Github user gatorsmile commented on a diff in the pull request:
https://github.com/apache/spark/pull/19752#discussion_r153079586
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/conditionalExpressions.scala
---
@@ -211,111 +231,62 @@ abstract class CaseWhenBase(
val elseCase = elseValue.map(" ELSE " + _.sql).getOrElse("")
"CASE" + cases + elseCase + " END"
}
-}
-
-
-/**
- * Case statements of the form "CASE WHEN a THEN b [WHEN c THEN d]* [ELSE
e] END".
- * When a = true, returns b; when c = true, returns d; else returns e.
- *
- * @param branches seq of (branch condition, branch value)
- * @param elseValue optional value for the else branch
- */
-// scalastyle:off line.size.limit
-@ExpressionDescription(
- usage = "CASE WHEN expr1 THEN expr2 [WHEN expr3 THEN expr4]* [ELSE
expr5] END - When `expr1` = true, returns `expr2`; else when `expr3` = true,
returns `expr4`; else returns `expr5`.",
- arguments = """
- Arguments:
- * expr1, expr3 - the branch condition expressions should all be
boolean type.
- * expr2, expr4, expr5 - the branch value expressions and else value
expression should all be
- same type or coercible to a common type.
- """,
- examples = """
- Examples:
- > SELECT CASE WHEN 1 > 0 THEN 1 WHEN 2 > 0 THEN 2.0 ELSE 1.2 END;
- 1
- > SELECT CASE WHEN 1 < 0 THEN 1 WHEN 2 > 0 THEN 2.0 ELSE 1.2 END;
- 2
- > SELECT CASE WHEN 1 < 0 THEN 1 WHEN 2 < 0 THEN 2.0 ELSE null END;
- NULL
- """)
-// scalastyle:on line.size.limit
-case class CaseWhen(
- val branches: Seq[(Expression, Expression)],
- val elseValue: Option[Expression] = None)
- extends CaseWhenBase(branches, elseValue) with CodegenFallback with
Serializable {
-
- override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
- super[CodegenFallback].doGenCode(ctx, ev)
- }
-
- def toCodegen(): CaseWhenCodegen = {
- CaseWhenCodegen(branches, elseValue)
- }
-}
-
-/**
- * CaseWhen expression used when code generation condition is satisfied.
- * OptimizeCodegen optimizer replaces CaseWhen into CaseWhenCodegen.
- *
- * @param branches seq of (branch condition, branch value)
- * @param elseValue optional value for the else branch
- */
-case class CaseWhenCodegen(
- val branches: Seq[(Expression, Expression)],
- val elseValue: Option[Expression] = None)
- extends CaseWhenBase(branches, elseValue) with Serializable {
override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
- // Generate code that looks like:
- //
- // condA = ...
- // if (condA) {
- // valueA
- // } else {
- // condB = ...
- // if (condB) {
- // valueB
- // } else {
- // condC = ...
- // if (condC) {
- // valueC
- // } else {
- // elseValue
- // }
- // }
- // }
+ val conditionMet = ctx.freshName("caseWhenConditionMet")
--- End diff --
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