Function selectors::parser::parse_selector

fn parse_selector<'i, 't, P, Impl>(
    parser: &P,
    input: &mut Parser<'i, 't>,
    state: SelectorParsingState,
    parse_relative: ParseRelative
) -> Result<Selector<Impl>, ParseError<'i, P::Error>>where
    P: Parser<'i, Impl = Impl>,
    Impl: SelectorImpl,

Build up a Selector. selector : simple_selector_sequence [ combinator simple_selector_sequence ]* ;

Err means invalid selector.