[SPARK-9155][SQL] codegen StringSpace

Jira https://issues.apache.org/jira/browse/SPARK-9155

Author: Tarek Auel <tarek.auel@googlemail.com>

Closes #7531 from tarekauel/SPARK-9155 and squashes the following commits:

423c426 [Tarek Auel] [SPARK-9155] language typo fix
e34bd1b [Tarek Auel] [SPARK-9155] moved creation of blank string to UTF8String
4bc33e6 [Tarek Auel] [SPARK-9155] codegen StringSpace

1 files changed, 7 insertions, 5 deletions

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringOperations.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringOperations.scala
index 6608036f01..e42be85367 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringOperations.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringOperations.scala
@@ -593,17 +593,19 @@ case class StringReverse(child: Expression) extends UnaryExpression with String2
  * Returns a n spaces string.
  */
 case class StringSpace(child: Expression)
-  extends UnaryExpression with ImplicitCastInputTypes with CodegenFallback {
+  extends UnaryExpression with ImplicitCastInputTypes {
 
   override def dataType: DataType = StringType
   override def inputTypes: Seq[DataType] = Seq(IntegerType)
 
   override def nullSafeEval(s: Any): Any = {
-    val length = s.asInstanceOf[Integer]
+    val length = s.asInstanceOf[Int]
+    UTF8String.blankString(if (length < 0) 0 else length)
+  }
 
-    val spaces = new Array[Byte](if (length < 0) 0 else length)
-    java.util.Arrays.fill(spaces, ' '.asInstanceOf[Byte])
-    UTF8String.fromBytes(spaces)
+  override def genCode(ctx: CodeGenContext, ev: GeneratedExpressionCode): String = {
+    nullSafeCodeGen(ctx, ev, (length) =>
+      s"""${ev.primitive} = UTF8String.blankString(($length < 0) ? 0 : $length);""")
   }
 
   override def prettyName: String = "space"