Github user marmbrus commented on a diff in the pull request:
https://github.com/apache/spark/pull/3433#discussion_r22011924
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringOperations.scala
---
@@ -272,3 +272,31 @@ case class Substring(str: Expression, pos: Expression,
len: Expression) extends
case _ => s"SUBSTR($str, $pos, $len)"
}
}
+
+/**
+ * A function that concatenates two strings.
+ */
+case class Concat(left: Expression, right: Expression) extends
BinaryExpression {
+
+ type EvaluatedType = Any
+
+ def nullable: Boolean = left.nullable || right.nullable
+ override def dataType: DataType = StringType
+
+ override def eval(input: Row): Any = {
+ val leftEvaled = left.eval(input)
+ val rightEvaled = right.eval(input)
+
+ if (leftEvaled == null || rightEvaled == null) {
+ null
+ } else {
+ val leftStr = leftEvaled.toString
+ val rightStr = rightEvaled.toString
+ leftStr + rightStr
+ }
+ }
+
+ def symbol: String = "||"
+
+ override def toString() = s"$left $nodeName $right"
--- End diff --
This is automatically defined by `BinaryExpression`.
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