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https://issues.apache.org/jira/browse/FLINK-7147?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16099831#comment-16099831
]
ASF GitHub Bot commented on FLINK-7147:
---------------------------------------
Github user dawidwys commented on a diff in the pull request:
https://github.com/apache/flink/pull/4296#discussion_r129263762
--- Diff:
flink-libraries/flink-cep/src/test/java/org/apache/flink/cep/nfa/GreedyITCase.java
---
@@ -0,0 +1,290 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.cep.nfa;
+
+import org.apache.flink.cep.Event;
+import org.apache.flink.cep.nfa.compiler.NFACompiler;
+import org.apache.flink.cep.pattern.Pattern;
+import org.apache.flink.cep.pattern.conditions.SimpleCondition;
+import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
+import org.apache.flink.util.TestLogger;
+
+import com.google.common.collect.Lists;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.apache.flink.cep.nfa.NFATestUtilities.compareMaps;
+import static org.apache.flink.cep.nfa.NFATestUtilities.feedNFA;
+
+/**
+ * IT tests covering {@link Pattern#greedy()}.
+ */
+public class GreedyITCase extends TestLogger {
+
+ @Test
+ public void testGreedyFollowedBy() {
+ List<StreamRecord<Event>> inputEvents = new ArrayList<>();
+
+ Event c = new Event(40, "c", 1.0);
+ Event a1 = new Event(41, "a", 2.0);
+ Event a2 = new Event(42, "a", 2.0);
+ Event a3 = new Event(43, "a", 2.0);
+ Event d = new Event(44, "d", 3.0);
+
+ inputEvents.add(new StreamRecord<>(c, 1));
+ inputEvents.add(new StreamRecord<>(a1, 2));
+ inputEvents.add(new StreamRecord<>(a2, 3));
+ inputEvents.add(new StreamRecord<>(a3, 4));
+ inputEvents.add(new StreamRecord<>(d, 5));
+
+ // c a* d
+ Pattern<Event, ?> pattern =
Pattern.<Event>begin("start").where(new SimpleCondition<Event>() {
+ private static final long serialVersionUID =
5726188262756267490L;
+
+ @Override
+ public boolean filter(Event value) throws Exception {
+ return value.getName().equals("c");
+ }
+ }).followedBy("middle").where(new SimpleCondition<Event>() {
+ private static final long serialVersionUID =
5726188262756267490L;
+
+ @Override
+ public boolean filter(Event value) throws Exception {
+ return value.getName().equals("a");
+ }
+ }).oneOrMore().optional().greedy().followedBy("end").where(new
SimpleCondition<Event>() {
+ private static final long serialVersionUID =
5726188262756267490L;
+
+ @Override
+ public boolean filter(Event value) throws Exception {
+ return value.getName().equals("d");
+ }
+ });
+
+ NFA<Event> nfa = NFACompiler.compile(pattern,
Event.createTypeSerializer(), false);
+
+ final List<List<Event>> resultingPatterns =
feedNFA(inputEvents, nfa);
+
+ compareMaps(resultingPatterns, Lists.<List<Event>>newArrayList(
+ Lists.newArrayList(c, a1, a2, a3, d)
+ ));
+ }
+
+ @Test
+ public void testGreedyUtil() {
+ List<StreamRecord<Event>> inputEvents = new ArrayList<>();
+
+ Event c = new Event(40, "c", 1.0);
+ Event a1 = new Event(41, "a", 2.0);
+ Event a2 = new Event(42, "a", 3.0);
+ Event a3 = new Event(43, "a", 4.0);
+ Event d = new Event(44, "d", 3.0);
+
+ inputEvents.add(new StreamRecord<>(c, 1));
+ inputEvents.add(new StreamRecord<>(a1, 2));
+ inputEvents.add(new StreamRecord<>(a2, 3));
+ inputEvents.add(new StreamRecord<>(a3, 4));
+ inputEvents.add(new StreamRecord<>(d, 5));
+
+ // c a* d
+ Pattern<Event, ?> pattern =
Pattern.<Event>begin("start").where(new SimpleCondition<Event>() {
+ private static final long serialVersionUID =
5726188262756267490L;
+
+ @Override
+ public boolean filter(Event value) throws Exception {
+ return value.getName().equals("c");
+ }
+ }).followedBy("middle").where(new SimpleCondition<Event>() {
+ private static final long serialVersionUID =
5726188262756267490L;
+
+ @Override
+ public boolean filter(Event value) throws Exception {
+ return value.getName().equals("a");
+ }
+ }).oneOrMore().optional().greedy().until(new
SimpleCondition<Event>() {
+ private static final long serialVersionUID =
5726188262756267490L;
+
+ @Override
+ public boolean filter(Event value) throws Exception {
+ return value.getPrice() > 3.0;
+ }
+ }).followedBy("end").where(new SimpleCondition<Event>() {
+ private static final long serialVersionUID =
5726188262756267490L;
+
+ @Override
+ public boolean filter(Event value) throws Exception {
+ return value.getName().equals("d");
+ }
+ });
+
+ NFA<Event> nfa = NFACompiler.compile(pattern,
Event.createTypeSerializer(), false);
+
+ final List<List<Event>> resultingPatterns =
feedNFA(inputEvents, nfa);
+
+ compareMaps(resultingPatterns, Lists.<List<Event>>newArrayList(
+ Lists.newArrayList(c, a1, a2, d)
+ ));
+ }
+
+ @Test
+ public void testEndWithGreedy() {
+ List<StreamRecord<Event>> inputEvents = new ArrayList<>();
+
+ Event c = new Event(40, "c", 1.0);
+ Event a1 = new Event(41, "a", 2.0);
+ Event a2 = new Event(42, "a", 2.0);
+ Event a3 = new Event(43, "a", 2.0);
+ Event d = new Event(44, "d", 2.0);
+
+ inputEvents.add(new StreamRecord<>(c, 1));
+ inputEvents.add(new StreamRecord<>(a1, 2));
+ inputEvents.add(new StreamRecord<>(a2, 3));
+ inputEvents.add(new StreamRecord<>(a3, 4));
+ inputEvents.add(new StreamRecord<>(d, 5));
+
+ // c a*
+ Pattern<Event, ?> pattern =
Pattern.<Event>begin("start").where(new SimpleCondition<Event>() {
+ private static final long serialVersionUID =
5726188262756267490L;
+
+ @Override
+ public boolean filter(Event value) throws Exception {
+ return value.getName().equals("c");
+ }
+ }).followedBy("end").where(new SimpleCondition<Event>() {
+ private static final long serialVersionUID =
5726188262756267490L;
+
+ @Override
+ public boolean filter(Event value) throws Exception {
+ return value.getName().equals("a");
+ }
+ }).oneOrMore().optional().greedy();
+
+ NFA<Event> nfa = NFACompiler.compile(pattern,
Event.createTypeSerializer(), false);
+
+ final List<List<Event>> resultingPatterns =
feedNFA(inputEvents, nfa);
+
+ compareMaps(resultingPatterns, Lists.<List<Event>>newArrayList(
+ Lists.newArrayList(c, a1, a2, a3)
--- End diff --
I have some doubts about this result. I think in this case the result
should be:
`{c, a1, a2, a3}, {c, a1, a2}, {c, a1}, {c}`.
Otherwise we would not be able to emit results at all, as assuming the
stream is unbounded there still may occur some `a4`, doesn't it?
> Support greedy quantifier in CEP
> --------------------------------
>
> Key: FLINK-7147
> URL: https://issues.apache.org/jira/browse/FLINK-7147
> Project: Flink
> Issue Type: Sub-task
> Components: CEP, Table API & SQL
> Reporter: Dian Fu
> Assignee: Dian Fu
>
> Greedy quantifier will try to match the token as many times as possible. For
> example, for pattern {{a b* c}} (skip till next is used) and inputs {{a b1 b2
> c}}, if the quantifier for {{b}} is greedy, it will only output {{a b1 b2 c}}.
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