(*  Title:      HOL/ex/sledgehammer_tactics.ML

    Author:     Jasmin Blanchette, TU Muenchen

    Copyright   2010, 2011

Sledgehammer as a tactic.

*)

signature SLEDGEHAMMER_TACTICS =

sig

  type relevance_override = Sledgehammer_Filter.relevance_override

  val sledgehammer_with_metis_tac :

    Proof.context -> (string * string) list -> relevance_override -> int

    -> tactic

  val sledgehammer_as_oracle_tac :

    Proof.context -> (string * string) list -> relevance_override -> int

    -> tactic

end;

structure Sledgehammer_Tactics : SLEDGEHAMMER_TACTICS =

struct

open Sledgehammer_Filter

fun run_atp override_params relevance_override i n ctxt goal =

  let

    val chained_ths = [] (* a tactic has no chained ths *)

    val params as {provers, relevance_thresholds, max_relevant, slicing, ...} =

      Sledgehammer_Isar.default_params ctxt override_params

    val name = hd provers

    val prover =

      Sledgehammer_Provers.get_prover ctxt Sledgehammer_Provers.Normal name

    val default_max_relevant =

      Sledgehammer_Provers.default_max_relevant_for_prover ctxt slicing name

    val is_built_in_const =

      Sledgehammer_Provers.is_built_in_const_for_prover ctxt name

    val relevance_fudge =

      Sledgehammer_Provers.relevance_fudge_for_prover ctxt name

    val (_, hyp_ts, concl_t) = ATP_Util.strip_subgoal ctxt goal i

    val facts =

      Sledgehammer_Filter.nearly_all_facts ctxt relevance_override chained_ths

                                           hyp_ts concl_t

      |> Sledgehammer_Filter.relevant_facts ctxt relevance_thresholds

             (the_default default_max_relevant max_relevant) is_built_in_const

             relevance_fudge relevance_override chained_ths hyp_ts concl_t

    val problem =

      {state = Proof.init ctxt, goal = goal, subgoal = i, subgoal_count = n,

       facts = map Sledgehammer_Provers.Untranslated_Fact facts,

       smt_filter = NONE}

  in

    (case prover params (K (K "")) problem of

      {outcome = NONE, used_facts, ...} => used_facts |> map fst |> SOME

    | _ => NONE)

      handle ERROR message => (warning ("Error: " ^ message ^ "\n"); NONE)

  end

fun thms_of_name ctxt name =

  let

    val lex = Keyword.get_lexicons

    val get = maps (Proof_Context.get_fact ctxt o fst)

  in

    Source.of_string name

    |> Symbol.source

    |> Token.source {do_recover=SOME false} lex Position.start

    |> Token.source_proper

    |> Source.source Token.stopper (Parse_Spec.xthms1 >> get) NONE

    |> Source.exhaust

  end

fun sledgehammer_with_metis_tac ctxt override_params relevance_override i th =

  case run_atp override_params relevance_override i i ctxt th of

    SOME facts =>

    Metis_Tactics.metis_tac [] ctxt (maps (thms_of_name ctxt) facts) i th

  | NONE => Seq.empty

fun sledgehammer_as_oracle_tac ctxt override_params relevance_override i th =

  let

    val thy = Proof_Context.theory_of ctxt

    val xs = run_atp (override_params @ [("sound", "true")]) relevance_override

                     i i ctxt th

  in if is_some xs then Skip_Proof.cheat_tac thy th else Seq.empty end

end;