Method exec_dfa_reverse_suffix

regex/src/exec.rs:779–815

reduces constant overhead

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

    /// matching engine should be used.
    #[inline(always)] // reduces constant overhead
    fn exec_dfa_reverse_suffix(
        &self,
        text: &[u8],
        original_start: usize,
    ) -> Option<dfa::Result<(usize, usize)>> {
        use dfa::Result::*;

        let lcs = self.ro.suffixes.lcs();
        debug_assert!(lcs.len() >= 1);
        let mut start = original_start;
        let mut end = start;
        let mut last_literal = start;
        while end <= text.len() {
            last_literal += match lcs.find(&text[last_literal..]) {
                None => return Some(NoMatch(text.len())),
                Some(i) => i,
            };
            end = last_literal + lcs.len();
            match dfa::Fsm::reverse(
                &self.ro.dfa_reverse,
                self.cache,
                false,
                &text[start..end],
                end - start,
            ) {
                Match(0) | NoMatch(0) => return None,
                Match(i) => return Some(Match((start + i, end))),
                NoMatch(i) => {
                    start += i;
                    last_literal += 1;
                    continue;
                }
                Quit => return Some(Quit),
            };
        }
        Some(NoMatch(text.len()))
    }

    /// Finds the leftmost-first match (start and end) using only the DFA
    /// by scanning for suffix literals.