(*  Title:      Pure/System/isabelle_process.ML

    Author:     Makarius

Isabelle process wrapper -- interaction via external program.

General format of process output:

  (1) unmarked stdout/stderr, no line structure (output should be

  processed immediately as it arrives);

  (2) properly marked-up messages, e.g. for writeln channel

  "\002A" ^ props ^ "\002,\n" ^ text ^ "\002.\n"

  where the props consist of name=value lines terminated by "\002,\n"

  each, and the remaining text is any number of lines (output is

  supposed to be processed in one piece);

  (3) special init message holds "pid" and "session" property;

  (4) message content is encoded in YXML format.

*)

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 *)

fun special ch = Symbol.STX ^ ch;

val special_sep = special ",";

val special_end = special ".";

local

fun clean_string bad str =

  if exists_string (member (op =) bad) str then

    translate_string (fn c => if member (op =) bad c then Symbol.DEL else c) str

  else str;

fun message_props props =

  let val clean = clean_string [Symbol.STX, "\n", "\r"]

  in implode (map (fn (x, y) => clean x ^ "=" ^ clean y ^ special_sep ^ "\n") props) end;

fun message_pos trees = trees |> get_first

  (fn XML.Elem (name, atts, ts) =>

        if name = Markup.positionN then SOME (Position.of_properties atts)

        else message_pos ts

    | _ => NONE);

fun output out_stream s = NAMED_CRITICAL "IO" (fn () =>

  (TextIO.output (out_stream, s); TextIO.output (out_stream, "\n")));

in

fun message _ _ "" = ()

  | message out_stream ch body =

      let

        val pos = the_default Position.none (message_pos (YXML.parse_body body));

        val props =

          Position.properties_of (Position.thread_data ())

          |> Position.default_properties pos;

        val txt = clean_string [Symbol.STX] body;

      in output out_stream (special ch ^ message_props props ^ txt ^ special_end) end;

fun init_message out_stream =

  let

    val pid = (Markup.pidN, process_id ());

    val session = (Markup.sessionN, List.last (Session.id ()) handle List.Empty => "unknown");

    val text = Session.welcome ();

  in output out_stream (special "A" ^ message_props [pid, session] ^ text ^ special_end) end;

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 out_stream =

      if out = "-" then TextIO.stdOut

      else

        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 TextIO.stdOut);

        in out_stream end;

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

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

  in

    Output.status_fn   := message out_stream "B";

    Output.writeln_fn  := message out_stream "C";

    Output.priority_fn := message out_stream "D";

    Output.tracing_fn  := message out_stream "E";

    Output.warning_fn  := message out_stream "F";

    Output.error_fn    := message out_stream "G";

    Output.debug_fn    := message out_stream "H";

    Output.prompt_fn   := ignore;

    out_stream

  end;

end;

(* init *)

fun init out =

 (change print_mode (update (op =) isabelle_processN);

  setup_channels out |> init_message;

  OuterKeyword.report ();

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

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

end;