Scala example source code file (Replayer.scala)

This example Scala source code file (Replayer.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

boolean, compiler, eof, logger, logreplay, none, nsc, option, pickler, some, string, unpicklesuccess

The Replayer.scala Scala example source code

package scala.tools.nsc.interactive

import java.io.{Reader, Writer}

import Pickler._
import Lexer.EOF

abstract class LogReplay {
  def logreplay(event: String, x: => Boolean): Boolean
  def logreplay[T: Pickler](event: String, x: => Option[T]): Option[T]
  def close()
  def flush()
}

class Logger(wr0: Writer) extends LogReplay {
  val wr = new PrettyWriter(wr0)
  private var first = true
  private def insertComma() = if (first) first = false else wr.write(",")

  def logreplay(event: String, x: => Boolean) = {
    val xx = x
    if (xx) { insertComma(); pkl[Unit].labelled(event).pickle(wr, ()) }
    xx
  }
  def logreplay[T: Pickler](event: String, x: => Option[T]) = {
    val xx = x
    xx match {
      case Some(y) => insertComma(); pkl[T].labelled(event).pickle(wr, y)
      case None =>
    }
    xx
  }
  def close() { wr.close() }
  def flush() { wr.flush() }
}

object NullLogger extends LogReplay {
  def logreplay(event: String, x: => Boolean) = x
  def logreplay[T: Pickler](event: String, x: => Option[T]) = x
  def close() {}
  def flush() {}
}

class Replayer(raw: Reader) extends LogReplay {
  private val rd = new Lexer(raw)
  private var nextComma = false

  private def eatComma() =
    if (nextComma) { rd.accept(','); nextComma = false }

  def logreplay(event: String, x: => Boolean) =
    if (rd.token == EOF) NullLogger.logreplay(event, x)
    else {
      eatComma()
      pkl[Unit].labelled(event).unpickle(rd) match {
        case UnpickleSuccess(_) => nextComma = true; true
        case _ => false
      }
    }

  def logreplay[T: Pickler](event: String, x: => Option[T]) =
    if (rd.token == EOF) NullLogger.logreplay(event, x)
    else {
      eatComma()
      pkl[T].labelled(event).unpickle(rd) match {
        case UnpickleSuccess(y) => nextComma = true; Some(y)
        case _ => None
      }
    }

  def close() { raw.close() }
  def flush() {}
}