Github user cloud-fan commented on a diff in the pull request: https://github.com/apache/spark/pull/18228#discussion_r126612867 --- Diff: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala --- @@ -1199,6 +1199,45 @@ case class Substring(str: Expression, pos: Expression, len: Expression) } /** + * Returns the rightmost n characters from the string. + */ +@ExpressionDescription( + usage = "_FUNC_(str, len) - Returns the rightmost `len` characters from the string `str`.", + extended = """ + Examples: + > SELECT _FUNC_('Spark SQL', 3); + SQL + """) +case class Right(str: Expression, len: Expression, child: Expression) extends RuntimeReplaceable { + def this(str: Expression, len: Expression) = { + this(str, len, If(LessThanOrEqual(len, Literal(0)), + Literal.create(UTF8String.EMPTY_UTF8, StringType), new Substring(str, UnaryMinus(len)))) + } + + override def flatArguments: Iterator[Any] = Iterator(str, len) + override def sql: String = s"$prettyName(${str.sql}, ${len.sql})" +} + +/** + * Returns the leftmost n characters from the string. + */ +@ExpressionDescription( + usage = "_FUNC_(str, len) - Returns the leftmost `len` characters from the string `str`.", --- End diff -- ditto
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