Github user davies commented on a diff in the pull request:
https://github.com/apache/spark/pull/7504#discussion_r34955580
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringOperations.scala
---
@@ -56,15 +51,76 @@ case class Concat(children: Seq[Expression]) extends
Expression with ImplicitCas
override protected def genCode(ctx: CodeGenContext, ev:
GeneratedExpressionCode): String = {
val evals = children.map(_.gen(ctx))
- val inputs = evals.map { eval => s"${eval.isNull} ? null :
${eval.primitive}" }.mkString(", ")
+ val inputs = evals.map { eval =>
+ s"${eval.isNull} ? (UTF8String)null : ${eval.primitive}"
+ }.mkString(", ")
evals.map(_.code).mkString("\n") + s"""
boolean ${ev.isNull} = false;
UTF8String ${ev.primitive} = UTF8String.concat($inputs);
+ if (${ev.primitive} == null) {
+ ${ev.isNull} = true;
+ }
"""
}
}
+/**
+ * An expression that concatenates multiple input strings or array of
strings into a single string,
+ * using a given separator (the first child).
+ *
+ * Returns null if the separator is null. Otherwise, concat_ws skips all
null values.
+ */
+case class ConcatWs(children: Seq[Expression])
+ extends Expression with ImplicitCastInputTypes with CodegenFallback {
+
+ require(children.nonEmpty, s"$prettyName requires at least one
argument.")
+
+ override def prettyName: String = "concat_ws"
+
+ /** The 1st child (separator) is str, and rest are either str or array
of str. */
+ override def inputTypes: Seq[AbstractDataType] = {
+ val arrayOrStr = TypeCollection(ArrayType(StringType), StringType)
+ StringType +: Seq.fill(children.size - 1)(arrayOrStr)
+ }
+
+ override def dataType: DataType = StringType
+
+ override def nullable: Boolean = children.head.nullable
+ override def foldable: Boolean = children.forall(_.foldable)
+
+ override def eval(input: InternalRow): Any = {
+ val flatInputs = children.flatMap { child =>
+ child.eval(input) match {
+ case s: UTF8String => Iterator(s)
+ case arr: Seq[_] => arr.asInstanceOf[Seq[UTF8String]]
+ case null => Iterator(null.asInstanceOf[UTF8String])
--- End diff --
minor: Can we just ignore the `null`?
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