src/Pure/ML/exn_properties.ML

tuned comments;

(*  Title:      Pure/ML/exn_properties.ML
    Author:     Makarius

Exception properties.
*)

signature EXN_PROPERTIES =
sig
  val position_of_polyml_location: ML_Compiler0.polyml_location -> Position.T
  val position: exn -> Position.T
  val get: exn -> Properties.T
  val identify: Properties.T -> exn -> exn
  val the_serial: exn -> int
  val ord: exn ord
end;

structure Exn_Properties: EXN_PROPERTIES =
struct

(* source locations *)

fun props_of_polyml_location (loc: ML_Compiler0.polyml_location) =
  (case YXML.parse_body (#file loc) of
    [] => []
  | [XML.Text file] =>
      if file = "Standard Basis" then []
      else [(Markup.fileN, ML_System.standard_path file)]
  | body => XML.Decode.properties body);

fun position_of_polyml_location loc =
  Position.of_props
   {line = FixedInt.toInt (#startLine loc),
    offset = FixedInt.toInt (#startPosition loc),
    end_offset = FixedInt.toInt (#endPosition loc),
    props = props_of_polyml_location loc};

fun position exn =
  (case Exn.polyml_location exn of
    NONE => Position.none
  | SOME loc => position_of_polyml_location loc);


(* exception properties *)

fun get exn =
  (case Exn.polyml_location exn of
    NONE => []
  | SOME loc => props_of_polyml_location loc);

fun update entries exn =
  let
    val loc =
      the_default {file = "", startLine = 0, endLine = 0, startPosition = 0, endPosition = 0}
        (Exn.polyml_location exn);
    val props = props_of_polyml_location loc;
    val props' = fold Properties.put entries props;
  in
    if props = props' then exn
    else
      let
        val loc' =
          {file = YXML.string_of_body (XML.Encode.properties props'),
            startLine = #startLine loc, endLine = #endLine loc,
            startPosition = #startPosition loc, endPosition = #endPosition loc};
      in
        Thread_Attributes.uninterruptible_body (fn _ =>
          PolyML.raiseWithLocation (exn, loc') handle exn' => exn')
      end
  end;


(* identification via serial numbers *)

fun identify default_props exn =
  if Exn.is_interrupt_proper exn then exn
  else
    let
      val props = get exn;
      val update_serial =
        if Properties.defined props Markup.serialN then []
        else [(Markup.serialN, serial_string ())];
      val update_props = filter_out (Properties.defined props o #1) default_props;
    in update (update_serial @ update_props) exn end;

fun the_serial exn =
  Value.parse_int (the (Properties.get (get exn) Markup.serialN));

val ord = rev_order o int_ord o apply2 the_serial;

end;