This code will never end

parboiled-bug.scala

import org.parboiled.scala._
import org.parboiled.support._
import org.parboiled.support.ParseTreeUtils

class HamlParser extends Parser {

    def Haml = rule {
        WhiteSpace ~ Doctype ~ EOI
    }

    def Doctype = rule {
        str("!!!") ~ WhiteSpace ~ Inline 
    }

    def Inline = rule {
        oneOrMore(anyOf(Characters.allBut("\r\n")))  // This line is the reason
    }

    def WhiteSpace: Rule0 = rule { zeroOrMore(anyOf(" \n\r\t\f")) }

    def NewLine = rule {
        "\n" | "\r" ~ optional("\n")
    }
}

object HamlParser {
    def main(args: Array[String]) {
        val input = """
!!! ABC"""
        val parser = new HamlParser { override val buildParseTree = true }
        val result = ReportingParseRunner(parser.Haml).run(input)
        val out = ParseTreeUtils.printNodeTree(result)

        if (!result.matched) {
            println(result.parseErrors.mkString("---\n"))
        }
        println(out)
    }
}