Scala example source code file (SymbolTable.scala)

This example Scala source code file (SymbolTable.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

annotation, boolean, collection, name, nophase, period, phase, reflection, string, symbol, t, unit, v

The SymbolTable.scala Scala example source code

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

package scala
package reflect
package internal

import scala.annotation.elidable
import scala.collection.{ mutable, immutable }
import util._
import java.util.concurrent.TimeUnit
import scala.reflect.internal.{TreeGen => InternalTreeGen}

abstract class SymbolTable extends macros.Universe
                              with Collections
                              with Names
                              with Symbols
                              with Types
                              with Variances
                              with Kinds
                              with ExistentialsAndSkolems
                              with FlagSets
                              with Scopes
                              with Mirrors
                              with Definitions
                              with Constants
                              with BaseTypeSeqs
                              with InfoTransformers
                              with transform.Transforms
                              with StdNames
                              with AnnotationInfos
                              with AnnotationCheckers
                              with Trees
                              with Printers
                              with Positions
                              with TypeDebugging
                              with Importers
                              with Required
                              with CapturedVariables
                              with StdAttachments
                              with StdCreators
                              with ReificationSupport
                              with PrivateWithin
                              with pickling.Translations
                              with FreshNames
                              with Internals
{

  val gen = new InternalTreeGen { val global: SymbolTable.this.type = SymbolTable.this }

  def log(msg: => AnyRef): Unit
  def deprecationWarning(pos: Position, msg: String): Unit = warning(msg)
  def warning(msg: String): Unit     = Console.err.println(msg)
  def inform(msg: String): Unit      = Console.err.println(msg)
  def globalError(msg: String): Unit = abort(msg)
  def abort(msg: String): Nothing    = throw new FatalError(supplementErrorMessage(msg))

  protected def elapsedMessage(msg: String, start: Long) =
    msg + " in " + (TimeUnit.NANOSECONDS.toMillis(System.nanoTime()) - start) + "ms"

  def informProgress(msg: String)          = if (settings.verbose) inform("[" + msg + "]")
  def informTime(msg: String, start: Long) = informProgress(elapsedMessage(msg, start))

  def shouldLogAtThisPhase = false
  def isPastTyper = false
  protected def isDeveloper: Boolean = settings.debug

  @deprecated("Use devWarning if this is really a warning; otherwise use log", "2.11.0")
  def debugwarn(msg: => String): Unit = devWarning(msg)

  /** Override with final implementation for inlining. */
  def debuglog(msg:  => String): Unit = if (settings.debug) log(msg)
  def devWarning(msg: => String): Unit = if (isDeveloper) Console.err.println(msg)
  def throwableAsString(t: Throwable): String = "" + t
  def throwableAsString(t: Throwable, maxFrames: Int): String = t.getStackTrace take maxFrames mkString "\n  at "

  @inline final def devWarningDumpStack(msg: => String, maxFrames: Int): Unit =
    devWarning(msg + "\n" + throwableAsString(new Throwable, maxFrames))

  /** Prints a stack trace if -Ydebug or equivalent was given, otherwise does nothing. */
  def debugStack(t: Throwable): Unit  = devWarning(throwableAsString(t))

  /** Overridden when we know more about what was happening during a failure. */
  def supplementErrorMessage(msg: String): String = msg

  private[scala] def printCaller[T](msg: String)(result: T) = {
    Console.err.println("%s: %s\nCalled from: %s".format(msg, result,
      (new Throwable).getStackTrace.drop(2).take(50).mkString("\n")))

    result
  }

  private[scala] def printResult[T](msg: String)(result: T) = {
    Console.err.println(msg + ": " + result)
    result
  }
  @inline
  final private[scala] def logResult[T](msg: => String)(result: T): T = {
    log(msg + ": " + result)
    result
  }
  @inline
  final private[scala] def debuglogResult[T](msg: => String)(result: T): T = {
    debuglog(msg + ": " + result)
    result
  }
  @inline
  final private[scala] def devWarningResult[T](msg: => String)(result: T): T = {
    devWarning(msg + ": " + result)
    result
  }
  @inline
  final private[scala] def logResultIf[T](msg: => String, cond: T => Boolean)(result: T): T = {
    if (cond(result))
      log(msg + ": " + result)

    result
  }
  @inline
  final private[scala] def debuglogResultIf[T](msg: => String, cond: T => Boolean)(result: T): T = {
    if (cond(result))
      debuglog(msg + ": " + result)

    result
  }

  @inline final def findSymbol(xs: TraversableOnce[Symbol])(p: Symbol => Boolean): Symbol = {
    xs find p getOrElse NoSymbol
  }

  // For too long have we suffered in order to sort NAMES.
  // I'm pretty sure there's a reasonable default for that.
  // Notice challenge created by Ordering's invariance.
  implicit def lowPriorityNameOrdering[T <: Names#Name]: Ordering[T] =
    SimpleNameOrdering.asInstanceOf[Ordering[T]]

  private object SimpleNameOrdering extends Ordering[Names#Name] {
    def compare(n1: Names#Name, n2: Names#Name) = (
      if (n1 eq n2) 0
      else n1.toString compareTo n2.toString
    )
  }

  /** Dump each symbol to stdout after shutdown.
   */
  final val traceSymbolActivity = sys.props contains "scalac.debug.syms"
  object traceSymbols extends {
    val global: SymbolTable.this.type = SymbolTable.this
  } with util.TraceSymbolActivity

  val treeInfo: TreeInfo { val global: SymbolTable.this.type }

  /** Check that the executing thread is the compiler thread. No-op here,
   *  overridden in interactive.Global. */
  @elidable(elidable.WARNING)
  def assertCorrectThread() {}

  /** A last effort if symbol in a select <owner>.<name> is not found.
   *  This is overridden by the reflection compiler to make up a package
   *  when it makes sense (i.e. <owner> is a package and <name> is a term name).
   */
  def missingHook(owner: Symbol, name: Name): Symbol = NoSymbol

  /** Returns the mirror that loaded given symbol */
  def mirrorThatLoaded(sym: Symbol): Mirror

  /** A period is an ordinal number for a phase in a run.
   *  Phases in later runs have higher periods than phases in earlier runs.
   *  Later phases have higher periods than earlier phases in the same run.
   */
  type Period = Int
  final val NoPeriod = 0

  /** An ordinal number for compiler runs. First run has number 1. */
  type RunId = Int
  final val NoRunId = 0

  // sigh, this has to be public or enteringPhase doesn't inline.
  var phStack: List[Phase] = Nil
  private[this] var ph: Phase = NoPhase
  private[this] var per = NoPeriod

  final def atPhaseStack: List[Phase] = phStack
  final def phase: Phase = {
    if (Statistics.hotEnabled)
      Statistics.incCounter(SymbolTableStats.phaseCounter)
    ph
  }

  def atPhaseStackMessage = atPhaseStack match {
    case Nil    => ""
    case ps     => ps.reverseMap("->" + _).mkString("(", " ", ")")
  }

  final def phase_=(p: Phase) {
    //System.out.println("setting phase to " + p)
    assert((p ne null) && p != NoPhase, p)
    ph = p
    per = period(currentRunId, p.id)
  }
  final def pushPhase(ph: Phase): Phase = {
    val current = phase
    phase = ph
    phStack ::= ph
    current
  }
  final def popPhase(ph: Phase) {
    phStack = phStack.tail
    phase = ph
  }

  /** The current compiler run identifier. */
  def currentRunId: RunId

  /** The run identifier of the given period. */
  final def runId(period: Period): RunId = period >> 8

  /** The phase identifier of the given period. */
  final def phaseId(period: Period): Phase#Id = period & 0xFF

  /** The current period. */
  final def currentPeriod: Period = {
    //assert(per == (currentRunId << 8) + phase.id)
    per
  }

  /** The phase associated with given period. */
  final def phaseOf(period: Period): Phase = phaseWithId(phaseId(period))

  final def period(rid: RunId, pid: Phase#Id): Period =
    (rid << 8) + pid

  /** Are we later than given phase in compilation? */
  final def isAtPhaseAfter(p: Phase) =
    p != NoPhase && phase.id > p.id

  /** Perform given operation at given phase. */
  @inline final def enteringPhase[T](ph: Phase)(op: => T): T = {
    val saved = pushPhase(ph)
    try op
    finally popPhase(saved)
  }

  final def findPhaseWithName(phaseName: String): Phase = {
    var ph = phase
    while (ph != NoPhase && ph.name != phaseName) {
      ph = ph.prev
    }
    if (ph eq NoPhase) phase else ph
  }
  final def enteringPhaseWithName[T](phaseName: String)(body: => T): T = {
    val phase = findPhaseWithName(phaseName)
    enteringPhase(phase)(body)
  }

  def slowButSafeEnteringPhase[T](ph: Phase)(op: => T): T = {
    if (isCompilerUniverse) enteringPhase(ph)(op)
    else op
  }

  @inline final def exitingPhase[T](ph: Phase)(op: => T): T = enteringPhase(ph.next)(op)
  @inline final def enteringPrevPhase[T](op: => T): T       = enteringPhase(phase.prev)(op)

  @inline final def enteringPhaseNotLaterThan[T](target: Phase)(op: => T): T =
    if (isAtPhaseAfter(target)) enteringPhase(target)(op) else op

  def slowButSafeEnteringPhaseNotLaterThan[T](target: Phase)(op: => T): T =
    if (isCompilerUniverse) enteringPhaseNotLaterThan(target)(op) else op

  final def isValid(period: Period): Boolean =
    period != 0 && runId(period) == currentRunId && {
      val pid = phaseId(period)
      if (phase.id > pid) infoTransformers.nextFrom(pid).pid >= phase.id
      else infoTransformers.nextFrom(phase.id).pid >= pid
    }

  final def isValidForBaseClasses(period: Period): Boolean = {
    def noChangeInBaseClasses(it: InfoTransformer, limit: Phase#Id): Boolean = (
      it.pid >= limit ||
      !it.changesBaseClasses && noChangeInBaseClasses(it.next, limit)
    )
    period != 0 && runId(period) == currentRunId && {
      val pid = phaseId(period)
      if (phase.id > pid) noChangeInBaseClasses(infoTransformers.nextFrom(pid), phase.id)
      else noChangeInBaseClasses(infoTransformers.nextFrom(phase.id), pid)
    }
  }

  def openPackageModule(container: Symbol, dest: Symbol) {
    // unlink existing symbols in the package
    for (member <- container.info.decls.iterator) {
      if (!member.isPrivate && !member.isConstructor) {
        // todo: handle overlapping definitions in some way: mark as errors
        // or treat as abstractions. For now the symbol in the package module takes precedence.
        for (existing <- dest.info.decl(member.name).alternatives)
          dest.info.decls.unlink(existing)
      }
    }
    // enter non-private decls the class
    for (member <- container.info.decls.iterator) {
      if (!member.isPrivate && !member.isConstructor) {
        dest.info.decls.enter(member)
      }
    }
    // enter decls of parent classes
    for (p <- container.parentSymbols) {
      if (p != definitions.ObjectClass) {
        openPackageModule(p, dest)
      }
    }
  }

  /** Convert array parameters denoting a repeated parameter of a Java method
   *  to `JavaRepeatedParamClass` types.
   */
  def arrayToRepeated(tp: Type): Type = tp match {
    case MethodType(params, rtpe) =>
      val formals = tp.paramTypes
      assert(formals.last.typeSymbol == definitions.ArrayClass, formals)
      val method = params.last.owner
      val elemtp = formals.last.typeArgs.head match {
        case RefinedType(List(t1, t2), _) if (t1.typeSymbol.isAbstractType && t2.typeSymbol == definitions.ObjectClass) =>
          t1 // drop intersection with Object for abstract types in varargs. UnCurry can handle them.
        case t =>
          t
      }
      val newParams = method.newSyntheticValueParams(formals.init :+ definitions.javaRepeatedType(elemtp))
      MethodType(newParams, rtpe)
    case PolyType(tparams, rtpe) =>
      PolyType(tparams, arrayToRepeated(rtpe))
  }

  abstract class SymLoader extends LazyType {
    def fromSource = false
  }

  /** if there's a `package` member object in `pkgClass`, enter its members into it. */
  def openPackageModule(pkgClass: Symbol) {

    val pkgModule = pkgClass.info.decl(nme.PACKAGEkw)
    def fromSource = pkgModule.rawInfo match {
      case ltp: SymLoader => ltp.fromSource
      case _ => false
    }
    if (pkgModule.isModule && !fromSource) {
      // println("open "+pkgModule)//DEBUG
      openPackageModule(pkgModule, pkgClass)
    }
  }

  object perRunCaches {
    import scala.collection.generic.Clearable

    // Weak references so the garbage collector will take care of
    // letting us know when a cache is really out of commission.
    import java.lang.ref.WeakReference
    private var caches = List[WeakReference[Clearable]]()

    def recordCache[T <: Clearable](cache: T): T = {
      caches ::= new WeakReference(cache)
      cache
    }

    def clearAll() = {
      debuglog("Clearing " + caches.size + " caches.")
      caches foreach (ref => Option(ref.get).foreach(_.clear))
      caches = caches.filterNot(_.get == null)
    }

    def newWeakMap[K, V]()        = recordCache(mutable.WeakHashMap[K, V]())
    def newMap[K, V]()            = recordCache(mutable.HashMap[K, V]())
    def newSet[K]()               = recordCache(mutable.HashSet[K]())
    def newWeakSet[K <: AnyRef]() = recordCache(new WeakHashSet[K]())

    def newAnyRefMap[K <: AnyRef, V]() = recordCache(mutable.AnyRefMap[K, V]())
    def newGeneric[T](f: => T): () => T = {
      val NoCached: T = null.asInstanceOf[T]
      var cached: T = NoCached
      var cachedRunId = NoRunId
      recordCache(new Clearable {
        def clear(): Unit = cached = NoCached
      })
      () => {
        if (currentRunId != cachedRunId || cached == NoCached) {
          cached = f
          cachedRunId = currentRunId
        }
        cached
      }
    }
  }

  /** The set of all installed infotransformers. */
  var infoTransformers = new InfoTransformer {
    val pid = NoPhase.id
    val changesBaseClasses = true
    def transform(sym: Symbol, tpe: Type): Type = tpe
  }

  /** The phase which has given index as identifier. */
  val phaseWithId: Array[Phase]

  /** Is this symbol table a part of a compiler universe?
   */
  def isCompilerUniverse = false

  @deprecated("Use enteringPhase", "2.10.0") // Used in SBT 0.12.4
  @inline final def atPhase[T](ph: Phase)(op: => T): T = enteringPhase(ph)(op)


  /**
   * Adds the `sm` String interpolator to a [[scala.StringContext]].
   */
  implicit val StringContextStripMarginOps: StringContext => StringContextStripMarginOps = util.StringContextStripMarginOps
}

object SymbolTableStats {
  val phaseCounter = Statistics.newCounter("#phase calls")
}