line number on rule

What is your question?

I have a grammar like this one, for JSON:

    ?start: value

    ?value: object
            | array
            | string
            | SIGNED_NUMBER      -> number
            | "true"             -> true
            | "false"            -> false
            | "null"             -> null

    array  : "[" [value ("," value)*] "]"
    object : "{" [pair ("," pair)*] "}"
    pair   : string ":" value

    string : ESCAPED_STRING

    %import common.ESCAPED_STRING
    %import common.SIGNED_NUMBER
    %import common.WS

    %ignore WS

if I do this on a transformer:

    @staticmethod
    @lark.v_args(inline=True)
    def string(token: lark.Token) -> frozendict:
        return frozendict({
            'column': token.column,
            'item': ast.literal_eval(token),
            'line': token.line
        })

I can get line and column numbers

however, in array, or object rules the tree.meta.line (or tree.line) attributes are empty (and raise an error)

    @staticmethod
    @lark.v_args(tree=True)
    def array(tree: lark.Tree) -> frozendict:

I would like to be able to get the line number of such properties

Thanks in advance!

[MegaIng]

@erezsh Slight correction: Just having an meta attribute actually doesn’t work, it needs to be an instance of either Token or Tree. It might be worth considering to change this though to support custom AST generation with meta information.

Maybe also move everything in Token into a meta attribute.

[erezsh]

You’re right. It has to subclass one of them to work.