Unbounded mutual recursion in Parser impl

[tari]

Unbounded mutual recursion in Parser impl

[Marwes]

I'd generally avoid implementing Parser manually as the addition of partial parsing complicates manual implementations quite a bit. Instead use combine::parser(|i| ...) if you need a manual function implementation.

If you still need a manual implementation I would copy paste from an implementation in the combine repository as it seems that just implementing parse_stream does not work, but parse_lazy does work.

impl<Input, P> Parser<Input> for Satisfy<Input, P>
where
    Input: Stream,
    P: FnMut(Input::Token) -> bool,
{
    type Output = Input::Token;
    type PartialState = ();

    #[inline]
    fn parse_lazy(&mut self, input: &mut Input) -> ParseResult<Self::Output, Input::Error> {
        satisfy_impl(input, |c| {
            if (self.predicate)(c.clone()) {
                Some(c)
            } else {
                None
            }
        })
    }
}

[tari]

I can confirm that simply changing my impl to implement parse_lazy instead of parse_stream fixes the issue I was seeing.

That suggests to me that the Parser documentation should be changed to suggest that implementers implement parse_lazy only, rather than either of that or parse_stream. Would that be reasonable, or is there something else that means sometimes users could want to implement parse_stream?