INTERFACE EventFile;

IMPORT Rd;

TYPE
  T = RECORD
    imports  : Import;
    alg_data : TEXT;
    events   : Event;
  END;

TYPE
  Import = REF RECORD
    next      : Import;
    interface : TEXT;
  END;

TYPE
  EventKind = { Output, Update, Feedback };

CONST
  EventKindName = ARRAY EventKind OF TEXT {
    "OutputEvent", "UpdateEvent", "FeedbackEvent"
  };

TYPE
  Event = REF RECORD
    next     : Event;
    priority : TEXT;
    name     : TEXT;
    args     : EventArg;
    kind     : EventKind;
  END;

TYPE
  ArgMode = { Value, Readonly };

TYPE
  EventArg = REF RECORD
    next    : EventArg;
    mode    : ArgMode;
    name    : TEXT;
    type    : TEXT;
    printer : TEXT;
  END;

PROCEDURE Parse (rd: Rd.T;  VAR(*OUT*) t: T): TEXT;

Parse the event file contained in rd and leave it's AST in t. If everything went well, return NIL. Otherwise, return a message describing the problem.

END EventFile.

The syntax of event files is:

event_file ::= { import } [ algdata ] { event } import ::= IMPORT [ name_list ] ; algdata ::= ALGDATA ... event ::= event_type [ priority ] name [ event_args ] ; event_type ::= OUTPUT | PROCEDURE | UPDATE | FEEDBACK priority ::= [ digit ] event_args ::= ( [ arg { ; arg } ] ) arg ::= [ arg_mode ] name_list : arg_type [ arg_printer ] arg_mode ::= VALUE | READONLY arg_type ::= name arg_printer ::= [ [ name ] ]

name_list ::= name { , name } name ::= alpha { letter } letter ::= alpha | digit | . | _ alpha ::= a | b | ... | z | A | B | .. | Z digit ::= 0 | 1 | ... | 9

Event files use Modula-3 comment conventions. (ie. nesting (*..

"s)
*)