Method find_dfa_forward

regex/src/exec.rs:686–716

reduces constant overhead

(
        &self,
        text: &[u8],
        start: usize,
    )

    /// matching engine should be used.
    #[inline(always)] // reduces constant overhead
    fn find_dfa_forward(
        &self,
        text: &[u8],
        start: usize,
    ) -> dfa::Result<(usize, usize)> {
        use dfa::Result::*;
        let end = match dfa::Fsm::forward(
            &self.ro.dfa,
            self.cache,
            false,
            text,
            start,
        ) {
            NoMatch(i) => return NoMatch(i),
            Quit => return Quit,
            Match(end) if start == end => return Match((start, start)),
            Match(end) => end,
        };
        // Now run the DFA in reverse to find the start of the match.
        match dfa::Fsm::reverse(
            &self.ro.dfa_reverse,
            self.cache,
            false,
            &text[start..],
            end - start,
        ) {
            Match(s) => Match((start + s, end)),
            NoMatch(i) => NoMatch(i),
            Quit => Quit,
        }
    }

    /// Finds the leftmost-first match (start and end) using only the DFA,
    /// but assumes the regex is anchored at the end and therefore starts at