[SPARK-12568][SQL] Add BINARY to Encoders

Author: Michael Armbrust <michael@databricks.com>

Closes #10516 from marmbrus/datasetCleanup.

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

@@ -157,6 +157,12 @@ object Encoders {
     */
   def TIMESTAMP: Encoder[java.sql.Timestamp] = ExpressionEncoder()
 
+  /**
+    * An encoder for arrays of bytes.
+    * @since 1.6.1
+    */
+  def BINARY: Encoder[Array[Byte]] = ExpressionEncoder()
+
   /**
    * Creates an encoder for Java Bean of type T.
    *

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/encoders/ExpressionEncoder.scala

@@ -198,6 +198,15 @@ case class ExpressionEncoder[T](
   @transient
   private lazy val constructProjection = GenerateSafeProjection.generate(fromRowExpression :: Nil)
 
+  /**
+   * Returns this encoder where it has been bound to its own output (i.e. no remaping of columns
+   * is performed).
+   */
+  def defaultBinding: ExpressionEncoder[T] = {
+    val attrs = schema.toAttributes
+    resolve(attrs, OuterScopes.outerScopes).bind(attrs)
+  }
+
   /**
    * Returns an encoded version of `t` as a Spark SQL row.  Note that multiple calls to
    * toRow are allowed to return the same actual [[InternalRow]] object.  Thus, the caller should

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/encoders/ExpressionEncoderSuite.scala

@@ -77,6 +77,8 @@ class JavaSerializable(val value: Int) extends Serializable {
 }
 
 class ExpressionEncoderSuite extends SparkFunSuite {
+  OuterScopes.outerScopes.put(getClass.getName, this)
+
   implicit def encoder[T : TypeTag]: ExpressionEncoder[T] = ExpressionEncoder()
 
   // test flat encoders
@@ -278,8 +280,6 @@ class ExpressionEncoderSuite extends SparkFunSuite {
     }
   }
 
-  private val outers: ConcurrentMap[String, AnyRef] = new MapMaker().weakValues().makeMap()
-  outers.put(getClass.getName, this)
   private def encodeDecodeTest[T : ExpressionEncoder](
       input: T,
       testName: String): Unit = {
@@ -287,7 +287,7 @@ class ExpressionEncoderSuite extends SparkFunSuite {
       val encoder = implicitly[ExpressionEncoder[T]]
       val row = encoder.toRow(input)
       val schema = encoder.schema.toAttributes
-      val boundEncoder = encoder.resolve(schema, outers).bind(schema)
+      val boundEncoder = encoder.defaultBinding
       val convertedBack = try boundEncoder.fromRow(row) catch {
         case e: Exception =>
           fail(