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https://issues.apache.org/jira/browse/FLINK-6927?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16069897#comment-16069897
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ASF GitHub Bot commented on FLINK-6927:
---------------------------------------
Github user dawidwys commented on a diff in the pull request:
https://github.com/apache/flink/pull/4153#discussion_r124999092
--- Diff:
flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/compiler/NFACompiler.java
---
@@ -455,6 +548,76 @@ private void addStopStateToLooping(final State<T>
loopingState) {
}
/**
+ * Create all the states for the group pattern.
+ *
+ * @param groupPattern the group pattern to create the states
for
+ * @param sinkState the state that the group pattern being
converted should point to
+ * @param proceedState the state that the group pattern being
converted should proceed to
+ * @param isOptional whether the group pattern being converted
is optional
+ * @return the first state of the states of the group pattern
+ */
+ private State<T> createGroupPatternState(
+ final GroupPattern<T, ?> groupPattern,
+ final State<T> sinkState,
+ final State<T> proceedState,
+ final boolean isOptional) {
+ final IterativeCondition<T> trueFunction =
BooleanConditions.trueFunction();
+
+ Pattern<T, ?> oldCurrentPattern = currentPattern;
+ Pattern<T, ?> oldFollowingPattern = followingPattern;
+ GroupPattern<T, ?> oldGroupPattern =
currentGroupPattern;
+ try {
--- End diff --
What is the point of this `try` block? Why not:
private State<T> createGroupPatternState(
final GroupPattern<T, ?> groupPattern,
final State<T> sinkState,
final State<T> proceedState,
final boolean isOptional) {
final IterativeCondition<T> trueFunction =
BooleanConditions.trueFunction();
Pattern<T, ?> oldCurrentPattern = currentPattern;
Pattern<T, ?> oldFollowingPattern = followingPattern;
GroupPattern<T, ?> oldGroupPattern = currentGroupPattern;
State<T> lastSink = sinkState;
currentGroupPattern = groupPattern;
currentPattern = groupPattern.getRawPattern();
lastSink = createMiddleStates(lastSink);
lastSink = convertPattern(lastSink);
if (isOptional) {
// for the first state of a group pattern, its PROCEED
edge should point to
// the following state of that group pattern
lastSink.addProceed(proceedState, trueFunction);
}
currentPattern = oldCurrentPattern;
followingPattern = oldFollowingPattern;
currentGroupPattern = oldGroupPattern;
return lastSink;
}
> Support pattern group in CEP
> ----------------------------
>
> Key: FLINK-6927
> URL: https://issues.apache.org/jira/browse/FLINK-6927
> Project: Flink
> Issue Type: Sub-task
> Components: CEP
> Reporter: Dian Fu
> Assignee: Dian Fu
>
> We should add support for pattern group. This would enrich the set of
> supported patterns. For example, users can write patterns like this with this
> feature available:
> {code}
> A --> (B --> C.times(3)).optional() --> D
> {code}
> or
> {code}
> A --> (B --> C).times(3) --> D
> {code}
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