update code as comments

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

@@ -304,7 +304,7 @@ case class StringLength(child: Expression) extends UnaryExpression with ExpectsI
  */
 case class Ascii(child: Expression) extends UnaryExpression with ExpectsInputTypes {
   override def dataType: DataType = IntegerType
-  override def expectedChildTypes: Seq[DataType] = Seq(StringType)
+  override def inputTypes: Seq[DataType] = Seq(StringType)
 
   override def eval(input: InternalRow): Any = {
     val string = child.eval(input)
@@ -320,15 +320,15 @@ case class Ascii(child: Expression) extends UnaryExpression with ExpectsInputTyp
     }
   }
 
-  override def toString: String = s"ascii($child)"
+  override def toString: String = s"ASCII($child)"
 }
 
 /**
  * Converts the argument from binary to a base 64 string.
  */
 case class Base64(child: Expression) extends UnaryExpression with ExpectsInputTypes {
   override def dataType: DataType = StringType
-  override def expectedChildTypes: Seq[DataType] = Seq(BinaryType)
+  override def inputTypes: Seq[DataType] = Seq(BinaryType)
 
   override def eval(input: InternalRow): Any = {
     val bytes = child.eval(input)
@@ -341,15 +341,15 @@ case class Base64(child: Expression) extends UnaryExpression with ExpectsInputTy
     }
   }
 
-  override def toString: String = s"base64($child)"
+  override def toString: String = s"BASE64($child)"
 }
 
 /**
  * Converts the argument from a base 64 string to BINARY.
  */
 case class UnBase64(child: Expression) extends UnaryExpression with ExpectsInputTypes {
   override def dataType: DataType = BinaryType
-  override def expectedChildTypes: Seq[DataType] = Seq(StringType)
+  override def inputTypes: Seq[DataType] = Seq(StringType)
 
   override def eval(input: InternalRow): Any = {
     val string = child.eval(input)
@@ -360,21 +360,20 @@ case class UnBase64(child: Expression) extends UnaryExpression with ExpectsInput
     }
   }
 
-  override def toString: String = s"unbase64($child)"
+  override def toString: String = s"UNBASE64($child)"
 }
 
 /**
  * Decodes the first argument into a String using the provided character set
  * (one of 'US-ASCII', 'ISO-8859-1', 'UTF-8', 'UTF-16BE', 'UTF-16LE', 'UTF-16').
  * If either argument is null, the result will also be null. (As of Hive 0.12.0.).
  */
-case class Decode(bin: Expression, charset: Expression)
-  extends Expression with ExpectsInputTypes {
+case class Decode(bin: Expression, charset: Expression) extends Expression with ExpectsInputTypes {
   override def children: Seq[Expression] = bin :: charset :: Nil
   override def foldable: Boolean = bin.foldable && charset.foldable
   override def nullable: Boolean = bin.nullable || charset.nullable
   override def dataType: DataType = StringType
-  override def expectedChildTypes: Seq[DataType] = Seq(BinaryType, StringType)
+  override def inputTypes: Seq[DataType] = Seq(BinaryType, StringType)
 
   override def eval(input: InternalRow): Any = {
     val l = bin.eval(input)
@@ -391,11 +390,11 @@ case class Decode(bin: Expression, charset: Expression)
     }
   }
 
-  override def toString: String = s"decode($bin, $charset)"
+  override def toString: String = s"DECODE($bin, $charset)"
 }
 
 /**
-* Encodes the first argument into a BINARY using the provided character set
+ * Encodes the first argument into a BINARY using the provided character set
  * (one of 'US-ASCII', 'ISO-8859-1', 'UTF-8', 'UTF-16BE', 'UTF-16LE', 'UTF-16').
  * If either argument is null, the result will also be null. (As of Hive 0.12.0.)
 */
@@ -405,7 +404,7 @@ case class Encode(value: Expression, charset: Expression)
   override def foldable: Boolean = value.foldable && charset.foldable
   override def nullable: Boolean = value.nullable || charset.nullable
   override def dataType: DataType = BinaryType
-  override def expectedChildTypes: Seq[DataType] = Seq(StringType, StringType)
+  override def inputTypes: Seq[DataType] = Seq(StringType, StringType)
 
   override def eval(input: InternalRow): Any = {
     val l = value.eval(input)
@@ -422,7 +421,7 @@ case class Encode(value: Expression, charset: Expression)
     }
   }
 
-  override def toString: String = s"encode($value, $charset)"
+  override def toString: String = s"ENCODE($value, $charset)"
 }