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Prototype implementation using Scala reflection to show accessible members when running cbt #538

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91ea7c1
prototype
megri Jun 26, 2017
086dc48
attempt at "reifying" TypeTag
megri Jun 26, 2017
2554db8
clean up
megri Jun 26, 2017
b4e1ace
remove newline to shrink diff
megri Jun 26, 2017
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66 changes: 47 additions & 19 deletions stage2/Lib.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -3,14 +3,15 @@ package cbt
import java.io._
import java.net._
import java.lang.reflect.InvocationTargetException
import java.nio.file.{Path =>_,_}
import java.nio.file.{Path => _, _}
import java.nio.file.Files._
import java.security.MessageDigest
import java.util.jar._
import java.lang.reflect.Method

import scala.util._
import scala.reflect.NameTransformer
import scala.reflect.{api, ClassTag, NameTransformer}
import scala.reflect.runtime.universe

// pom model
case class Developer(id: String, name: String, timezone: String, url: URL)
Expand Down Expand Up @@ -56,22 +57,49 @@ final class Lib(val logger: Logger) extends
}

// task reflection helpers
def taskMethods(cls:Class[_]): Map[String, Method] =
Stream
.iterate(cls.asInstanceOf[Class[Any]])(_.getSuperclass)
.takeWhile(_ != null)
.toVector
.dropRight(1) // drop Object
.reverse
.flatMap(
c =>
c
.getMethods
.filter( _.isPublic )
.filter( _.parameterTypes.length == 0 )
.map(m => NameTransformer.decode(m.getName) -> m)
.filterNot(_._1 contains "$")
).toMap
def taskMethods(cls: Class[_]) = {
val mirror = universe.runtimeMirror(cls.getClassLoader)

// implements ideas from https://stackoverflow.com/questions/23785439/getting-typetag-from-a-classname-string
val reifiedTypeTag: universe.TypeTag[_] = {
val sym = mirror.classSymbol(cls)
val tpe = sym.selfType

universe.TypeTag(
mirror,
new api.TypeCreator {
def apply[U <: api.Universe with Singleton](m: api.Mirror[U]) =
if (m eq mirror) tpe.asInstanceOf[U # Type]
else throw new IllegalArgumentException(s"Type tag defined in $mirror cannot be migrated to other mirrors.")
}
)
}

def declaredIn(tpe: universe.Type) = {
tpe
.decls
.collect {
case m if
!m.isConstructor &&
m.isPublic &&
m.isMethod &&
!m.name.decodedName.toString.contains("$") &&
m.asMethod.paramLists.forall(_.isEmpty) =>

val methodF: AnyRef => AnyRef = instance => mirror.reflect(instance).reflectMethod(m.asMethod).apply().asInstanceOf[AnyRef]
m.name.decodedName.toString -> methodF
}
.toMap
}

reifiedTypeTag.tpe
.baseClasses
.dropRight(2) // drop … <: Object <: Any
.foldLeft(Map.empty[String, AnyRef => AnyRef]) {
case (map, symbol) =>
map ++ declaredIn(symbol.typeSignature)
}
}

def taskNames(cls: Class[_]): Seq[String] = taskMethods(cls).keys.toVector.sorted

Expand Down Expand Up @@ -152,7 +180,7 @@ final class Lib(val logger: Logger) extends
logger.lib("Calling task " ++ taskName.toString)
taskMethods(obj.getClass).get(name).map{ method =>
callInternal(
Option(trapExitCodeOrValue(method.invoke(obj)).merge /* null in case of Unit */ ).getOrElse(
Option(trapExitCodeOrValue(method(obj)).merge /* null in case of Unit */ ).getOrElse(
().asInstanceOf[AnyRef]
),
members.tail,
Expand Down