WIP

Author: concretevitamin

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

@@ -202,6 +202,8 @@ case class If(predicate: Expression, trueValue: Expression, falseValue: Expressi
   override def toString = s"if ($predicate) $trueValue else $falseValue"
 }
 
+// TODO: break this down into two cases to eliminate branching during eval().
+
 /**
  * Two types of Case statements: either "CASE WHEN a THEN b [WHEN c THEN d]* [ELSE e] END"
  * or "CASE a WHEN b THEN c [WHEN d THEN e]* [ELSE f] END", depending on whether `key` is defined.
@@ -212,7 +214,7 @@ case class If(predicate: Expression, trueValue: Expression, falseValue: Expressi
  * val for the default catch-all case (if provided). Hence, `branches` consist of at least two
  * elements, and can have an odd or even length.
  */
-case class Case(key: Option[Expression], branches: Seq[Expression]) extends Expression {
+case class CaseWhen(key: Option[Expression], branches: Seq[Expression]) extends Expression {
   def children = key.toSeq ++ branches
 
   override def nullable = branches
@@ -232,7 +234,7 @@ case class Case(key: Option[Expression], branches: Seq[Expression]) extends Expr
         case Seq(elseValue) => elseValue.dataType
       }.toSeq
     lazy val dataTypesEqual = dataTypes.drop(1).map(_ == dataTypes(0)).reduce(_ && _)
-    childrenResolved && dataTypesEqual
+    if (dataTypes.size == 1) true else childrenResolved && dataTypesEqual
   }
 
   def dataType = {
@@ -244,6 +246,8 @@ case class Case(key: Option[Expression], branches: Seq[Expression]) extends Expr
 
   type EvaluatedType = Any
 
+  // TODO: change eval() to use while, etc.
+
   override def eval(input: Row): Any = {
     def slidingCheck(expectedVal: Any): Any = {
       branches.sliding(2, 2).foldLeft(None.asInstanceOf[Option[Any]]) {

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/package.scala

@@ -115,7 +115,7 @@ package object util {
   }
 
   /* FIX ME
-  implicit class debugLogging(a: AnyRef) {
+  implicit class debugLogging(a: Any) {
     def debugLogging() {
       org.apache.log4j.Logger.getLogger(a.getClass.getName).setLevel(org.apache.log4j.Level.DEBUG)
     }

sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala

@@ -909,9 +909,9 @@ object HiveQl {
 
     /* Case statements */
     case Token("TOK_FUNCTION", Token(WHEN(), Nil) :: branches) =>
-      Case(None, branches.map(nodeToExpr))
+      CaseWhen(None, branches.map(nodeToExpr))
     case Token("TOK_FUNCTION", Token(CASE(), Nil) :: branches) =>
-      Case(Some(nodeToExpr(branches(0))), branches.drop(1).map(nodeToExpr))
+      CaseWhen(Some(nodeToExpr(branches(0))), branches.drop(1).map(nodeToExpr))
 
     /* Complex datatype manipulation */
     case Token("[", child :: ordinal :: Nil) =>