Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/7181#discussion_r33752534
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/math.scala
---
@@ -303,6 +295,66 @@ case class Hex(child: Expression) extends
UnaryExpression with Serializable {
}
}
+/**
+ * Performs the inverse operation of HEX.
+ * Resulting characters are returned as a byte array.
+ */
+case class Unhex(child: Expression)
+ extends UnaryExpression with AutoCastInputTypes with Serializable {
+
+ override def nullable: Boolean = true
+ override def dataType: DataType = BinaryType
+ override def inputTypes: Seq[DataType] = Seq(BinaryType)
+
+ override def eval(input: InternalRow): Any = {
+ val num = child.eval(input)
+ if (num == null) {
+ null
+ } else {
+ unhex(num.asInstanceOf[UTF8String].getBytes)
+ }
+ }
+
+ // lookup table to translate '0' -> 0 ... 'F'/'f' -> 15
+ private[this] val unhexDigits = {
--- End diff --
why would it be more clear? are you thinking about the distance between its
definition and where it is used?
this is one case where java beats scala with static fields. Ideally all the
string functions should just be member functions in UTF8String.
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