[GitHub] [spark] cloud-fan commented on a change in pull request #35459: [SPARK-38159][SQL] Minor refactor of MetadataAttribute unapply method

[GitBox <gi...@apache.org>]

cloud-fan commented on a change in pull request #35459:
URL: https://github.com/apache/spark/pull/35459#discussion_r803292430



##########
File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/namedExpressions.scala
##########
@@ -451,3 +451,21 @@ object MetadataAttribute {
     } else None
   }
 }
+
+/**
+ * The internal representation of the FileSourceMetadataAttribute,
+ * it sets `__metadata_col` to `true` in AttributeReference metadata with the attr name `_metadata`
+ * - unapply() will check if an attribute reference is the file source metadata attribute reference
+ */
+object FileSourceMetadataAttribute {
+
+  val ATTRIBUTE_NAME = "_metadata"
+
+  def unapply(attr: AttributeReference): Option[AttributeReference] = {
+    if (attr.metadata.contains(METADATA_COL_ATTR_KEY)

Review comment:
       nit:
   ```
   attr match {
     case MetadataAttribute(a) if a.name.equalsIgnoreCase(ATTRIBUTE_NAME) => Some(attr)
     case _ => None
   }
   ```




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