Scala example source code file (MatchCps.scala)

This example Scala source code file (MatchCps.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

compiler, cpssymbols, markercpsadaptminus, markercpsadaptplus, markercpssynth, markercpstypes, matchcps, nsc, patternmatching, set, string, type

The MatchCps.scala Scala example source code

/* NSC -- new Scala compiler
 *
 * Copyright 2011-2013 LAMP/EPFL
 * @author Adriaan Moors
 */

package scala.tools.nsc.transform.patmat

/** Segregating this super hacky CPS code. */
trait MatchCps {
  self: PatternMatching =>

  import global._

  // duplicated from CPSUtils (avoid dependency from compiler -> cps plugin...)
  private object CpsSymbols {
    private def cpsSymbol(name: String) = rootMirror.getClassIfDefined(s"scala.util.continuations.$name")

    val MarkerCPSAdaptPlus  = cpsSymbol("cpsPlus")
    val MarkerCPSAdaptMinus = cpsSymbol("cpsMinus")
    val MarkerCPSSynth      = cpsSymbol("cpsSynth")
    val MarkerCPSTypes      = cpsSymbol("cpsParam")
    val stripTriggerCPSAnns = Set[Symbol](MarkerCPSSynth, MarkerCPSAdaptMinus, MarkerCPSAdaptPlus)
    val strippedCPSAnns     = stripTriggerCPSAnns + MarkerCPSTypes

    // when one of the internal cps-type-state annotations is present, strip all CPS annotations
    // a cps-type-state-annotated type makes no sense as an expected type (matchX.tpe is used as pt in translateMatch)
    // (only test availability of MarkerCPSAdaptPlus assuming they are either all available or none of them are)
    def removeCPSFromPt(pt: Type): Type = (
      if (MarkerCPSAdaptPlus.exists && (stripTriggerCPSAnns exists pt.hasAnnotation))
        pt filterAnnotations (ann => !(strippedCPSAnns exists ann.matches))
      else
        pt
    )
  }
  def removeCPSFromPt(pt: Type): Type = CpsSymbols removeCPSFromPt pt
}