(*  Title:      Pure/ML/ml_context.ML

    ID:         $Id$

    Author:     Makarius

ML context and antiquotations.

*)

signature BASIC_ML_CONTEXT =

sig

  val bind_thm: string * thm -> unit

  val bind_thms: string * thm list -> unit

  val thm: xstring -> thm

  val thms: xstring -> thm list

end

signature ML_CONTEXT =

sig

  include BASIC_ML_CONTEXT

  val the_generic_context: unit -> Context.generic

  val the_global_context: unit -> theory

  val the_local_context: unit -> Proof.context

  val exec: (unit -> unit) -> Context.generic -> Context.generic

  val stored_thms: thm list ref

  val ml_store_thm: string * thm -> unit

  val ml_store_thms: string * thm list -> unit

  type antiq =

    {struct_name: string, background: Proof.context} ->

      (Proof.context -> string * string) * Proof.context

  val add_antiq: string ->

    (Context.generic * Args.T list -> antiq * (Context.generic * Args.T list)) -> unit

  val trace: bool ref

  val eval_wrapper: (string -> unit) * (string -> 'a) -> bool -> Position.T -> string -> unit

  val eval: bool -> Position.T -> string -> unit

  val eval_file: Path.T -> unit

  val eval_in: Context.generic option -> bool -> Position.T -> string -> unit

  val evaluate: (string -> unit) * (string -> 'b) -> bool ->

    string * (unit -> 'a) option ref -> string -> 'a

  val expression: Position.T -> string -> string -> string -> Context.generic -> Context.generic

end

structure ML_Context: ML_CONTEXT =

struct

(** implicit ML context **)

val the_generic_context = Context.the_thread_data;

val the_global_context = Context.theory_of o the_generic_context;

val the_local_context = Context.proof_of o the_generic_context;

fun exec (e: unit -> unit) context =

  (case Context.setmp_thread_data (SOME context) (fn () => (e (); Context.thread_data ())) () of

    SOME context' => context'

  | NONE => error "Missing context after execution");

(* theorem bindings *)

val stored_thms: thm list ref = ref [];

fun ml_store sel (name, ths) =

  let

    val ths' = Context.>>> (Context.map_theory_result (PureThy.store_thms (name, ths)));

    val _ =

      if name = "" then ()

      else if not (ML_Syntax.is_identifier name) then

        error ("Cannot bind theorem(s) " ^ quote name ^ " as ML value")

      else setmp stored_thms ths' (fn () =>

        use_text (0, "") Output.ml_output true

          ("val " ^ name ^ " = " ^ sel ^ "(! ML_Context.stored_thms);")) ();

  in () end;

val ml_store_thms = ml_store "";

fun ml_store_thm (name, th) = ml_store "hd" (name, [th]);

fun bind_thm (name, thm) = ml_store_thm (name, Drule.standard thm);

fun bind_thms (name, thms) = ml_store_thms (name, map Drule.standard thms);

fun thm name = ProofContext.get_thm (the_local_context ()) name;

fun thms name = ProofContext.get_thms (the_local_context ()) name;

(** ML antiquotations **)

(* antiquotation commands *)

type antiq =

  {struct_name: string, background: Proof.context} ->

    (Proof.context -> string * string) * Proof.context;

local

val global_parsers = ref (Symtab.empty:

  (Context.generic * Args.T list -> antiq * (Context.generic * Args.T list)) Symtab.table);

in

fun add_antiq name scan = CRITICAL (fn () =>

  change global_parsers (fn tab =>

   (if not (Symtab.defined tab name) then ()

    else warning ("Redefined ML antiquotation: " ^ quote name);

    Symtab.update (name, scan) tab)));

fun antiquotation src ctxt =

  let val ((name, _), pos) = Args.dest_src src in

    (case Symtab.lookup (! global_parsers) name of

      NONE => error ("Unknown ML antiquotation command: " ^ quote name ^ Position.str_of pos)

    | SOME scan => Args.context_syntax "ML antiquotation" scan src ctxt)

  end;

end;

(* parsing and evaluation *)

local

structure P = OuterParse;

val antiq =

  P.!!! (P.position P.xname -- P.arguments --| Scan.ahead P.eof)

  >> (fn ((x, pos), y) => Args.src ((x, y), pos));

fun eval_antiquotes struct_name (txt, pos) opt_ctxt =

  let

    val ants = Antiquote.read (txt, pos);

    val ((ml_env, ml_body), opt_ctxt') =

      if not (exists Antiquote.is_antiq ants) then (("", Symbol.escape txt), opt_ctxt)

      else

        let

          val ctxt =

            (case opt_ctxt of

              NONE => error ("Unknown context -- cannot expand ML antiquotations" ^

                Position.str_of pos)

            | SOME context => Context.proof_of context);

          val lex = #1 (OuterKeyword.get_lexicons ());

          fun no_decl _ = ("", "");

          fun expand (Antiquote.Text s) state = (K ("", Symbol.escape s), state)

            | expand (Antiquote.Antiq (x, _)) (scope, background) =

                let

                  val context = Stack.top scope;

                  val (f, context') = antiquotation (Antiquote.read_arguments lex antiq x) context;

                  val (decl, background') = f {background = background, struct_name = struct_name};

                in (decl, (Stack.map_top (K context') scope, background')) end

            | expand (Antiquote.Open _) (scope, background) =

                (no_decl, (Stack.push scope, background))

            | expand (Antiquote.Close _) (scope, background) =

                (no_decl, (Stack.pop scope, background));

          val (decls, (_, ctxt')) = fold_map expand ants (Stack.init ctxt, ctxt);

          val ml = decls |> map (fn decl => decl ctxt') |> split_list |> pairself implode;

        in (ml, SOME (Context.Proof ctxt')) end;

  in (("structure " ^ struct_name ^ " =\nstruct\n" ^ ml_env ^ "end;", ml_body), opt_ctxt') end;

in

val trace = ref false;

fun eval_wrapper pr verbose pos txt =

  let

    val struct_name =

      if Multithreading.available then "Isabelle" ^ serial_string ()

      else "Isabelle";

    val ((env, body), env_ctxt) = eval_antiquotes struct_name (txt, pos) (Context.thread_data ());

    val _ = if ! trace then tracing (cat_lines [env, body]) else ();

    fun eval_raw p =

      use_text (the_default 1 (Position.line_of p), the_default "ML" (Position.file_of p)) pr;

  in

    Context.setmp_thread_data env_ctxt (fn () => eval_raw Position.none false env) ();

    NAMED_CRITICAL "ML" (fn () => eval_raw pos verbose body); (* FIXME non-critical with local ML env *)

    forget_structure struct_name

  end;

end;

(* ML evaluation *)

val eval = eval_wrapper Output.ml_output;

fun eval_file path = eval true (Path.position path) (File.read path);

fun eval_in context verbose pos txt =

  Context.setmp_thread_data context (fn () => eval verbose pos txt) ();

fun evaluate pr verbose (ref_name, r) txt = NAMED_CRITICAL "ML" (fn () =>

  let

    val _ = r := NONE;

    val _ = eval_wrapper pr verbose Position.none

      ("val _ = (" ^ ref_name ^ " := SOME (fn () => " ^ txt ^ "))");

  in (case ! r of NONE => error ("Bad evaluation for " ^ ref_name) | SOME e => e) end) ();

fun expression pos bind body txt =

  exec (fn () => eval false pos

    ("Context.set_thread_data (SOME (let " ^ bind ^ " = " ^ txt ^ " in " ^ body ^

      " end (ML_Context.the_generic_context ())));"));

end;

structure Basic_ML_Context: BASIC_ML_CONTEXT = ML_Context;

open Basic_ML_Context;