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PackratParsers and RegexParsers / JavaTokenParsers don't work well in combination #318

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scabug opened this issue Dec 14, 2013 · 2 comments
Open

PackratParsers and RegexParsers / JavaTokenParsers don't work well in combination #318

scabug opened this issue Dec 14, 2013 · 2 comments

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@scabug
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scabug commented Dec 14, 2013

We have a parser that inherits from both JavaTokenParsers and PackratParsers; and it turns out that the .parse() method that the former provides (via RegexParsers) is incompatible with the latter. And, to make matters worse, that incompatibility only shows up very rarely; I'm filing this bug so that at least there will be some google hit out there if somebody else runs into this error.

Basically, the situation is this: I'm calling

parser.parse(parser.definitionOfSomeTerm, "input string")

And, depending on the details of what I'm trying to parse and what the input is, I'll occasionally get this:

scala.util.parsing.input.CharSequenceReader cannot be cast to scala.util.parsing.combinator.PackratParsers$PackratReader
java.lang.ClassCastException: scala.util.parsing.input.CharSequenceReader cannot be cast to scala.util.parsing.combinator.PackratParsers$PackratReader
	at scala.util.parsing.combinator.PackratParsers$$anon$2.apply(PackratParsers.scala:239)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$flatMap$1.apply(Parsers.scala:239)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$flatMap$1.apply(Parsers.scala:239)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$flatMap$1.apply(Parsers.scala:239)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$flatMap$1.apply(Parsers.scala:239)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$map$1.apply(Parsers.scala:242)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$map$1.apply(Parsers.scala:242)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$flatMap$1.apply(Parsers.scala:239)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$flatMap$1.apply(Parsers.scala:239)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$flatMap$1.apply(Parsers.scala:239)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$flatMap$1.apply(Parsers.scala:239)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$map$1.apply(Parsers.scala:242)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$map$1.apply(Parsers.scala:242)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$flatMap$1.apply(Parsers.scala:239)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$flatMap$1.apply(Parsers.scala:239)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$flatMap$1.apply(Parsers.scala:239)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$flatMap$1.apply(Parsers.scala:239)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$map$1.apply(Parsers.scala:242)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$map$1.apply(Parsers.scala:242)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$map$1.apply(Parsers.scala:242)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$map$1.apply(Parsers.scala:242)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Success.flatMapWithNext(Parsers.scala:142)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$flatMap$1.apply(Parsers.scala:239)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$flatMap$1.apply(Parsers.scala:239)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$map$1.apply(Parsers.scala:242)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$map$1.apply(Parsers.scala:242)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1$$anonfun$apply$2.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1$$anonfun$apply$2.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Failure.append(Parsers.scala:202)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$Parser$$anonfun$append$1.apply(Parsers.scala:254)
	at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
	at scala.util.parsing.combinator.RegexParsers$class.parse(RegexParsers.scala:148)
	at com.sumologic.stream_language.language.SearchQueryParserV2.parse(SearchQueryParserV2.scala:12)

The problem is that RegexParsersers.parse(Parser, CharSequence) constructs a CharSequenceReader, while PackratParsers assumes that it's passed a PackratReader. (But it doesn't actually use that assumption much of the time.)

It's easy to work around once you know the problem: wrap it like this:

  def parseSubstring[T](parser: Parser[T], input: String): ParseResult[T] = {
    parse(parser, new PackratReader(new CharSequenceReader(input)))
  }

And quite possibly it's the case that we shouldn't inherit from PackratParsers at all, I'm honestly not sure why we are. Still, it seems a little unfortunate that PackratParsers has a type restriction that is documented in the Scaladoc but not enforced in the underlying code.
@scabug
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scabug commented Dec 14, 2013

Imported From: https://issues.scala-lang.org/browse/SI-8080?orig=1
Reporter: David Carlton (davidcarltonsumo)
Affected Versions: 2.10.2

@scabug scabug closed this as completed Jul 17, 2015
@SethTisue SethTisue transferred this issue from scala/bug Nov 19, 2020
@scala scala deleted a comment from scabug Nov 19, 2020
@SethTisue SethTisue reopened this Nov 19, 2020
ilya-klyuchnikov added a commit to ilya-klyuchnikov/tapl-scala that referenced this issue Mar 9, 2021
@ilya-klyuchnikov
PackratParsers: workaround for scala/scala-parser-combinators#318
8045d83
@ilya-klyuchnikov ilya-klyuchnikov mentioned this issue Mar 9, 2021
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@ilya-klyuchnikov
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I started getting the similar error just after updating to Scala 3 and scala-parser-combinators 1.2.0-M2. - My (working for me) local fix is ilya-klyuchnikov/tapl-scala@8045d83

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@SethTisue @ilya-klyuchnikov @scabug