Github user kl0u commented on a diff in the pull request:
https://github.com/apache/flink/pull/3477#discussion_r106108473
--- Diff:
flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/compiler/NFACompiler.java
---
@@ -74,88 +76,233 @@
*/
@SuppressWarnings("unchecked")
public static <T> NFAFactory<T> compileFactory(
- Pattern<T, ?> pattern,
- TypeSerializer<T> inputTypeSerializer,
+ final Pattern<T, ?> pattern,
+ final 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);
+ return new NFAFactoryImpl<>(inputTypeSerializer, 0,
Collections.<State<T>>emptyList(), timeoutHandling);
} else {
- // set of all generated states
- Map<String, State<T>> states = new HashMap<>();
- long windowTime;
+ final NFAFactoryCompiler<T> nfaFactoryCompiler = new
NFAFactoryCompiler<>(pattern);
+ nfaFactoryCompiler.compileFactory();
+ return new NFAFactoryImpl<>(inputTypeSerializer,
nfaFactoryCompiler.getWindowTime(), nfaFactoryCompiler.getStates(),
timeoutHandling);
+ }
+ }
- // this is used to enforse pattern name uniqueness.
- Set<String> patternNames = new HashSet<>();
+ private static class NFAFactoryCompiler<T> {
- Pattern<T, ?> succeedingPattern;
- State<T> succeedingState;
- Pattern<T, ?> currentPattern = pattern;
+ private final Set<String> usedNames = new HashSet<>();
+ private final List<State<T>> states = new ArrayList<>();
+ private long windowTime = 0;
+ private Pattern<T, ?> currentPattern;
+
+ NFAFactoryCompiler(final Pattern<T, ?> pattern) {
+ this.currentPattern = pattern;
+ }
+
+ /**
+ * Compiles the given pattern into a {@link NFAFactory}. The
NFA factory can be used to create
+ * multiple NFAs.
+ */
+ void compileFactory() {
// 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());
+ State<T> sinkState = createEndingState();
+ // add all the normal states
+ sinkState = createMiddleStates(sinkState);
+ // add the beginning state
+ createStartState(sinkState);
+ }
+
+ List<State<T>> getStates() {
+ return states;
+ }
- states.put(currentPattern.getName(), currentState);
+ long getWindowTime() {
+ return windowTime;
+ }
+
+ private State<T> createEndingState() {
+ State<T> sinkState = new State<>(ENDING_STATE_NAME,
State.StateType.Final);
+ states.add(sinkState);
+ usedNames.add(ENDING_STATE_NAME);
windowTime = currentPattern.getWindowTime() != null ?
currentPattern.getWindowTime().toMilliseconds() : 0L;
+ return sinkState;
+ }
- while (currentPattern.getPrevious() != null) {
- succeedingPattern = currentPattern;
- succeedingState = currentState;
- currentPattern = currentPattern.getPrevious();
+ private State<T> createMiddleStates(final State<T> sinkState) {
- if
(!patternNames.add(currentPattern.getName())) {
- throw new
MalformedPatternException("Duplicate pattern name: " + currentPattern.getName()
+ ". " +
- "Pattern names must be
unique.");
+ State<T> lastSink = sinkState;
+ while (currentPattern.getPrevious() != null) {
+ State<T> sourceState;
+
+ checkPatternNameUniqueness();
+
+ sourceState = new
State<>(currentPattern.getName(), State.StateType.Normal);
+ states.add(sourceState);
+ usedNames.add(sourceState.getName());
+
+ if (currentPattern.getQuantifier().isLooping())
{
+ convertToLooping(lastSink, sourceState);
+
+ if
(currentPattern.getQuantifier().isAtLeastOne()) {
+ sourceState =
createFirstMandatoryStateOfLoop(
+ sourceState,
+ State.StateType.Normal
+ );
+ states.add(sourceState);
+
usedNames.add(sourceState.getName());
+ }
+ } else if (currentPattern.getQuantifier() ==
Quantifier.TIMES) {
+ sourceState =
convertToTimesState(lastSink, sourceState, currentPattern.getTimes());
+ } else {
+ convertToSingletonState(
+ lastSink,
+ sourceState);
}
- Time currentWindowTime =
currentPattern.getWindowTime();
+ currentPattern = currentPattern.getPrevious();
+ lastSink = sourceState;
+ final 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();
}
+ }
+
+ return lastSink;
+ }
- if
(states.containsKey(currentPattern.getName())) {
- currentState =
states.get(currentPattern.getName());
+ private void checkPatternNameUniqueness() {
+ if (usedNames.contains(currentPattern.getName())) {
+ throw new MalformedPatternException(
+ "Duplicate pattern name: " +
currentPattern.getName() + ". " +
+ "Pattern names must be unique.");
+ }
+ }
+
+ @SuppressWarnings("unchecked")
+ private State<T> createStartState(State<T> sinkState) {
+ final State<T> beginningState;
+
+ checkPatternNameUniqueness();
+
+ if (currentPattern.getQuantifier().isLooping()) {
+ final State<T> loopingState;
+ if
(currentPattern.getQuantifier().isAtLeastOne()) {
+ loopingState = new
State<>(currentPattern.getName(), State.StateType.Normal);
+ beginningState =
createFirstMandatoryStateOfLoop(loopingState, State.StateType.Start);
+ states.add(loopingState);
} else {
- currentState = new
State<>(currentPattern.getName(), State.StateType.Normal);
- states.put(currentState.getName(),
currentState);
+ loopingState = new
State<>(currentPattern.getName(), State.StateType.Start);
+ beginningState = loopingState;
}
-
- 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
- ));
+ convertToLooping(sinkState, loopingState);
+ } else if (currentPattern.getQuantifier() ==
Quantifier.TIMES) {
+ if (currentPattern.getTimes() > 1) {
+ final State<T> timesState = new
State<>(currentPattern.getName(), State.StateType.Normal);
+ states.add(timesState);
+ sinkState =
convertToTimesState(sinkState, timesState, currentPattern.getTimes() - 1);
}
+ beginningState = new
State<>(currentPattern.getName(), State.StateType.Start);
+ beginningState.addTake(sinkState,
(FilterFunction<T>) currentPattern.getFilterFunction());
+ } else {
+ beginningState = new
State<>(currentPattern.getName(), State.StateType.Start);
+ beginningState.addTake(sinkState,
(FilterFunction<T>) currentPattern.getFilterFunction());
}
- // add the beginning state
- final State<T> beginningState;
+ states.add(beginningState);
+ usedNames.add(beginningState.getName());
+
+ return beginningState;
+ }
+
+ private State<T> convertToTimesState(State<T> sinkState,
State<T> sourceState, int times) {
+ convertToSingletonState(sinkState, sourceState);
+ for (int i = 0; i < times - 1; i++) {
+ sinkState = sourceState;
+ sourceState = new
State<>(currentPattern.getName(), State.StateType.Normal);
+ states.add(sourceState);
+ convertToSingletonState(sinkState, sourceState);
+ }
+ return sourceState;
+ }
+
+ @SuppressWarnings("unchecked")
+ private void convertToSingletonState(
+ final State<T> sinkState,
+ final State<T> sourceState) {
+
+ final FilterFunction<T> currentFilterFunction =
(FilterFunction<T>) currentPattern.getFilterFunction();
+ final FilterFunction<T> trueFunction =
FilterFunctions.trueFunction();
+ sourceState.addTake(sinkState, currentFilterFunction);
+
+ final State<T> ignoreState;
+ if (currentPattern.getQuantifier() ==
Quantifier.OPTIONAL) {
+ sourceState.addProceed(sinkState, trueFunction);
+ ignoreState = new
State<>(currentPattern.getName(), State.StateType.Normal);
- if (states.containsKey(BEGINNING_STATE_NAME)) {
- beginningState =
states.get(BEGINNING_STATE_NAME);
+ ignoreState.addTake(sinkState,
currentFilterFunction);
+ states.add(ignoreState);
} else {
- beginningState = new
State<>(BEGINNING_STATE_NAME, State.StateType.Start);
- states.put(BEGINNING_STATE_NAME,
beginningState);
+ ignoreState = sourceState;
+ }
+
+ if (currentPattern instanceof FollowedByPattern) {
+ sourceState.addIgnore(ignoreState,
trueFunction);
+ }
+ }
+
+ @SuppressWarnings("unchecked")
+ private State<T> createFirstMandatoryStateOfLoop(
+ final State<T> sinkState,
+ final State.StateType stateType) {
+
+ final FilterFunction<T> currentFilterFunction =
(FilterFunction<T>) currentPattern.getFilterFunction();
+ final State<T> firstState = new
State<>(currentPattern.getName(), stateType);
+
+ firstState.addTake(sinkState, currentFilterFunction);
+ if (currentPattern instanceof FollowedByPattern) {
+ if (currentPattern.getQuantifier() ==
Quantifier.ONE_OR_MORE_COMBINATIONS) {
--- End diff --
In the `Quantifier` you can add a flag like `isCombinations` for the
`ONE_OR_MORE_COMBINATIONS` and the `ZERO_OR_MORE_COMBINATIONS` and check it
here. Given that you already check for `atLeastOne` in the check I proposed
above, this will be sufficient.
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