beliefer commented on a change in pull request #27507:
URL: https://github.com/apache/spark/pull/27507#discussion_r463051470
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/regexpExpressions.scala
##########
@@ -421,20 +423,59 @@ object RegExpExtract {
}
}
+abstract class RegExpExtractBase
+ extends TernaryExpression with ImplicitCastInputTypes with NullIntolerant {
+ def subject: Expression
+ def regexp: Expression
+ def idx: Expression
+
+ // last regex in string, we will update the pattern iff regexp value changed.
+ @transient private var lastRegex: UTF8String = _
+ // last regex pattern, we cache it for performance concern
+ @transient private var pattern: Pattern = _
+
+ override def inputTypes: Seq[AbstractDataType] = Seq(StringType, StringType,
IntegerType)
+ override def children: Seq[Expression] = subject :: regexp :: idx :: Nil
+
+ protected def getLastMatcher(s: Any, p: Any): Matcher = {
+ if (!p.equals(lastRegex)) {
+ // regex value changed
+ lastRegex = p.asInstanceOf[UTF8String].clone()
+ pattern = Pattern.compile(lastRegex.toString)
+ }
+ pattern.matcher(s.toString)
+ }
+}
+
/**
* Extract a specific(idx) group identified by a Java regex.
*
* NOTE: this expression is not THREAD-SAFE, as it has some internal mutable
status.
*/
@ExpressionDescription(
- usage = "_FUNC_(str, regexp[, idx]) - Extracts a group that matches
`regexp`.",
+ usage = """
+ _FUNC_(str, regexp[, idx]) - Extract the first string in the `str` that
match the `regexp`
+ expression and corresponding to the regex group index.
+ """,
arguments = """
Arguments:
* str - a string expression.
- * regexp - a string representing a regular expression.
- The regex string should be a Java regular expression.
- * idx - an integer expression that representing the group index. The
group index should be
- non-negative. If `idx` is not specified, the default group index
value is 1.
+ * regexp - a string representing a regular expression. The regex string
should be a
+ Java regular expression.
+
+ Since Spark 2.0, string literals (including regex patterns) are
unescaped in our SQL
+ parser. For example, to match "\abc", a regular expression for
`regexp` can be
+ "^\\abc$".
+
+ There is a SQL config 'spark.sql.parser.escapedStringLiterals' that
can be used to
+ fallback to the Spark 1.6 behavior regarding string literal parsing.
For example,
+ if the config is enabled, the `regexp` that can match "\abc" is
"^\abc$".
+ * idx - an integer expression that representing the group index. The
regex maybe contains
+ multiple groups. `idx` indicates which regex group to extract. The
group index should
+ be non-negative. If `idx` is not specified, the default group index
value is 1. The
+ `idx` parameter is the Java regex Matcher group() method index. See
+ docs/api/java/util/regex/Matcher.html for more information on the
`idx` or Java regex
Review comment:
Because
https://github.com/apache/spark/blob/5250f988a32a8b5599f6038702da7e31dcbaccd8/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/regexpExpressions.scala#L488
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:
[email protected]
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
