Examples with FollowedByPattern org.apache.flink.cep.pattern.FollowedByPattern used on opensource projects

Example 1 with FollowedByPattern

use of org.apache.flink.cep.pattern.FollowedByPattern in project flink by apache.

the class NFACompiler method compileFactory.

/**
	 * Compiles the given pattern into a {@link NFAFactory}. The NFA factory can be used to create
	 * multiple NFAs.
	 *
	 * @param pattern Definition of sequence pattern
	 * @param inputTypeSerializer Serializer for the input type
	 * @param timeoutHandling True if the NFA shall return timed out event patterns
	 * @param <T> Type of the input events
	 * @return Factory for NFAs corresponding to the given pattern
	 */
@SuppressWarnings("unchecked")
public static <T> NFAFactory<T> compileFactory(Pattern<T, ?> pattern, TypeSerializer<T> inputTypeSerializer, boolean timeoutHandling) {
    if (pattern == null) {
        // return a factory for empty NFAs
        return new NFAFactoryImpl<T>(inputTypeSerializer, 0, Collections.<State<T>>emptyList(), timeoutHandling);
    } else {
        // set of all generated states
        Map<String, State<T>> states = new HashMap<>();
        long windowTime;
        // this is used to enforse pattern name uniqueness.
        Set<String> patternNames = new HashSet<>();
        Pattern<T, ?> succeedingPattern;
        State<T> succeedingState;
        Pattern<T, ?> currentPattern = pattern;
        // we're traversing the pattern from the end to the beginning --> the first state is the final state
        State<T> currentState = new State<>(currentPattern.getName(), State.StateType.Final);
        patternNames.add(currentPattern.getName());
        states.put(currentPattern.getName(), currentState);
        windowTime = currentPattern.getWindowTime() != null ? currentPattern.getWindowTime().toMilliseconds() : 0L;
        while (currentPattern.getPrevious() != null) {
            succeedingPattern = currentPattern;
            succeedingState = currentState;
            currentPattern = currentPattern.getPrevious();
            if (!patternNames.add(currentPattern.getName())) {
                throw new MalformedPatternException("Duplicate pattern name: " + currentPattern.getName() + ". " + "Pattern names must be unique.");
            }
            Time currentWindowTime = currentPattern.getWindowTime();
            if (currentWindowTime != null && currentWindowTime.toMilliseconds() < windowTime) {
                // the window time is the global minimum of all window times of each state
                windowTime = currentWindowTime.toMilliseconds();
            }
            if (states.containsKey(currentPattern.getName())) {
                currentState = states.get(currentPattern.getName());
            } else {
                currentState = new State<>(currentPattern.getName(), State.StateType.Normal);
                states.put(currentState.getName(), currentState);
            }
            currentState.addStateTransition(new StateTransition<T>(StateTransitionAction.TAKE, succeedingState, (FilterFunction<T>) succeedingPattern.getFilterFunction()));
            if (succeedingPattern instanceof FollowedByPattern) {
                // the followed by pattern entails a reflexive ignore transition
                currentState.addStateTransition(new StateTransition<T>(StateTransitionAction.IGNORE, currentState, null));
            }
        }
        // add the beginning state
        final State<T> beginningState;
        if (states.containsKey(BEGINNING_STATE_NAME)) {
            beginningState = states.get(BEGINNING_STATE_NAME);
        } else {
            beginningState = new State<>(BEGINNING_STATE_NAME, State.StateType.Start);
            states.put(BEGINNING_STATE_NAME, beginningState);
        }
        beginningState.addStateTransition(new StateTransition<T>(StateTransitionAction.TAKE, currentState, (FilterFunction<T>) currentPattern.getFilterFunction()));
        return new NFAFactoryImpl<T>(inputTypeSerializer, windowTime, new HashSet<>(states.values()), timeoutHandling);
    }
}