Github user davies commented on a diff in the pull request:
https://github.com/apache/spark/pull/10677#discussion_r51644299
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/bitwiseExpressions.scala
---
@@ -124,3 +124,47 @@ case class BitwiseNot(child: Expression) extends
UnaryExpression with ExpectsInp
protected override def nullSafeEval(input: Any): Any = not(input)
}
+
+/**
+ * A function that reverse the lowest N bits of a integer.
+ *
+ * Note: this is only used for grouping_id()
+ */
+case class BitwiseReverse(child: Expression, width: Int)
+ extends UnaryExpression with ExpectsInputTypes {
+
+ override def inputTypes: Seq[AbstractDataType] = Seq(IntegerType)
+
+ override def dataType: DataType = IntegerType
+
+ override def toString: String = s"^$child"
+
+ override def genCode(ctx: CodeGenContext, ev: GeneratedExpressionCode):
String = {
+ nullSafeCodeGen(ctx, ev, c => {
+ val v = ctx.freshName("v")
+ val i = ctx.freshName("i")
+ s"""
+ | int $v = $c;
+ | ${ev.value} = 0;
+ | for (int $i = 0; $i < $width; $i ++) {
+ | ${ev.value} <<= 1;
+ | ${ev.value} |= $v & 1;
+ | $v >>>= 1;
+ | }
+ """.stripMargin
+ })
+ }
+
+ protected override def nullSafeEval(input: Any): Any = {
+ var v = input.asInstanceOf[Int]
--- End diff --
Great, will do.
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