Question: how to prevent lark from recognizing parts of an identifier as a keyword?

Hi, I have a little question.

parser = Lark('''
    ?start: value 
            | start "or" value -> or
    ?value: DIGIT -> digit 
            | ID -> id

    DIGIT: /[1-9]\d*/

    %import common.CNAME -> ID

    %import common.WS
    %ignore WS
    ''', parser='lalr')

print(parser.parse("1orfoo").pretty())

This code outputs the following:

or
  digit 1
  id    foo

What can I do to make lakr recognize orfoo as an identifier (thus throwing a syntax error in this case)?

[erezsh]

Sorry, this one slipped through the cracks.

That answer may work for this simple grammar, but it will severely limit your grammar going forward, if you plan to add more complex rules.

Maybe that’s fine for your use-case. But just fyi, there is another solution, which is to use a regex lookahead and ensure there’s no character after or:

_OR: /or(?!\w)/

[thautwarm]

This is a severe problem.