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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