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https://issues.apache.org/jira/browse/FLINK-9990?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16643258#comment-16643258
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ASF GitHub Bot commented on FLINK-9990:
---------------------------------------
xccui commented on a change in pull request #6448: [FLINK-9990] [table] Add
regexp_extract supported in TableAPI and SQL
URL: https://github.com/apache/flink/pull/6448#discussion_r223678697
##########
File path:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/runtime/functions/ScalarFunctions.scala
##########
@@ -219,6 +220,31 @@ object ScalarFunctions {
str.replaceAll(regex, Matcher.quoteReplacement(replacement))
}
+ /**
+ * Returns a string extracted with a specified regular expression and a
regex match group index.
+ */
+ def regexp_extract(str: String, regex: String, extractIndex: Integer):
String = {
+ if (str == null || regex == null) {
+ return null
+ }
+
+ val m = Pattern.compile(regex).matcher(str)
+ if (m.find) {
+ val mr = m.toMatchResult
+ return mr.group(extractIndex)
+ }
+
+ ""
Review comment:
I think when no matching found, the method should return null instead of an
empty string, right?
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> Add regexp_extract supported in TableAPI and SQL
> ------------------------------------------------
>
> Key: FLINK-9990
> URL: https://issues.apache.org/jira/browse/FLINK-9990
> Project: Flink
> Issue Type: Sub-task
> Components: Table API & SQL
> Reporter: vinoyang
> Assignee: vinoyang
> Priority: Minor
> Labels: pull-request-available
>
> regex_extract is a very useful function, it returns a string based on a regex
> pattern and a index.
> For example :
> {code:java}
> regexp_extract('foothebar', 'foo(.*?)(bar)', 2) // returns 'bar.'
> {code}
> It is provided as a UDF in Hive, more details please see[1].
> [1]: https://cwiki.apache.org/confluence/display/Hive/LanguageManual+UDF
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