rep o snd) rep_table 1

        val min_univ_card =

          NameTable.fold (curry Int.max o min_univ_card_of_rep o snd) rep_table

                         (univ_card nat_card int_card main_j0 [] KK.True)

        val _ = check_arity min_univ_card min_highest_arity

        val def_us = map (choose_reps_in_nut scope unsound rep_table true)

                         def_us

        val nondef_us = map (choose_reps_in_nut scope unsound rep_table false)

                            nondef_us

(*

        val _ = List.app (priority o string_for_nut ctxt)

                         (free_names @ sel_names @ nonsel_names @

                          nondef_us @ def_us)

*)

        val (free_rels, pool, rel_table) =

          rename_free_vars free_names initial_pool NameTable.empty

        val (sel_rels, pool, rel_table) =

          rename_free_vars sel_names pool rel_table

        val (other_rels, pool, rel_table) =

          rename_free_vars nonsel_names pool rel_table

        val nondef_us = map (rename_vars_in_nut pool rel_table) nondef_us

        val def_us = map (rename_vars_in_nut pool rel_table) def_us

        val nondef_fs = map (kodkod_formula_from_nut ofs kk) nondef_us

        val def_fs = map (kodkod_formula_from_nut ofs kk) def_us

        val formula = fold (fold s_and) [def_fs, nondef_fs] KK.True

        val comment = (if unsound then "unsound" else "sound") ^ "\n" ^

                      PrintMode.setmp [] multiline_string_for_scope scope

        val kodkod_sat_solver =

          Kodkod_SAT.sat_solver_spec effective_sat_solver |> snd

        val bit_width = if bits = 0 then 16 else bits + 1

        val delay = if unsound then

                      Option.map (fn time => Time.- (time, Time.now ()))

                                 deadline

                      |> unsound_delay_for_timeout

                    else

                      0

        val settings = [("solver", commas (map quote kodkod_sat_solver)),

                        ("skolem_depth", "-1"),

                        ("bit_width", string_of_int bit_width),

                        ("symmetry_breaking", signed_string_of_int sym_break),

                        ("sharing", signed_string_of_int sharing_depth),

                        ("flatten", Bool.toString flatten_props),

                        ("delay", signed_string_of_int delay)]

        val plain_rels = free_rels @ other_rels

        val plain_bounds = map (bound_for_plain_rel ctxt debug) plain_rels

        val plain_axioms = map (declarative_axiom_for_plain_rel kk) plain_rels

        val sel_bounds = map (bound_for_sel_rel ctxt debug datatypes) sel_rels

        val dtype_axioms =

          declarative_axioms_for_datatypes hol_ctxt binarize bits ofs kk

                                           rel_table datatypes

        val declarative_axioms = plain_axioms @ dtype_axioms

        val univ_card = Int.max (univ_card nat_card int_card main_j0

                                     (plain_bounds @ sel_bounds) formula,

                                 main_j0 |> bits > 0 ? Integer.add (bits + 1))

        val built_in_bounds = bounds_for_built_in_rels_in_formula debug

                                  univ_card nat_card int_card main_j0 formula

        val bounds = built_in_bounds @ plain_bounds @ sel_bounds

                     |> not debug ? merge_bounds

        val highest_arity =

          fold Integer.max (map (fst o fst) (maps fst bounds)) 0

        val formula = fold_rev s_and declarative_axioms formula

        val _ = if bits = 0 then () else check_bits bits formula

        val _ = if formula = KK.False then ()

                else check_arity univ_card highest_arity

      in

        SOME ({comment = comment, settings = settings, univ_card = univ_card,

               tuple_assigns = [], bounds = bounds,

               int_bounds = if bits = 0 then sequential_int_bounds univ_card

                            else pow_of_two_int_bounds bits main_j0,

               expr_assigns = [], formula = formula},

              {free_names = free_names, sel_names = sel_names,

               nonsel_names = nonsel_names, rel_table = rel_table,

               unsound = unsound, scope = scope})

      end

      handle TOO_LARGE (loc, msg) =>

             if loc = "Nitpick_Kodkod.check_arity" andalso

                not (Typtab.is_empty ofs) then

               problem_for_scope unsound

                   {hol_ctxt = hol_ctxt, binarize = binarize,

                    card_assigns = card_assigns, bits = bits,

                    bisim_depth = bisim_depth, datatypes = datatypes,

                    ofs = Typtab.empty}

             else if loc = "Nitpick.pick_them_nits_in_term.\

                           \problem_for_scope" then

               NONE

             else

               (Unsynchronized.change too_big_scopes (cons scope);

                print_v (fn () => ("Limit reached: " ^ msg ^

                                   ". Skipping " ^ (if unsound then "potential"

                                                    else "genuine") ^

                                   " component of scope."));

                NONE)

           | TOO_SMALL (_, msg) =>

             (print_v (fn () => ("Limit reached: " ^ msg ^

                                 ". Skipping " ^ (if unsound then "potential"

                                                  else "genuine") ^

                                 " component of scope."));

              NONE)

    val das_wort_model =

      (if falsify then "counterexample" else "model")

      |> not standard ? prefix "nonstandard "

    val scopes = Unsynchronized.ref []

    val generated_scopes = Unsynchronized.ref []

    val generated_problems = Unsynchronized.ref ([] : rich_problem list)

    val checked_problems = Unsynchronized.ref (SOME [])

    val met_potential = Unsynchronized.ref 0

    (* rich_problem list -> int list -> unit *)

    fun update_checked_problems problems =

      List.app (Unsynchronized.change checked_problems o Option.map o cons

                o nth problems)

    (* string -> unit *)

    fun show_kodkod_warning "" = ()

      | show_kodkod_warning s = print_m (fn () => "Kodkod warning: " ^ s ^ ".")

    (* bool -> KK.raw_bound list -> problem_extension -> bool * bool option *)

    fun print_and_check_model genuine bounds

            ({free_names, sel_names, nonsel_names, rel_table, scope, ...}

             : problem_extension) =

      let

        val (reconstructed_model, codatatypes_ok) =

          reconstruct_hol_model {show_skolems = show_skolems,

                                 show_datatypes = show_datatypes,

                                 show_consts = show_consts}

              scope formats frees free_names sel_names nonsel_names rel_table

              bounds

        val genuine_means_genuine =

          got_all_user_axioms andalso none_true wfs andalso

          sound_finitizes andalso codatatypes_ok

      in

        (pprint (Pretty.chunks

             [Pretty.blk (0,

                  (pstrs ("Nitpick found a" ^

                          (if not genuine then " potential "

                           else if genuine_means_genuine then " "

                           else " quasi genuine ") ^ das_wort_model) @

                   (case pretties_for_scope scope verbose of

                      [] => []

                    | pretties => pstrs " for " @ pretties) @

                   [Pretty.str ":\n"])),

              Pretty.indent indent_size reconstructed_model]);

         if genuine then

           (if check_genuine andalso standard then

              case prove_hol_model scope tac_timeout free_names sel_names

                                   rel_table bounds assms_t of

                SOME true =>

                print ("Confirmation by \"auto\": The above " ^

                       das_wort_model ^ " is really genuine.")

              | SOME false =>

                if genuine_means_genuine then

                  error ("A supposedly genuine " ^ das_wort_model ^ " was \

                         \shown to be spurious by \"auto\".\nThis should never \

                         \happen.\nPlease send a bug report to blanchet\

                         \te@in.tum.de.")

                 else

                   print ("Refutation by \"auto\": The above " ^

                          das_wort_model ^ " is spurious.")

               | NONE => print "No confirmation by \"auto\"."

            else

              ();

            if not standard andalso likely_in_struct_induct_step then

              print "The existence of a nonstandard model suggests that the \

                    \induction hypothesis is not general enough or perhaps \

                    \even wrong. See the \"Inductive Properties\" section of \

                    \the Nitpick manual for details (\"isabelle doc nitpick\")."

            else

              ();

            if has_syntactic_sorts orig_t then

              print "Hint: Maybe you forgot a type constraint?"

            else

              ();

            if not genuine_means_genuine then

              if no_poly_user_axioms then

                let

                  val options =

                    [] |> not got_all_mono_user_axioms

                          ? cons ("user_axioms", "\"true\"")

                       |> not (none_true wfs)

                          ? cons ("wf", "\"smart\" or \"false\"")

                       |> not sound_finitizes

                          ? cons ("finitize", "\"smart\" or \"false\"")

                       |> not codatatypes_ok

                          ? cons ("bisim_depth", "a nonnegative value")

                  val ss =

                    map (fn (name, value) => quote name ^ " set to " ^ value)

                        options

                in

                  print ("Try again with " ^

                         space_implode " "

                             (Sledgehammer_Util.serial_commas "and" ss) ^

                         " to confirm that the " ^ das_wort_model ^

                         " is genuine.")

                end

              else

                print ("Nitpick is unable to guarantee the authenticity of \

                       \the " ^ das_wort_model ^ " in the presence of \

                       \polymorphic axioms.")

            else

              ();

            NONE)

         else

           if not genuine then

             (Unsynchronized.inc met_potential;

              if check_potential then

                let

                  val status = prove_hol_model scope tac_timeout free_names

                                              sel_names rel_table bounds assms_t

                in

                  (case status of

                     SOME true => print ("Confirmation by \"auto\": The \

                                         \above " ^ das_wort_model ^

                                         " is genuine.")

                   | SOME false => print ("Refutation by \"auto\": The above " ^

                                          das_wort_model ^ " is spurious.")

                   | NONE => print "No confirmation by \"auto\".");

                  status

                end

              else

                NONE)

           else

             NONE)

        |> pair genuine_means_genuine

      end

    (* bool * int * int * int -> bool -> rich_problem list

       -> bool * int * int * int *)

    fun solve_any_problem (found_really_genuine, max_potential, max_genuine,

                           donno) first_time problems =

      let

        val max_potential = Int.max (0, max_potential)

        val max_genuine = Int.max (0, max_genuine)

        (* bool -> int * KK.raw_bound list -> bool * bool option *)

        fun print_and_check genuine (j, bounds) =

          print_and_check_model genuine bounds (snd (nth problems j))

        val max_solutions = max_potential + max_genuine

                            |> not need_incremental ? curry Int.min 1

      in

        if max_solutions <= 0 then

          (found_really_genuine, 0, 0, donno)

        else

          case KK.solve_any_problem overlord deadline max_threads max_solutions

                                    (map fst problems) of

            KK.JavaNotInstalled =>

            (print_m install_java_message;

             (found_really_genuine, max_potential, max_genuine, donno + 1))

          | KK.KodkodiNotInstalled =>

            (print_m install_kodkodi_message;

             (found_really_genuine, max_potential, max_genuine, donno + 1))

          | KK.Normal ([], unsat_js, s) =>

            (update_checked_problems problems unsat_js; show_kodkod_warning s;

             (found_really_genuine, max_potential, max_genuine, donno))

          | KK.Normal (sat_ps, unsat_js, s) =>

            let

              val (lib_ps, con_ps) =

                List.partition (#unsound o snd o nth problems o fst) sat_ps

            in

              update_checked_problems problems (unsat_js @ map fst lib_ps);

              show_kodkod_warning s;

              if null con_ps then

                let

                  val genuine_codes =

                    lib_ps |> take max_potential

                           |> map (print_and_check false)

                           |> filter (curry (op =) (SOME true) o snd)

                  val found_really_genuine =

                    found_really_genuine orelse exists fst genuine_codes

                  val num_genuine = length genuine_codes

                  val max_genuine = max_genuine - num_genuine

                  val max_potential = max_potential

                                      - (length lib_ps - num_genuine)

                in

                  if max_genuine <= 0 then

                    (found_really_genuine, 0, 0, donno)

                  else

                    let

                      (* "co_js" is the list of sound problems whose unsound

                         pendants couldn't be satisfied and hence that most

                         probably can't be satisfied themselves. *)

                      val co_js =

                        map (fn j => j - 1) unsat_js

                        |> filter (fn j =>

                                      j >= 0 andalso

                                      scopes_equivalent

                                          (#scope (snd (nth problems j)),

                                           #scope (snd (nth problems (j + 1)))))

                      val bye_js = sort_distinct int_ord (map fst sat_ps @

                                                          unsat_js @ co_js)

                      val problems =

                        problems |> filter_out_indices bye_js

                                 |> max_potential <= 0

                                    ? filter_out (#unsound o snd)

                    in

                      solve_any_problem (found_really_genuine, max_potential,

                                         max_genuine, donno) false problems

                    end

                end

              else

                let

                  val genuine_codes =

                    con_ps |> take max_genuine

                           |> map (print_and_check true)

                  val max_genuine = max_genuine - length genuine_codes

                  val found_really_genuine =

                    found_really_genuine orelse exists fst genuine_codes

                in

                  if max_genuine <= 0 orelse not first_time then

                    (found_really_genuine, 0, max_genuine, donno)

                  else

                    let

                      val bye_js = sort_distinct int_ord

                                                 (map fst sat_ps @ unsat_js)

                      val problems =

                        problems |> filter_out_indices bye_js

                                 |> filter_out (#unsound o snd)

                    in

                      solve_any_problem (found_really_genuine, 0, max_genuine,

                                         donno) false problems

                    end

                end

            end

          | KK.TimedOut unsat_js =>

            (update_checked_problems problems unsat_js; raise TimeLimit.TimeOut)

          | KK.Interrupted NONE => (checked_problems := NONE; do_interrupted ())

          | KK.Interrupted (SOME unsat_js) =>

            (update_checked_problems problems unsat_js; do_interrupted ())

          | KK.Error (s, unsat_js) =>

            (update_checked_problems problems unsat_js;

             print_v (K ("Kodkod error: " ^ s ^ "."));

             (found_really_genuine, max_potential, max_genuine, donno + 1))

      end

    (* int -> int -> scope list -> bool * int * int * int

       -> bool * int * int * int *)

    fun run_batch j n scopes (found_really_genuine, max_potential, max_genuine,

                              donno) =

      let

        val _ =

          if null scopes then

            print_m (K "The scope specification is inconsistent.")

          else if verbose then

            pprint (Pretty.chunks

                [Pretty.blk (0,

                     pstrs ((if n > 1 then

                               "Batch " ^ string_of_int (j + 1) ^ " of " ^

                               signed_string_of_int n ^ ": "

                             else

                               "") ^

                            "Trying " ^ string_of_int (length scopes) ^

                            " scope" ^ plural_s_for_list scopes ^ ":")),

                 Pretty.indent indent_size

                     (Pretty.chunks (map2

                          (fn j => fn scope =>

                              Pretty.block (

                                  (case pretties_for_scope scope true of

                                     [] => [Pretty.str "Empty"]

                                   | pretties => pretties) @

                                  [Pretty.str (if j = 1 then "." else ";")]))

                          (length scopes downto 1) scopes))])

          else

            ()

        (* scope * bool -> rich_problem list * bool

           -> rich_problem list * bool *)

        fun add_problem_for_scope (scope, unsound) (problems, donno) =

          (check_deadline ();

           case problem_for_scope unsound scope of

             SOME problem =>

             (problems

              |> (null problems orelse

                  not (KK.problems_equivalent (fst problem, fst (hd problems))))

                  ? cons problem, donno)

           | NONE => (problems, donno + 1))

        val (problems, donno) =

          fold add_problem_for_scope

               (map_product pair scopes

                    ((if max_genuine > 0 then [false] else []) @

                     (if max_potential > 0 then [true] else [])))

               ([], donno)

        val _ = Unsynchronized.change generated_problems (append problems)

        val _ = Unsynchronized.change generated_scopes (append scopes)

        val _ =

          if j + 1 = n then

            let

              val (unsound_problems, sound_problems) =

                List.partition (#unsound o snd) (!generated_problems)

            in

              if not (null sound_problems) andalso

                 forall (KK.is_problem_trivially_false o fst)

                        sound_problems then

                print_m (fn () =>

                    "Warning: The conjecture either trivially holds for the \

                    \given scopes or lies outside Nitpick's supported \

                    \fragment." ^

                    (if exists (not o KK.is_problem_trivially_false o fst)

                               unsound_problems then

                       " Only potential counterexamples may be found."

                     else

                       ""))

              else

                ()

            end

          else

            ()

      in

        solve_any_problem (found_really_genuine, max_potential, max_genuine,

                           donno) true (rev problems)

      end

    (* rich_problem list -> scope -> int *)

    fun scope_count (problems : rich_problem list) scope =

      length (filter (curry scopes_equivalent scope o #scope o snd) problems)

    (* string -> string *)

    fun excipit did_so_and_so =

      let

        (* rich_problem list -> rich_problem list *)

        val do_filter =

          if !met_potential = max_potential then filter_out (#unsound o snd)

          else I

        val total = length (!scopes)

        val unsat =

          fold (fn scope =>

                   case scope_count (do_filter (!generated_problems)) scope of

                     0 => I

                   | n =>

                     scope_count (do_filter (these (!checked_problems)))

                                 scope = n

                     ? Integer.add 1) (!generated_scopes) 0

      in

        "Nitpick " ^ did_so_and_so ^

        (if is_some (!checked_problems) andalso total > 0 then

           " " ^ string_of_int (Int.min (total - 1, unsat)) ^ " of " ^

           string_of_int total ^ " scope" ^ plural_s total

         else

           "") ^ "."

      end

    (* int -> int -> scope list -> bool * int * int * int -> KK.outcome *)

    fun run_batches _ _ []

                    (found_really_genuine, max_potential, max_genuine, donno) =

        if donno > 0 andalso max_genuine > 0 then

          (print_m (fn () => excipit "checked"); "unknown")

        else if max_genuine = original_max_genuine then

          if max_potential = original_max_potential then

            (print_m (fn () =>

                 "Nitpick found no " ^ das_wort_model ^ "." ^

                 (if not standard andalso likely_in_struct_induct_step then

                    " This suggests that the induction hypothesis might be \

                    \general enough to prove this subgoal."

                  else

                    "")); "none")

          else

            (print_m (fn () =>

                 "Nitpick could not find a" ^

                 (if max_genuine = 1 then " better " ^ das_wort_model ^ "."

                  else "ny better " ^ das_wort_model ^ "s.")); "potential")

        else if found_really_genuine then

          "genuine"

        else

          "quasi_genuine"

      | run_batches j n (batch :: batches) z =

        let val (z as (_, _, max_genuine, _)) = run_batch j n batch z in

          run_batches (j + 1) n (if max_genuine > 0 then batches else []) z

        end

    val (skipped, the_scopes) =

      all_scopes hol_ctxt binarize sym_break cards_assigns maxes_assigns

                 iters_assigns bitss bisim_depths mono_Ts nonmono_Ts deep_dataTs

                 finitizable_dataTs

    val _ = if skipped > 0 then

              print_m (fn () => "Too many scopes. Skipping " ^

                                string_of_int skipped ^ " scope" ^

                                plural_s skipped ^

                                ". (Consider using \"mono\" or \

                                \\"merge_type_vars\" to prevent this.)")

            else

              ()

    val _ = scopes := the_scopes

    val batches = batch_list batch_size (!scopes)

    val outcome_code =

      (run_batches 0 (length batches) batches

                   (false, max_potential, max_genuine, 0)

       handle Exn.Interrupt => do_interrupted ())

      handle TimeLimit.TimeOut =>

             (print_m (fn () => excipit "ran out of time after checking");

              if !met_potential > 0 then "potential" else "unknown")

           | Exn.Interrupt =>

             if auto orelse debug then raise Interrupt

             else error (excipit "was interrupted after checking")

    val _ = print_v (fn () => "Total time: " ^

                              signed_string_of_int (Time.toMilliseconds

                                    (Timer.checkRealTimer timer)) ^ " ms.")

  in (outcome_code, !state_ref) end

  handle Exn.Interrupt =>

         if auto orelse #debug params then

           raise Interrupt

         else