Github user marmbrus commented on a diff in the pull request:
https://github.com/apache/spark/pull/11809#discussion_r56867675
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/planning/patterns.scala
---
@@ -202,3 +202,25 @@ object Unions {
}
}
}
+
+/**
+ * A pattern that finds the original expression from a sequence of casts.
+ */
+object Casts {
+ def unapply(expr: Expression): Option[Attribute] = expr match {
+ case c: Cast => collectCasts(expr)
+ case _ => None
+ }
+
+ private def collectCasts(e: Expression): Option[Attribute] = {
+ if (e.isInstanceOf[Cast]) {
+ collectCasts(e.children(0))
+ } else {
+ if (e.isInstanceOf[Attribute]) {
+ Some(e.asInstanceOf[Attribute])
--- End diff --
Any time you see `isInstanceOf` / `asInstanceOf` you might want to be using
matching instead...
```scala
e match {
case a: Attribute => Some(a)
case Cast(e, _) => Some(collectCasts(e))
case _ => None
}
```
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