Github user kiszk commented on a diff in the pull request:
https://github.com/apache/spark/pull/20938#discussion_r182534094
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/collectionOperations.scala
---
@@ -287,3 +289,160 @@ case class ArrayContains(left: Expression, right:
Expression)
override def prettyName: String = "array_contains"
}
+
+/**
+ * Transforms an array of arrays into a single array.
+ */
+@ExpressionDescription(
+ usage = "_FUNC_(arrayOfArrays) - Transforms an array of arrays into a
single array.",
+ examples = """
+ Examples:
+ > SELECT _FUNC_(array(array(1, 2), array(3, 4));
+ [1,2,3,4]
+ """,
+ since = "2.4.0")
+case class Flatten(child: Expression) extends UnaryExpression {
+
+ override def nullable: Boolean = child.nullable || dataType.containsNull
+
+ override def dataType: ArrayType = {
+ child
+ .dataType.asInstanceOf[ArrayType]
+ .elementType.asInstanceOf[ArrayType]
+ }
+
+ override def checkInputDataTypes(): TypeCheckResult = child.dataType
match {
+ case ArrayType(_: ArrayType, _) =>
+ TypeCheckResult.TypeCheckSuccess
+ case _ =>
+ TypeCheckResult.TypeCheckFailure(
+ s"The argument should be an array of arrays, " +
+ s"but '${child.sql}' is of ${child.dataType.simpleString} type."
+ )
+ }
+
+ override def nullSafeEval(array: Any): Any = {
+ val elements = array.asInstanceOf[ArrayData].toObjectArray(dataType)
+
+ if (elements.contains(null)) {
+ null
+ } else {
+ val flattened = elements.flatMap(
+ _.asInstanceOf[ArrayData].toObjectArray(dataType.elementType)
+ )
+ new GenericArrayData(flattened)
+ }
+ }
+
+ override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
+ nullSafeCodeGen(ctx, ev, c => {
+ val code = if (CodeGenerator.isPrimitiveType(dataType.elementType)) {
+ genCodeForConcatOfPrimitiveElements(ctx, c, ev.value)
+ } else {
+ genCodeForConcatOfComplexElements(ctx, c, ev.value)
+ }
+ nullElementsProtection(ev, c, code)
+ })
+ }
+
+ private def nullElementsProtection(
+ ev: ExprCode,
+ childVariableName: String,
+ coreLogic: String): String = {
+ s"""
+ |for(int z=0; z < $childVariableName.numElements(); z++) {
+ | ${ev.isNull} |= $childVariableName.isNullAt(z);
+ |}
+ |if(!${ev.isNull}) {
+ | $coreLogic
+ |}
+ """.stripMargin
+ }
+
+ private def genCodeForNumberOfElements(
+ ctx: CodegenContext,
+ childVariableName: String) : (String, String) = {
+ val variableName = ctx.freshName("numElements")
+ val code = s"""
+ |int $variableName = 0;
+ |for(int z=0; z < $childVariableName.numElements(); z++) {
+ | $variableName += $childVariableName.getArray(z).numElements();
+ |}
+ """.stripMargin
+ (code, variableName)
+ }
+
+ private def genCodeForConcatOfPrimitiveElements(
+ ctx: CodegenContext,
+ childVariableName: String,
+ arrayDataName: String): String = {
+ val arrayName = ctx.freshName("array")
+ val arraySizeName = ctx.freshName("size")
+ val counter = ctx.freshName("counter")
+ val tempArrayDataName = ctx.freshName("tempArrayData")
+
+ val elementType = dataType.elementType
+ val (numElemCode, numElemName) = genCodeForNumberOfElements(ctx,
childVariableName)
+
+ val unsafeArraySizeInBytes = s"""
+ |int $arraySizeName =
UnsafeArrayData.calculateHeaderPortionInBytes($numElemName) +
+
|${classOf[ByteArrayMethods].getName}.roundNumberOfBytesToNearestWord(
+ | ${elementType.defaultSize} * $numElemName
+ |);
+ """.stripMargin
+ val baseOffset = Platform.BYTE_ARRAY_OFFSET
+
+ val primitiveValueTypeName =
CodeGenerator.primitiveTypeName(elementType)
+
+ s"""
+ |$numElemCode
+ |$unsafeArraySizeInBytes
+ |byte[] $arrayName = new byte[$arraySizeName];
--- End diff --
Sorry for late comment. I think that it is fine to use `byte[]` for now.
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