Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/6822#discussion_r33757090
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/math.scala
---
@@ -160,6 +162,82 @@ case class Expm1(child: Expression) extends
UnaryMathExpression(math.expm1, "EXP
case class Floor(child: Expression) extends
UnaryMathExpression(math.floor, "FLOOR")
+object Factorial {
+
+ def factorial(n: Int): Long = {
+ if (n < factorials.length) factorials(n) else Long.MaxValue
+ }
+
+ private val factorials: Array[Long] = Array[Long](
+ 1,
+ 1,
+ 2,
+ 6,
+ 24,
+ 120,
+ 720,
+ 5040,
+ 40320,
+ 362880,
+ 3628800,
+ 39916800,
+ 479001600,
+ 6227020800L,
+ 87178291200L,
+ 1307674368000L,
+ 20922789888000L,
+ 355687428096000L,
+ 6402373705728000L,
+ 121645100408832000L,
+ 2432902008176640000L
+ )
+}
+
+case class Factorial(child: Expression)
+ extends UnaryExpression with Serializable with ExpectsInputTypes {
+
+ override def inputTypes: Seq[Any] = Seq(IntegerType)
+
+ override def dataType: DataType = LongType
+
+ override def foldable: Boolean = child.foldable
+
+ // If the value not in the range of [0, 20], it still will be null, so
set it to be true here.
+ override def nullable: Boolean = true
+
+ override def toString: String = s"factorial($child)"
+
+ override def eval(input: InternalRow): Any = {
+ val evalE = child.eval(input)
+ if (evalE == null) {
+ null
+ } else {
+ val input = evalE.asInstanceOf[Integer]
+ if (input > 20 || input < 0) {
+ null
+ } else {
+ Factorial.factorial(input)
+ }
+ }
+ }
+
+ override def genCode(ctx: CodeGenContext, ev: GeneratedExpressionCode):
String = {
+ val eval = child.gen(ctx)
+ eval.code + s"""
+ boolean ${ev.isNull} = ${eval.isNull};
+ ${ctx.javaType(dataType)} ${ev.primitive} =
${ctx.defaultValue(dataType)};
+ if (!${ev.isNull}) {
+ if (${eval.primitive} > 20 || ${eval.primitive} < 0) {
+ ${ev.isNull} = true;
+ } else {
+ ${ev.primitive} =
+
org.apache.spark.sql.catalyst.expressions.Factorial.factorial(${eval.primitive});
--- End diff --
can you indent this by 2 space
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