[sql] Rename Expression.apply to eval for better readability.

Also used this opportunity to add a bunch of override's and made some members private.

Author: Reynold Xin <[email protected]>

Closes apache#340 from rxin/eval and squashes the following commits:

a7c7ca7 [Reynold Xin] Fixed conflicts in merge.
9069de6 [Reynold Xin] Merge branch 'master' into eval
3ccc313 [Reynold Xin] Merge branch 'master' into eval
1a47e10 [Reynold Xin] Renamed apply to eval for generators and added a bunch of override's.
ea061de [Reynold Xin] Rename Expression.apply to eval for better readability.

Author: rxin

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

@@ -45,7 +45,7 @@ case class BoundReference(ordinal: Int, baseReference: Attribute)
 
   override def toString = s"$baseReference:$ordinal"
 
-  override def apply(input: Row): Any = input(ordinal)
+  override def eval(input: Row): Any = input(ordinal)
 }
 
 /**

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

@@ -185,8 +185,8 @@ case class Cast(child: Expression, dataType: DataType) extends UnaryExpression {
     case DoubleType => castToDouble
   }
 
-  override def apply(input: Row): Any = {
-    val evaluated = child.apply(input)
+  override def eval(input: Row): Any = {
+    val evaluated = child.eval(input)
     if (evaluated == null) {
       null
     } else {

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

@@ -17,8 +17,8 @@
 
 package org.apache.spark.sql.catalyst.expressions
 
-import org.apache.spark.sql.catalyst.trees
 import org.apache.spark.sql.catalyst.errors.TreeNodeException
+import org.apache.spark.sql.catalyst.trees
 import org.apache.spark.sql.catalyst.trees.TreeNode
 import org.apache.spark.sql.catalyst.types.{DataType, FractionalType, IntegralType, NumericType, NativeType}
 
@@ -50,7 +50,7 @@ abstract class Expression extends TreeNode[Expression] {
   def references: Set[Attribute]
 
   /** Returns the result of evaluating this expression on a given input Row */
-  def apply(input: Row = null): EvaluatedType =
+  def eval(input: Row = null): EvaluatedType =
     throw new TreeNodeException(this, s"No function to evaluate expression. type: ${this.nodeName}")
 
   /**
@@ -73,7 +73,7 @@ abstract class Expression extends TreeNode[Expression] {
    */
   @inline
   def n1(e: Expression, i: Row, f: ((Numeric[Any], Any) => Any)): Any  = {
-    val evalE = e.apply(i)
+    val evalE = e.eval(i)
     if (evalE == null) {
       null
     } else {
@@ -102,11 +102,11 @@ abstract class Expression extends TreeNode[Expression] {
       throw new TreeNodeException(this,  s"Types do not match ${e1.dataType} != ${e2.dataType}")
     }
 
-    val evalE1 = e1.apply(i)
+    val evalE1 = e1.eval(i)
     if(evalE1 == null) {
       null
     } else {
-      val evalE2 = e2.apply(i)
+      val evalE2 = e2.eval(i)
       if (evalE2 == null) {
         null
       } else {
@@ -135,11 +135,11 @@ abstract class Expression extends TreeNode[Expression] {
       throw new TreeNodeException(this,  s"Types do not match ${e1.dataType} != ${e2.dataType}")
     }
 
-    val evalE1 = e1.apply(i: Row)
+    val evalE1 = e1.eval(i: Row)
     if(evalE1 == null) {
       null
     } else {
-      val evalE2 = e2.apply(i: Row)
+      val evalE2 = e2.eval(i: Row)
       if (evalE2 == null) {
         null
       } else {
@@ -168,11 +168,11 @@ abstract class Expression extends TreeNode[Expression] {
       throw new TreeNodeException(this,  s"Types do not match ${e1.dataType} != ${e2.dataType}")
     }
 
-    val evalE1 = e1.apply(i)
+    val evalE1 = e1.eval(i)
     if(evalE1 == null) {
       null
     } else {
-      val evalE2 = e2.apply(i)
+      val evalE2 = e2.eval(i)
       if (evalE2 == null) {
         null
       } else {
@@ -205,11 +205,11 @@ abstract class Expression extends TreeNode[Expression] {
       throw new TreeNodeException(this,  s"Types do not match ${e1.dataType} != ${e2.dataType}")
     }
 
-    val evalE1 = e1.apply(i)
+    val evalE1 = e1.eval(i)
     if(evalE1 == null) {
       null
     } else {
-      val evalE2 = e2.apply(i)
+      val evalE2 = e2.eval(i)
       if (evalE2 == null) {
         null
       } else {
@@ -231,7 +231,7 @@ abstract class BinaryExpression extends Expression with trees.BinaryNode[Express
 
   override def foldable = left.foldable && right.foldable
 
-  def references = left.references ++ right.references
+  override def references = left.references ++ right.references
 
   override def toString = s"($left $symbol $right)"
 }
@@ -243,5 +243,5 @@ abstract class LeafExpression extends Expression with trees.LeafNode[Expression]
 abstract class UnaryExpression extends Expression with trees.UnaryNode[Expression] {
   self: Product =>
 
-  def references = child.references
+  override def references = child.references
 }

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

@@ -27,11 +27,12 @@ class Projection(expressions: Seq[Expression]) extends (Row => Row) {
     this(expressions.map(BindReferences.bindReference(_, inputSchema)))
 
   protected val exprArray = expressions.toArray
+
   def apply(input: Row): Row = {
     val outputArray = new Array[Any](exprArray.length)
     var i = 0
     while (i < exprArray.length) {
-      outputArray(i) = exprArray(i).apply(input)
+      outputArray(i) = exprArray(i).eval(input)
       i += 1
     }
     new GenericRow(outputArray)
@@ -58,7 +59,7 @@ case class MutableProjection(expressions: Seq[Expression]) extends (Row => Row)
   def apply(input: Row): Row = {
     var i = 0
     while (i < exprArray.length) {
-      mutableRow(i) = exprArray(i).apply(input)
+      mutableRow(i) = exprArray(i).eval(input)
       i += 1
     }
     mutableRow

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

@@ -212,8 +212,8 @@ class RowOrdering(ordering: Seq[SortOrder]) extends Ordering[Row] {
     var i = 0
     while (i < ordering.size) {
       val order = ordering(i)
-      val left = order.child.apply(a)
-      val right = order.child.apply(b)
+      val left = order.child.eval(a)
+      val right = order.child.eval(b)
 
       if (left == null && right == null) {
         // Both null, continue looking.

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

@@ -27,13 +27,13 @@ case class ScalaUdf(function: AnyRef, dataType: DataType, children: Seq[Expressi
   def references = children.flatMap(_.references).toSet
   def nullable = true
 
-  override def apply(input: Row): Any = {
+  override def eval(input: Row): Any = {
     children.size match {
-      case 1 => function.asInstanceOf[(Any) => Any](children(0).apply(input))
+      case 1 => function.asInstanceOf[(Any) => Any](children(0).eval(input))
       case 2 =>
         function.asInstanceOf[(Any, Any) => Any](
-          children(0).apply(input),
-          children(1).apply(input))
+          children(0).eval(input),
+          children(1).eval(input))
     }
   }
 }

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

@@ -30,7 +30,7 @@ case class WrapDynamic(children: Seq[Attribute]) extends Expression {
   def references = children.toSet
   def dataType = DynamicType
 
-  override def apply(input: Row): DynamicRow = input match {
+  override def eval(input: Row): DynamicRow = input match {
     // Avoid copy for generic rows.
     case g: GenericRow => new DynamicRow(children, g.values)
     case otherRowType => new DynamicRow(children, otherRowType.toArray)