Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/5798#discussion_r29586723
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/package.scala
---
@@ -77,4 +77,33 @@ package object expressions {
/** Uses the given row to store the output of the projection. */
def target(row: MutableRow): MutableProjection
}
+
+ /**
+ * A utility classes for check the expression equality in semantic, not
literally.
+ */
+ trait ExpressionEquals
+
+ private[this] class AttributeRefEquals(private val normalized:
Expression)
+ extends ExpressionEquals {
+ override def equals(other: Any): Boolean = other match {
+ case o: AttributeRefEquals => normalized == o.normalized
+ case _ => false
+ }
+
+ override def hashCode(): Int = normalized.hashCode()
+ }
+
+ object ExpressionEquals {
+ def apply(e: Expression): ExpressionEquals = new
AttributeRefEquals(normalize(e))
+
+ protected def normalize(expr: Expression): Expression =
expr.transformUp {
+ case n: AttributeReference =>
+ // We don't care about the name of AttributeReference in its
semantic equality check
+ new AttributeReference(null, n.dataType, n.nullable,
n.metadata)(n.exprId, n.qualifiers)
+ }
+
+ def semanticEquals(l: Expression, r: Expression): Boolean = {
--- End diff --
Seems it's never used?
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