Getting unintended panic

[Vaimer9]

I've found time to get working again and found myself stuck another problem. After changing the source code to work for multiple lines, I was getting an unintended panic:

for the following input:

fn firstfunction(a, b, c) {
    echo line_one
    echo line_two
}

fn secondfunction(b) {
    echo extras
}

I was wondering if you could let me know why this was happening

[zesterer]

This panic happens because the parser matched a repeating pattern without consuming any input. This is almost always a bug in the parser (and it's common enough that I chose to add a panic for it). For example:

let a_chain = just('a').repeated();

let a_chain_chain = a_chain.repeated();

This parser will loop infinitely on the input b because the first parser, a_chain, is permitted to consume none of the input, and a_chain_chain looks for that input many times, leading to an infinite loop.

In your parser, you have .or_not().repeated(). This is highly suspect: or_not is permitted to consume no inputs (as in the example I gave) and repeated will look for that pattern many times. I would suggest refactoring this.

[Vaimer9]

Makes sense! removing the .or_not() behind the repeated removes the panic, although the output I get is not expected:

Ok(
    Fn {
        name: "firstfunction",
        args: [
            "a",
            "b",
            "c",
        ],
        body: Some(
            [
                Command(
                    "echo line_one echo line_two",
                ),
            ],
        ),
        then: Some(
            Fn {
                name: "secondfunction",
                args: [
                    "b",
                ],
                body: Some(
                    [
                        Command(
                            "echo extras",
                        ),
                    ],
                ),
                then: None,
            },
        ),
    },
)

I needed there to be 2 Commands rather than a single Command comprising of two lines.
I thought take_until(just('\n') would be helpful but I can't do that as I need expr rather than just a string, my next move was trying out then_ignore(just('\n')) but that also raised unexpected behavior. What should I do?

[Vaimer9]

I wanted semicolons rather than tabs

[zesterer]

Just so you're aware, .padded_by(whitespace()) is the same thing as .padded(). The whitespace parser also recognises newlines.

[zesterer]

Additionally, padded_by recognises <padding><inner><padding>. You probably want .then_ignore(just(';')) to recognise a trailing semicolon.

[Vaimer9]

That does not seem to help either, although I get your point with adding the .then_ignore()

[Vaimer9]

nevermind it runs perfectly now, misplaced the delimited_by()