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https://issues.apache.org/jira/browse/FLINK-3318?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15839911#comment-15839911
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ASF GitHub Bot commented on FLINK-3318:
---------------------------------------
Github user mushketyk commented on the issue:
https://github.com/apache/flink/pull/2361
Let's see if I understand correctly the test case you are describing. Do
you mean that a pattern like:
```java
begin().oneOrMany().where("a")
.next().optional().where("b")
```
won't work using current `NFA`. But as a result of this change if we have a
sequence "aaab", the NFA should emit two matching patterns: "aaa" and "aaab"?
> Add support for quantifiers to CEP's pattern API
> ------------------------------------------------
>
> Key: FLINK-3318
> URL: https://issues.apache.org/jira/browse/FLINK-3318
> Project: Flink
> Issue Type: Improvement
> Components: CEP
> Affects Versions: 1.0.0
> Reporter: Till Rohrmann
> Assignee: Ivan Mushketyk
> Priority: Minor
>
> It would be a good addition to extend the pattern API to support quantifiers
> known from regular expressions (e.g. Kleene star, ?, +, or count bounds).
> This would considerably enrich the set of supported patterns.
> Implementing the count bounds could be done by unrolling the pattern state.
> In order to support the Kleene star operator, the {{NFACompiler}} has to be
> extended to insert epsilon-transition between a Kleene start state and the
> succeeding pattern state. In order to support {{?}}, one could insert two
> paths from the preceding state, one which accepts the event and another which
> directly goes into the next pattern state.
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