Github user ueshin commented on a diff in the pull request: https://github.com/apache/spark/pull/21045#discussion_r192849800 --- Diff: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/collectionOperations.scala --- @@ -128,6 +128,175 @@ case class MapKeys(child: Expression) override def prettyName: String = "map_keys" } +@ExpressionDescription( + usage = """_FUNC_(a1, a2, ...) - Returns a merged array containing in the N-th position the + N-th value of each array given.""", + examples = """ + Examples: + > SELECT _FUNC_(array(1, 2, 3), array(2, 3, 4)); + [[1, 2], [2, 3], [3, 4]] + > SELECT _FUNC_(array(1, 2), array(2, 3), array(3, 4)); + [[1, 2, 3], [2, 3, 4]] + """, + since = "2.4.0") +case class Zip(children: Seq[Expression]) extends Expression with ExpectsInputTypes { + + override def inputTypes: Seq[AbstractDataType] = Seq.fill(children.length)(ArrayType) + + override def dataType: DataType = ArrayType(mountSchema) + + override def nullable: Boolean = children.forall(_.nullable) + + private lazy val arrayTypes = children.map(_.dataType.asInstanceOf[ArrayType]) + + private lazy val arrayElementTypes = arrayTypes.map(_.elementType) + + def mountSchema: StructType = { + val fields = children.zip(arrayElementTypes).zipWithIndex.map { + case ((expr: NamedExpression, elementType), _) => + StructField(expr.name, elementType, nullable = true) + case ((_, elementType), idx) => + StructField(s"$idx", elementType, nullable = true) + } + StructType(fields) + } + + val numberOfArrays: Int = children.length + + def emptyInputGenCode(ev: ExprCode): ExprCode = { + val genericArrayData = classOf[GenericArrayData].getName + + ev.copy(code""" + |${CodeGenerator.javaType(dataType)} ${ev.value} = new $genericArrayData(new Object[0]); + |${ev.isNull} = true; + """.stripMargin) + } + + def nonEmptyInputGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = { + val genericArrayData = classOf[GenericArrayData].getName + val genericInternalRow = classOf[GenericInternalRow].getName + val arrVals = ctx.freshName("arrVals") + val arrCardinality = ctx.freshName("arrCardinality") + val biggestCardinality = ctx.freshName("biggestCardinality") + + val myobject = ctx.freshName("myobject") + val j = ctx.freshName("j") + val i = ctx.freshName("i") + val args = ctx.freshName("args") + + val evals = children.map(_.genCode(ctx)) + val inputs = evals.zipWithIndex.map { case (eval, index) => + s""" + |${eval.code} + |if (!${eval.isNull} && $biggestCardinality != -1) { --- End diff -- We should evaluate `$biggestCardinality != -1` before `${eval.code}`? We don't need to evaluate the rest of children if we find there is a null child.
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