Github user viirya commented on the issue:
https://github.com/apache/spark/pull/21405
@mgaido91 Yes, as @rednaxelafx said in previous RP, #19813 will be the
first use case. I'd like to use this API to transform statement-based
expressions in code blocks.
For example, `code` contains Java code of an expression. We find it is too
long and we need to split it out as function. Because statement-based
expressions can't be directly passed into. We need to transform them as
variables first. I think the usage would looks like:
```scala
val collectedStatements = HashMap[ExprValue, ExprValue]
val transformed = code.transformExprValues {
case s @ SimpleExprValue(_, javaType) =>
if (collectedStatements.contains(s)) {
collectedStatements(s)
} else {
val aliasedVariable = JavaCode.variable(ctx.freshName("var"),
javaType)
collectedStatements += s -> aliasedVariable
aliasedVariable
}
}
val createVariables = collectedStatements.foldLeft(EmptyBlock) { (block,
(statement, variable)) =>
block + code"${statement.javaType.getName} $variable = $statement;"
}
ev.copy(code = createVariables + transformed)
```
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