Simplify implementation of InSet.

Author: marmbrus

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

@@ -99,10 +99,10 @@ case class In(value: Expression, list: Seq[Expression]) extends Predicate {
  * Optimized version of In clause, when all filter values of In clause are
  * static.
  */
-case class InSet(value: Expression, hset: HashSet[Any], child: Seq[Expression]) 
+case class InSet(value: Expression, hset: Set[Any])
   extends Predicate {
 
-  def children = child
+  def children = value :: Nil
 
   def nullable = true // TODO: Figure out correct nullability semantics of IN.
   override def toString = s"$value INSET ${hset.mkString("(", ",", ")")}"

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala

@@ -289,7 +289,7 @@ object OptimizeIn extends Rule[LogicalPlan] {
     case q: LogicalPlan => q transformExpressionsDown {
       case In(v, list) if !list.exists(!_.isInstanceOf[Literal]) =>
           val hSet = list.map(e => e.eval(null))
-          InSet(v, HashSet() ++ hSet, v +: list)
+          InSet(v, HashSet() ++ hSet)
     }
   }
 }

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala

@@ -158,13 +158,13 @@ class ExpressionEvaluationSuite extends FunSuite {
     val nl = Literal(null)
     val s = Seq(one, two)
     val nullS = Seq(one, two, null)
-    checkEvaluation(InSet(one, hS, one +: s), true)
-    checkEvaluation(InSet(two, hS, two +: s), true)
-    checkEvaluation(InSet(two, nS, two +: nullS), true)
-    checkEvaluation(InSet(nl, nS, nl +: nullS), true)
-    checkEvaluation(InSet(three, hS, three +: s), false)
-    checkEvaluation(InSet(three, nS, three +: nullS), false)
-    checkEvaluation(InSet(one, hS, one +: s) && InSet(two, hS, two +: s), true)
+    checkEvaluation(InSet(one, hS), true)
+    checkEvaluation(InSet(two, hS), true)
+    checkEvaluation(InSet(two, nS), true)
+    checkEvaluation(InSet(nl, nS), true)
+    checkEvaluation(InSet(three, hS), false)
+    checkEvaluation(InSet(three, nS), false)
+    checkEvaluation(InSet(one, hS) && InSet(two, hS), true)
   }
 
   test("MaxOf") {

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/OptimizeInSuite.scala

@@ -52,8 +52,7 @@ class OptimizeInSuite extends PlanTest {
     val optimized = Optimize(originalQuery.analyze)
     val correctAnswer =
       testRelation
-        .where(InSet(UnresolvedAttribute("a"), HashSet[Any]()+1+2, 
-            UnresolvedAttribute("a") +: Seq(Literal(1),Literal(2))))
+        .where(InSet(UnresolvedAttribute("a"), HashSet[Any]()+1+2))
         .analyze
 
     comparePlans(optimized, correctAnswer)