def _MergeField(tokenizer, message, allow_multiple_scalars):
  """Merges a single protocol message field into a message.

  Args:
    tokenizer: A tokenizer to parse the field name and values.
    message: A protocol message to record the data.
    allow_multiple_scalars: Determines if repeated values for a non-repeated
      field are permitted, e.g., the string "foo: 1 foo: 2" for a
      required/optional field named "foo".

  Raises:
    ParseError: In case of ASCII parsing problems.
  """
  message_descriptor = message.DESCRIPTOR
  if tokenizer.TryConsume('['):
    name = [tokenizer.ConsumeIdentifier()]
    while tokenizer.TryConsume('.'):
      name.append(tokenizer.ConsumeIdentifier())
    name = '.'.join(name)

    if not message_descriptor.is_extendable:
      raise tokenizer.ParseErrorPreviousToken(
          'Message type "%s" does not have extensions.' %
          message_descriptor.full_name)

    field = message.Extensions._FindExtensionByName(name)

    if not field:
      raise tokenizer.ParseErrorPreviousToken(
          'Extension "%s" not registered.' % name)
    elif message_descriptor != field.containing_type:
      raise tokenizer.ParseErrorPreviousToken(
          'Extension "%s" does not extend message type "%s".' % (
              name, message_descriptor.full_name))
    tokenizer.Consume(']')
  else:
    name = tokenizer.ConsumeIdentifier()
    field = message_descriptor.fields_by_name.get(name, None)




    if not field:
      field = message_descriptor.fields_by_name.get(name.lower(), None)
      if field and field.type != descriptor.FieldDescriptor.TYPE_GROUP:
        field = None

    if (field and field.type == descriptor.FieldDescriptor.TYPE_GROUP and
        field.message_type.name != name):
      field = None

    if not field:
      raise tokenizer.ParseErrorPreviousToken(
          'Message type "%s" has no field named "%s".' % (
              message_descriptor.full_name, name))

  if field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
    tokenizer.TryConsume(':')

    if tokenizer.TryConsume('<'):
      end_token = '>'
    else:
      tokenizer.Consume('{')
      end_token = '}'

    if field.label == descriptor.FieldDescriptor.LABEL_REPEATED:
      if field.is_extension:
        sub_message = message.Extensions[field].add()
      else:
        sub_message = getattr(message, field.name).add()
    else:
      if field.is_extension:
        sub_message = message.Extensions[field]
      else:
        sub_message = getattr(message, field.name)
      sub_message.SetInParent()

    while not tokenizer.TryConsume(end_token):
      if tokenizer.AtEnd():
        raise tokenizer.ParseErrorPreviousToken('Expected "%s".' % (end_token))
      _MergeField(tokenizer, sub_message, allow_multiple_scalars)
  else:
    _MergeScalarField(tokenizer, message, field, allow_multiple_scalars)



  if not tokenizer.TryConsume(','):
    tokenizer.TryConsume(';')
dataset/ETHPy150Open AppScale/appscale/AppServer/google/net/proto2/python/public/text_format.py/_MergeField/original