ljleb
commented
5 years ago Okay, so I successfully reproduced on 2.1.7:
object App {
def main(args: Array[String]): Unit = {
println(new ABParser("ab").Main.run().get)
}
}
import org.parboiled2._
import shapeless._
trait A
trait B
case class B2A(b: B) extends A
case class A2B(a: A) extends B
class ABParser(override val input: ParserInput) extends Parser {
def Main: Rule1[A] = rule {
BRule ~ BReduction ~ B2ARule
}
def BRule: Rule1[B] = rule {
push(new B {})
}
def BReduction: Rule[B :: HNil, B :: HNil] = rule {
((B2ACapture | B2ARule) ~ A2BCapture).*
}
def B2ARule: Rule[B :: HNil, A :: HNil] = rule {
MATCH ~> B2A
}
def B2ACapture: Rule[B :: HNil, A :: HNil] = rule {
str("a") ~> B2A
}
def A2BCapture: Rule[A :: HNil, B :: HNil] = rule {
str("b") ~> A2B
}
}Executing the above app crashes (on parboiled2-2.1.7 with SBT):
Exception in thread "main" java.lang.ClassCastException: B2A cannot be cast to B
at ClassCastParser.B2ARule(ClassCastParser.scala:25)
at ClassCastParser.Main(ClassCastParser.scala:14)
at App$.$anonfun$main$1(App.scala:3)
at org.parboiled2.Parser.runRule$1(Parser.scala:143)
at org.parboiled2.Parser.phase0_initialRun$1(Parser.scala:151)
at org.parboiled2.Parser.__run(Parser.scala:209)
at App$.main(App.scala:3)
at App.main(App.scala)
Process finished with exit code 1
sirthias
I am trying to parse my own language with parboiled.
This line from a test for the parser implementation:
fails to be parsed because this rule always throws a
ClassCastException:when the parser successfully matches it.
Here is the log:
I will try to reproduce using a minimal code base soon: there is a lot of stuff in my project that is not required for the exception to show up. This might help for now.