Group all operators used in Pratt parsing in error messages

[jimmycuadra]

I'm using the pratt module to handle binary and prefix operations and when there is an error parsing the input, each operator is listed separately in the message about what was expected next. For example:

found '{' expected '<', '.', '=', '&&', '||', '==', '!=', '<=', '>=', '>', '*', '/', '%', '+', '-', expression, or '}'

Is there a way to group these together in such a way that the error message in this case would show something like this instead?

found '{' expected '.', operator, expression, or '}'

The arguments passed to Parser::pratt look roughly like this:

infix(
    left(2),
    just(Token::And),
    |lhs: Spanned<Expr>, _, rhs, extra| {
        (
            Expr::Operation(Box::new(lhs), Operator::And, Box::new(rhs)),
            extra.span(),
        )
    },
),

I can provide more context from my code if needed.

[zesterer]

Yep! You can use .labelled(...) to replace the name of a parser pattern. For example, just(Token::And).labelled("operator") should do the job.

[jimmycuadra]

Awesome, thanks! I've been using labels on different expressions, but it didn't occur to me I could use the same label on different parsers and have them all combined in error messages!