[jboss-jira] [JBoss JIRA] (JASSIST-251) Support looking up nested class with non standard anonymous class name (from Scala)

[Patson Luk (JIRA)]

Patson Luk created JASSIST-251:
----------------------------------

             Summary: Support looking up nested class with non standard anonymous class name (from Scala)
                 Key: JASSIST-251
                 URL: https://issues.jboss.org/browse/JASSIST-251
             Project: Javassist
          Issue Type: Feature Request
            Reporter: Patson Luk
            Assignee: Shigeru Chiba
         Attachments: Test$$anonfun$main$1.class, Test$.class

The existing code within CtClassType.getNestedClasses() uses check 

{code}
 if (name.lastIndexOf('$') < thisName.length())
{code}
To check if the names from the "InnerClasses" attribute are the immediate nested class of the current CtClassType instance.

This works fine for well formatted anonymous class name that adheres to the Java Language spec that:
{quote}
The binary name of an anonymous class (§15.9.5) consists of the binary
name of its immediately enclosing type, followed by $, followed by a nonempty
sequence of digits.
{quote}

However, for JVM language like Scala that converts anonymous class to names that do not follow that standard, for sample code like
{code}
object Test {
   def main(args: Array[String]): Unit = {
    val list = List(1, 2, 3)
    println(list.map(_ * 2))
  }
}
{code} 

generates several java class files. Two class files (attached) in particular "Test$.class" and "Test$$anonfun$main$1.class" show "immediate nested classes" relationship in the generated byte code as
# Test$ has InnerClasses attribute entry with name "Test$$anonfun$main$1" 
# Test$$anonfun$main$1 has EnclosingMethod attribute value "Test$.main"

But "Test$$anonfun$main$1.class" does not conform to the JLS naming (otherwise it should have been "Test$$1.class" instead)

With the current check in place for getNestedClasses(), the anonymous class will not be returned as an immediate nested class of "Test$", however with a minor change it should be able to do that:

{code}
// if it is an immediate nested class
//if (name.lastIndexOf('$') < thisName.length()) instead of checking name, check the actual declaring class
CtClass nestedClass = classPool.get(name);
CtClass declaringClass = nestedClass.getDeclaringClass();
if (declaringClass == null || declaringClass.equals(this)) {
    list.add(nestedClass);
}
{code}

I tagged this as a feature request as i do not know the policy of supporting non Java language.

Please kindly advise and many thanks in advance!





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