Github user mn-mikke commented on a diff in the pull request:
https://github.com/apache/spark/pull/21282#discussion_r192875181
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/collectionOperations.scala
---
@@ -308,6 +309,234 @@ case class MapEntries(child: Expression) extends
UnaryExpression with ExpectsInp
override def prettyName: String = "map_entries"
}
+/**
+ * Returns a map created from the given array of entries.
+ */
+@ExpressionDescription(
+ usage = "_FUNC_(arrayOfEntries) - Returns a map created from the given
array of entries.",
+ examples = """
+ Examples:
+ > SELECT _FUNC_(array(struct(1, 'a'), struct(2, 'b')));
+ {1:"a",2:"b"}
+ """,
+ since = "2.4.0")
+case class MapFromEntries(child: Expression) extends UnaryExpression {
+
+ @transient
+ private lazy val dataTypeDetails: Option[(MapType, Boolean, Boolean)] =
child.dataType match {
+ case ArrayType(
+ StructType(Array(
+ StructField(_, keyType, keyNullable, _),
+ StructField(_, valueType, valueNullable, _))),
+ containsNull) => Some((MapType(keyType, valueType, valueNullable),
keyNullable, containsNull))
+ case _ => None
+ }
+
+ private def nullEntries: Boolean = dataTypeDetails.get._3
+
+ override def dataType: MapType = dataTypeDetails.get._1
+
+ override def checkInputDataTypes(): TypeCheckResult = dataTypeDetails
match {
+ case Some(_) => TypeCheckResult.TypeCheckSuccess
+ case None => TypeCheckResult.TypeCheckFailure(s"'${child.sql}' is of "
+
+ s"${child.dataType.simpleString} type. $prettyName accepts only
arrays of pair structs.")
+ }
+
+ override protected def nullSafeEval(input: Any): Any = {
+ val arrayData = input.asInstanceOf[ArrayData]
+ val length = arrayData.numElements()
+ val numEntries = if (nullEntries) (0 until
length).count(!arrayData.isNullAt(_)) else length
+ val keyArray = new Array[AnyRef](numEntries)
+ val valueArray = new Array[AnyRef](numEntries)
+ var i = 0
+ var j = 0
+ while (i < length) {
+ if (!arrayData.isNullAt(i)) {
--- End diff --
Hi @ueshin,
wouldn't it be better return `null` in this case? And follow null handling
of other functions like `flatten`?
```
flatten(array(array(1,2), null, array(3,4))) => null
```
WDYT?
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