rowan_nom

Function opt

Source 
pub fn opt<'slice, 'src: 'slice, Lang: Language, E, IE>(
    parser: impl Parser<Input<'slice, 'src, Lang>, Children<Lang, E>, IE>,
) -> impl FnMut(Input<'slice, 'src, Lang>) -> IResult<'slice, 'src, Lang, E, IE>
where
    Lang::Kind: 'static,
Expand description

Optional parser, will return None on nom::Err::Error.

Similar to nom::combinator::opt.