(*  Title:      HOL/Tools/Sledgehammer/sledgehammer_provers.ML

    Author:     Fabian Immler, TU Muenchen

    Author:     Makarius

    Author:     Jasmin Blanchette, TU Muenchen

Generic prover abstraction for Sledgehammer.

*)

signature SLEDGEHAMMER_PROVERS =

sig

  type failure = ATP_Proof.failure

  type locality = Sledgehammer_Filter.locality

  type relevance_fudge = Sledgehammer_Filter.relevance_fudge

  type translated_formula = Sledgehammer_ATP_Translate.translated_formula

  type type_system = Sledgehammer_ATP_Translate.type_system

  type minimize_command = Sledgehammer_ATP_Reconstruct.minimize_command

  datatype rich_type_system =

    Dumb_Type_Sys of type_system |

    Smart_Type_Sys of bool

  type params =

    {debug: bool,

     verbose: bool,

     overlord: bool,

     blocking: bool,

     provers: string list,

     type_sys: rich_type_system,

     relevance_thresholds: real * real,

     max_relevant: int option,

     monomorphize_limit: int,

     explicit_apply: bool,

     isar_proof: bool,

     isar_shrink_factor: int,

     slicing: bool,

     timeout: Time.time,

     expect: string}

  datatype prover_fact =

    Untranslated_Fact of (string * locality) * thm |

    SMT_Weighted_Fact of (string * locality) * (int option * thm)

  type prover_problem =

    {state: Proof.state,

     goal: thm,

     subgoal: int,

     subgoal_count: int,

     facts: prover_fact list,

     smt_filter: (string * locality) SMT_Solver.smt_filter_data option}

  type prover_result =

    {outcome: failure option,

     used_facts: (string * locality) list,

     run_time_in_msecs: int option,

     message: string}

  type prover = params -> minimize_command -> prover_problem -> prover_result

  val smt_triggers : bool Config.T

  val smt_weights : bool Config.T

  val smt_weight_min_facts : int Config.T

  val smt_min_weight : int Config.T

  val smt_max_weight : int Config.T

  val smt_max_weight_index : int Config.T

  val smt_weight_curve : (int -> int) Unsynchronized.ref

  val smt_max_slices : int Config.T

  val smt_slice_fact_frac : real Config.T

  val smt_slice_time_frac : real Config.T

  val smt_slice_min_secs : int Config.T

  val das_Tool : string

  val select_smt_solver : string -> Proof.context -> Proof.context

  val is_smt_prover : Proof.context -> string -> bool

  val is_prover_supported : Proof.context -> string -> bool

  val is_prover_installed : Proof.context -> string -> bool

  val default_max_relevant_for_prover : Proof.context -> bool -> string -> int

  val is_built_in_const_for_prover :

    Proof.context -> string -> string * typ -> term list -> bool * term list

  val atp_relevance_fudge : relevance_fudge

  val smt_relevance_fudge : relevance_fudge

  val relevance_fudge_for_prover : Proof.context -> string -> relevance_fudge

  val dest_dir : string Config.T

  val problem_prefix : string Config.T

  val measure_run_time : bool Config.T

  val weight_smt_fact :

    Proof.context -> int -> ((string * locality) * thm) * int

    -> (string * locality) * (int option * thm)

  val untranslated_fact : prover_fact -> (string * locality) * thm

  val smt_weighted_fact :

    Proof.context -> int -> prover_fact * int

    -> (string * locality) * (int option * thm)

  val supported_provers : Proof.context -> unit

  val kill_provers : unit -> unit

  val running_provers : unit -> unit

  val messages : int option -> unit

  val get_prover : Proof.context -> bool -> string -> prover

end;

structure Sledgehammer_Provers : SLEDGEHAMMER_PROVERS =

struct

open ATP_Problem

open ATP_Proof

open ATP_Systems

open Metis_Translate

open Sledgehammer_Util

open Sledgehammer_Filter

open Sledgehammer_ATP_Translate

open Sledgehammer_ATP_Reconstruct

(** The Sledgehammer **)

(* Identifier to distinguish Sledgehammer from other tools using

   "Async_Manager". *)

val das_Tool = "Sledgehammer"

val select_smt_solver =

  Context.proof_map o SMT_Config.select_solver

fun is_smt_prover ctxt name =

  member (op =) (SMT_Solver.available_solvers_of ctxt) name

fun is_prover_supported ctxt name =

  let val thy = Proof_Context.theory_of ctxt in

    is_smt_prover ctxt name orelse member (op =) (supported_atps thy) name

  end

fun is_prover_installed ctxt =

  is_smt_prover ctxt orf is_atp_installed (Proof_Context.theory_of ctxt)

fun get_slices slicing slices =

  (0 upto length slices - 1) ~~ slices |> not slicing ? (List.last #> single)

fun default_max_relevant_for_prover ctxt slicing name =

  let val thy = Proof_Context.theory_of ctxt in

    if is_smt_prover ctxt name then

      SMT_Solver.default_max_relevant ctxt name

    else

      fold (Integer.max o snd o snd o snd)

           (get_slices slicing (#best_slices (get_atp thy name) ctxt)) 0

  end

(* These are either simplified away by "Meson.presimplify" (most of the time) or

   handled specially via "fFalse", "fTrue", ..., "fequal". *)

val atp_irrelevant_consts =

  [@{const_name False}, @{const_name True}, @{const_name Not},

   @{const_name conj}, @{const_name disj}, @{const_name implies},

   @{const_name HOL.eq}, @{const_name If}, @{const_name Let}]

fun is_built_in_const_for_prover ctxt name =

  if is_smt_prover ctxt name then

    let val ctxt = ctxt |> select_smt_solver name in

      fn x => fn ts =>

         if SMT_Builtin.is_builtin_num_ext ctxt (list_comb (Const x, ts)) then

           (true, [])

         else if SMT_Builtin.is_builtin_fun_ext ctxt x ts then

           (true, ts)

         else

           (false, ts)

    end

  else

    fn (s, _) => fn ts => (member (op =) atp_irrelevant_consts s, ts)

(* FUDGE *)

val atp_relevance_fudge =

  {allow_ext = true,

   local_const_multiplier = 1.5,

   worse_irrel_freq = 100.0,

   higher_order_irrel_weight = 1.05,

   abs_rel_weight = 0.5,

   abs_irrel_weight = 2.0,

   skolem_irrel_weight = 0.75,

   theory_const_rel_weight = 0.5,

   theory_const_irrel_weight = 0.25,

   intro_bonus = 0.15,

   elim_bonus = 0.15,

   simp_bonus = 0.15,

   local_bonus = 0.55,

   assum_bonus = 1.05,

   chained_bonus = 1.5,

   max_imperfect = 11.5,

   max_imperfect_exp = 1.0,

   threshold_divisor = 2.0,

   ridiculous_threshold = 0.01}

(* FUDGE (FIXME) *)

val smt_relevance_fudge =

  {allow_ext = false,

   local_const_multiplier = #local_const_multiplier atp_relevance_fudge,

   worse_irrel_freq = #worse_irrel_freq atp_relevance_fudge,

   higher_order_irrel_weight = #higher_order_irrel_weight atp_relevance_fudge,

   abs_rel_weight = #abs_rel_weight atp_relevance_fudge,

   abs_irrel_weight = #abs_irrel_weight atp_relevance_fudge,

   skolem_irrel_weight = #skolem_irrel_weight atp_relevance_fudge,

   theory_const_rel_weight = #theory_const_rel_weight atp_relevance_fudge,

   theory_const_irrel_weight = #theory_const_irrel_weight atp_relevance_fudge,

   intro_bonus = #intro_bonus atp_relevance_fudge,

   elim_bonus = #elim_bonus atp_relevance_fudge,

   simp_bonus = #simp_bonus atp_relevance_fudge,

   local_bonus = #local_bonus atp_relevance_fudge,

   assum_bonus = #assum_bonus atp_relevance_fudge,

   chained_bonus = #chained_bonus atp_relevance_fudge,

   max_imperfect = #max_imperfect atp_relevance_fudge,

   max_imperfect_exp = #max_imperfect_exp atp_relevance_fudge,

   threshold_divisor = #threshold_divisor atp_relevance_fudge,

   ridiculous_threshold = #ridiculous_threshold atp_relevance_fudge}

fun relevance_fudge_for_prover ctxt name =

  if is_smt_prover ctxt name then smt_relevance_fudge else atp_relevance_fudge

fun supported_provers ctxt =

  let

    val thy = Proof_Context.theory_of ctxt

    val (remote_provers, local_provers) =

      sort_strings (supported_atps thy) @

      sort_strings (SMT_Solver.available_solvers_of ctxt)

      |> List.partition (String.isPrefix remote_prefix)

  in

    Output.urgent_message ("Supported provers: " ^

                           commas (local_provers @ remote_provers) ^ ".")

  end

fun kill_provers () = Async_Manager.kill_threads das_Tool "provers"

fun running_provers () = Async_Manager.running_threads das_Tool "provers"

val messages = Async_Manager.thread_messages das_Tool "prover"

(** problems, results, ATPs, etc. **)

datatype rich_type_system =

  Dumb_Type_Sys of type_system |

  Smart_Type_Sys of bool

type params =

  {debug: bool,

   verbose: bool,

   overlord: bool,

   blocking: bool,

   provers: string list,

   type_sys: rich_type_system,

   relevance_thresholds: real * real,

   max_relevant: int option,

   monomorphize_limit: int,

   explicit_apply: bool,

   isar_proof: bool,

   isar_shrink_factor: int,

   slicing: bool,

   timeout: Time.time,

   expect: string}

datatype prover_fact =

  Untranslated_Fact of (string * locality) * thm |

  SMT_Weighted_Fact of (string * locality) * (int option * thm)

type prover_problem =

  {state: Proof.state,

   goal: thm,

   subgoal: int,

   subgoal_count: int,

   facts: prover_fact list,

   smt_filter: (string * locality) SMT_Solver.smt_filter_data option}

type prover_result =

  {outcome: failure option,

   message: string,

   used_facts: (string * locality) list,

   run_time_in_msecs: int option}

type prover = params -> minimize_command -> prover_problem -> prover_result

(* configuration attributes *)

val dest_dir =

  Attrib.setup_config_string @{binding sledgehammer_dest_dir} (K "")

  (* Empty string means create files in Isabelle's temporary files directory. *)

val problem_prefix =

  Attrib.setup_config_string @{binding sledgehammer_problem_prefix} (K "prob")

val measure_run_time =

  Attrib.setup_config_bool @{binding sledgehammer_measure_run_time} (K false)

fun with_path cleanup after f path =

  Exn.capture f path

  |> tap (fn _ => cleanup path)

  |> Exn.release

  |> tap (after path)

fun proof_banner auto =

  if auto then "Auto Sledgehammer found a proof" else "Try this command"

val smt_triggers =

  Attrib.setup_config_bool @{binding sledgehammer_smt_triggers} (K true)

val smt_weights =

  Attrib.setup_config_bool @{binding sledgehammer_smt_weights} (K true)

val smt_weight_min_facts =

  Attrib.setup_config_int @{binding sledgehammer_smt_weight_min_facts} (K 20)

(* FUDGE *)

val smt_min_weight =

  Attrib.setup_config_int @{binding sledgehammer_smt_min_weight} (K 0)

val smt_max_weight =

  Attrib.setup_config_int @{binding sledgehammer_smt_max_weight} (K 10)

val smt_max_weight_index =

  Attrib.setup_config_int @{binding sledgehammer_smt_max_weight_index} (K 200)

val smt_weight_curve = Unsynchronized.ref (fn x : int => x * x)

fun smt_fact_weight ctxt j num_facts =

  if Config.get ctxt smt_weights andalso

     num_facts >= Config.get ctxt smt_weight_min_facts then

    let

      val min = Config.get ctxt smt_min_weight

      val max = Config.get ctxt smt_max_weight

      val max_index = Config.get ctxt smt_max_weight_index

      val curve = !smt_weight_curve

    in

      SOME (max - (max - min + 1) * curve (Int.max (0, max_index - j - 1))

            div curve max_index)

    end

  else

    NONE

fun weight_smt_fact ctxt num_facts ((info, th), j) =

  let val thy = Proof_Context.theory_of ctxt in

    (info, (smt_fact_weight ctxt j num_facts, th |> Thm.transfer thy))

  end

fun untranslated_fact (Untranslated_Fact p) = p

  | untranslated_fact (SMT_Weighted_Fact (info, (_, th))) = (info, th)

fun atp_translated_fact ctxt fact =

    translate_atp_fact ctxt false (untranslated_fact fact)

fun smt_weighted_fact _ _ (SMT_Weighted_Fact p, _) = p

  | smt_weighted_fact ctxt num_facts (fact, j) =

    (untranslated_fact fact, j) |> weight_smt_fact ctxt num_facts

fun overlord_file_location_for_prover prover =

  (getenv "ISABELLE_HOME_USER", "prob_" ^ prover)

(* generic TPTP-based ATPs *)

fun int_opt_add (SOME m) (SOME n) = SOME (m + n)

  | int_opt_add _ _ = NONE

val atp_blacklist_max_iters = 10

(* Important messages are important but not so important that users want to see

   them each time. *)

val atp_important_message_keep_quotient = 10

val fallback_best_type_systems =

  [Preds (Polymorphic, Const_Arg_Types), Simple All_Types]

fun adjust_dumb_type_sys formats (Simple level) =

    if member (op =) formats Tff then (Tff, Simple level)

    else (Fof, Preds (Mangled_Monomorphic, level))

  | adjust_dumb_type_sys formats type_sys =

    if member (op =) formats Fof then (Fof, type_sys)

    else (Tff, Simple (level_of_type_sys type_sys))

fun determine_format_and_type_sys _ formats (Dumb_Type_Sys type_sys) =

    adjust_dumb_type_sys formats type_sys

  | determine_format_and_type_sys best_type_systems formats

                                  (Smart_Type_Sys full_types) =

    map type_sys_from_string best_type_systems @ fallback_best_type_systems

    |> find_first (if full_types then is_type_sys_virtually_sound else K true)

    |> the |> adjust_dumb_type_sys formats

fun run_atp auto name

        ({exec, required_execs, arguments, proof_delims, known_failures,

          conj_sym_kind, prem_kind, formats, best_slices, best_type_systems,

          ...} : atp_config)

        ({debug, verbose, overlord, type_sys, max_relevant, monomorphize_limit,

          explicit_apply, isar_proof, isar_shrink_factor, slicing, timeout, ...}

         : params)

        minimize_command ({state, goal, subgoal, facts, ...} : prover_problem) =

  let

    val thy = Proof.theory_of state

    val ctxt = Proof.context_of state

    val (format, type_sys) =

      determine_format_and_type_sys best_type_systems formats type_sys

    val (_, hyp_ts, concl_t) = strip_subgoal goal subgoal

    val (dest_dir, problem_prefix) =

      if overlord then overlord_file_location_for_prover name

      else (Config.get ctxt dest_dir, Config.get ctxt problem_prefix)

    val problem_file_name =

      Path.basic (problem_prefix ^ (if overlord then "" else serial_string ()) ^

                  "_" ^ string_of_int subgoal)

    val problem_path_name =

      if dest_dir = "" then

        File.tmp_path problem_file_name

      else if File.exists (Path.explode dest_dir) then

        Path.append (Path.explode dest_dir) problem_file_name

      else

        error ("No such directory: " ^ quote dest_dir ^ ".")

    val measure_run_time = verbose orelse Config.get ctxt measure_run_time

    val command = Path.explode (getenv (fst exec) ^ "/" ^ snd exec)

    fun split_time s =

      let

        val split = String.tokens (fn c => str c = "\n")

        val (output, t) = s |> split |> split_last |> apfst cat_lines

        fun as_num f = f >> (fst o read_int)

        val num = as_num (Scan.many1 Symbol.is_ascii_digit)

        val digit = Scan.one Symbol.is_ascii_digit

        val num3 = as_num (digit ::: digit ::: (digit >> single))

        val time = num --| Scan.$$ "." -- num3 >> (fn (a, b) => a * 1000 + b)

        val as_time = Scan.read Symbol.stopper time o raw_explode

      in (output, as_time t) end

    fun run_on prob_file =

      case filter (curry (op =) "" o getenv o fst) (exec :: required_execs) of

        (home_var, _) :: _ =>

        error ("The environment variable " ^ quote home_var ^ " is not set.")

      | [] =>

        if File.exists command then

          let

            (* If slicing is disabled, we expand the last slice to fill the

               entire time available. *)

            val actual_slices = get_slices slicing (best_slices ctxt)

            val num_actual_slices = length actual_slices

            fun monomorphize_facts facts =

              let

                val repair_context =

                  Config.put SMT_Config.verbose debug

                  #> Config.put SMT_Config.monomorph_full false

                  #> Config.put SMT_Config.monomorph_limit monomorphize_limit

                val facts = facts |> map untranslated_fact

                (* pseudo-theorem involving the same constants as the subgoal *)

                val subgoal_th =

                  Logic.list_implies (hyp_ts, concl_t)

                  |> Skip_Proof.make_thm thy

                val indexed_facts =

                  (~1, subgoal_th) :: (0 upto length facts - 1 ~~ map snd facts)

              in

                SMT_Monomorph.monomorph indexed_facts (repair_context ctxt)

                |> fst |> sort (int_ord o pairself fst)

                |> filter_out (curry (op =) ~1 o fst)

                |> map (Untranslated_Fact o apfst (fst o nth facts))

              end

            fun run_slice blacklist

                          (slice, (time_frac, (complete, default_max_relevant)))

                          time_left =

              let

                val num_facts =

                  length facts |> is_none max_relevant

                                  ? Integer.min default_max_relevant

                val fairly_sound = is_type_sys_fairly_sound type_sys

                val facts =

                  facts |> not fairly_sound

                           ? filter_out (is_dangerous_term o prop_of o snd

                                         o untranslated_fact)

                        |> take num_facts

                        |> not (null blacklist)

                           ? filter_out (member (op =) blacklist o fst

                                         o untranslated_fact)

                        |> polymorphism_of_type_sys type_sys <> Polymorphic

                           ? monomorphize_facts

                        |> map (atp_translated_fact ctxt)

                val real_ms = Real.fromInt o Time.toMilliseconds

                val slice_timeout =

                  ((real_ms time_left

                    |> (if slice < num_actual_slices - 1 then

                          curry Real.min (time_frac * real_ms timeout)

                        else

                          I))

                   * 0.001) |> seconds

                val _ =

                  if debug then

                    quote name ^ " slice #" ^ string_of_int (slice + 1) ^

                    " with " ^ string_of_int num_facts ^ " fact" ^

                    plural_s num_facts ^ " for " ^

                    string_from_time slice_timeout ^ "..."

                    |> Output.urgent_message

                  else

                    ()

                val (atp_problem, pool, conjecture_offset, facts_offset,

                     fact_names) =

                  prepare_atp_problem ctxt conj_sym_kind prem_kind type_sys

                                      explicit_apply hyp_ts concl_t facts

                fun weights () = atp_problem_weights atp_problem

                val core =

                  File.shell_path command ^ " " ^

                  arguments ctxt slice slice_timeout weights ^ " " ^

                  File.shell_path prob_file

                val command =

                  (if measure_run_time then

                     "TIMEFORMAT='%3R'; { time " ^ core ^ " ; }"

                   else

                     "exec " ^ core) ^ " 2>&1"

                val _ =

                  atp_problem

                  |> tptp_strings_for_atp_problem format

                  |> cons ("% " ^ command ^ "\n")

                  |> File.write_list prob_file

                val conjecture_shape =

                  conjecture_offset + 1

                    upto conjecture_offset + length hyp_ts + 1

                  |> map single

                val ((output, msecs), res_code) =

                  bash_output command

                  |>> (if overlord then

                         prefix ("% " ^ command ^ "\n% " ^ timestamp () ^ "\n")

                       else

                         I)

                  |>> (if measure_run_time then split_time else rpair NONE)

                val (atp_proof, outcome) =

                  extract_tstplike_proof_and_outcome debug verbose complete

                      res_code proof_delims known_failures output

                  |>> atp_proof_from_tstplike_proof

                val (conjecture_shape, facts_offset, fact_names) =

                  if is_none outcome then

                    repair_conjecture_shape_and_fact_names type_sys output

                        conjecture_shape facts_offset fact_names

                  else

                    (* don't bother repairing *)

                    (conjecture_shape, facts_offset, fact_names)

                val outcome =

                  case outcome of

                    NONE =>

                    if is_unsound_proof type_sys conjecture_shape facts_offset

                                        fact_names atp_proof then

                      SOME (UnsoundProof (is_type_sys_virtually_sound type_sys))

                    else

                      NONE

                  | SOME Unprovable =>

                    if null blacklist then outcome

                    else SOME IncompleteUnprovable

                  | _ => outcome

              in

                ((pool, conjecture_shape, facts_offset, fact_names),

                 (output, msecs, atp_proof, outcome))

              end

            val timer = Timer.startRealTimer ()

            fun maybe_run_slice blacklist slice

                                (result as (_, (_, msecs0, _, SOME _))) =

                let

                  val time_left = Time.- (timeout, Timer.checkRealTimer timer)

                in

                  if Time.<= (time_left, Time.zeroTime) then

                    result

                  else

                    (run_slice blacklist slice time_left

                     |> (fn (stuff, (output, msecs, atp_proof, outcome)) =>

                            (stuff, (output, int_opt_add msecs0 msecs, atp_proof,

                                     outcome))))

                end

              | maybe_run_slice _ _ result = result

            fun maybe_blacklist_facts_and_retry iter blacklist

                    (result as ((_, _, facts_offset, fact_names),

                                (_, _, atp_proof, SOME (UnsoundProof false)))) =

                (case used_facts_in_atp_proof type_sys facts_offset fact_names

                                              atp_proof of

                   [] => result

                 | new_baddies =>

                   let val blacklist = new_baddies @ blacklist in

                     result

                     |> maybe_run_slice blacklist (List.last actual_slices)

                     |> iter < atp_blacklist_max_iters

                        ? maybe_blacklist_facts_and_retry (iter + 1) blacklist

                   end)

              | maybe_blacklist_facts_and_retry _ _ result = result

          in

            ((Symtab.empty, [], 0, Vector.fromList []),

             ("", SOME 0, [], SOME InternalError))

            |> fold (maybe_run_slice []) actual_slices

               (* The ATP found an unsound proof? Automatically try again

                  without the offending facts! *)

            |> maybe_blacklist_facts_and_retry 0 []

          end

        else

          error ("Bad executable: " ^ Path.print command ^ ".")

    (* If the problem file has not been exported, remove it; otherwise, export

       the proof file too. *)

    fun cleanup prob_file =

      if dest_dir = "" then try File.rm prob_file else NONE

    fun export prob_file (_, (output, _, _, _)) =

      if dest_dir = "" then

        ()

      else

        File.write (Path.explode (Path.implode prob_file ^ "_proof")) output

    val ((pool, conjecture_shape, facts_offset, fact_names),

         (output, msecs, atp_proof, outcome)) =

      with_path cleanup export run_on problem_path_name

    val important_message =

      if not auto andalso

         random_range 0 (atp_important_message_keep_quotient - 1) = 0 then

        extract_important_message output

      else

        ""

    fun append_to_message message =

      message ^

      (if verbose then

         "\nATP real CPU time: " ^

         string_from_time (Time.fromMilliseconds (the msecs)) ^ "."

       else

         "") ^

      (if important_message <> "" then

         "\n\nImportant message from Dr. Geoff Sutcliffe:\n" ^ important_message

       else

         "")

    val isar_params = (ctxt, debug, isar_shrink_factor, pool, conjecture_shape)

    val metis_params =

      (proof_banner auto, minimize_command, type_sys, atp_proof, facts_offset,

       fact_names, goal, subgoal)

    val (outcome, (message, used_facts)) =

      case outcome of

        NONE =>

        (NONE, proof_text isar_proof isar_params metis_params

               |>> append_to_message)

      | SOME ProofMissing =>

        (NONE, metis_proof_text metis_params |>> append_to_message)

      | SOME failure => (outcome, (string_for_failure failure, []))

  in

    {outcome = outcome, message = message, used_facts = used_facts,

     run_time_in_msecs = msecs}

  end

(* "SMT_Failure.Abnormal_Termination" carries the solver's return code. Until

   these are sorted out properly in the SMT module, we have to interpret these

   ourselves. *)

val remote_smt_failures =

  [(22, CantConnect),

   (2, NoLibwwwPerl)]

val z3_wrapper_failures =

  [(10, NoRealZ3),

   (11, InternalError),

   (12, InternalError),

   (13, InternalError)]

val z3_failures =

  [(101, OutOfResources),

   (103, MalformedInput),

   (110, MalformedInput)]

val unix_failures =

  [(139, Crashed)]

val smt_failures =

  remote_smt_failures @ z3_wrapper_failures @ z3_failures @ unix_failures

fun failure_from_smt_failure (SMT_Failure.Counterexample {is_real_cex, ...}) =

    if is_real_cex then Unprovable else IncompleteUnprovable

  | failure_from_smt_failure SMT_Failure.Time_Out = TimedOut

  | failure_from_smt_failure (SMT_Failure.Abnormal_Termination code) =

    (case AList.lookup (op =) smt_failures code of

       SOME failure => failure

     | NONE => UnknownError ("Abnormal termination with exit code " ^

                             string_of_int code ^ "."))

  | failure_from_smt_failure SMT_Failure.Out_Of_Memory = OutOfResources

  | failure_from_smt_failure (SMT_Failure.Other_Failure msg) =

    UnknownError msg

(* FUDGE *)

val smt_max_slices =

  Attrib.setup_config_int @{binding sledgehammer_smt_max_slices} (K 8)

val smt_slice_fact_frac =

  Attrib.setup_config_real @{binding sledgehammer_smt_slice_fact_frac} (K 0.5)

val smt_slice_time_frac =

  Attrib.setup_config_real @{binding sledgehammer_smt_slice_time_frac} (K 0.5)

val smt_slice_min_secs =

  Attrib.setup_config_int @{binding sledgehammer_smt_slice_min_secs} (K 5)

fun smt_filter_loop ctxt name

                    ({debug, verbose, overlord, monomorphize_limit, timeout,

                      slicing, ...} : params)

                    state i smt_filter =

  let

    val max_slices = if slicing then Config.get ctxt smt_max_slices else 1

    val repair_context =

      select_smt_solver name

      #> Config.put SMT_Config.verbose debug

      #> (if overlord then

            Config.put SMT_Config.debug_files

                       (overlord_file_location_for_prover name

                        |> (fn (path, name) => path ^ "/" ^ name))

          else

            I)

      #> Config.put SMT_Config.infer_triggers (Config.get ctxt smt_triggers)

      #> Config.put SMT_Config.monomorph_full false

      #> Config.put SMT_Config.monomorph_limit monomorphize_limit

    val state = state |> Proof.map_context repair_context

    fun do_slice timeout slice outcome0 time_so_far facts =

      let

        val timer = Timer.startRealTimer ()

        val ms = timeout |> Time.toMilliseconds

        val slice_timeout =

          if slice < max_slices then

            Int.min (ms,

                Int.max (1000 * Config.get ctxt smt_slice_min_secs,

                    Real.ceil (Config.get ctxt smt_slice_time_frac

                               * Real.fromInt ms)))

            |> Time.fromMilliseconds

          else

            timeout

        val num_facts = length facts

        val _ =

          if debug then

            quote name ^ " slice " ^ string_of_int slice ^ " with " ^

            string_of_int num_facts ^ " fact" ^ plural_s num_facts ^ " for " ^

            string_from_time slice_timeout ^ "..."

            |> Output.urgent_message

          else

            ()

        val birth = Timer.checkRealTimer timer

        val _ =

          if debug then Output.urgent_message "Invoking SMT solver..." else ()

        val (outcome, used_facts) =

          (case (slice, smt_filter) of

             (1, SOME head) => head |> apsnd (apsnd repair_context)

           | _ => SMT_Solver.smt_filter_preprocess state facts i)

          |> SMT_Solver.smt_filter_apply slice_timeout

          |> (fn {outcome, used_facts} => (outcome, used_facts))

          handle exn => if Exn.is_interrupt exn then

                          reraise exn

                        else

                          (ML_Compiler.exn_message exn

                           |> SMT_Failure.Other_Failure |> SOME, [])

        val death = Timer.checkRealTimer timer

        val outcome0 = if is_none outcome0 then SOME outcome else outcome0

        val time_so_far = Time.+ (time_so_far, Time.- (death, birth))

        val too_many_facts_perhaps =

          case outcome of

            NONE => false

          | SOME (SMT_Failure.Counterexample _) => false

          | SOME SMT_Failure.Time_Out => slice_timeout <> timeout

          | SOME (SMT_Failure.Abnormal_Termination _) => true (* kind of *)

          | SOME SMT_Failure.Out_Of_Memory => true

          | SOME (SMT_Failure.Other_Failure _) => true

        val timeout = Time.- (timeout, Timer.checkRealTimer timer)

      in

        if too_many_facts_perhaps andalso slice < max_slices andalso

           num_facts > 0 andalso Time.> (timeout, Time.zeroTime) then

          let

            val new_num_facts =

              Real.ceil (Config.get ctxt smt_slice_fact_frac

                         * Real.fromInt num_facts)

            val _ =

              if verbose andalso is_some outcome then

                quote name ^ " invoked with " ^ string_of_int num_facts ^

                " fact" ^ plural_s num_facts ^ ": " ^

                string_for_failure (failure_from_smt_failure (the outcome)) ^

                " Retrying with " ^ string_of_int new_num_facts ^ " fact" ^

                plural_s new_num_facts ^ "..."

                |> Output.urgent_message

              else

                ()

          in

            facts |> take new_num_facts

                  |> do_slice timeout (slice + 1) outcome0 time_so_far

          end

        else

          {outcome = if is_none outcome then NONE else the outcome0,

           used_facts = used_facts,

           run_time_in_msecs = SOME (Time.toMilliseconds time_so_far)}

      end

  in do_slice timeout 1 NONE Time.zeroTime end

(* taken from "Mirabelle" and generalized *)

fun can_apply timeout tac state i =

  let

    val {context = ctxt, facts, goal} = Proof.goal state

    val full_tac = Method.insert_tac facts i THEN tac ctxt i

  in

    case try (TimeLimit.timeLimit timeout (Seq.pull o full_tac)) goal of

      SOME (SOME _) => true

    | _ => false

  end

val smt_metis_timeout = seconds 1.0

fun can_apply_metis debug state i ths =

  can_apply smt_metis_timeout

            (Config.put Metis_Tactics.verbose debug

             #> (fn ctxt => Metis_Tactics.metis_tac ctxt ths)) state i

fun run_smt_solver auto name (params as {debug, verbose, ...}) minimize_command

                   ({state, subgoal, subgoal_count, facts, smt_filter, ...}

                    : prover_problem) =

  let

    val ctxt = Proof.context_of state

    val num_facts = length facts

    val facts = facts ~~ (0 upto num_facts - 1)

                |> map (smt_weighted_fact ctxt num_facts)

    val {outcome, used_facts, run_time_in_msecs} =

      smt_filter_loop ctxt name params state subgoal smt_filter facts

    val (chained_lemmas, other_lemmas) = split_used_facts (map fst used_facts)

    val outcome = outcome |> Option.map failure_from_smt_failure

    val message =

      case outcome of

        NONE =>

        let

          val (method, settings) =

            if can_apply_metis debug state subgoal (map snd used_facts) then

              ("metis", "")

            else

              ("smt", if name = SMT_Solver.solver_name_of ctxt then ""

                      else "smt_solver = " ^ maybe_quote name)

        in

          try_command_line (proof_banner auto)

              (apply_on_subgoal settings subgoal subgoal_count ^

               command_call method (map fst other_lemmas)) ^

          minimize_line minimize_command

                        (map fst (other_lemmas @ chained_lemmas)) ^

          (if verbose then

             "\nSMT solver real CPU time: " ^

             string_from_time (Time.fromMilliseconds (the run_time_in_msecs)) ^

             "."

           else

             "")

        end

      | SOME failure => string_for_failure failure

  in

    {outcome = outcome, used_facts = map fst used_facts,

     run_time_in_msecs = run_time_in_msecs, message = message}

  end

fun get_prover ctxt auto name =

  let val thy = Proof_Context.theory_of ctxt in

    if is_smt_prover ctxt name then

      run_smt_solver auto name

    else if member (op =) (supported_atps thy) name then

      run_atp auto name (get_atp thy name)

    else

      error ("No such prover: " ^ name ^ ".")

  end

end;