Github user gatorsmile commented on a diff in the pull request:
https://github.com/apache/spark/pull/12646#discussion_r137082903
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala
---
@@ -503,69 +504,319 @@ case class FindInSet(left: Expression, right:
Expression) extends BinaryExpressi
override def prettyName: String = "find_in_set"
}
+trait String2TrimExpression extends Expression with ImplicitCastInputTypes
{
+
+ override def dataType: DataType = StringType
+ override def inputTypes: Seq[AbstractDataType] =
Seq.fill(children.size)(StringType)
+
+ override def nullable: Boolean = children.exists(_.nullable)
+ override def foldable: Boolean = children.forall(_.foldable)
+
+ override def sql: String = {
+ if (children.size == 1) {
+ val childrenSQL = children.map(_.sql).mkString(", ")
+ s"$prettyName($childrenSQL)"
+ } else {
+ val trimSQL = children(0).map(_.sql).mkString(", ")
+ val tarSQL = children(1).map(_.sql).mkString(", ")
+ s"$prettyName($trimSQL, $tarSQL)"
+ }
+ }
+}
+
+object StringTrim {
+ def apply(str: Expression, trimStr: Expression) : StringTrim =
StringTrim(str, Some(trimStr))
+ def apply(str: Expression) : StringTrim = StringTrim(str, None)
+}
+
/**
- * A function that trim the spaces from both ends for the specified string.
- */
+ * A function that takes a character string, removes the leading and
trailing characters matching with the characters
+ * in the trim string, returns the new string.
+ * If BOTH and trimStr keywords are not specified, it defaults to remove
space character from both ends. The trim
+ * function will have one argument, which contains the source string.
+ * If BOTH and trimStr keywords are specified, it trims the characters
from both ends, and the trim function will have
+ * two arguments, the first argument contains trimStr, the second argument
contains the source string.
+ * trimStr: A character string to be trimmed from the source string, if it
has multiple characters, the function
+ * searches for each character in the source string, removes the
characters from the source string until it
+ * encounters the first non-match character.
+ * BOTH: removes any characters from both ends of the source string that
matches characters in the trim string.
--- End diff --
Nit: `characters ` -> `character`
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