maropu commented on a change in pull request #28420:
URL: https://github.com/apache/spark/pull/28420#discussion_r418346518
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
##########
@@ -323,6 +323,20 @@ trait RuntimeReplaceable extends UnaryExpression with
Unevaluable {
// two `RuntimeReplaceable` are considered to be semantically equal if their
"child" expressions
// are semantically equal.
override lazy val canonicalized: Expression = child.canonicalized
+
+ override def innerChildren: Seq[Expression] = sys.error("RuntimeReplaceable
must implement" +
+ " innerChildren with the original parameters")
+
+ protected val sqlStrSeparator: String = ", "
Review comment:
We need this variable? It seems only `Extract` uses this.
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
##########
@@ -323,6 +323,20 @@ trait RuntimeReplaceable extends UnaryExpression with
Unevaluable {
// two `RuntimeReplaceable` are considered to be semantically equal if their
"child" expressions
// are semantically equal.
override lazy val canonicalized: Expression = child.canonicalized
+
+ override def innerChildren: Seq[Expression] = sys.error("RuntimeReplaceable
must implement" +
Review comment:
Since compilers cannot catch the case where one forget to override this,
how about it like this?
```
// RuntimeReplaceable
def exprsReplaced: Seq[Expression]
override def innerChildren: Seq[Expression] = exprsReplaced
// e.g., ParseToTimestamp
override def exprsReplaced: Seq[Expression] = Seq(Some(left),
format).flatten
```
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
##########
@@ -323,6 +323,20 @@ trait RuntimeReplaceable extends UnaryExpression with
Unevaluable {
// two `RuntimeReplaceable` are considered to be semantically equal if their
"child" expressions
// are semantically equal.
override lazy val canonicalized: Expression = child.canonicalized
+
+ override def innerChildren: Seq[Expression] = sys.error("RuntimeReplaceable
must implement" +
+ " innerChildren with the original parameters")
+
+ protected val sqlStrSeparator: String = ", "
+
+ override def sql: String = RuntimeReplaceable.this.prettyName +
+ prettyChildren.map(_.sql).mkString("(", sqlStrSeparator, ")")
+
+ protected var prettyChildren: Seq[Expression] = innerChildren
Review comment:
I think its better to user `var` where possible, so how about it like
this?
```
// RuntimeReplaceable
def newInstance(innerChildren: Seq[Expression]): RuntimeReplaceable
// e.g., ParseToTimestamp
override def newInstance(innerChildren: Seq[Expression]): ParseToTimestamp
= {
innerChildren match {
case Seq(left) => ParseToTimestamp(left, None, child)
case Seq(left, format) => ParseToTimestamp(left, Some(format), child)
}
}
```
Then, update the `toPrettySQL` in `utils.package`;
```
def toPrettySQL(e: Expression): String = e match {
case r: RuntimeReplaceable =>
r.newInstance(r.innerChildren.map(usePrettyExpression)).sql
case _ => usePrettyExpression(e).sql
}
```
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