[SPARK-8970][SQL] remove unnecessary abstraction for ExtractValue

Author: Wenchen Fan <cloud0fan@outlook.com>

Closes #7339 from cloud-fan/minor and squashes the following commits:

84a2128 [Wenchen Fan] remove unapply
6a37c12 [Wenchen Fan] remove unnecessary abstraction for ExtractValue

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala

@@ -141,7 +141,8 @@ class Analyzer(
           child match {
             case _: UnresolvedAttribute => u
             case ne: NamedExpression => ne
-            case ev: ExtractValueWithStruct => Alias(ev, ev.field.name)()
+            case g: GetStructField => Alias(g, g.field.name)()
+            case g: GetArrayStructFields => Alias(g, g.field.name)()
             case g: Generator if g.resolved && g.elementTypes.size > 1 => MultiAlias(g, Nil)
             case e if !e.resolved => u
             case other => Alias(other, s"_c$i")()

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

@@ -78,12 +78,6 @@ object ExtractValue {
     }
   }
 
-  def unapply(g: ExtractValue): Option[(Expression, Expression)] = g match {
-    case o: GetArrayItem => Some((o.child, o.ordinal))
-    case o: GetMapValue => Some((o.child, o.key))
-    case s: ExtractValueWithStruct => Some((s.child, null))
-  }
-
   /**
    * Find the ordinal of StructField, report error if no desired field or over one
    * desired fields are found.
@@ -103,32 +97,17 @@ object ExtractValue {
   }
 }
 
-/**
- * A common interface of all kinds of extract value expressions.
- * Note: concrete extract value expressions are created only by `ExtractValue.apply`,
- * we don't need to do type check for them.
- */
-trait ExtractValue {
-  self: Expression =>
-}
-
-abstract class ExtractValueWithStruct extends UnaryExpression with ExtractValue {
-  self: Product =>
-
-  def field: StructField
-  override def toString: String = s"$child.${field.name}"
-}
-
 /**
  * Returns the value of fields in the Struct `child`.
  *
  * No need to do type checking since it is handled by [[ExtractValue]].
  */
 case class GetStructField(child: Expression, field: StructField, ordinal: Int)
-  extends ExtractValueWithStruct {
+  extends UnaryExpression {
 
   override def dataType: DataType = field.dataType
   override def nullable: Boolean = child.nullable || field.nullable
+  override def toString: String = s"$child.${field.name}"
 
   protected override def nullSafeEval(input: Any): Any =
     input.asInstanceOf[InternalRow](ordinal)
@@ -155,10 +134,11 @@ case class GetArrayStructFields(
     child: Expression,
     field: StructField,
     ordinal: Int,
-    containsNull: Boolean) extends ExtractValueWithStruct {
+    containsNull: Boolean) extends UnaryExpression {
 
   override def dataType: DataType = ArrayType(field.dataType, containsNull)
   override def nullable: Boolean = child.nullable || containsNull || field.nullable
+  override def toString: String = s"$child.${field.name}"
 
   protected override def nullSafeEval(input: Any): Any = {
     input.asInstanceOf[Seq[InternalRow]].map { row =>
@@ -191,8 +171,7 @@ case class GetArrayStructFields(
  *
  * No need to do type checking since it is handled by [[ExtractValue]].
  */
-case class GetArrayItem(child: Expression, ordinal: Expression)
-  extends BinaryExpression with ExtractValue {
+case class GetArrayItem(child: Expression, ordinal: Expression) extends BinaryExpression {
 
   override def toString: String = s"$child[$ordinal]"
 
@@ -231,12 +210,11 @@ case class GetArrayItem(child: Expression, ordinal: Expression)
 }
 
 /**
- * Returns the value of key `ordinal` in Map `child`.
+ * Returns the value of key `key` in Map `child`.
  *
  * No need to do type checking since it is handled by [[ExtractValue]].
  */
-case class GetMapValue(child: Expression, key: Expression)
-  extends BinaryExpression with ExtractValue {
+case class GetMapValue(child: Expression, key: Expression) extends BinaryExpression {
 
   override def toString: String = s"$child[$key]"
 

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

@@ -275,8 +275,12 @@ object NullPropagation extends Rule[LogicalPlan] {
       case e @ Count(Literal(null, _)) => Cast(Literal(0L), e.dataType)
       case e @ IsNull(c) if !c.nullable => Literal.create(false, BooleanType)
       case e @ IsNotNull(c) if !c.nullable => Literal.create(true, BooleanType)
-      case e @ ExtractValue(Literal(null, _), _) => Literal.create(null, e.dataType)
-      case e @ ExtractValue(_, Literal(null, _)) => Literal.create(null, e.dataType)
+      case e @ GetArrayItem(Literal(null, _), _) => Literal.create(null, e.dataType)
+      case e @ GetArrayItem(_, Literal(null, _)) => Literal.create(null, e.dataType)
+      case e @ GetMapValue(Literal(null, _), _) => Literal.create(null, e.dataType)
+      case e @ GetMapValue(_, Literal(null, _)) => Literal.create(null, e.dataType)
+      case e @ GetStructField(Literal(null, _), _, _) => Literal.create(null, e.dataType)
+      case e @ GetArrayStructFields(Literal(null, _), _, _, _) => Literal.create(null, e.dataType)
       case e @ EqualNullSafe(Literal(null, _), r) => IsNull(r)
       case e @ EqualNullSafe(l, Literal(null, _)) => IsNull(l)
       case e @ Count(expr) if !expr.nullable => Count(Literal(1))