/**
* Increments the byte buffer to the next String in binary order after s that will not put the
* machine into a reject state. If such a string does not exist, returns false.
*
* <p>The correctness of this method depends upon the automaton being deterministic, and having no
* transitions to dead states.
*
* @return true if more possible solutions exist for the DFA
*/
private boolean nextString() {
int state;
int pos = 0;
savedStates.grow(seekBytesRef.length + 1);
final int[] states = savedStates.ints;
states[0] = runAutomaton.getInitialState();
while (true) {
curGen++;
linear = false;
// walk the automaton until a character is rejected.
for (state = states[pos]; pos < seekBytesRef.length; pos++) {
visited[state] = curGen;
int nextState = runAutomaton.step(state, seekBytesRef.bytes[pos] & 0xff);
if (nextState == -1) break;
states[pos + 1] = nextState;
// we found a loop, record it for faster enumeration
if (!finite && !linear && visited[nextState] == curGen) {
setLinear(pos);
}
state = nextState;
}
// take the useful portion, and the last non-reject state, and attempt to
// append characters that will match.
if (nextString(state, pos)) {
return true;
} else {
/* no more solutions exist from this useful portion, backtrack */
if ((pos = backtrack(pos)) < 0) /* no more solutions at all */ return false;
final int newState = runAutomaton.step(states[pos], seekBytesRef.bytes[pos] & 0xff);
if (newState >= 0 && runAutomaton.isAccept(newState))
/* String is good to go as-is */
return true;
/* else advance further */
// TODO: paranoia? if we backtrack thru an infinite DFA, the loop detection is important!
// for now, restart from scratch for all infinite DFAs
if (!finite) pos = 0;
}
}
}
