(*  Title:      Pure/ProofGeneral/proof_general_pgip.ML

     Author:     David Aspinall and Markus Wenzel

 Isabelle configuration for Proof General using PGIP protocol.

 See http://proofgeneral.inf.ed.ac.uk/kit

 *)

 signature PROOF_GENERAL_PGIP =

 sig

   val new_thms_deps: theory -> theory -> string list * string list

   val init_pgip: bool -> unit             (* main PGIP loop with true; fail with false *)

   (* These two are just to support the semi-PGIP Emacs mode *)

   val init_pgip_channel: (string -> unit) -> unit

   val process_pgip: string -> unit

   (* More message functions... *)

   val nonfatal_error : string -> unit     (* recoverable (batch) error: carry on scripting *)

   val log_msg : string -> unit            (* for internal log messages *)

   val error_with_pos : PgipTypes.displayarea -> PgipTypes.fatality -> Position.T -> string -> unit

   val get_currently_open_file : unit -> Path.T option  (* interface focus *)

   val add_preference: string -> Preferences.preference -> unit

 end

 structure ProofGeneralPgip : PROOF_GENERAL_PGIP =

 struct

 open Pgip;

 (** print mode **)

 val proof_generalN = "ProofGeneral";

 val pgmlsymbols_flag = Unsynchronized.ref true;

 (* assembling and issuing PGIP packets *)

 val pgip_refid = Unsynchronized.ref NONE: string option Unsynchronized.ref;

 val pgip_refseq = Unsynchronized.ref NONE: int option Unsynchronized.ref;

 local

   val pgip_class  = "pg"

   val pgip_tag = "Isabelle/Isar"

   val pgip_id = Unsynchronized.ref ""

   val pgip_seq = Unsynchronized.ref 0

   fun pgip_serial () = Unsynchronized.inc pgip_seq

   fun assemble_pgips pgips =

     Pgip { tag = SOME pgip_tag,

            class = pgip_class,

            seq = pgip_serial (),

            id = ! pgip_id,

            destid = ! pgip_refid,

            (* destid=refid since Isabelle only communicates back to sender *)

            refid = ! pgip_refid,

            refseq = ! pgip_refseq,

            content = pgips }

 in

 fun init_pgip_session_id () =

     pgip_id := getenv "HOSTNAME" ^ "/" ^ getenv "USER" ^ "/" ^

                getenv "ISABELLE_PID" ^ "/" ^ Time.toString (Time.now ())

 fun matching_pgip_id id = (id = ! pgip_id)

 val output_xml_fn = Unsynchronized.ref Output.writeln_default

 fun output_xml s = ! output_xml_fn (XML.string_of s);

 val output_pgips = XML.string_of o PgipOutput.output o assemble_pgips o map PgipOutput.output;

 val output_pgmlterm = XML.string_of o Pgml.pgmlterm_to_xml;

 val output_pgmltext = XML.string_of o Pgml.pgml_to_xml;

 fun issue_pgip_rawtext str =

   output_xml (PgipOutput.output (assemble_pgips (YXML.parse_body str)));

 fun issue_pgip pgipop =

   output_xml (PgipOutput.output (assemble_pgips [PgipOutput.output pgipop]));

 end;

 (** messages and notification **)

 (* PGML terms *)

 local

 fun pgml_sym s =

   if ! pgmlsymbols_flag then

     (case Symbol.decode s of

       Symbol.Sym name => Pgml.Sym {name = name, content = s}

     | _ => Pgml.Str s)

   else Pgml.Str s;

 val pgml_syms = map pgml_sym o Symbol.explode;

 val token_markups =

  [Markup.tclassN, Markup.tfreeN, Markup.tvarN, Markup.freeN,

   Markup.boundN, Markup.varN, Markup.skolemN];

 in

 fun pgml_terms (XML.Elem (name, atts, body)) =

       if member (op =) token_markups name then

         let val content = pgml_syms (Buffer.content (fold XML.add_content body Buffer.empty))

         in [Pgml.Atoms {kind = SOME name, content = content}] end

       else

         let val content = maps pgml_terms body in

           if name = Markup.blockN then

             [Pgml.Box {orient = NONE, indent = Properties.get_int atts Markup.indentN, content = content}]

           else if name = Markup.breakN then

             [Pgml.Break {mandatory = NONE, indent = Properties.get_int atts Markup.widthN}]

           else if name = Markup.fbreakN then

             [Pgml.Break {mandatory = SOME true, indent = NONE}]

           else content

         end

   | pgml_terms (XML.Text text) = map (Pgml.Raw o Pgml.atom_to_xml) (pgml_syms text);

 end;

 (* messages *)

 fun pgml area content =

   Pgml.Pgml {version = NONE, systemid = NONE, area = SOME area, content = content};

 fun message_content default_area s =

   let

     val body = YXML.parse_body s;

     val area =

       (case body of

         [XML.Elem (name, _, _)] =>

           if name = Markup.stateN then PgipTypes.Display else default_area

       | _ => default_area);

   in Pgml.pgml_to_xml (pgml area (maps pgml_terms body)) end;

 fun normalmsg area s = issue_pgip

   (Normalresponse {content = [message_content area s]});

 fun errormsg area fatality s = issue_pgip

   (Errorresponse {fatality = fatality, location = NONE, content = [message_content area s]});

 (*error responses with useful locations*)

 fun error_with_pos area fatality pos s = issue_pgip

   (Errorresponse {

     fatality = fatality,

     location = SOME (PgipIsabelle.location_of_position pos),

     content = [message_content area s]});

 fun panic s = (errormsg Message Panic ("## SYSTEM EXIT ##\n" ^ s); exit 1);

 fun nonfatal_error s = errormsg Message Nonfatal s;

 fun log_msg s = errormsg Message Log s;

 (* NB: all of standard functions print strings terminated with new lines, but we don't

    add new lines explicitly in PGIP: they are left implicit.  It means that PGIP messages

    can't be written without newlines. *)

 fun setup_messages () =

  (Output.writeln_fn := (fn s => normalmsg Message s);

   Output.status_fn := (fn _ => ());

   Output.priority_fn := (fn s => normalmsg Status s);

   Output.tracing_fn := (fn s => normalmsg Tracing s);

   Output.warning_fn := (fn s => errormsg Message Warning s);

   Output.error_fn := (fn s => errormsg Message Fatal s);

   Output.debug_fn := (fn s => errormsg Message Debug s));

 (* immediate messages *)

 fun tell_clear_goals () =

     issue_pgip (Normalresponse { content = [Pgml.pgml_to_xml (pgml Display [])] })

 fun tell_clear_response () =

     issue_pgip (Normalresponse { content = [Pgml.pgml_to_xml (pgml Message [])] })

 fun tell_file_loaded completed path   =

     issue_pgip (Informfileloaded {url=PgipTypes.pgipurl_of_path path,

                                   completed=completed})

 fun tell_file_outdated completed path   =

     issue_pgip (Informfileoutdated {url=PgipTypes.pgipurl_of_path path,

                                     completed=completed})

 fun tell_file_retracted completed path =

     issue_pgip (Informfileretracted {url=PgipTypes.pgipurl_of_path path,

                                      completed=completed})

 (* theory loader actions *)

 local

   (* da: TODO: PGIP has a completed flag so the prover can indicate to the

      interface which files are busy performing a particular action.

      To make use of this we need to adjust the hook in thy_info.ML

      (may actually be difficult to tell the interface *which* action is in

       progress, but we could add a generic "Lock" action which uses

       informfileloaded: the broker/UI should not infer too much from incomplete

       operations).

    *)

 fun trace_action action name =

   if action = ThyInfo.Update then

     List.app (tell_file_loaded true) (ThyInfo.loaded_files name)

   else if action = ThyInfo.Outdate then

     List.app (tell_file_outdated true) (ThyInfo.loaded_files name)

   else if action = ThyInfo.Remove then

       List.app (tell_file_retracted true) (ThyInfo.loaded_files name)

   else ()

 in

   fun setup_thy_loader () = ThyInfo.add_hook trace_action;

   fun sync_thy_loader () = List.app (trace_action ThyInfo.Update) (ThyInfo.get_names ());

 end;

 (* get informed about files *)

 val thy_name = Path.implode o #1 o Path.split_ext o Path.base;

 val inform_file_retracted = ThyInfo.if_known_thy ThyInfo.remove_thy o thy_name;

 val inform_file_processed = ThyInfo.if_known_thy ThyInfo.touch_child_thys o thy_name;

 fun proper_inform_file_processed path state =

   let val name = thy_name path in

     if Toplevel.is_toplevel state andalso ThyInfo.known_thy name then

      (ThyInfo.touch_child_thys name;

       ThyInfo.register_thy name handle ERROR msg =>

        (warning (cat_lines [msg, "Failed to register theory: " ^ quote name]);

         tell_file_retracted true (Path.base path)))

     else raise Toplevel.UNDEF

   end;

 (* restart top-level loop (keeps most state information) *)

 val welcome = priority o Session.welcome;

 fun restart () =

     (sync_thy_loader ();

      tell_clear_goals ();

      tell_clear_response ();

      Isar.init ();

      welcome ());

 (* theorem dependencies *)

 local

 fun add_proof_body (PBody {thms, ...}) =

   thms |> fold (fn (_, (name, _, _)) => name <> "" ? Symtab.update (name, ()));

 fun add_thm th =

   (case Thm.proof_body_of th of 

     PBody {proof = PThm (_, ((name, _, _), body)), ...} =>

       if Thm.has_name_hint th andalso Thm.get_name_hint th = name

       then add_proof_body (Future.join body)

       else I

   | body => add_proof_body body);

 in

 fun thms_deps ths =

   let

     (* FIXME proper derivation names!? *)

     val names = map Thm.get_name_hint (filter Thm.has_name_hint ths);

     val deps = Symtab.keys (fold add_thm ths Symtab.empty);

   in (names, deps) end;

 fun new_thms_deps thy thy' =

   let

     val prev_facts = PureThy.facts_of thy;

     val facts = PureThy.facts_of thy';

   in thms_deps (maps #2 (Facts.dest_static [prev_facts] facts)) end;

 end;

 (* theorem dependeny output *)

 val show_theorem_dependencies = Unsynchronized.ref false;

 local

 val spaces_quote = space_implode " " o map quote;

 fun thm_deps_message (thms, deps) =

   let

     val valuethms = XML.Elem ("value", [("name", "thms")], [XML.Text thms]);

     val valuedeps = XML.Elem ("value", [("name", "deps")], [XML.Text deps]);

   in

     issue_pgip (Metainforesponse

       {attrs = [("infotype", "isabelle_theorem_dependencies")],

        content = [valuethms, valuedeps]})

   end;

 in

 fun setup_present_hook () = Toplevel.add_hook (fn _ => fn state => fn state' =>

   if ! show_theorem_dependencies andalso

     can Toplevel.theory_of state andalso Toplevel.is_theory state'

   then

     let val (names, deps) = new_thms_deps (Toplevel.theory_of state) (Toplevel.theory_of state') in

       if null names orelse null deps then ()

       else thm_deps_message (spaces_quote names, spaces_quote deps)

     end

   else ());

 end;

 (** lexicalstructure element with keywords (PGIP version of elisp keywords file) **)

 fun lexicalstructure_keywords () =

     let val keywords = OuterKeyword.dest_keywords ()

         val commands = OuterKeyword.dest_commands ()

         fun keyword_elt kind keyword =

             XML.Elem("keyword", [("word", keyword), ("category", kind)], [])

         in

             (* Also, note we don't call init_outer_syntax here to add interface commands,

             but they should never appear in scripts anyway so it shouldn't matter *)

             Lexicalstructure

               {content = map (keyword_elt "minor") keywords @ map (keyword_elt "major") commands}

         end

 (* TODO: we can issue a lexicalstructure/keyword when the syntax gets extended dynamically;

    hooks needed in outer_syntax.ML to do that. *)

 (* Configuration: GUI config, proverinfo messages *)

 local

     val isabellewww = "http://isabelle.in.tum.de/"

     val staticconfig = "~~/lib/ProofGeneral/pgip_isar.xml"

     fun orenv v d = case getenv v of "" => d  | s => s

     fun config_file()  = orenv "ISABELLE_PGIPCONFIG" staticconfig

     fun isabelle_www() = orenv "ISABELLE_HOMEPAGE" isabellewww

 in

 fun send_pgip_config () =

     let

         val path = Path.explode (config_file())

         val ex = File.exists path

         val wwwpage =

             (Url.explode (isabelle_www()))

             handle ERROR _ =>

                    (panic ("Error in URL in environment variable ISABELLE_HOMEPAGE.");

                         Url.explode isabellewww)

         val proverinfo =

             Proverinfo { name = "Isabelle",

                          version = Distribution.version,

                          instance = Session.name(),

                          descr = "The Isabelle/Isar theorem prover",

                          url = wwwpage,

                          filenameextns = ".thy;" }

     in

         if ex then

             (issue_pgip proverinfo;

              issue_pgip_rawtext (File.read path);

              issue_pgip (lexicalstructure_keywords()))

         else panic ("PGIP configuration file \"" ^ config_file() ^ "\" not found")

     end;

 end

 (* Preferences: tweak for PGIP interfaces *)

 val preferences = Unsynchronized.ref Preferences.pure_preferences;

 fun add_preference cat pref =

   CRITICAL (fn () => Unsynchronized.change preferences (Preferences.add cat pref));

 fun setup_preferences_tweak () =

   CRITICAL (fn () => Unsynchronized.change preferences

    (Preferences.set_default ("show-question-marks", "false") #>

     Preferences.remove "show-question-marks" #>   (* we use markup, not ?s *)

     Preferences.remove "theorem-dependencies" #>  (* set internally *)

     Preferences.remove "full-proofs"));           (* set internally *)

 (* Sending commands to Isar *)

 fun isarcmd s = Isar.>>> (OuterSyntax.parse Position.none s);

 (* TODO:

     - apply a command given a transition function;

     - fix position from path of currently open file [line numbers risk garbling though].

 *)

 (* load an arbitrary file (must be .thy or .ML) *)

 fun use_thy_or_ml_file file =

     let

         val (path,extn) = Path.split_ext (Path.explode file)

     in

         case extn of

             "" => isarcmd ("use_thy " ^ quote (Path.implode path))

           | "thy" => isarcmd ("use_thy " ^ quote (Path.implode path))

           | "ML" => isarcmd ("use " ^ quote file)

           | other => error ("Don't know how to read a file with extension " ^ quote other)

     end

 (******* PGIP actions *******)

 (* Responses to each of the PGIP input commands.

    These are programmed uniformly for extensibility. *)

 fun askpgip (Askpgip _) =

     (issue_pgip

          (Usespgip { version = PgipIsabelle.isabelle_pgip_version_supported,

                      pgipelems = PgipIsabelle.accepted_inputs });

      send_pgip_config())

 fun askpgml (Askpgml _) =

     issue_pgip

         (Usespgml { version = PgipIsabelle.isabelle_pgml_version_supported })

 fun askprefs (Askprefs _) =

     let

         fun preference_of {name, descr, default, pgiptype, get, set } =

             { name = name, descr = SOME descr, default = SOME default,

               pgiptype = pgiptype }

     in

         List.app (fn (prefcat, prefs) =>

                      issue_pgip (Hasprefs {prefcategory=SOME prefcat,

                                            prefs=map preference_of prefs}))

                  (!preferences)

     end

 fun askconfig (Askconfig _) = () (* TODO: add config response *)

 local

     fun lookuppref pref =

         case AList.lookup (op =)

                           (map (fn p => (#name p,p))

                                (maps snd (!preferences))) pref of

             NONE => error ("Unknown prover preference: " ^ quote pref)

           | SOME p => p

 in

 fun setpref (Setpref vs) =

     let

         val name = #name vs

         val value = #value vs

         val set = #set (lookuppref name)

     in

         set value

     end

 fun getpref (Getpref vs) =

     let

         val name = #name vs

         val get = #get (lookuppref name)

     in

         issue_pgip (Prefval {name=name, value=get ()})

     end

 end

 fun proverinit _ = restart ()

 fun proverexit _ = isarcmd "quit"

 fun set_proverflag_quiet b =

     isarcmd (if b then "disable_pr" else "enable_pr")

 fun set_proverflag_pgmlsymbols b =

     (pgmlsymbols_flag := b;

       NAMED_CRITICAL "print_mode" (fn () =>

         Unsynchronized.change print_mode

             (fn mode =>

                 remove (op =) Symbol.xsymbolsN mode @ (if b then [Symbol.xsymbolsN] else []))))

 fun set_proverflag_thmdeps b =

     (show_theorem_dependencies := b;

      Proofterm.proofs := (if b then 1 else 2))

 fun setproverflag (Setproverflag vs) =

     let

         val flagname = #flagname vs

         val value = #value vs

     in

         (case flagname of

              "quiet"            => set_proverflag_quiet value

            | "pgmlsymbols"      => set_proverflag_pgmlsymbols value

            | "metainfo:thmdeps" => set_proverflag_thmdeps value

            | _ => log_msg ("Unrecognised prover control flag: " ^

                            (quote flagname) ^ " ignored."))

     end

 fun dostep (Dostep vs) =

     let

         val text = #text vs

     in

         isarcmd text

     end

 fun undostep (Undostep vs) =

     let

         val times = #times vs

     in

         isarcmd ("undos_proof " ^ Int.toString times)

     end

 fun redostep _ = sys_error "redo unavailable"

 fun abortgoal _ = isarcmd "kill" (* was: ProofGeneral.kill_proof *)

 (*** PGIP identifier tables ***)

 (* TODO: these ones should be triggered by hooks after a

    declaration addition/removal, to be sent automatically. *)

 fun addids t  = issue_pgip (Addids {idtables = [t]})

 fun delids t  = issue_pgip (Delids {idtables = [t]})

 local

 fun theory_facts name =

   let val thy = ThyInfo.get_theory name

   in (map PureThy.facts_of (Theory.parents_of thy), PureThy.facts_of thy) end;

 fun thms_of_thy name = map fst (theory_facts name |-> Facts.extern_static);

 fun qualified_thms_of_thy name = map fst (theory_facts name |-> Facts.dest_static);

 in

 fun askids (Askids vs) =

     let

         val url = #url vs            (* ask for identifiers within a file *)

         val thyname = #thyname vs    (* ask for identifiers within a theory *)

         val objtype = #objtype vs    (* ask for identifiers of a particular type *)

         fun idtable ty ctx ids = {objtype=ty,context=ctx,ids=ids}

         fun setids t = issue_pgip (Setids {idtables = [t]})

         (* fake one-level nested "subtheories" by picking apart names. *)

         val immed_thms_of_thy = filter_out Long_Name.is_qualified o thms_of_thy

         fun thy_prefix s = case Long_Name.explode s of

                                     x::_::_ => SOME x  (* String.find? *)

                                   | _ => NONE

         fun subthys_of_thy s =

             List.foldl  (fn (NONE,xs) => xs | (SOME x,xs) => insert op= x xs) []

                    (map thy_prefix (thms_of_thy s))

         fun subthms_of_thy thy =

             (case thy_prefix thy of

                  NONE => immed_thms_of_thy thy

                | SOME prf => filter (String.isPrefix (unprefix (prf ^ Long_Name.separator) thy))

                                     (thms_of_thy prf))

     in

         case (thyname,objtype) of

            (NONE, NONE) =>

            setids (idtable ObjFile NONE (ThyInfo.get_names())) (*FIXME: uris*)

          | (NONE, SOME ObjFile) =>

            setids (idtable ObjFile NONE (ThyInfo.get_names())) (*FIXME: uris*)

          | (SOME fi, SOME ObjFile) =>

            setids (idtable ObjTheory (SOME fi) [fi])       (* TODO: check exists *)

          | (NONE, SOME ObjTheory) =>

            setids (idtable ObjTheory NONE (ThyInfo.get_names()))

          | (SOME thy, SOME ObjTheory) =>

            setids (idtable ObjTheory (SOME thy) (subthys_of_thy thy))

          | (SOME thy, SOME ObjTheorem) =>

            setids (idtable ObjTheorem (SOME thy) (subthms_of_thy thy))

          | (NONE, SOME ObjTheorem) =>

            (* A large query, but not unreasonable. ~5000 results for HOL.*)

            (* Several setids should be allowed, but Eclipse code is currently broken:

               List.app (fn thy => setids (idtable ObjTheorem (SOME thy) (subthms_of_thy thy)))

                          (ThyInfo.get_names()) *)

            setids (idtable ObjTheorem NONE (* this one gives ~7000 for HOL *)

                            (maps qualified_thms_of_thy (ThyInfo.get_names())))

          | _ => warning ("askids: ignored argument combination")

     end

 end;

 fun askrefs (Askrefs vs) =

     let

         val url = #url vs            (* ask for references of a file (i.e. immediate pre-requisites) *)

         val thyname = #thyname vs    (* ask for references of a theory (other theories) *)

         val objtype = #objtype vs    (* ask for references of a particular type... *)

         val name = #name vs          (*   ... with this name *)

         fun idtable ty ctx ids = {objtype=ty,context=ctx,ids=ids}

         val thy_name = Path.implode o #1 o Path.split_ext o Path.base

         fun filerefs f =

             let val thy = thy_name f

                 val filerefs = #uses (ThyLoad.deps_thy (Path.dir f) thy)

             in

                 issue_pgip (Setrefs {url=url, thyname=NONE, objtype=SOME PgipTypes.ObjFile,

                                      name=NONE, idtables=[], fileurls=filerefs})

             end

         fun thyrefs thy =

             let val thyrefs = #imports (ThyLoad.deps_thy Path.current thy)

             in

                 issue_pgip (Setrefs {url=url, thyname=thyname, objtype=SOME PgipTypes.ObjTheory,

                                      name=NONE, idtables=[{context=NONE, objtype=PgipTypes.ObjTheory,

                                                            ids=thyrefs}], fileurls=[]})

             end

         fun thmrefs thmname =

             let

                 (* TODO: interim: this is probably not right.

                    What we want is mapping onto simple PGIP name/context model. *)

                 val ctx = Toplevel.context_of (Isar.state ()) (* NB: raises UNDEF *)

                 val thy = ProofContext.theory_of ctx

                 val ths = [PureThy.get_thm thy thmname]

                 val deps = #2 (thms_deps ths);

             in

                 if null deps then ()

                 else issue_pgip (Setrefs {url=url, thyname=thyname, name=name,

                                           objtype=SOME PgipTypes.ObjTheorem,

                                           idtables=[{context=NONE, objtype=PgipTypes.ObjTheorem,

                                                      ids=deps}], fileurls=[]})

             end

     in

         case (url,thyname,objtype,name) of

             (SOME file, NONE, _, _)  => filerefs file

           | (_,SOME thy,_,_)         => thyrefs thy

           | (_,_,SOME PgipTypes.ObjTheorem,SOME thmname) => thmrefs thmname

           | _  => error ("Unimplemented/invalid case of <askrefs>")

     end

 fun showid (Showid vs) =

     let

         val thyname = #thyname vs

         val objtype = #objtype vs

         val name = #name vs

         val topthy = Toplevel.theory_of o Isar.state

         fun splitthy id =

             let val comps = Long_Name.explode id

             in case comps of

                    (thy::(rest as _::_)) => (ThyInfo.get_theory thy, space_implode "." rest)

                  | [plainid] => (topthy(),plainid)

                  | _ => raise Toplevel.UNDEF (* assert false *)

             end

         fun idvalue strings =

             issue_pgip (Idvalue { thyname=thyname, objtype=objtype, name=name,

                                   text=[XML.Elem("pgml",[],

                                                  maps YXML.parse_body strings)] })

         fun strings_of_thm (thy, name) =

           map (Display.string_of_thm_global thy) (PureThy.get_thms thy name)

         val string_of_thy = Pretty.string_of o Proof_Display.pretty_full_theory false

     in

         case (thyname, objtype) of

             (_, ObjTheory) => idvalue [string_of_thy (ThyInfo.get_theory name)]

           | (SOME thy, ObjTheorem) => idvalue (strings_of_thm (ThyInfo.get_theory thy, name))

           | (NONE, ObjTheorem) => idvalue (strings_of_thm (splitthy name))

           | (_, ot) => error ("Cannot show objects of type "^(PgipTypes.name_of_objtype ot))

     end

 (*** Inspecting state ***)

 (* The file which is currently being processed interactively.

    In the pre-PGIP code, this was informed to Isabelle and the theory loader

    on completion, but that allows for circularity in case we read

    ourselves.  So PGIP opens the filename at the start of a script.

    We ought to prevent problems by modifying the theory loader to know

    about this special status, but for now we just keep a local reference.

 *)

 val currently_open_file = Unsynchronized.ref (NONE : pgipurl option)

 fun get_currently_open_file () = ! currently_open_file;

 fun askguise _ =

     (* The "guise" is the PGIP abstraction of the prover's state.

        The <informguise> message is merely used for consistency checking. *)

     let

         val openfile = !currently_open_file

         val topthy = Toplevel.theory_of o Isar.state

         val topthy_name = Context.theory_name o topthy

         val opentheory = SOME (topthy_name()) handle Toplevel.UNDEF => NONE

         fun topproofpos () = try Toplevel.proof_position_of (Isar.state ());

         val openproofpos = topproofpos()

     in

         issue_pgip (Informguise { file = openfile,

                                   theory = opentheory,

                                   (* would be nice to get thm name... *)

                                   theorem = NONE,

                                   proofpos = openproofpos })

     end

 fun parsescript (Parsescript vs) =

     let

         val text = #text vs

         val systemdata = #systemdata vs

         val location = #location vs   (* TODO: extract position *)

         val doc = PgipParser.pgip_parser Position.none text

         val sysattrs = PgipTypes.opt_attr "systemdata" systemdata

         val locattrs = PgipTypes.attrs_of_location location

      in

         issue_pgip (Parseresult { attrs= sysattrs@locattrs,

                                   doc = doc,

                                   errs = [] })

     end

 fun showproofstate _ = isarcmd "pr"

 fun showctxt _ = isarcmd "print_context"

 fun searchtheorems (Searchtheorems vs) =

     let

         val arg = #arg vs

     in

         isarcmd ("find_theorems " ^ arg)

     end

 fun setlinewidth (Setlinewidth vs) =

     let

         val width = #width vs

     in

         isarcmd ("pretty_setmargin " ^ Int.toString width) (* FIXME: conversion back/forth! *)

     end

 fun viewdoc (Viewdoc vs) =

     let

         val arg = #arg vs

     in

         isarcmd ("print_" ^ arg)   (* FIXME: isabelle doc?.  Return URLs, maybe? *)

     end

 (*** Theory ***)

 fun doitem (Doitem vs) =

     let

         val text = #text vs

     in

         isarcmd text

     end

 fun undoitem _ =

     isarcmd "undo"

 fun redoitem _ =

     isarcmd "redo"

 fun aborttheory _ =

     isarcmd "kill"  (* was: "init_toplevel" *)

 fun retracttheory (Retracttheory vs) =

     let

         val thyname = #thyname vs

     in

         isarcmd ("kill_thy " ^ quote thyname)

     end

 (*** Files ***)

 (* Path management: we allow theory files to have dependencies in

    their own directory, but when we change directory for a new file we

    remove the path.  Leaving it there can cause confusion with

    difference in batch mode.

    NB: PGIP does not assume that the prover has a load path.

 *)

 local

     val current_working_dir = Unsynchronized.ref (NONE : string option)

 in

 fun changecwd_dir newdirpath =

    let

        val newdir = File.platform_path newdirpath

    in

        (case (!current_working_dir) of

             NONE => ()

           | SOME dir => ThyLoad.del_path dir;

         ThyLoad.add_path newdir;

         current_working_dir := SOME newdir)

    end

 end

 fun changecwd (Changecwd vs) =

     let

         val url = #url vs

         val newdir = PgipTypes.path_of_pgipurl url

     in

         changecwd_dir url

     end

 fun openfile (Openfile vs) =

   let

       val url = #url vs

       val filepath = PgipTypes.path_of_pgipurl url

       val filedir = Path.dir filepath

       val thy_name = Path.implode o #1 o Path.split_ext o Path.base

       val openfile_retract = Output.no_warnings_CRITICAL

         (ThyInfo.if_known_thy ThyInfo.remove_thy) o thy_name;

   in

       case !currently_open_file of

           SOME f => raise PGIP ("<openfile> when a file is already open!\nCurrently open file: " ^

                                 PgipTypes.string_of_pgipurl url)

         | NONE => (openfile_retract filepath;

                    changecwd_dir filedir;

                    priority ("Working in file: " ^ PgipTypes.string_of_pgipurl url);

                    currently_open_file := SOME url)

   end

 fun closefile _ =

     case !currently_open_file of

         SOME f => (proper_inform_file_processed f (Isar.state());

                    priority ("Finished working in file: " ^ PgipTypes.string_of_pgipurl f);

                    currently_open_file := NONE)

       | NONE => raise PGIP ("<closefile> when no file is open!")

 fun loadfile (Loadfile vs) =

     let

         val url = #url vs

     in

         (* da: this doesn't seem to cause a problem, batch loading uses

            a different state context.  Of course confusion is still possible,

            e.g. file loaded depends on open file which is not yet saved. *)

         (* case !currently_open_file of

             SOME f => raise PGIP ("<loadfile> when a file is open!\nCurrently open file: " ^

                                   PgipTypes.string_of_pgipurl url)

           | NONE => *)

         use_thy_or_ml_file (File.platform_path url)

     end

 fun abortfile _ =

     case !currently_open_file of

         SOME f => (isarcmd "init_toplevel";

                    priority ("Aborted working in file: " ^

                              PgipTypes.string_of_pgipurl f);

                    currently_open_file := NONE)

       | NONE => raise PGIP ("<abortfile> when no file is open!")

 fun retractfile (Retractfile vs) =

     let

         val url = #url vs

     in

         case !currently_open_file of

             SOME f => raise PGIP ("<retractfile> when a file is open!")

           | NONE => (priority ("Retracting file: " ^ PgipTypes.string_of_pgipurl url);

                      (* TODO: next should be in thy loader, here just for testing *)

                      let

                          val name = thy_name url

                      in List.app (tell_file_retracted false) (ThyInfo.loaded_files name) end;

                      inform_file_retracted url)

     end

 (*** System ***)

 fun systemcmd (Systemcmd vs) =

   let

       val arg = #arg vs

   in

       isarcmd arg

   end

 exception PGIP_QUIT;

 fun quitpgip _ = raise PGIP_QUIT

 fun process_input inp = case inp

  of Pgip.Askpgip _          => askpgip inp

   | Pgip.Askpgml _          => askpgml inp

   | Pgip.Askprefs _         => askprefs inp

   | Pgip.Askconfig _        => askconfig inp

   | Pgip.Getpref _          => getpref inp

   | Pgip.Setpref _          => setpref inp

   | Pgip.Proverinit _       => proverinit inp

   | Pgip.Proverexit _       => proverexit inp

   | Pgip.Setproverflag _    => setproverflag inp

   | Pgip.Dostep _           => dostep inp

   | Pgip.Undostep _         => undostep inp

   | Pgip.Redostep _         => redostep inp

   | Pgip.Forget _           => error "<forget> not implemented by Isabelle"

   | Pgip.Restoregoal _      => error "<restoregoal> not implemented by Isabelle"

   | Pgip.Abortgoal _        => abortgoal inp

   | Pgip.Askids _           => askids inp

   | Pgip.Askrefs _          => askrefs inp

   | Pgip.Showid _           => showid inp

   | Pgip.Askguise _         => askguise inp

   | Pgip.Parsescript _      => parsescript inp

   | Pgip.Showproofstate _   => showproofstate inp

   | Pgip.Showctxt _         => showctxt inp

   | Pgip.Searchtheorems _   => searchtheorems inp

   | Pgip.Setlinewidth _     => setlinewidth inp

   | Pgip.Viewdoc _          => viewdoc inp

   | Pgip.Doitem _           => doitem inp

   | Pgip.Undoitem _         => undoitem inp

   | Pgip.Redoitem _         => redoitem inp

   | Pgip.Aborttheory _      => aborttheory inp

   | Pgip.Retracttheory _    => retracttheory inp

   | Pgip.Loadfile _         => loadfile inp

   | Pgip.Openfile _         => openfile inp

   | Pgip.Closefile _        => closefile inp

   | Pgip.Abortfile _        => abortfile inp

   | Pgip.Retractfile _      => retractfile inp

   | Pgip.Changecwd _        => changecwd inp

   | Pgip.Systemcmd _        => systemcmd inp

   | Pgip.Quitpgip _         => quitpgip inp

 fun process_pgip_element pgipxml =

     case pgipxml of

         xml as (XML.Elem elem) =>

         (case Pgip.input elem of

              NONE => warning ("Unrecognized PGIP command, ignored: \n" ^

                               (XML.string_of xml))

            | SOME inp => (process_input inp)) (* errors later; packet discarded *)

       | XML.Text t => ignored_text_warning t

 and ignored_text_warning t =

     if size (Symbol.strip_blanks t) > 0 then

            warning ("Ignored text in PGIP packet: \n" ^ t)

     else ()

 fun process_pgip_tree xml =

     (pgip_refid := NONE;

      pgip_refseq := NONE;

      (case xml of

           XML.Elem ("pgip", attrs, pgips) =>

           (let

                val class = PgipTypes.get_attr "class" attrs

                val dest  = PgipTypes.get_attr_opt "destid" attrs

                val seq = PgipTypes.read_pgipnat (PgipTypes.get_attr "seq" attrs)

                (* Respond to prover broadcasts, or messages for us. Ignore rest *)

                val processit =

                    case dest of

                        NONE =>    class = "pa"

                      | SOME id => matching_pgip_id id

            in if processit then

                   (pgip_refid :=  PgipTypes.get_attr_opt "id" attrs;

                    pgip_refseq := SOME seq;

                    List.app process_pgip_element pgips;

                    (* return true to indicate <ready/> *)

                    true)

               else

                   (* no response to ignored messages. *)

                   false

            end)

         | _ => raise PGIP "Invalid PGIP packet received")

      handle PGIP msg =>

             (Output.error_msg ((msg ^ "\nPGIP error occured in XML text below:\n") ^

                                (XML.string_of xml));

              true))

 (* External input *)

 val process_pgip_plain = K () o process_pgip_tree o XML.parse

 (* PGIP loop: process PGIP input only *)

 local

 exception XML_PARSE

 fun loop ready src =

     let

         val _ = if ready then issue_pgip (Ready ()) else ()

         val pgipo =

           (case try Source.get_single src of

             SOME pgipo => pgipo

           | NONE => raise XML_PARSE)

     in

         case pgipo of

              NONE  => ()

            | SOME (pgip,src') =>

              let

                  val ready' = (process_pgip_tree pgip)

                                 handle PGIP_QUIT => raise PGIP_QUIT

                                      | e => (handler (e,SOME src'); true)

              in

                  loop ready' src'

              end

     end handle e => handler (e,SOME src)  (* error in XML parse or Ready issue *)

 and handler (e,srco) =

     case (e,srco) of

         (XML_PARSE,SOME src) =>

         panic "Invalid XML input, aborting" (* TODO: attempt recovery  *)

       | (Exn.Interrupt,SOME src) =>

         (Output.error_msg "Interrupt during PGIP processing"; loop true src)

       | (Toplevel.UNDEF,SOME src) =>

         (Output.error_msg "No working context defined"; loop true src)

       | (e,SOME src) =>

         (Output.error_msg (ML_Compiler.exn_message e); loop true src)

       | (PGIP_QUIT,_) => ()

       | (_,NONE) => ()

 in

   (* TODO: add socket interface *)

   val xmlP = XML.parse_comments |-- XML.parse_element >> single

   val tty_src = Source.set_prompt "" (Source.source Symbol.stopper xmlP NONE Source.tty)

   fun pgip_toplevel x = loop true x

 end

 (* Extra command for embedding prover-control inside document (obscure/debug usage). *)

 fun init_outer_syntax () =

   OuterSyntax.improper_command "ProofGeneral.process_pgip" "(internal)" OuterKeyword.control

     (OuterParse.text >> (Toplevel.no_timing oo

       (fn txt => Toplevel.imperative (fn () => process_pgip_plain txt))));

 (* init *)

 val initialized = Unsynchronized.ref false;

 fun init_pgip false = panic "No Proof General interface support for Isabelle/classic mode."

   | init_pgip true =

       (! initialized orelse

         (setup_preferences_tweak ();

          Output.add_mode proof_generalN Output.default_output Output.default_escape;

          Markup.add_mode proof_generalN YXML.output_markup;

          setup_messages ();

          Output.no_warnings_CRITICAL init_outer_syntax ();

          setup_thy_loader ();

          setup_present_hook ();

          init_pgip_session_id ();

          welcome ();

          Unsynchronized.set initialized);

         sync_thy_loader ();

        Unsynchronized.change print_mode (update (op =) proof_generalN);

        pgip_toplevel tty_src);

 (** Out-of-loop PGIP commands (for Emacs hybrid mode) **)

 local

     val pgip_output_channel = Unsynchronized.ref Output.writeln_default

 in

 (* Set recipient for PGIP results *)

 fun init_pgip_channel writefn =

     (init_pgip_session_id();

      pgip_output_channel := writefn)

 (* Process a PGIP command.

    This works for preferences but not generally guaranteed

    because we haven't done full setup here (e.g., no pgml mode)  *)

 fun process_pgip str =

      setmp_CRITICAL output_xml_fn (!pgip_output_channel) process_pgip_plain str

 end

 end;