/** * Calculate the set of states that are accepting and have a true self loop. */ public void calculateAcceptingTrueLoops() { _accepting_true_loops = new BitSet(); //BitSet isAcceptingTrueLoop= *_accepting_true_loops; BitSet isAcceptingTrueLoop = _accepting_true_loops;////////changed SCCs sccs = getSCCs(); for (int scc = 0; scc < sccs.countSCCs(); ++scc) { if (sccs[scc].cardinality() == 1) { int state_id = sccs[scc].nextSetBit(0); NBA_State state = _nba[state_id]; if (!state.isFinal()) { // not final, consider next continue; } if (!sccs.successors(scc).isEmpty())//////////note here { // there are edges leaving this state, consider next continue; } bool no_empty_to = true; if (sccs.stateIsReachable(state_id, state_id)) { // state has at least one self-loop // we have to check that there is no edge with empty To //for (typename NBA_t::edge_iterator eit=state->edges_begin(); eit!=state->edges_end(); ++eit) //BitSet[] edges = state._edge_manager._container._storage; //foreach (BitSet eit in edges) for (KeyValuePair <APElement, BitSet> eit = state.edges_begin(); !state.edges_end(); eit = state.increment()) { BitSet edge = eit.Value; if (edge.isEmpty()) { // not all edges lead back to the state... no_empty_to = false; break; } } if (no_empty_to) { // When we are here the state is a final true loop isAcceptingTrueLoop.set(state_id); // std::cerr << "True Loop: " << state_id << std::endl; } } } } }
/** * Remove states from the set of accepting (final) states when this is redundant. * @param sccs the SCCs of the NBA */ public void removeRedundantFinalStates(SCCs sccs) { for (int scc = 0; scc < sccs.countSCCs(); ++scc) { if (sccs[scc].cardinality() == 1) { int state_id = sccs[scc].nextSetBit(0); NBA_State state = this[state_id]; if (state.isFinal()) { if (!sccs.stateIsReachable(state_id, state_id)) { // The state is final and has no self-loop // -> the final flag is redundant state.setFinal(false); // std::cerr << "Removing final flag for " << state_id << std::endl; } } } } }
/** * Calculates BitSet which specifies which states in the NBA * only have accepting successors. */ public void calculateStatesWithAllSuccAccepting() { _allSuccAccepting = new BitSet(); BitSet result = _allSuccAccepting; SCCs sccs = getSCCs(); List <bool> scc_all_final = new List <bool>(); Ultility.resize(scc_all_final, sccs.countSCCs()); for (int i = 0; i < scc_all_final.Count; i++) { scc_all_final[i] = false; } for (int i = sccs.countSCCs(); i > 0; --i) { // go backward in topological order... int scc = (sccs.topologicalOrder())[i - 1]; BitSet states_in_scc = sccs[scc]; // check to see if all states in this SCC are final scc_all_final[scc] = true; //for (BitSetIterator it=BitSetIterator(states_in_scc);it!=BitSetIterator::end(states_in_scc);++it) for (int it = BitSetIterator.start(states_in_scc); it != BitSetIterator.end(states_in_scc); it = BitSetIterator.increment(states_in_scc, it)) { if (!_nba[it].isFinal()) { scc_all_final[scc] = false; break; } } bool might_be_final = false; if (scc_all_final[scc] == false) { if (states_in_scc.length() == 1) { // there is only one state in this scc ... int state = states_in_scc.nextSetBit(0); if (sccs.stateIsReachable(state, state) == false) { // ... and it doesn't loop to itself might_be_final = true; } } } if (scc_all_final[scc] == true || might_be_final) { // Check to see if all successors are final... bool all_successors_are_final = true; BitSet scc_succ = sccs.successors(scc); //for (BitSetIterator it=BitSetIterator(scc_succ); it!=BitSetIterator::end(scc_succ); ++it) { for (int it = BitSetIterator.start(scc_succ); it != BitSetIterator.end(scc_succ); it = BitSetIterator.increment(scc_succ, it)) { if (!scc_all_final[it]) { all_successors_are_final = false; break; } } if (all_successors_are_final) { // Add all states in this SCC to the result-set result.Or(states_in_scc); if (might_be_final) { scc_all_final[scc] = true; } } } } }
/** Check if the NBA is empty. * @return true iff the NBA has no accepting run. */ public bool emptinessCheck() { SCCs sccs = getSCCs(); #if VERBOSE std::cerr << sccs << "\n"; std::cerr << " Reachability: " << std::endl; std::vector <BitSet> *reachable = sccs.getReachabilityForAllStates(); for (unsigned int t = 0; t < reachable->size(); t++) { std::cerr << t << " -> " << (*reachable)[t] << std::endl; } delete reachable; #endif for (int scc = 0; scc < sccs.countSCCs(); ++scc) { BitSet states_in_scc = sccs[scc]; // check to see if there is an accepting state in this SCC //for (BitSetIterator it=BitSetIterator(states_in_scc); it!=BitSetIterator::end(states_in_scc); ++it) for (int it = BitSetIterator.start(states_in_scc); it != BitSetIterator.end(states_in_scc); it = BitSetIterator.increment(states_in_scc, it)) { int state = it; #if VERBOSE std::cerr << "Considering state " << state << std::endl; #endif if (_nba[state].isFinal()) { // check to see if this SCC is a trivial SCC (can't reach itself) #if VERBOSE std::cerr << " +final"; std::cerr << " " << states_in_scc.cardinality(); #endif if (states_in_scc.cardinality() == 1) { // there is only one state in this scc ... #if VERBOSE std::cerr << " +single"; #endif if (sccs.stateIsReachable(state, state) == false) { // ... and it doesn't loop to itself // -> can not guarantee accepting run #if VERBOSE std::cerr << " -no_loop" << std::endl; #endif continue; } } // if we are here, the SCC has more than 1 state or // exactly one self-looping state // -> accepting run #if VERBOSE std::cerr << "+acc" << std::endl; #endif // check that SCC can be reached from initial state Debug.Assert(_nba.getStartState() != null); if (sccs.stateIsReachable(_nba.getStartState().getName(), state)) { #if VERBOSE std::cerr << "Found accepting state = " << state << std::endl; #endif return(false); } #if VERBOSE std::cerr << "Not reachable!" << std::endl; #endif continue; } } } return(true); }