Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/10734#discussion_r49556863
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/conditionalExpressions.scala
---
@@ -81,44 +81,39 @@ case class If(predicate: Expression, trueValue:
Expression, falseValue: Expressi
/**
* Case statements of the form "CASE WHEN a THEN b [WHEN c THEN d]* [ELSE
e] END".
* When a = true, returns b; when c = true, returns d; else returns e.
+ *
+ * @param branches seq of (branch condition, branch value)
+ * @param elseValue optional value for the else branch
*/
-case class CaseWhen(branches: Seq[Expression]) extends Expression {
-
- // Use private[this] Array to speed up evaluation.
- @transient private[this] lazy val branchesArr = branches.toArray
-
- override def children: Seq[Expression] = branches
-
- @transient lazy val whenList =
- branches.sliding(2, 2).collect { case Seq(whenExpr, _) => whenExpr
}.toSeq
-
- @transient lazy val thenList =
- branches.sliding(2, 2).collect { case Seq(_, thenExpr) => thenExpr
}.toSeq
+case class CaseWhen(branches: Seq[(Expression, Expression)], elseValue:
Option[Expression] = None)
--- End diff --
That was the original version - and I changed to this one after discussing
with @marmbrus because it is more explicit and the dimension of "whenList" and
"thenList" are guaranteed to be the same by the type signature.
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