[SPARK-17263][SQL] Add hexadecimal literal parsing

## What changes were proposed in this pull request?
This PR adds the ability to parse SQL (hexadecimal) binary literals (AKA bit strings). It follows the following syntax `X'[Hexadecimal Characters]+'`, for example: `X'01AB'` would create a binary the following binary array `0x01AB`.

If an uneven number of hexadecimal characters is passed, then the upper 4 bits of the initial byte are kept empty, and the lower 4 bits are filled using the first character. For example `X'1C7'` would create the following binary array `0x01C7`.

Binary data (Array[Byte]) does not have a proper `hashCode` and `equals` functions. This meant that comparing `Literal`s containing binary data was a pain. I have updated Literal.hashCode and Literal.equals to deal properly with binary data.

## How was this patch tested?
Added tests to the `ExpressionParserSuite`, `SQLQueryTestSuite` and `ExpressionSQLBuilderSuite`.

Author: Herman van Hovell <hvanhovell@databricks.com>

Closes #14832 from hvanhovell/SPARK-17263.

2 files changed, 41 insertions, 14 deletions

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/literals.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/literals.scala
index 41e3952f0e..a597a17aad 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/literals.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/literals.scala
@@ -19,7 +19,9 @@ package org.apache.spark.sql.catalyst.expressions
 
 import java.nio.charset.StandardCharsets
 import java.sql.{Date, Timestamp}
+import java.util
 import java.util.Objects
+import javax.xml.bind.DatatypeConverter
 
 import org.json4s.JsonAST._
 
@@ -168,14 +170,29 @@ case class Literal (value: Any, dataType: DataType) extends LeafExpression with
   override def foldable: Boolean = true
   override def nullable: Boolean = value == null
 
-  override def toString: String = if (value != null) value.toString else "null"
+  override def toString: String = value match {
+    case null => "null"
+    case binary: Array[Byte] => s"0x" + DatatypeConverter.printHexBinary(binary)
+    case other => other.toString
+  }
 
-  override def hashCode(): Int = 31 * (31 * Objects.hashCode(dataType)) + Objects.hashCode(value)
+  override def hashCode(): Int = {
+    val valueHashCode = value match {
+      case null => 0
+      case binary: Array[Byte] => util.Arrays.hashCode(binary)
+      case other => other.hashCode()
+    }
+    31 * Objects.hashCode(dataType) + valueHashCode
+  }
 
   override def equals(other: Any): Boolean = other match {
+    case o: Literal if !dataType.equals(o.dataType) => false
     case o: Literal =>
-      dataType.equals(o.dataType) &&
-        (value == null && null == o.value || value != null && value.equals(o.value))
+      (value, o.value) match {
+        case (null, null) => true
+        case (a: Array[Byte], b: Array[Byte]) => util.Arrays.equals(a, b)
+        case (a, b) => a != null && a.equals(b)
+      }
     case _ => false
   }
 
@@ -269,6 +286,7 @@ case class Literal (value: Any, dataType: DataType) extends LeafExpression with
     case (v: Decimal, t: DecimalType) => v + "BD"
     case (v: Int, DateType) => s"DATE '${DateTimeUtils.toJavaDate(v)}'"
     case (v: Long, TimestampType) => s"TIMESTAMP('${DateTimeUtils.toJavaTimestamp(v)}')"
+    case (v: Array[Byte], BinaryType) => s"X'${DatatypeConverter.printHexBinary(v)}'"
     case _ => value.toString
   }
 }
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala
index 893db93368..42fbc16d03 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala
@@ -18,6 +18,7 @@
 package org.apache.spark.sql.catalyst.parser
 
 import java.sql.{Date, Timestamp}
+import javax.xml.bind.DatatypeConverter
 
 import scala.collection.JavaConverters._
 import scala.collection.mutable.ArrayBuffer
@@ -1215,19 +1216,27 @@ class AstBuilder extends SqlBaseBaseVisitor[AnyRef] with Logging {
    * {{{
    *   [TYPE] '[VALUE]'
    * }}}
-   * Currently Date and Timestamp typed literals are supported.
-   *
-   * TODO what the added value of this over casting?
+   * Currently Date, Timestamp and Binary typed literals are supported.
    */
   override def visitTypeConstructor(ctx: TypeConstructorContext): Literal = withOrigin(ctx) {
     val value = string(ctx.STRING)
-    ctx.identifier.getText.toUpperCase match {
-      case "DATE" =>
-        Literal(Date.valueOf(value))
-      case "TIMESTAMP" =>
-        Literal(Timestamp.valueOf(value))
-      case other =>
-        throw new ParseException(s"Literals of type '$other' are currently not supported.", ctx)
+    val valueType = ctx.identifier.getText.toUpperCase
+    try {
+      valueType match {
+        case "DATE" =>
+          Literal(Date.valueOf(value))
+        case "TIMESTAMP" =>
+          Literal(Timestamp.valueOf(value))
+        case "X" =>
+          val padding = if (value.length % 2 == 1) "0" else ""
+          Literal(DatatypeConverter.parseHexBinary(padding + value))
+        case other =>
+          throw new ParseException(s"Literals of type '$other' are currently not supported.", ctx)
+      }
+    } catch {
+      case e: IllegalArgumentException =>
+        val message = Option(e.getMessage).getOrElse(s"Exception parsing $valueType")
+        throw new ParseException(message, ctx)
     }
   }