Fix issues according to PR comments

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/SqlParser.scala

@@ -122,16 +122,6 @@ class SqlParser extends StandardTokenParsers {
   protected val RIGHT = Keyword("RIGHT")
   protected val SELECT = Keyword("SELECT")
   protected val STRING = Keyword("STRING")
-  protected val FLOAT = Keyword("FLOAT")
-  protected val SMALLINT = Keyword("SMALLINT")
-  protected val TINYINT = Keyword("TINYINT")
-  protected val INT = Keyword("INT")
-  protected val BIGINT = Keyword("BIGINT")
-  protected val DECIMAL = Keyword("DECIMAL")
-  protected val DOUBLE = Keyword("DOUBLE")
-  protected val BOOLEAN = Keyword("BOOLEAN")
-  protected val BINARY = Keyword("BINARY")
-  protected val TIMESTAMP = Keyword("TIMESTAMP")
   protected val SUM = Keyword("SUM")
   protected val TRUE = Keyword("TRUE")
   protected val UNION = Keyword("UNION")
@@ -348,15 +338,5 @@ class SqlParser extends StandardTokenParsers {
     literal
 
   protected lazy val dataType: Parser[DataType] =
-    STRING ^^^ StringType |
-    FLOAT ^^^ FloatType |
-    TINYINT ^^^ ByteType |
-    SMALLINT ^^^ ShortType |
-    INT ^^^ IntegerType |
-    BIGINT ^^^ LongType |
-    DECIMAL ^^^ DecimalType |
-    DOUBLE ^^^ DoubleType |
-    BOOLEAN ^^^ BooleanType |
-    BINARY ^^^ BinaryType |
-    TIMESTAMP ^^^ TimestampType
+    STRING ^^^ StringType
 }

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

@@ -113,37 +113,37 @@ package object dsl {
       def expr = attr
       def attr = analysis.UnresolvedAttribute(s)
 
-      /** Creates a new typed attributes of type boolean */
+      /** Creates a new AttributeReference of type boolean */
       def boolean = AttributeReference(s, BooleanType, nullable = false)()
 
-      /** Creates a new typed attributes of type byte */
+      /** Creates a new AttributeReference of type byte */
       def byte = AttributeReference(s, ByteType, nullable = false)()
 
-      /** Creates a new typed attributes of type short */
+      /** Creates a new AttributeReference of type short */
       def short = AttributeReference(s, ShortType, nullable = false)()
 
-      /** Creates a new typed attributes of type int */
+      /** Creates a new AttributeReference of type int */
       def int = AttributeReference(s, IntegerType, nullable = false)()
 
-      /** Creates a new typed attributes of type long */
+      /** Creates a new AttributeReference of type long */
       def long = AttributeReference(s, LongType, nullable = false)()
 
-      /** Creates a new typed attributes of type float */
+      /** Creates a new AttributeReference of type float */
       def float = AttributeReference(s, FloatType, nullable = false)()
 
-      /** Creates a new typed attributes of type double */
+      /** Creates a new AttributeReference of type double */
       def double = AttributeReference(s, DoubleType, nullable = false)()
 
-      /** Creates a new typed attributes of type string */
+      /** Creates a new AttributeReference of type string */
       def string = AttributeReference(s, StringType, nullable = false)()
 
-      /** Creates a new typed attributes of type decimal */
+      /** Creates a new AttributeReference of type decimal */
       def decimal = AttributeReference(s, DecimalType, nullable = false)()
 
-      /** Creates a new typed attributes of type timestamp */
+      /** Creates a new AttributeReference of type timestamp */
       def timestamp = AttributeReference(s, TimestampType, nullable = false)()
 
-      /** Creates a new typed attributes of type binary */
+      /** Creates a new AttributeReference of type binary */
       def binary = AttributeReference(s, BinaryType, nullable = false)()
     }
 

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

@@ -18,7 +18,6 @@
 package org.apache.spark.sql.catalyst.expressions
 
 import java.sql.Timestamp
-import java.lang.{NumberFormatException => NFE} 
 
 import org.apache.spark.sql.catalyst.types._
 
@@ -105,7 +104,7 @@ case class Cast(child: Expression, dataType: DataType) extends UnaryExpression {
 
   def castToLong: Any => Long = child.dataType match {
     case StringType => nullOrCast[String, Long](_, s => try s.toLong catch {
-      case _: NFE => null.asInstanceOf[Long]
+      case _: NumberFormatException => null.asInstanceOf[Long]
     })
     case BooleanType => nullOrCast[Boolean, Long](_, b => if(b) 1 else 0)
     case TimestampType => nullOrCast[Timestamp, Long](_, t => timestampToDouble(t).toLong)
@@ -115,7 +114,7 @@ case class Cast(child: Expression, dataType: DataType) extends UnaryExpression {
 
   def castToInt: Any => Int = child.dataType match {
     case StringType => nullOrCast[String, Int](_, s => try s.toInt catch {
-      case _: NFE => null.asInstanceOf[Int]
+      case _: NumberFormatException => null.asInstanceOf[Int]
     })
     case BooleanType => nullOrCast[Boolean, Int](_, b => if(b) 1 else 0)
     case TimestampType => nullOrCast[Timestamp, Int](_, t => timestampToDouble(t).toInt)
@@ -125,7 +124,7 @@ case class Cast(child: Expression, dataType: DataType) extends UnaryExpression {
 
   def castToShort: Any => Short = child.dataType match {
     case StringType => nullOrCast[String, Short](_, s => try s.toShort catch {
-      case _: NFE => null.asInstanceOf[Short]
+      case _: NumberFormatException => null.asInstanceOf[Short]
     })
     case BooleanType => nullOrCast[Boolean, Short](_, b => if(b) 1 else 0)
     case TimestampType => nullOrCast[Timestamp, Short](_, t => timestampToDouble(t).toShort)
@@ -135,7 +134,7 @@ case class Cast(child: Expression, dataType: DataType) extends UnaryExpression {
 
   def castToByte: Any => Byte = child.dataType match {
     case StringType => nullOrCast[String, Byte](_, s => try s.toByte catch {
-      case _: NFE => null.asInstanceOf[Byte]
+      case _: NumberFormatException => null.asInstanceOf[Byte]
     })
     case BooleanType => nullOrCast[Boolean, Byte](_, b => if(b) 1 else 0)
     case TimestampType => nullOrCast[Timestamp, Byte](_, t => timestampToDouble(t).toByte)
@@ -145,7 +144,7 @@ case class Cast(child: Expression, dataType: DataType) extends UnaryExpression {
 
   def castToDecimal: Any => BigDecimal = child.dataType match {
     case StringType => nullOrCast[String, BigDecimal](_, s => try s.toDouble catch {
-      case _: NFE => null.asInstanceOf[BigDecimal]
+      case _: NumberFormatException => null.asInstanceOf[BigDecimal]
     })
     case BooleanType => nullOrCast[Boolean, BigDecimal](_, b => if(b) 1 else 0)
     case TimestampType => nullOrCast[Timestamp, BigDecimal](_, t => timestampToDouble(t))
@@ -154,7 +153,7 @@ case class Cast(child: Expression, dataType: DataType) extends UnaryExpression {
 
   def castToDouble: Any => Double = child.dataType match {
     case StringType => nullOrCast[String, Double](_, s => try s.toDouble catch {
-      case _: NFE => null.asInstanceOf[Int]
+      case _: NumberFormatException => null.asInstanceOf[Int]
     })
     case BooleanType => nullOrCast[Boolean, Double](_, b => if(b) 1 else 0)
     case TimestampType => nullOrCast[Timestamp, Double](_, t => timestampToDouble(t))
@@ -164,7 +163,7 @@ case class Cast(child: Expression, dataType: DataType) extends UnaryExpression {
 
   def castToFloat: Any => Float = child.dataType match {
     case StringType => nullOrCast[String, Float](_, s => try s.toFloat catch {
-      case _: NFE => null.asInstanceOf[Int]
+      case _: NumberFormatException => null.asInstanceOf[Int]
     })
     case BooleanType => nullOrCast[Boolean, Float](_, b => if(b) 1 else 0)
     case TimestampType => nullOrCast[Timestamp, Float](_, t => timestampToDouble(t).toFloat)

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

@@ -86,6 +86,11 @@ abstract class Expression extends TreeNode[Expression] {
     }
   }
 
+  /**
+   * Evaluation helper function for 2 Numeric children expressions. Those expressions are supposed 
+   * to be in the same data type, and also the return type.
+   * Either one of the expressions result is null, the evaluation result should be null.
+   */
   @inline
   protected final def n2(
       i: Row,
@@ -115,6 +120,11 @@ abstract class Expression extends TreeNode[Expression] {
     }
   }
 
+  /**
+   * Evaluation helper function for 2 Fractional children expressions. Those expressions are  
+   * supposed to be in the same data type, and also the return type.
+   * Either one of the expressions result is null, the evaluation result should be null.
+   */
   @inline
   protected final def f2(
       i: Row,
@@ -143,6 +153,11 @@ abstract class Expression extends TreeNode[Expression] {
     }
   }
 
+  /**
+   * Evaluation helper function for 2 Integral children expressions. Those expressions are  
+   * supposed to be in the same data type, and also the return type.
+   * Either one of the expressions result is null, the evaluation result should be null.
+   */
   @inline
   protected final def i2(
       i: Row,
@@ -170,7 +185,16 @@ abstract class Expression extends TreeNode[Expression] {
       }
     }
   }
-
+
+  /**
+   * Evaluation helper function for 2 Comparable children expressions. Those expressions are  
+   * supposed to be in the same data type, and the return type should be Integer:
+   * Negative value: 1st argument less than 2nd argument
+   * Zero:  1st argument equals 2nd argument
+   * Positive value: 1st argument greater than 2nd argument
+   * 
+   * Either one of the expressions result is null, the evaluation result should be null.
+   */
   @inline
   protected final def c2(
       i: Row,