Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/6405#discussion_r31108889
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
---
@@ -124,12 +124,45 @@ case class GroupExpression(children: Seq[Expression])
extends Expression {
override def dataType: DataType = throw new UnsupportedOperationException
}
+trait TypeConstraint {
+ self: Expression =>
+
+ def isTypeMatch: Boolean
+
+ def errorMessage: String
+
+ override lazy val resolved = childrenResolved && isTypeMatch
+}
+
/**
* Expressions that require a specific `DataType` as input should
implement this trait
* so that the proper type conversions can be performed in the analyzer.
*/
-trait ExpectsInputTypes {
+trait ExpectsInputTypes extends TypeConstraint {
+ self: Expression =>
def expectedChildTypes: Seq[DataType]
+ def isTypeMatch: Boolean = children.map(_.dataType) == expectedChildTypes
+
+ // This won't be called as we always do type cast for it in
`HiveTypeCoercion`.
+ def errorMessage: String = throw new UnsupportedOperationException
+}
+
+trait TypeEqualConstraint extends TypeConstraint {
--- End diff --
I'd remove this and just put it in the 3 places that use this right now. It
is not that big of deal to duplicate this tiny amount of code.
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