Scala example source code file (ByteCode.scala)

This example Scala source code file (ByteCode.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Scala tags/keywords

bytecode, decoder, decoder, jclass, module, none, none, option, option, string, string, threading, threads

The Scala ByteCode.scala source code

/* NSC -- new Scala compiler
 * Copyright 2005-2011 LAMP/EPFL
 * @author Paul Phillips
 */

package scala.tools.nsc
package interpreter

import java.lang.reflect
import java.util.concurrent.ConcurrentHashMap
import util.ScalaClassLoader
import ScalaClassLoader.getSystemLoader

object ByteCode {
  /** Until I figure out why I can't get scalap onto the classpath such
   *  that the compiler will bootstrap, we have to use reflection.
   */
  private lazy val DECODER: Option[AnyRef] =
    for (clazz <- getSystemLoader.tryToLoadClass[AnyRef]("scala.tools.scalap.Decode$")) yield
      clazz.getField("MODULE$").get()
  
  private def decoderMethod(name: String, args: JClass*): Option[reflect.Method] = {
    for (decoder <- DECODER ; m <- Option(decoder.getClass.getMethod(name, args: _*))) yield m
  }   

  private lazy val aliasMap = {
    for (module <- DECODER ; method <- decoderMethod("typeAliases", classOf[String])) yield
      method.invoke(module, _: String).asInstanceOf[Option[Map[String, String]]]
  }
  
  /** Scala sig bytes.
   */
  def scalaSigBytesForPath(path: String) =
    for {
      module <- DECODER
      method <- decoderMethod("scalaSigAnnotationBytes", classOf[String])
      names <- method.invoke(module, path).asInstanceOf[Option[Array[Byte]]]
    }
    yield names  
  
  /** Attempts to retrieve case parameter names for given class name.
   */
  def caseParamNamesForPath(path: String) =
    for {
      module <- DECODER
      method <- decoderMethod("caseParamNames", classOf[String])
      names <- method.invoke(module, path).asInstanceOf[Option[List[String]]]
    }
    yield names

  def aliasesForPackage(pkg: String) = aliasMap flatMap (_(pkg))
  
  /** Attempts to find type aliases in package objects.
   */
  def aliasForType(path: String): Option[String] = {
    val (pkg, name) = (path lastIndexOf '.') match {
      case -1   => return None
      case idx  => (path take idx, path drop (idx + 1))
    }
    aliasesForPackage(pkg) flatMap (_ get name)
  }
}