LuciferYang commented on a change in pull request #35694:
URL: https://github.com/apache/spark/pull/35694#discussion_r822278258
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/trees/TreeNode.scala
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@@ -246,6 +246,16 @@ abstract class TreeNode[BaseType <: TreeNode[BaseType]]
extends Product with Tre
children.foldLeft(Option.empty[BaseType]) { (l, r) => l.orElse(r.find(f)) }
}
+ /**
+ * Test whether there is [[TreeNode]] satisfies the conditions specified in
`f`.
+ * The condition is recursively applied to this node and all of its children
(pre-order).
+ */
+ def exists(f: BaseType => Boolean): Boolean = if (f(this)) {
Review comment:
Like the following?
```scala
def exists(pf: PartialFunction[BaseType, Boolean]): Boolean = {
if (pf.applyOrElse(this, { _: Any => false})) {
true
} else {
children.exists(c => pf.applyOrElse(c, { _: Any => false}))
}
}
```
This implementation is more like `PartialFunction#cond` as follows:
```scala
/** Creates a Boolean test based on a value and a partial function.
* It behaves like a 'match' statement with an implied 'case _ => false'
* following the supplied cases.
*
* @param x the value to test
* @param pf the partial function
* @return true, iff `x` is in the domain of `pf` and `pf(x) == true`.
*/
def cond[T](x: T)(pf: PartialFunction[T, Boolean]): Boolean =
pf.applyOrElse(x, constFalse)
```
This requires the assumption that `case _ => false`
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