beliefer commented on a change in pull request #29891:
URL: https://github.com/apache/spark/pull/29891#discussion_r506004054
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/regexpExpressions.scala
##########
@@ -318,16 +320,46 @@ case class StringSplit(str: Expression, regex:
Expression, limit: Expression)
*/
// scalastyle:off line.size.limit
@ExpressionDescription(
- usage = "_FUNC_(str, regexp, rep) - Replaces all substrings of `str` that
match `regexp` with `rep`.",
+ usage = "_FUNC_(str, regexp, rep[, position]) - Replaces all substrings of
`str` that match `regexp` with `rep`.",
+ arguments = """
+ Arguments:
+ * str - a string expression to search for a regular expression pattern
match.
+ * 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$".
+
+ There is a SQL config 'spark.sql.parser.escapedStringLiterals' that
can be used to
+ fallback to the Spark 1.6 behavior regarding string literal parsing.
For example,
+ if the config is enabled, the `regexp` that can match "\abc" is
"^\abc$".
+ * rep - a string expression to replace matched substrings.
+ * position - a positive integer expression that indicates the position
within `str` to begin searching.
+ The default is 1. If position is greater than the number of
characters in `str`, the result is `str`.
+ """,
examples = """
Examples:
> SELECT _FUNC_('100-200', '(\\d+)', 'num');
num-num
""",
since = "1.5.0")
// scalastyle:on line.size.limit
-case class RegExpReplace(subject: Expression, regexp: Expression, rep:
Expression)
- extends TernaryExpression with ImplicitCastInputTypes with NullIntolerant {
+case class RegExpReplace(subject: Expression, regexp: Expression, rep:
Expression, pos: Expression)
+ extends QuaternaryExpression with ImplicitCastInputTypes with NullIntolerant
{
+
+ override def checkInputDataTypes(): TypeCheckResult = {
+ if (!pos.foldable) {
+ return TypeCheckFailure(s"Position expression must be foldable, but got
$pos")
+ }
+
+ val i = pos.eval().asInstanceOf[Int]
Review comment:
```
WITH strings AS ( SELECT 'healthy, wealthy, and wise' s FROM dual ) SELECT
s "STRING",
regexp_replace( s, '\w', 'something', NULL ) "MODIFIED_STRING"
FROM
strings;
```
STRING | MODIFIED_STRING
-- | --
healthy, wealthy, and wise |
Vertica
```
dbadmin=> select regexp_replace('healthy, wealthy, and wise', '\\w',
'something', null);
regexp_replace
----------------
(1 row)
```
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