Scala example source code file (ShowPickled.scala)

This example Scala source code file (ShowPickled.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

aliassym, array, classsym, extmodclassref, extref, int, modulesym, picklebuffer, pickling, reflection, string, typesym

The ShowPickled.scala Scala example source code

/* NSC -- new Scala compiler
 * Copyright 2005-2013 LAMP/EPFL
 * @author  Martin Odersky
 */

package scala
package tools
package nsc
package util

import java.io.PrintStream
import java.lang.Long.toHexString
import java.lang.Float.intBitsToFloat
import java.lang.Double.longBitsToDouble
import scala.reflect.internal.{Flags, Names}
import scala.reflect.internal.pickling.{ PickleBuffer, PickleFormat }

object ShowPickled extends Names {
  import PickleFormat._

  case class PickleBufferEntry(num: Int, startIndex: Int, tag: Int, bytes: Array[Byte]) {
    def isName = tag == TERMname || tag == TYPEname
    def hasName = tag match {
      case TYPEsym | ALIASsym | CLASSsym | MODULEsym | VALsym | EXTref | EXTMODCLASSref => true
      case _                                                                            => false
    }
    def readName =
      if (isName) new String(bytes, "UTF-8")
      else sys.error("%s is no name" format tagName)
    def nameIndex =
      if (hasName) readNat(bytes, 0)
      else sys.error("%s has no name" format tagName)

    def tagName = tag2string(tag)
    override def toString = "%d,%d: %s".format(num, startIndex, tagName)
  }

  case class PickleBufferEntryList(entries: IndexedSeq[PickleBufferEntry]) {
    def nameAt(idx: Int) = {
      val entry = entries(idx)
      if (entry.isName) entry.readName
      else if (entry.hasName) entries(entry.nameIndex).readName
      else "?"
    }
  }

  def makeEntryList(buf: PickleBuffer, index: Array[Int]) = {
    val entries = buf.toIndexedSeq.zipWithIndex map {
      case ((tag, data), num) => PickleBufferEntry(num, index(num), tag, data)
    }

    PickleBufferEntryList(entries)
  }

  def tag2string(tag: Int): String = tag match {
    case TERMname       => "TERMname"
    case TYPEname       => "TYPEname"
    case NONEsym        => "NONEsym"
    case TYPEsym        => "TYPEsym"
    case ALIASsym       => "ALIASsym"
    case CLASSsym       => "CLASSsym"
    case MODULEsym      => "MODULEsym"
    case VALsym         => "VALsym"
    case EXTref         => "EXTref"
    case EXTMODCLASSref => "EXTMODCLASSref"
    case NOtpe          => "NOtpe"
    case NOPREFIXtpe    => "NOPREFIXtpe"
    case THIStpe        => "THIStpe"
    case SINGLEtpe      => "SINGLEtpe"
    case CONSTANTtpe    => "CONSTANTtpe"
    case TYPEREFtpe     => "TYPEREFtpe"
    case TYPEBOUNDStpe  => "TYPEBOUNDStpe"
    case REFINEDtpe     => "REFINEDtpe"
    case CLASSINFOtpe   => "CLASSINFOtpe"
    case METHODtpe      => "METHODtpe"
    case POLYtpe        => "POLYtpe"
    case IMPLICITMETHODtpe => "METHODtpe" // IMPLICITMETHODtpe no longer used.
    case SUPERtpe       => "SUPERtpe"
    case LITERALunit    => "LITERALunit"
    case LITERALboolean => "LITERALboolean"
    case LITERALbyte    => "LITERALbyte"
    case LITERALshort   => "LITERALshort"
    case LITERALchar    => "LITERALchar"
    case LITERALint     => "LITERALint"
    case LITERALlong    => "LITERALlong"
    case LITERALfloat   => "LITERALfloat"
    case LITERALdouble  => "LITERALdouble"
    case LITERALstring  => "LITERALstring"
    case LITERALnull    => "LITERALnull"
    case LITERALclass   => "LITERALclass"
    case LITERALenum    => "LITERALenum"
    case SYMANNOT       => "SYMANNOT"
    case CHILDREN       => "CHILDREN"
    case ANNOTATEDtpe   => "ANNOTATEDtpe"
    case ANNOTINFO      => "ANNOTINFO"
    case ANNOTARGARRAY  => "ANNOTARGARRAY"
    case EXISTENTIALtpe => "EXISTENTIALtpe"
    case TREE           => "TREE"
    case MODIFIERS      => "MODIFIERS"

    case _ => "***BAD TAG***(" + tag + ")"
  }

  /** Extremely regrettably, essentially copied from PickleBuffer.
   */
  def readNat(data: Array[Byte], index: Int): Int = {
    var idx = index
    var result = 0L
    var b = 0L
    do {
      b = data(idx).toLong
      idx += 1
      result = (result << 7) + (b & 0x7f)
    } while((b & 0x80) != 0L)

    result.toInt
  }

  def printFile(buf: PickleBuffer, out: PrintStream) {
    out.println("Version " + buf.readNat() + "." + buf.readNat())
    val index = buf.createIndex
    val entryList = makeEntryList(buf, index)
    buf.readIndex = 0

    def p(s: String) = out print s

    def printNameRef() {
      val idx = buf.readNat()
      val name = entryList nameAt idx
      val toPrint = " %s(%s)".format(idx, name)

      out print toPrint
    }

    def printNat() = p(" " + buf.readNat())
    def printReadNat(x: Int) = p(" " + x)

    def printSymbolRef() = printNat()
    def printTypeRef() = printNat()
    def printConstantRef() = printNat()
    def printAnnotInfoRef() = printNat()
    def printConstAnnotArgRef() = printNat()
    def printAnnotArgRef() = printNat()

    def printSymInfo(end: Int) {
      printNameRef()
      printSymbolRef()
      val pflags = buf.readLongNat()
      def printFlags(privateWithin: Option[Int]) = {
        val accessBoundary = (
          for (idx <- privateWithin) yield {
            val s = entryList nameAt idx
            idx + "(" + s + ")"
          }
        )
        val flagString = {
          val arg1 = Flags.pickledToRawFlags(pflags)
          accessBoundary match {
            case Some(pw) => Flags.flagsToString(arg1, pw)
            case _        => Flags.flagsToString(arg1)
          }
        }

        out.print(" %s[%s]".format(toHexString(pflags), flagString))
      }

      /* Might be info or privateWithin */
      val x = buf.readNat()
      if (buf.readIndex == end) {
        printFlags(None)
        printReadNat(x)
      }
      else {
        printFlags(Some(x))
        printTypeRef()
      }
    }

    /* Note: the entries which require some semantic analysis to be correctly
     * interpreted are for the most part going to tell you the wrong thing.
     * It's not so easy to duplicate the logic applied in the UnPickler.
     */
    def printEntry(i: Int) {
      buf.readIndex = index(i)
      p(i + "," + buf.readIndex + ": ")
      val tag = buf.readByte()
      out.print(tag2string(tag))
      val len = buf.readNat()
      val end = len + buf.readIndex
      p(" " + len + ":")
      tag match {
        case TERMname =>
          out.print(" ")
          out.print(newTermName(buf.bytes, buf.readIndex, len).toString)
          buf.readIndex = end
        case TYPEname =>
          out.print(" ")
          out.print(newTypeName(buf.bytes, buf.readIndex, len))
          buf.readIndex = end
        case TYPEsym | ALIASsym | CLASSsym | MODULEsym | VALsym =>
          printSymInfo(end)
          if (tag == CLASSsym && (buf.readIndex < end)) printTypeRef()
        case EXTref | EXTMODCLASSref =>
          printNameRef()
          if (buf.readIndex < end) { printSymbolRef() }
        case THIStpe =>
          printSymbolRef()
        case SINGLEtpe =>
          printTypeRef(); printSymbolRef()
        case CONSTANTtpe =>
          printTypeRef(); printConstantRef()
        case TYPEREFtpe =>
          printTypeRef(); printSymbolRef(); buf.until(end, printTypeRef)
        case TYPEBOUNDStpe =>
          printTypeRef(); printTypeRef()
        case REFINEDtpe =>
          printSymbolRef(); buf.until(end, printTypeRef)
        case CLASSINFOtpe =>
          printSymbolRef(); buf.until(end, printTypeRef)
        case METHODtpe | IMPLICITMETHODtpe =>
          printTypeRef(); buf.until(end, printTypeRef)
        case POLYtpe =>
          printTypeRef(); buf.until(end, printSymbolRef)
        case LITERALboolean =>
          out.print(if (buf.readLong(len) == 0L) " false" else " true")
        case LITERALbyte    =>
          out.print(" " + buf.readLong(len).toByte)
        case LITERALshort   =>
          out.print(" " + buf.readLong(len).toShort)
        case LITERALchar    =>
          out.print(" " + buf.readLong(len).toChar)
        case LITERALint     =>
          out.print(" " + buf.readLong(len).toInt)
        case LITERALlong    =>
          out.print(" " + buf.readLong(len))
        case LITERALfloat   =>
          out.print(" " + intBitsToFloat(buf.readLong(len).toInt))
        case LITERALdouble  =>
          out.print(" " + longBitsToDouble(buf.readLong(len)))
        case LITERALstring  =>
          printNameRef()
        case LITERALenum    =>
          printSymbolRef()
        case LITERALnull    =>
          out.print(" <null>")
        case LITERALclass   =>
          printTypeRef()
        case CHILDREN       =>
          printSymbolRef(); buf.until(end, printSymbolRef)
        case SYMANNOT       =>
          printSymbolRef(); printTypeRef(); buf.until(end, printAnnotArgRef)
        case ANNOTATEDtpe   =>
          printTypeRef(); buf.until(end, printAnnotInfoRef)
        case ANNOTINFO      =>
          printTypeRef(); buf.until(end, printAnnotArgRef)
        case ANNOTARGARRAY  =>
          buf.until(end, printConstAnnotArgRef)
        case EXISTENTIALtpe =>
          printTypeRef(); buf.until(end, printSymbolRef)

        case _ =>
      }
      out.println()
      if (buf.readIndex != end) {
        out.println("BAD ENTRY END: computed = %d, actual = %d, bytes = %s".format(
          end, buf.readIndex, buf.bytes.slice(index(i), (end max buf.readIndex)).mkString(", ")
        ))
      }
    }

    for (i <- 0 until index.length) printEntry(i)
  }

  def fromFile(path: String) = fromBytes(io.File(path).toByteArray())
  def fromBytes(data: => Array[Byte]): Option[PickleBuffer] =
    try Some(new PickleBuffer(data, 0, data.length))
    catch { case _: Exception => None }

  def show(what: String, pickle: PickleBuffer) = {
    Console.println(what)
    val saved = pickle.readIndex
    pickle.readIndex = 0
    printFile(pickle, Console.out)
    pickle.readIndex = saved
  }

  def main(args: Array[String]) {
    args foreach { arg =>
      fromFile(arg) match {
        case Some(pb) => show(arg + ":", pb)
        case _        => Console.println("Cannot read " + arg)
      }
    }
  }
}