Struct Try 

pub struct Try;

try to parse

• ParseErrorKind::Unmatch will be transformed into None,

• ParseErrorKind::Semantic will still be Err

• otherwith, Ok with Some in will be return

so that you can use ? as usual after using match / if let ~

Trait Implementations

impl<P> ParseMapper<P> for Try

type Result = Result<Option<P>, ParseError>

mapped result

fn map(self, result: Result<P, ParseError>) -> Result<Option<P>, ParseError>

map a Result<P, ParseError> to ParseMapper::Result