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Fix edge case where one side of regexp choice ends in duplicate string anchors #5664

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merged 2 commits into from
May 28, 2022
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Fix edge case where one side of regexp choice ends in duplicate string anchors #5664

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ff261bd
Handle case where regex choice ends with multiple anchors on one side
anthony-chang May 26, 2022
f158c16
Merge branch 'branch-22.06' of github.com:nvidia/spark-rapids into fi…
anthony-chang May 26, 2022
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9 changes: 7 additions & 2 deletions sql-plugin/src/main/scala/com/nvidia/spark/rapids/RegexParser.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -1169,13 +1169,18 @@ class CudfRegexTranspiler(mode: RegexMode) {
def endsWithLineAnchor(e: RegexAST): Boolean = {
e match {
case RegexSequence(parts) if parts.nonEmpty =>
endsWithLineAnchor(parts.last)
val j = parts.lastIndexWhere {
case RegexEmpty() => false
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This looks fine for this specific instance but do you think it is worth introducing a new step where we rewrite the AST tree and discard any RegexEmpty instances?

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Where would we have this step though? rewrite will be where all the RegexEmptys are introduced, and discarding them after rewrite won't be useful.

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I see. Ok, let's see if there are other cases that come up where we need to add explicit handling of RegexEmpty and if so then we may want to at least introduce some utility methods.

case _ => true
}
endsWithLineAnchor(parts(j))
case RegexEscaped('A') => true
case _ => isBeginOrEndLineAnchor(e)
}
}
if (endsWithLineAnchor(ll) || endsWithLineAnchor(rr)) {
throw new RegexUnsupportedException(nothingToRepeat)
throw new RegexUnsupportedException(
"cuDF does not support terms ending with line anchors on one side of a choice")
}

RegexChoice(ll, rr)
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8 changes: 8 additions & 0 deletions tests/src/test/scala/com/nvidia/spark/rapids/RegularExpressionTranspilerSuite.scala
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Expand Up @@ -81,6 +81,14 @@ class RegularExpressionTranspilerSuite extends FunSuite with Arm {
)
}

test("cuDF does not support terms ending with line anchors on one side of a choice") {
val patterns = Seq(",\u000b\u000b$$|,\u000bz\f", "1|2$$", "a$\\Z|b", "a|b^^")
patterns.foreach(pattern =>
assertUnsupported(pattern, RegexFindMode,
"cuDF does not support terms ending with line anchors on one side of a choice")
)
}

test("cuDF unsupported choice cases") {
val input = Seq("cat", "dog")
val patterns = Seq("c*|d*", "c*|dog", "[cat]{3}|dog")
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