(*  Title:      Pure/System/isabelle_process.ML

     Author:     Makarius

 Isabelle process wrapper.

 General format of process output:

   (1) message = "\002"  header chunk  body chunk

   (2) chunk = size (ASCII digits)  \n  content (YXML)

 *)

 signature ISABELLE_PROCESS =

 sig

   val isabelle_processN: string

   val init: string -> unit

 end;

 structure Isabelle_Process: ISABELLE_PROCESS =

 struct

 (* print modes *)

 val isabelle_processN = "isabelle_process";

 val _ = Output.add_mode isabelle_processN Output.default_output Output.default_escape;

 val _ = Markup.add_mode isabelle_processN YXML.output_markup;

 (* message markup *)

 local

 fun chunk s = string_of_int (size s) ^ "\n" ^ s;

 fun message _ _ _ "" = ()

   | message out_stream ch props body =

       let

         val header = YXML.string_of (XML.Elem (ch, map (pairself YXML.binary_text) props, []));

         val msg = Symbol.STX ^ chunk header ^ chunk body;

       in TextIO.output (out_stream, msg) (*atomic output*) end;

 in

 fun standard_message out_stream ch body =

   message out_stream ch (Position.properties_of (Position.thread_data ())) body;

 fun init_message out_stream =

   message out_stream "A" [(Markup.pidN, process_id ())] (Session.welcome ());

 end;

 (* channels *)

 local

 fun auto_flush stream =

   let

     val _ = TextIO.StreamIO.setBufferMode (TextIO.getOutstream stream, IO.BLOCK_BUF);

     fun loop () =

       (OS.Process.sleep (Time.fromMilliseconds 50); try TextIO.flushOut stream; loop ());

   in loop end;

 in

 fun setup_channels out =

   let

     val path = File.platform_path (Path.explode out);

     val out_stream = TextIO.openOut path;  (*fifo blocks until reader is ready*)

     val _ = OS.FileSys.remove path;  (*prevent alien access, indicate writer is ready*)

     val _ = SimpleThread.fork false (auto_flush out_stream);

     val _ = SimpleThread.fork false (auto_flush TextIO.stdOut);

     val _ = SimpleThread.fork false (auto_flush TextIO.stdErr);

   in

     Output.status_fn   := standard_message out_stream "B";

     Output.writeln_fn  := standard_message out_stream "C";

     Output.tracing_fn  := standard_message out_stream "D";

     Output.warning_fn  := standard_message out_stream "E";

     Output.error_fn    := standard_message out_stream "F";

     Output.debug_fn    := standard_message out_stream "G";

     Output.priority_fn := ! Output.writeln_fn;

     Output.prompt_fn   := ignore;

     out_stream

   end;

 end;

 (* init *)

 fun init out =

  (Unsynchronized.change print_mode

     (fold (update op =) [isabelle_processN, Keyword.keyword_status_reportN, Pretty.symbolicN]);

   setup_channels out |> init_message;

   Keyword.report ();

   Output.status (Markup.markup Markup.ready "");

   Isar.toplevel_loop {init = true, welcome = false, sync = true, secure = true});

 end;