How to use org.apache.flink.cep.nfa

@Override
public NFAState deserialize(DataInputView source) throws IOException {
  PriorityQueue<ComputationState> partialMatches = deserializeComputationStates(source);
  PriorityQueue<ComputationState> completedMatches = deserializeComputationStates(source);
  return new NFAState(partialMatches, completedMatches);
}

@Override
public void serialize(NFAState record, DataOutputView target) throws IOException {
  serializeComputationStates(record.getPartialMatches(), target);
  serializeComputationStates(record.getCompletedMatches(), target);
}

public static ComputationState createStartState(final String state) {
  return createStartState(state, new DeweyNumber(1));
}

  @Override
  public void process(Object key, ValueState<MigratedNFA<IN>> state) throws Exception {
    MigratedNFA<IN> oldState = state.value();
    computationStates.update(new NFAState(oldState.getComputationStates()));
    org.apache.flink.cep.nfa.SharedBuffer<IN> sharedBuffer = oldState.getSharedBuffer();
    partialMatches.init(sharedBuffer.getEventsBuffer(), sharedBuffer.getPages());
    state.clear();
  }
}

/**
 * Tear-down method for the NFA.
 */
public void close() throws Exception {
  for (State<T> state : getStates()) {
    for (StateTransition<T> transition : state.getStateTransitions()) {
      IterativeCondition condition = transition.getCondition();
      FunctionUtils.closeFunction(condition);
    }
  }
}

private boolean isStartState(ComputationState state) {
  State<T> stateObject = getState(state);
  if (stateObject == null) {
    throw new FlinkRuntimeException("State " + state.getCurrentStateName() + " does not exist in the NFA. NFA has states "
      + states.values());
  }
  return stateObject.isStart();
}

private boolean isFinalState(ComputationState state) {
  State<T> stateObject = getState(state);
  if (stateObject == null) {
    throw new FlinkRuntimeException("State " + state.getCurrentStateName() + " does not exist in the NFA. NFA has states "
      + states.values());
  }
  return stateObject.isFinal();
}

  private boolean isSelfIgnore(final StateTransition<T> edge) {
    return isEquivalentState(edge.getTargetState(), currentState) &&
      edge.getAction() == StateTransitionAction.IGNORE;
  }
}

void add(StateTransition<T> edge) {
  if (!isSelfIgnore(edge)) {
    if (edge.getAction() == StateTransitionAction.IGNORE) {
      totalIgnoreBranches++;
    } else if (edge.getAction() == StateTransitionAction.TAKE) {
      totalTakeBranches++;
    }
  }
  edges.add(edge);
}

private boolean isStateTimedOut(final ComputationState state, final long timestamp) {
  return !isStartState(state) && windowTime > 0L && timestamp - state.getStartTimestamp() >= windowTime;
}

  @Override
  public NFA<T> createNFA() {
    return new NFA<>(states, windowTime, timeoutHandling);
  }
}

public NFASerializer(TypeSerializer<T> typeSerializer) {
  this(typeSerializer,
    new org.apache.flink.cep.nfa.SharedBuffer.SharedBufferSerializer<>(
      StringSerializer.INSTANCE,
      typeSerializer));
}

  @Override
  protected NFAStateSerializer createOuterSerializerWithNestedSerializers(TypeSerializer<?>[] nestedSerializers) {

    @SuppressWarnings("unchecked")
    TypeSerializer<DeweyNumber> versionSerializer = (TypeSerializer<DeweyNumber>) nestedSerializers[0];

    @SuppressWarnings("unchecked")
    TypeSerializer<NodeId> nodeIdSerializer = (TypeSerializer<NodeId>) nestedSerializers[1];

    @SuppressWarnings("unchecked")
    TypeSerializer<EventId> eventIdSerializer = (TypeSerializer<EventId>) nestedSerializers[2];

    return new NFAStateSerializer(versionSerializer, nodeIdSerializer, eventIdSerializer);
  }
}

@Override
public MigratedNFA<T> deserialize(
    MigratedNFA<T> reuse,
    DataInputView source) throws IOException {
  return deserialize(source);
}

@Override
public TypeSerializerConfigSnapshot<SharedBuffer<V>> snapshotConfiguration() {
  return new SharedBufferSerializerConfigSnapshot<>(
    keySerializer,
    valueSerializer,
    versionSerializer);
}

  public static ComputationState createState(
      final String currentState,
      final NodeId previousEntry,
      final DeweyNumber version,
      final long startTimestamp,
      final EventId startEventID) {
    return new ComputationState(currentState, previousEntry, version, startEventID, startTimestamp);
  }
}

@Override
protected TypeSerializer<?>[] getNestedSerializers(NFAStateSerializer outerSerializer) {
  TypeSerializer<DeweyNumber> versionSerializer = outerSerializer.getVersionSerializer();
  TypeSerializer<NodeId> nodeIdSerializer = outerSerializer.getNodeIdSerializer();
  TypeSerializer<EventId> eventIdSerializer = outerSerializer.getEventIdSerializer();
  return new TypeSerializer[]{versionSerializer, nodeIdSerializer, eventIdSerializer};
}

public NFA(
    final Collection<State<T>> validStates,
    final long windowTime,
    final boolean handleTimeout) {
  this.windowTime = windowTime;
  this.handleTimeout = handleTimeout;
  this.states = loadStates(validStates);
}

@Override
public void copy(DataInputView source, DataOutputView target) throws IOException {
  copyStates(source, target); // copy partial matches
  copyStates(source, target); // copy completed matches
}

@Override
public NFAState copy(NFAState from, NFAState reuse) {
  return copy(from);
}