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ASF GitHub Bot commented on FLINK-7169: --------------------------------------- Github user dawidwys commented on a diff in the pull request: https://github.com/apache/flink/pull/4331#discussion_r132384194 --- Diff: flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/compiler/NFACompiler.java --- @@ -150,6 +160,59 @@ long getWindowTime() { } /** + * Check pattern after match skip strategy. + */ + private void checkPatternSkipStrategy() { + AfterMatchSkipStrategy afterMatchSkipStrategy = currentPattern.getAfterMatchSkipStrategy(); + if (afterMatchSkipStrategy.getStrategy() == AfterMatchSkipStrategy.SkipStrategy.SKIP_TO_FIRST || + afterMatchSkipStrategy.getStrategy() == AfterMatchSkipStrategy.SkipStrategy.SKIP_TO_LAST) { + Pattern<T, ?> pattern = currentPattern; + while (!pattern.getName().equals(afterMatchSkipStrategy.getPatternName())) { + pattern = pattern.getPrevious(); + } + // pattern name match check. + if (pattern == null) { + throw new MalformedPatternException("the pattern name specified in AfterMatchSkipStrategy " + + "can not be found in the given Pattern"); + } else { + // can not be used with optional states. + if (pattern.getQuantifier().hasProperty(Quantifier.QuantifierProperty.OPTIONAL)) { + throw new MalformedPatternException("the AfterMatchSkipStrategy " + + afterMatchSkipStrategy.getStrategy() + " can not be used with optional pattern"); + } + } + + // start position check. + if (pattern.getPrevious() == null) { --- End diff -- I personally see no reason for a semantic with RuntimeException. I can't think of any use-case for it. Maybe let's finish this PR without the switch and exceptions and open a JIRA with the switch, ideally with some use-case's for that semantic, so we can further agree on that and see if anyone needs it. > Support AFTER MATCH SKIP function in CEP library API > ---------------------------------------------------- > > Key: FLINK-7169 > URL: https://issues.apache.org/jira/browse/FLINK-7169 > Project: Flink > Issue Type: Sub-task > Components: CEP > Reporter: Yueting Chen > Assignee: Yueting Chen > Fix For: 1.4.0 > > > In order to support Oracle's MATCH_RECOGNIZE on top of the CEP library, we > need to support AFTER MATCH SKIP function in CEP API. > There're four options in AFTER MATCH SKIP, listed as follows: > 1. AFTER MATCH SKIP TO NEXT ROW: resume pattern matching at the row after the > first row of the current match. > 2. AFTER MATCH SKIP PAST LAST ROW: resume pattern matching at the next row > after the last row of the current match. > 3. AFTER MATCH SKIP TO FIST *RPV*: resume pattern matching at the first row > that is mapped to the row pattern variable RPV. > 4. AFTER MATCH SKIP TO LAST *RPV*: resume pattern matching at the last row > that is mapped to the row pattern variable RPV. > I think we can introduce a new function to `CEP` class, which takes a new > parameter as AfterMatchSKipStrategy. > The new API may looks like this > {code} > public static <T> PatternStream<T> pattern(DataStream<T> input, Pattern<T, ?> > pattern, AfterMatchSkipStrategy afterMatchSkipStrategy) > {code} > We can also make `SKIP TO NEXT ROW` as the default option, because that's > what CEP library behaves currently. -- This message was sent by Atlassian JIRA (v6.4.14#64029)