riaps_lang errors out if *.riaps uses no messages

riaps_lang produces the following error:

riaps@riapsvbox:~/riaps-tests/temp$ riaps_lang A.riaps
Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/textx/model.py", line 153, in _parse
    return self.parser_model.parse(self)
  File "/usr/local/lib/python3.5/dist-packages/arpeggio/__init__.py", line 283, in parse
    result = self._parse(parser)
  File "/usr/local/lib/python3.5/dist-packages/arpeggio/__init__.py", line 362, in _parse
    result = e.parse(parser)
  File "/usr/local/lib/python3.5/dist-packages/arpeggio/__init__.py", line 768, in parse
    result = self._parse(parser)
  File "/usr/local/lib/python3.5/dist-packages/arpeggio/__init__.py", line 920, in _parse
    parser._nm_raise(self, c_pos, parser)
  File "/usr/local/lib/python3.5/dist-packages/arpeggio/__init__.py", line 1672, in _nm_raise
    raise self.nm
  File "/usr/local/lib/python3.5/dist-packages/arpeggio/__init__.py", line 463, in _parse
    result = p(parser)
  File "/usr/local/lib/python3.5/dist-packages/arpeggio/__init__.py", line 283, in parse
    result = self._parse(parser)
  File "/usr/local/lib/python3.5/dist-packages/arpeggio/__init__.py", line 362, in _parse
    result = e.parse(parser)
  File "/usr/local/lib/python3.5/dist-packages/arpeggio/__init__.py", line 283, in parse
    result = self._parse(parser)
  File "/usr/local/lib/python3.5/dist-packages/arpeggio/__init__.py", line 507, in _parse
    result = p(parser)
  File "/usr/local/lib/python3.5/dist-packages/arpeggio/__init__.py", line 283, in parse
    result = self._parse(parser)
  File "/usr/local/lib/python3.5/dist-packages/arpeggio/__init__.py", line 362, in _parse
    result = e.parse(parser)
  File "/usr/local/lib/python3.5/dist-packages/arpeggio/__init__.py", line 768, in parse
    result = self._parse(parser)
  File "/usr/local/lib/python3.5/dist-packages/arpeggio/__init__.py", line 874, in _parse
    parser._nm_raise(self, c_pos, parser)
  File "/usr/local/lib/python3.5/dist-packages/arpeggio/__init__.py", line 1672, in _nm_raise
    raise self.nm
arpeggio.NoMatch: Expected 'message' at position /home/riaps/riaps-tests/temp/A.riaps:(5, 3) => 'ssary;    *component '.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/riaps/lang/lang.py", line 429, in compileModel
    example_riaps_model = riaps_meta.model_from_file(join(this_folder,modelFileName))
  File "/usr/local/lib/python3.5/dist-packages/textx/metamodel.py", line 465, in model_from_file
    encoding, debug=debug)
  File "/usr/local/lib/python3.5/dist-packages/textx/model.py", line 168, in get_model_from_file
    debug=debug)
  File "/usr/local/lib/python3.5/dist-packages/textx/model.py", line 191, in get_model_from_str
    self.parse(model_str, file_name=file_name)
  File "/usr/local/lib/python3.5/dist-packages/arpeggio/__init__.py", line 1470, in parse
    self.parse_tree = self._parse()
  File "/usr/local/lib/python3.5/dist-packages/textx/model.py", line 156, in _parse
    raise TextXSyntaxError(text(e), line, col)
textx.exceptions.TextXSyntaxError: Expected 'message' at position /home/riaps/riaps-tests/temp/A.riaps:(5, 3) => 'ssary;    *component '.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/bin/riaps_lang", line 15, in <module>
    main()
  File "/usr/local/lib/python3.5/dist-packages/riaps/lang/lang.py", line 475, in main
    return compileModel(args.model,args.verbose)
  File "/usr/local/lib/python3.5/dist-packages/riaps/lang/lang.py", line 437, in compileModel
    raise LangError(errMsg)
riaps.lang.lang.LangError: Syntax error: Expected 'message' at position /home/riaps/riaps-tests/temp/A.riaps:(5, 3) => 'ssary;    *component '.

For the following .riaps file:

app testA{

  //message Unnecessary;

  component A{
    timer clock 1000;
  }

  actor ActorA {
  {
  compA : A;
  }
  }
}

Uncommenting message Unnecessary lets the app compile and run as expected. I think we should allow the user to create apps that don't need any messages.

For fun, here is the component code and .depl:

# import riaps
from riaps.run.comp import Component
import logging
import random
import os
import time

# CPU limited component

class A(Component):
    def __init__(self):
        super(A, self).__init__()

        self.pid = os.getpid()

        logpath = '/tmp/CompA.log'
        try:
            os.remove(logpath)
        except OSError:
            pass

        self.fh = logging.FileHandler(logpath)
        self.fh.setLevel(logging.DEBUG)
        self.fh.setFormatter(self.logformatter)
        self.logger.addHandler(self.fh)

        self.logger.info("Started A")

    def on_clock(self):
        msg = self.clock.recv_pyobj()
        self.logger.info("Time: %s" % msg)

app testA {
  on all ActorA;
}

RIAPS / riaps-dsml

riaps_lang errors out if *.riaps uses no messages #27