minor code style fix

Author: JihongMA

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/functions.scala

@@ -302,14 +302,15 @@ abstract class StddevAgg(child: Expression) extends AlgebraicAggregate {
   private val currentAvg = AttributeReference("currentAvg", resultType)()
   private val currentMk = AttributeReference("currentMk", resultType)()
 
-  override val bufferAttributes = preCount :: currentCount :: preAvg :: currentAvg :: currentMk :: Nil
+  override val bufferAttributes = preCount :: currentCount :: preAvg ::
+                                  currentAvg :: currentMk :: Nil
 
   override val initialValues = Seq(
-    /* preCount = */ Cast(Literal(0), resultType), 
+    /* preCount = */ Cast(Literal(0), resultType),
     /* currentCount = */ Cast(Literal(0), resultType),
-    /* preAvg = */ Cast(Literal(0), resultType), 
-    /* currentAvg = */ Cast(Literal(0), resultType), 
-    /* currentMk = */ Cast(Literal(0), resultType) 
+    /* preAvg = */ Cast(Literal(0), resultType),
+    /* currentAvg = */ Cast(Literal(0), resultType),
+    /* currentMk = */ Cast(Literal(0), resultType)
   )
 
   override val updateExpressions = {
@@ -330,16 +331,17 @@ abstract class StddevAgg(child: Expression) extends AlgebraicAggregate {
 
     Seq(
       /* preCount = */ If(IsNull(child), preCount, currentCount),
-      /* currentCount = */ If(IsNull(child), currentCount, Add(currentCount, Cast(Literal(1), resultType))),
+      /* currentCount = */ If(IsNull(child), currentCount,
+                           Add(currentCount, Cast(Literal(1), resultType))),
       /* preAvg = */ If(IsNull(child), preAvg, currentAvg),
       /* currentAvg = */ If(IsNull(child), currentAvg, avgAdd),
       /* currentMk = */ If(IsNull(child), currentMk, mkAdd)
     )
   }
 
   override val mergeExpressions = {
-  
-    //count merge
+
+    // count merge
     def countMerge: Expression = {
       currentCount.left + currentCount.right
     }

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregates.scala

@@ -702,7 +702,7 @@ abstract class StddevAgg1(child: Expression) extends UnaryExpression with Partia
     case _ => DoubleType
   }
 
-  def isSample: Boolean 
+  def isSample: Boolean
 
   override def asPartial: SplitEvaluation = {
     val partialStd = Alias(ComputePartialStd(child), "PartialStddev")()
@@ -803,8 +803,11 @@ case class ComputePartialStdFunction (
   }
 }
 
-case class MergePartialStd(child: Expression, isSample: Boolean) extends UnaryExpression with AggregateExpression1 {
-  def this() = this(null, false) //required for serialization
+case class MergePartialStd(
+    child: Expression,
+    isSample: Boolean
+) extends UnaryExpression with AggregateExpression1 {
+  def this() = this(null, false) // required for serialization
 
   override def children: Seq[Expression] = child:: Nil
   override def nullable: Boolean = false
@@ -937,11 +940,11 @@ case class StddevFunction(
     if (curCount == 0) null
     else if (curCount < 2) zero.eval(null)
     else {
-      // when total count > 2, 
+      // when total count > 2,
       // stddev_samp = sqrt(curMk/(curCount - 1))
       // stddev_pop = sqrt(curMk/curCount)
       val varCol = {
-        if(isSample) {
+        if (isSample) {
           Divide(curMk, Cast(Literal(curCount - 1), computeType))
         }
         else {