(*  Title:      Pure/ML/ml_thms.ML

    Author:     Makarius

Isar theorem values within ML.

*)

signature ML_THMS =

sig

  val the_thms: Proof.context -> int -> thm list

  val the_thm: Proof.context -> int -> thm

end;

structure ML_Thms: ML_THMS =

struct

(* auxiliary facts table *)

structure AuxFacts = ProofDataFun

(

  type T = thm list Inttab.table;

  fun init _ = Inttab.empty;

);

val put_thms = AuxFacts.map o Inttab.update;

fun the_thms ctxt name = the (Inttab.lookup (AuxFacts.get ctxt) name);

fun the_thm ctxt name = the_single (the_thms ctxt name);

fun thm_bind kind a i =

  "val " ^ a ^ " = ML_Thms.the_" ^ kind ^

    " (ML_Context.the_local_context ()) " ^ string_of_int i ^ ";\n";

(* fact references *)

fun thm_antiq kind scan = ML_Context.add_antiq kind

  (fn _ => scan >> (fn ths => fn {struct_name, background} =>

    let

      val i = serial ();

      val (a, background') = background

        |> ML_Antiquote.variant kind ||> put_thms (i, ths);

      val ml = (thm_bind kind a i, struct_name ^ "." ^ a);

    in (K ml, background') end));

val _ = thm_antiq "thm" (Attrib.thm >> single);

val _ = thm_antiq "thms" Attrib.thms;

(* ad-hoc goals *)

val by = Args.$$$ "by";

val goal = Scan.unless (Scan.lift by) Args.prop;

val _ = ML_Context.add_antiq "lemma"

  (fn pos => Args.context -- Args.mode "open" -- Scan.repeat1 goal --

      Scan.lift (by |-- Method.parse -- Scan.option Method.parse) >>

    (fn (((ctxt, is_open), props), methods) => fn {struct_name, background} =>

      let

        val i = serial ();

        val prep_result =

          Goal.norm_result #> Thm.default_position pos #> not is_open ? Thm.close_derivation;

        fun after_qed [res] goal_ctxt =

          put_thms (i, map prep_result (ProofContext.export goal_ctxt ctxt res)) goal_ctxt;

        val ctxt' = ctxt

          |> Proof.theorem_i NONE after_qed [map (rpair []) props]

          |> Proof.global_terminal_proof methods;

        val (a, background') = background

          |> ML_Antiquote.variant "lemma" ||> put_thms (i, the_thms ctxt' i);

        val ml = (thm_bind (if length props = 1 then "thm" else "thms") a i, struct_name ^ "." ^ a);

      in (K ml, background') end));

end;