Scala example source code file (AsmUtils.scala)

This example Scala source code file (AsmUtils.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

asm, asmutils, bytecode, classnode, compiler, methodnode, nsc, textifier, traceclassvisitor, tracemethodvisitor, unit

The AsmUtils.scala Scala example source code

/* NSC -- new Scala compiler
 * Copyright 2005-2014 LAMP/EPFL
 * @author  Martin Odersky
 */

package scala.tools.nsc.backend.jvm

import scala.tools.asm.tree.{ClassNode, MethodNode}
import java.io.PrintWriter
import scala.tools.asm.util.{TraceClassVisitor, TraceMethodVisitor, Textifier}

object AsmUtils {

  /**
   * Print the bytecode of methods generated by GenBCode to the standard output. Only methods
   * whose name contains `traceMethodPattern` are traced.
   */
  final val traceMethodEnabled = false
  final val traceMethodPattern = ""

  /**
   * Print the bytecode of classes generated by GenBCode to the standard output.
   */
  final val traceClassEnabled = false
  final val traceClassPattern = ""

  /**
   * Print the bytedcode of classes as they are serialized by the ASM library. The serialization
   * performed by `asm.ClassWriter` can change the code generated by GenBCode. For example, it
   * introduces stack map frames, it computes the maximal stack sizes, and it replaces dead
   * code by NOPs (see also https://github.com/scala/scala/pull/3726#issuecomment-42861780).
   */
  final val traceSerializedClassEnabled = false
  final val traceSerializedClassPattern = ""

  def traceMethod(mnode: MethodNode): Unit = {
    println(s"Bytecode for method ${mnode.name}")
    val p = new Textifier
    val tracer = new TraceMethodVisitor(p)
    mnode.accept(tracer)
    val w = new PrintWriter(System.out)
    p.print(w)
    w.flush()
  }

  def traceClass(cnode: ClassNode): Unit = {
    println(s"Bytecode for class ${cnode.name}")
    val w = new PrintWriter(System.out)
    cnode.accept(new TraceClassVisitor(w))
    w.flush()
  }

}