/// \brief Adds a transition for a range of surrogate symbols for the specified state
static void add_surrogate_transition(const range<int>& surrogateRange, int currentState, int targetState, ndfa* nfa) {
// If the range is out of the range of valid surrogate characters then clip it
if (surrogateRange.lower() >= 0x110000) return;
if (surrogateRange.upper() > 0x110000) {
add_surrogate_transition(range<int>(surrogateRange.lower(), 0x110000), currentState, targetState, nfa);
return;
}
// Work out the range as surrogate pairs
pair<int, int> surrogateLower = surrogate_pair(surrogateRange.lower());
pair<int, int> surrogateHigher = surrogate_pair(surrogateRange.upper()-1);
// Action depends on whether or not there are 1, 2 or more 'upper' characters
if (surrogateLower.first == surrogateHigher.first) {
// Transit to a state if we match the 'upper' code point
int tmpState = nfa->add_state();
nfa->add_transition(currentState, range<int>(surrogateLower.first, surrogateLower.first+1), tmpState);
// Transit to the final state if we match any of the lower symbols
nfa->add_transition(tmpState, range<int>(surrogateLower.second, surrogateHigher.second+1), targetState);
} else {
// Transit to a new state for the lower set of symbols
int tmpState1 = nfa->add_state();
nfa->add_transition(currentState, range<int>(surrogateLower.first, surrogateLower.first+1), tmpState1);
// Transit to the final state for all the 'lower' symbols
nfa->add_transition(tmpState1, range<int>(surrogateLower.second, 0xdc00), targetState);
// ... do the same for the 'upper' set of symbols
int tmpState2 = nfa->add_state();
nfa->add_transition(currentState, range<int>(surrogateHigher.first, surrogateHigher.first+1), tmpState2);
// Transit to the final state for all the 'lower' symbols
nfa->add_transition(tmpState2, range<int>(0xd800, surrogateHigher.second+1), targetState);
// If there's a middle range, then add transitions for that as well
if (surrogateHigher.first-1 > surrogateLower.first) {
// Transit for all of the remaining 'higher' symbols
int tmpState3 = nfa->add_state();
nfa->add_transition(currentState, range<int>(surrogateLower.first+1, surrogateHigher.first), tmpState3);
// Accept for any 'lower' symbol
nfa->add_transition(tmpState3, range<int>(0xdc00, 0xe000), targetState);
}
}
}
