Github user wzhfy commented on a diff in the pull request:
https://github.com/apache/spark/pull/12646#discussion_r116656846
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala
---
@@ -461,68 +462,249 @@ case class FindInSet(left: Expression, right:
Expression) extends BinaryExpressi
}
/**
- * A function that trim the spaces from both ends for the specified string.
+ * A function that trim the spaces or a trim string from both ends for the
specified string.
*/
@ExpressionDescription(
- usage = "_FUNC_(str) - Removes the leading and trailing space characters
from `str`.",
+ usage = """
+ _FUNC_(str) - Removes the leading and trailing space characters from
`str`.
+ _FUNC_(BOTH trimString FROM str) - Remove the leading and trailing
trimString from `str`
+ _FUNC_(LEADING trimChar FROM str) - Remove the leading trimString from
`str`
+ _FUNC_(TRAILING trimChar FROM str) - Remove the trailing trimString
from `str`
+ """,
extended = """
+ Arguments:
+ str - a string expression
+ trimString - the trim string
+ BOTH, FROM - these are keyword to specify for trim string from both
side of the string
+ LEADING, FROM - these are keyword to specify for trim string from
left side of the string
+ TRAILING, FROM - these are keyword to specify for trim string from
right side of the string
Examples:
> SELECT _FUNC_(' SparkSQL ');
SparkSQL
+ > SELECT _FUNC_(BOTH 'SL' FROM 'SSparkSQLS');
+ parkSQ
+ > SELECT _FUNC_(LEADING 'paS' FROM 'SSparkSQLS');
+ rkSQLS
+ > SELECT _FUNC_(TRAILING 'SLQ' FROM 'SSparkSQLS');
+ SSparkS
""")
-case class StringTrim(child: Expression)
- extends UnaryExpression with String2StringExpression {
+case class StringTrim(children: Seq[Expression])
--- End diff --
Can we use `case class StringTrim(child: Expression, trimString:
Expression)` instead of `case class StringTrim(children: Seq[Expression])`? I
think the former is easier to understand.
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