Channel_name value expected format

[C47D]

Hi,

So far I've been using ldfparser in LDF files with no Channel_name postfix name definition, until today, I'm getting the following exception when trying to parse the attached snippet.ldf file (attached in case you need it):

snippet.ldf

LIN_description_file;
LIN_protocol_version = "2.1";
LIN_language_version = "2.1";
LIN_speed = 19.2 kbps;
Channel_name = Dummy;

Nodes {
  Master: BCM, 5 ms, 0.10 ms ;
  Slaves: Node ;
}

How I'm loading it:

import ldfparser

if __name__ == '__main__':
    old_ldf: ldfparser.LDF = ldfparser.parse_ldf(path = 'snippet.ldf')

Traceback (most recent call last):
  File "C:\Users\User\Desktop\ldf\venv\lib\site-packages\lark\lexer.py", line 478, in lex
    yield lexer.next_token(lexer_state, parser_state)
  File "C:\Users\User\Desktop\ldf\venv\lib\site-packages\lark\lexer.py", line 400, in next_token
    state=parser_state, terminals_by_name=self.terminals_by_name)
lark.exceptions.UnexpectedCharacters: No terminal matches 'D' in the current parser context, at line 5 col 16

Channel_name = Dummy;
               ^
Expected one of:
        * DBLQUOTE

Previous tokens: Token('EQUAL', '=')


During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "main.py", line 5, in <module>
    old_ldf: ldfparser.LDF = ldfparser.parse_ldf(path = 'snippet.ldf')
  File "C:\Users\User\Desktop\ldf\venv\lib\site-packages\ldfparser\parser.py", line 51, in parse_ldf
    json = parse_ldf_to_dict(path, capture_comments, encoding)
  File "C:\Users\User\Desktop\ldf\venv\lib\site-packages\ldfparser\parser.py", line 26, in parse_ldf_to_dict
    tree = parser.parse(ldf_file)
  File "C:\Users\User\Desktop\ldf\venv\lib\site-packages\lark\lark.py", line 581, in parse
    return self.parser.parse(text, start=start, on_error=on_error)
  File "C:\Users\User\Desktop\ldf\venv\lib\site-packages\lark\parser_frontends.py", line 106, in parse
    return self.parser.parse(stream, chosen_start, **kw)
  File "C:\Users\User\Desktop\ldf\venv\lib\site-packages\lark\parsers\lalr_parser.py", line 41, in parse
    return self.parser.parse(lexer, start)
  File "C:\Users\User\Desktop\ldf\venv\lib\site-packages\lark\parsers\lalr_parser.py", line 171, in parse
    return self.parse_from_state(parser_state)
  File "C:\Users\User\Desktop\ldf\venv\lib\site-packages\lark\parsers\lalr_parser.py", line 188, in parse_from_state
    raise e
  File "C:\Users\User\Desktop\ldf\venv\lib\site-packages\lark\parsers\lalr_parser.py", line 178, in parse_from_state
    for token in state.lexer.lex(state):
  File "C:\Users\User\Desktop\ldf\venv\lib\site-packages\lark\lexer.py", line 487, in lex
    raise UnexpectedToken(token, e.allowed, state=parser_state, token_history=[last_token], terminals_by_name=self.root_lexer.terminals_by_name)
lark.exceptions.UnexpectedToken: Unexpected token Token('CNAME', 'Dummy') at line 5, column 16.
Expected one of:
        * DBLQUOTE
Previous tokens: [Token('EQUAL', '=')]

After checking the Specification Revision 2.2A, I noticed the Channel_name value has to be quoted

I did so and the exception is gone:

LIN_description_file;
LIN_protocol_version = "2.1";
LIN_language_version = "2.1";
LIN_speed = 19.2 kbps;
Channel_name = "Dummy";

Nodes {
  Master: BCM, 5 ms, 0.10 ms ;
  Slaves: Node ;
}

Is this the expected Channel_name value format? Do you think it would be helpful to point this out in the exception message?

Thanks again for the awesome library 👍

[c4deszes]

Yes, the channel name should be quoted. If you have any doubts about the grammar I think the lark file says it all. The grammar reflects the 1.3-2.2A standards very closely with only minor deviations that lift a couple of restrictions, for example scientific notation.

For exceptions it could be better, and it also seems like lark-parser has gotten better in terms of error handling. Technically it would be possible to ignore this error and convert it into a warning and eventually the library will reach this point, but at the moment there are still parts of the LDF that are ignored when it comes to Python object creation.

[C47D]

Thanks for the information, it's not a problem for me to edit the LDF file and add the quotes to avoid the exception. If you think I can help with the improvement you mentioned please let me know. I will study both links you provided to get more familiar with them.