(*  Title:      Pure/PIDE/command.ML

     Author:     Makarius

 Prover command execution: read -- eval -- print.

 *)

 signature COMMAND =

 sig

   type span

   type eval_process

   type eval = {exec_id: Document_ID.exec, eval_process: eval_process}

   type print_process

   type print = {name: string, pri: int, exec_id: Document_ID.exec, print_process: print_process}

   type exec = eval * print list

   val read: (unit -> theory) -> span -> Toplevel.transition

   val no_eval: eval

   val eval_result_state: eval -> Toplevel.state

   val eval: (unit -> theory) -> span -> eval -> eval

   val print: string -> eval -> print list

   type print_fn = Toplevel.transition -> Toplevel.state -> unit

   val print_function: {name: string, pri: int} -> (string -> print_fn option) -> unit

   val no_exec: exec

   val exec_ids: exec -> Document_ID.exec list

   val exec_run: exec -> unit

   val stable_eval: eval -> bool

   val stable_print: print -> bool

 end;

 structure Command: COMMAND =

 struct

 (** memo results -- including physical interrupts! **)

 datatype 'a expr =

   Expr of unit -> 'a |

   Result of 'a Exn.result;

 abstype 'a memo = Memo of 'a expr Synchronized.var

 with

 fun memo e = Memo (Synchronized.var "Command.memo" (Expr e));

 fun memo_value a = Memo (Synchronized.var "Command.memo" (Result (Exn.Res a)));

 fun memo_eval (Memo v) =

   (case Synchronized.value v of

     Result res => res

   | _ =>

       Synchronized.guarded_access v

         (fn Result res => SOME (res, Result res)

           | Expr e =>

               let val res = Exn.capture e ();  (*sic!*)

               in SOME (res, Result res) end))

   |> Exn.release;

 fun memo_fork params (Memo v) =

   (case Synchronized.value v of

     Result _ => ()

   | _ => ignore ((singleton o Future.forks) params (fn () => memo_eval (Memo v))));

 fun memo_result (Memo v) =

   (case Synchronized.value v of

     Result res => Exn.release res

   | _ => raise Fail "Unfinished memo result");

 fun memo_stable (Memo v) =

   (case Synchronized.value v of

     Expr _ => true

   | Result res => not (Exn.is_interrupt_exn res));

 end;

 (** main phases **)

 type span = Token.T list

 type eval_state =

   {failed: bool, malformed: bool, command: Toplevel.transition, state: Toplevel.state};

 type eval_process = eval_state memo;

 type eval = {exec_id: Document_ID.exec, eval_process: eval_process};

 type print_process = unit memo;

 type print = {name: string, pri: int, exec_id: Document_ID.exec, print_process: print_process};

 (* read *)

 fun read init span =

   let

     val outer_syntax = #2 (Outer_Syntax.get_syntax ());

     val command_reports = Outer_Syntax.command_reports outer_syntax;

     val proper_range =

       Position.set_range (Token.position_range_of (#1 (take_suffix Token.is_improper span)));

     val pos =

       (case find_first Token.is_command span of

         SOME tok => Token.position_of tok

       | NONE => proper_range);

     val (is_malformed, token_reports) = Thy_Syntax.reports_of_tokens span;

     val _ = Position.reports_text (token_reports @ maps command_reports span);

   in

     if is_malformed then Toplevel.malformed pos "Malformed command syntax"

     else

       (case Outer_Syntax.read_spans outer_syntax span of

         [tr] =>

           if Keyword.is_control (Toplevel.name_of tr) then

             Toplevel.malformed pos "Illegal control command"

           else Toplevel.modify_init init tr

       | [] => Toplevel.ignored (Position.set_range (Token.position_range_of span))

       | _ => Toplevel.malformed proper_range "Exactly one command expected")

       handle ERROR msg => Toplevel.malformed proper_range msg

   end;

 (* eval *)

 val no_eval_state: eval_state =

   {failed = false, malformed = false, command = Toplevel.empty, state = Toplevel.toplevel};

 val no_eval: eval = {exec_id = Document_ID.none, eval_process = memo_value no_eval_state};

 fun eval_result ({eval_process, ...}: eval) = memo_result eval_process;

 val eval_result_state = #state o eval_result;

 local

 fun run int tr st =

   if Goal.future_enabled () andalso Keyword.is_diag (Toplevel.name_of tr) then

     (Goal.fork_params {name = "Toplevel.diag", pos = Toplevel.pos_of tr, pri = ~1}

       (fn () => Toplevel.command_exception int tr st); ([], SOME st))

   else Toplevel.command_errors int tr st;

 fun check_cmts span tr st' =

   Toplevel.setmp_thread_position tr

     (fn () =>

       Outer_Syntax.side_comments span |> maps (fn cmt =>

         (Thy_Output.check_text (Token.source_position_of cmt) st'; [])

           handle exn => ML_Compiler.exn_messages_ids exn)) ();

 fun proof_status tr st =

   (case try Toplevel.proof_of st of

     SOME prf => Toplevel.status tr (Proof.status_markup prf)

   | NONE => ());

 fun eval_state span tr ({malformed, state = st, ...}: eval_state) =

   if malformed then

     {failed = true, malformed = malformed, command = tr, state = Toplevel.toplevel}

   else

     let

       val malformed' = Toplevel.is_malformed tr;

       val is_init = Toplevel.is_init tr;

       val is_proof = Keyword.is_proof (Toplevel.name_of tr);

       val _ = Multithreading.interrupted ();

       val _ = Toplevel.status tr Markup.running;

       val (errs1, result) = run (is_init orelse is_proof) (Toplevel.set_print false tr) st;

       val errs2 = (case result of NONE => [] | SOME st' => check_cmts span tr st');

       val errs = errs1 @ errs2;

       val _ = Toplevel.status tr Markup.finished;

       val _ = List.app (Future.error_msg (Toplevel.pos_of tr)) errs;

     in

       (case result of

         NONE =>

           let

             val _ = if null errs then Exn.interrupt () else ();

             val _ = Toplevel.status tr Markup.failed;

           in {failed = true, malformed = malformed', command = tr, state = st} end

       | SOME st' =>

           let

             val _ = proof_status tr st';

           in {failed = false, malformed = malformed', command = tr, state = st'} end)

     end;

 in

 fun eval init span eval0 =

   let

     val exec_id = Document_ID.make ();

     fun process () =

       let

         val tr =

           Position.setmp_thread_data (Position.id_only (Document_ID.print exec_id))

             (fn () => read init span |> Toplevel.put_id exec_id) ();

       in eval_state span tr (eval_result eval0) end;

   in {exec_id = exec_id, eval_process = memo process} end;

 end;

 (* print *)

 type print_fn = Toplevel.transition -> Toplevel.state -> unit;

 local

 type print_function = string * (int * (string -> print_fn option));

 val print_functions = Synchronized.var "Command.print_functions" ([]: print_function list);

 fun output_error tr exn =

   List.app (Future.error_msg (Toplevel.pos_of tr)) (ML_Compiler.exn_messages_ids exn);

 fun print_error tr f x =

   (Toplevel.setmp_thread_position tr o Runtime.controlled_execution) f x

     handle exn => output_error tr exn;

 in

 fun print command_name eval =

   rev (Synchronized.value print_functions) |> map_filter (fn (name, (pri, get_print_fn)) =>

     (case Exn.capture (Runtime.controlled_execution get_print_fn) command_name of

       Exn.Res NONE => NONE

     | Exn.Res (SOME print_fn) =>

         let

           val exec_id = Document_ID.make ();

           fun process () =

             let

               val {failed, command, state = st', ...} = eval_result eval;

               val tr = Toplevel.put_id exec_id command;

             in if failed then () else print_error tr (fn () => print_fn tr st') () end;

         in SOME {name = name, pri = pri, exec_id = exec_id, print_process = memo process} end

     | Exn.Exn exn =>

         let

           val exec_id = Document_ID.make ();

           fun process () =

             let

               val {command, ...} = eval_result eval;

               val tr = Toplevel.put_id exec_id command;

             in output_error tr exn end;

         in SOME {name = name, pri = pri, exec_id = exec_id, print_process = memo process} end));

 fun print_function {name, pri} f =

   Synchronized.change print_functions (fn funs =>

    (if not (AList.defined (op =) funs name) then ()

     else warning ("Redefining command print function: " ^ quote name);

     AList.update (op =) (name, (pri, f)) funs));

 end;

 val _ =

   print_function {name = "print_state", pri = 0} (fn command_name => SOME (fn tr => fn st' =>

     let

       val is_init = Keyword.is_theory_begin command_name;

       val is_proof = Keyword.is_proof command_name;

       val do_print =

         not is_init andalso

           (Toplevel.print_of tr orelse (is_proof andalso Toplevel.is_proof st'));

     in if do_print then Toplevel.print_state false st' else () end));

 (** managed evaluation **)

 (* execution *)

 type exec = eval * print list;

 val no_exec: exec = (no_eval, []);

 fun exec_ids (({exec_id, ...}, prints): exec) = exec_id :: map #exec_id prints;

 fun exec_run (({eval_process, ...}, prints): exec) =

  (memo_eval eval_process;

   prints |> List.app (fn {name, pri, print_process, ...} =>

     memo_fork {name = name, group = NONE, deps = [], pri = pri, interrupts = true} print_process));

 (* stable situations after cancellation *)

 fun stable_goals exec_id =

   not (Par_Exn.is_interrupted (Future.join_results (Goal.peek_futures exec_id)));

 fun stable_eval ({exec_id, eval_process}: eval) =

   stable_goals exec_id andalso memo_stable eval_process;

 fun stable_print ({exec_id, print_process, ...}: print) =

   stable_goals exec_id andalso memo_stable print_process;

 end;