Method next_state

regex/src/dfa.rs:1368–1384

Returns the next state given the current state si and current byte b. {qcur,qnext} are used as scratch space for storing ordered NFA states. This tries to fetch the next state from the cache, but if that fails, it computes the next state, caches it and returns a pointer to it. The pointer can be to a real state, or it can be STATE_DEAD. STATE_UNKNOWN cannot be returned. None is returned if a ne

(
        &mut self,
        qcur: &mut SparseSet,
        qnext: &mut SparseSet,
        si: StatePtr,
        b: Byte,
    )

    /// None is returned if a new state could not be allocated (i.e., the DFA
    /// ran out of space and thinks it's running too slowly).
    fn next_state(
        &mut self,
        qcur: &mut SparseSet,
        qnext: &mut SparseSet,
        si: StatePtr,
        b: Byte,
    ) -> Option<StatePtr> {
        if si == STATE_DEAD {
            return Some(STATE_DEAD);
        }
        match self.cache.trans.next(si, self.byte_class(b)) {
            STATE_UNKNOWN => self.exec_byte(qcur, qnext, si, b),
            STATE_QUIT => None,
            STATE_DEAD => Some(STATE_DEAD),
            nsi => Some(nsi),
        }
    }

    /// Computes and returns the start state, where searching begins at
    /// position `at` in `text`. If the state has already been computed,