Github user viirya commented on a diff in the pull request:
https://github.com/apache/spark/pull/19964#discussion_r156650539
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala
---
@@ -299,33 +299,35 @@ case class Elt(children: Seq[Expression])
"""
}
- val cases = ctx.buildCodeBlocks(assignStringValue)
- val codes = if (cases.length == 1) {
- s"""
- UTF8String $stringVal = null;
- switch ($indexVal) {
- ${cases.head}
- }
- """
- } else {
- var prevFunc = "null"
- for (c <- cases.reverse) {
- val funcName = ctx.freshName("eltFunc")
- val funcBody = s"""
- private UTF8String $funcName(InternalRow ${ctx.INPUT_ROW}, int
$indexVal) {
- UTF8String $stringVal = null;
- switch ($indexVal) {
- $c
- default:
- return $prevFunc;
- }
- return $stringVal;
- }
- """
- val fullFuncName = ctx.addNewFunction(funcName, funcBody)
- prevFunc = s"$fullFuncName(${ctx.INPUT_ROW}, $indexVal)"
- }
- s"UTF8String $stringVal = $prevFunc;"
+ var prevFunc = "null"
+ var codes = ctx.splitExpressionsWithCurrentInputs(
+ expressions = assignStringValue,
+ funcName = "eltFunc",
+ extraArguments = ("int", indexVal) :: Nil,
+ returnType = "UTF8String",
+ makeSplitFunction = body =>
+ s"""
+ |UTF8String $stringVal = null;
+ |switch ($indexVal) {
+ | $body
+ | default:
+ | return $prevFunc;
+ |}
+ |return $stringVal;
+ """.stripMargin,
+ foldFunctions = funcs => s"UTF8String $stringVal = ${funcs.last};",
+ makeFunctionCallback = f => prevFunc = s"$f(${ctx.INPUT_ROW},
$indexVal)",
+ mergeSplit = false)
--- End diff --
I have thought about it. Other implementation needs to introduce at least
one global variable such as case when case. If we can tolerate it, it is ok for
me. Let's see what other reviewers think about it.
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