Scala example source code file (CleanUp.scala)

This example Scala source code file (CleanUp.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

apply, block, collection, compiler, dot, list, nil, nsc, ref, string, symbol, tree, type

The CleanUp.scala Scala example source code

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

package scala.tools.nsc
package transform

import symtab._
import Flags._
import scala.collection._
import scala.language.postfixOps

abstract class CleanUp extends Statics with Transform with ast.TreeDSL {
  import global._
  import definitions._
  import CODE._
  import treeInfo.StripCast

  /** the following two members override abstract members in Transform */
  val phaseName: String = "cleanup"

  /* used in GenBCode: collects ClassDef symbols owning a main(Array[String]) method */
  private var entryPoints: List[Symbol] = null
  def getEntryPoints: List[Symbol] = {
    assert(settings.isBCodeActive, "Candidate Java entry points are collected here only when GenBCode in use.")
    entryPoints sortBy ("" + _.fullName) // For predictably ordered error messages.
  }

  override def newPhase(prev: scala.tools.nsc.Phase): StdPhase = {
    entryPoints = if (settings.isBCodeActive) Nil else null;
    super.newPhase(prev)
  }

  protected def newTransformer(unit: CompilationUnit): Transformer =
    new CleanUpTransformer(unit)

  class CleanUpTransformer(unit: CompilationUnit) extends StaticsTransformer {
    private val newStaticMembers      = mutable.Buffer.empty[Tree]
    private val newStaticInits        = mutable.Buffer.empty[Tree]
    private val symbolsStoredAsStatic = mutable.Map.empty[String, Symbol]
    private def clearStatics() {
      newStaticMembers.clear()
      newStaticInits.clear()
      symbolsStoredAsStatic.clear()
    }
    private def transformTemplate(tree: Tree) = {
      val Template(_, _, body) = tree
      clearStatics()
      val newBody = transformTrees(body)
      val templ   = deriveTemplate(tree)(_ => transformTrees(newStaticMembers.toList) ::: newBody)
      try addStaticInits(templ, newStaticInits, localTyper) // postprocess to include static ctors
      finally clearStatics()
    }
    private def mkTerm(prefix: String): TermName = unit.freshTermName(prefix)

    //private val classConstantMeth = new HashMap[String, Symbol]
    //private val symbolStaticFields = new HashMap[String, (Symbol, Tree, Tree)]

    private var localTyper: analyzer.Typer = null

    private def typedWithPos(pos: Position)(tree: Tree) =
      localTyper.typedPos(pos)(tree)

    /** A value class is defined to be only Java-compatible values: unit is
      * not part of it, as opposed to isPrimitiveValueClass in definitions. scala.Int is
      * a value class, java.lang.Integer is not. */
    def isJavaValueClass(sym: Symbol) = boxedClass contains sym
    def isJavaValueType(tp: Type) = isJavaValueClass(tp.typeSymbol)

    /** The boxed type if it's a primitive; identity otherwise.
     */
    def toBoxedType(tp: Type) = if (isJavaValueType(tp)) boxedClass(tp.typeSymbol).tpe else tp

    def transformApplyDynamic(ad: ApplyDynamic) = {
      val qual0 = ad.qual
      val params = ad.args
        if (settings.logReflectiveCalls)
          unit.echo(ad.pos, "method invocation uses reflection")

        val typedPos = typedWithPos(ad.pos) _

        assert(ad.symbol.isPublic)
        var qual: Tree = qual0

        /* ### CREATING THE METHOD CACHE ### */

        def addStaticVariableToClass(forName: TermName, forType: Type, forInit: Tree, isFinal: Boolean): Symbol = {
          val flags = PRIVATE | STATIC | SYNTHETIC | (
            if (isFinal) FINAL else 0
          )

          val varSym = currentClass.newVariable(mkTerm("" + forName), ad.pos, flags.toLong) setInfoAndEnter forType
          if (!isFinal)
            varSym.addAnnotation(VolatileAttr)

          val varDef = typedPos(ValDef(varSym, forInit))
          newStaticMembers append transform(varDef)

          val varInit = typedPos( REF(varSym) === forInit )
          newStaticInits append transform(varInit)

          varSym
        }

        def addStaticMethodToClass(forBody: (Symbol, Symbol) => Tree): Symbol = {
          val methSym = currentClass.newMethod(mkTerm(nme.reflMethodName.toString), ad.pos, STATIC | SYNTHETIC)
          val params  = methSym.newSyntheticValueParams(List(ClassClass.tpe))
          methSym setInfoAndEnter MethodType(params, MethodClass.tpe)

          val methDef = typedPos(DefDef(methSym, forBody(methSym, params.head)))
          newStaticMembers append transform(methDef)
          methSym
        }

        def fromTypesToClassArrayLiteral(paramTypes: List[Type]): Tree =
          ArrayValue(TypeTree(ClassClass.tpe), paramTypes map LIT)

        def reflectiveMethodCache(method: String, paramTypes: List[Type]): Symbol = {
          /* Implementation of the cache is as follows for method "def xyz(a: A, b: B)"
             (SoftReference so that it does not interfere with classloader garbage collection,
             see ticket #2365 for details):

            var reflParams$Cache: Array[Class[_]] = Array[JClass](classOf[A], classOf[B])

            var reflPoly$Cache: SoftReference[scala.runtime.MethodCache] = new SoftReference(new EmptyMethodCache())

            def reflMethod$Method(forReceiver: JClass[_]): JMethod = {
              var methodCache: MethodCache = reflPoly$Cache.find(forReceiver)
              if (methodCache eq null) {
                methodCache = new EmptyMethodCache
                reflPoly$Cache = new SoftReference(methodCache)
              }
              var method: JMethod = methodCache.find(forReceiver)
              if (method ne null)
                return method
              else {
                method = ScalaRunTime.ensureAccessible(forReceiver.getMethod("xyz", reflParams$Cache))
                reflPoly$Cache = new SoftReference(methodCache.add(forReceiver, method))
                return method
              }
            }
          */

          val reflParamsCacheSym: Symbol =
            addStaticVariableToClass(nme.reflParamsCacheName, arrayType(ClassClass.tpe), fromTypesToClassArrayLiteral(paramTypes), true)

          def mkNewPolyCache = gen.mkSoftRef(NEW(TypeTree(EmptyMethodCacheClass.tpe)))
          val reflPolyCacheSym: Symbol = addStaticVariableToClass(nme.reflPolyCacheName, SoftReferenceClass.tpe, mkNewPolyCache, false)

          def getPolyCache = gen.mkCast(fn(REF(reflPolyCacheSym), nme.get), MethodCacheClass.tpe)

          addStaticMethodToClass((reflMethodSym, forReceiverSym) => {
            val methodCache = reflMethodSym.newVariable(mkTerm("methodCache"), ad.pos) setInfo MethodCacheClass.tpe
            val methodSym = reflMethodSym.newVariable(mkTerm("method"), ad.pos) setInfo MethodClass.tpe

            BLOCK(
              ValDef(methodCache, getPolyCache),
              IF (REF(methodCache) OBJ_EQ NULL) THEN BLOCK(
                REF(methodCache) === NEW(TypeTree(EmptyMethodCacheClass.tpe)),
                REF(reflPolyCacheSym) === gen.mkSoftRef(REF(methodCache))
              ) ENDIF,

              ValDef(methodSym, (REF(methodCache) DOT methodCache_find)(REF(forReceiverSym))),
              IF (REF(methodSym) OBJ_NE NULL) .
                THEN (Return(REF(methodSym)))
              ELSE {
                def methodSymRHS  = ((REF(forReceiverSym) DOT Class_getMethod)(LIT(method), REF(reflParamsCacheSym)))
                def cacheRHS      = ((REF(methodCache) DOT methodCache_add)(REF(forReceiverSym), REF(methodSym)))
                BLOCK(
                  REF(methodSym)        === (REF(currentRun.runDefinitions.ensureAccessibleMethod) APPLY (methodSymRHS)),
                  REF(reflPolyCacheSym) === gen.mkSoftRef(cacheRHS),
                  Return(REF(methodSym))
                )
              }
            )
          })
        }

        /* ### HANDLING METHODS NORMALLY COMPILED TO OPERATORS ### */

        def testForName(name: Name): Tree => Tree = t => (
          if (nme.CommonOpNames(name))
            gen.mkMethodCall(currentRun.runDefinitions.Boxes_isNumberOrBool, t :: Nil)
          else if (nme.BooleanOpNames(name))
            t IS_OBJ BoxedBooleanClass.tpe
          else
            gen.mkMethodCall(currentRun.runDefinitions.Boxes_isNumber, t :: Nil)
        )

        /*  The Tree => Tree function in the return is necessary to prevent the original qual
         *  from being duplicated in the resulting code.  It may be a side-effecting expression,
         *  so all the test logic is routed through gen.evalOnce, which creates a block like
         *    { val x$1 = qual; if (x$1.foo || x$1.bar) f1(x$1) else f2(x$1) }
         *  (If the compiler can verify qual is safe to inline, it will not create the block.)
         */
        def getPrimitiveReplacementForStructuralCall(name: Name): Option[(Symbol, Tree => Tree)] = {
          val methodName = (
            if (params.isEmpty) nme.primitivePostfixMethodName(name)
            else if (params.tail.isEmpty) nme.primitiveInfixMethodName(name)
            else nme.NO_NAME
          )
          getDeclIfDefined(BoxesRunTimeClass, methodName) match {
            case NoSymbol => None
            case sym      => assert(!sym.isOverloaded, sym) ; Some((sym, testForName(name)))
          }
        }

        /* ### BOXING PARAMS & UNBOXING RESULTS ### */

        /* Transforms the result of a reflective call (always an AnyRef) to
         * the actual result value (an AnyRef too). The transformation
         * depends on the method's static return type.
         * - for units (void), the reflective call will return null: a new
         *   boxed unit is generated.
         * - otherwise, the value is simply casted to the expected type. This
         *   is enough even for value (int et al.) values as the result of
         *   a dynamic call will box them as a side-effect. */

        /* ### CALLING THE APPLY ### */
        def callAsReflective(paramTypes: List[Type], resType: Type): Tree = {
          val runDefinitions = currentRun.runDefinitions
          import runDefinitions._

          gen.evalOnce(qual, currentOwner, unit) { qual1 =>
            /* Some info about the type of the method being called. */
            val methSym       = ad.symbol
            val boxedResType  = toBoxedType(resType)      // Int -> Integer
            val resultSym     = boxedResType.typeSymbol
            // If this is a primitive method type (like '+' in 5+5=10) then the
            // parameter types and the (unboxed) result type should all be primitive types,
            // and the method name should be in the primitive->structural map.
            def isJavaValueMethod = (
              (resType :: paramTypes forall isJavaValueType) && // issue #1110
              (getPrimitiveReplacementForStructuralCall(methSym.name).isDefined)
            )
            // Erasure lets Unit through as Unit, but a method returning Any will have an
            // erased return type of Object and should also allow Unit.
            def isDefinitelyUnit  = (resultSym == UnitClass)
            def isMaybeUnit       = (resultSym == ObjectClass) || isDefinitelyUnit
            // If there's any chance this signature could be met by an Array.
            val isArrayMethodSignature = {
              def typesMatchApply = paramTypes match {
                case List(tp) => tp <:< IntTpe
                case _        => false
              }
              def typesMatchUpdate = paramTypes match {
                case List(tp1, tp2) => (tp1 <:< IntTpe) && isMaybeUnit
                case _              => false
              }

              (methSym.name == nme.length && params.isEmpty) ||
              (methSym.name == nme.clone_ && params.isEmpty) ||
              (methSym.name == nme.apply  && typesMatchApply) ||
              (methSym.name == nme.update && typesMatchUpdate)
            }

            /* Some info about the argument at the call site. */
            val qualSym           = qual.tpe.typeSymbol
            val args              = qual1() :: params
            def isDefinitelyArray = (qualSym == ArrayClass)
            def isMaybeArray      = (qualSym == ObjectClass) || isDefinitelyArray
            def isMaybeBoxed      = platform isMaybeBoxed qualSym

            // This is complicated a bit by trying to handle Arrays correctly.
            // Under normal circumstances if the erased return type is Object then
            // we're not going to box it to Unit, but that is the situation with
            // a signature like def f(x: { def update(x: Int, y: Long): Any })
            //
            // However we only want to do that boxing if it has been determined
            // to be an Array and a method returning Unit.  But for this fixResult
            // could be called in one place: instead it is called separately from the
            // unconditional outcomes (genValueCall, genArrayCall, genDefaultCall.)
            def fixResult(tree: Tree, mustBeUnit: Boolean = false) =
              if (mustBeUnit || resultSym == UnitClass) BLOCK(tree, REF(BoxedUnit_UNIT))  // boxed unit
              else if (resultSym == ObjectClass) tree                                     // no cast necessary
              else gen.mkCast(tree, boxedResType)                                         // cast to expected type

            /* Normal non-Array call */
            def genDefaultCall = {
              // reflective method call machinery
              val invokeName  = MethodClass.tpe member nme.invoke_                                  // scala.reflect.Method.invoke(...)
              def cache       = REF(reflectiveMethodCache(ad.symbol.name.toString, paramTypes))     // cache Symbol
              def lookup      = Apply(cache, List(qual1() GETCLASS()))                                // get Method object from cache
              def invokeArgs  = ArrayValue(TypeTree(ObjectTpe), params)                       // args for invocation
              def invocation  = (lookup DOT invokeName)(qual1(), invokeArgs)                        // .invoke(qual1, ...)

              // exception catching machinery
              val invokeExc   = currentOwner.newValue(mkTerm(""), ad.pos) setInfo InvocationTargetExceptionClass.tpe
              def catchVar    = Bind(invokeExc, Typed(Ident(nme.WILDCARD), TypeTree(InvocationTargetExceptionClass.tpe)))
              def catchBody   = Throw(Apply(Select(Ident(invokeExc), nme.getCause), Nil))

              // try { method.invoke } catch { case e: InvocationTargetExceptionClass => throw e.getCause() }
              fixResult(TRY (invocation) CATCH { CASE (catchVar) ==> catchBody } ENDTRY)
            }

            /* A possible primitive method call, represented by methods in BoxesRunTime. */
            def genValueCall(operator: Symbol) = fixResult(REF(operator) APPLY args)
            def genValueCallWithTest = {
              getPrimitiveReplacementForStructuralCall(methSym.name) match {
                case Some((operator, test)) =>
                  IF (test(qual1())) THEN genValueCall(operator) ELSE genDefaultCall
                case _ =>
                  genDefaultCall
              }
            }

            /* A native Array call. */
            def genArrayCall = fixResult(
              methSym.name match {
                case nme.length => REF(boxMethod(IntClass)) APPLY (REF(arrayLengthMethod) APPLY args)
                case nme.update => REF(arrayUpdateMethod) APPLY List(args(0), (REF(unboxMethod(IntClass)) APPLY args(1)), args(2))
                case nme.apply  => REF(arrayApplyMethod) APPLY List(args(0), (REF(unboxMethod(IntClass)) APPLY args(1)))
                case nme.clone_ => REF(arrayCloneMethod) APPLY List(args(0))
              },
              mustBeUnit = methSym.name == nme.update
            )

            /* A conditional Array call, when we can't determine statically if the argument is
             * an Array, but the structural type method signature is consistent with an Array method
             * so we have to generate both kinds of code.
             */
            def genArrayCallWithTest =
              IF ((qual1() GETCLASS()) DOT nme.isArray) THEN genArrayCall ELSE genDefaultCall

            localTyper typed (
              if (isMaybeBoxed && isJavaValueMethod) genValueCallWithTest
              else if (isArrayMethodSignature && isDefinitelyArray) genArrayCall
              else if (isArrayMethodSignature && isMaybeArray) genArrayCallWithTest
              else genDefaultCall
            )
          }
        }

        {

        /* ### BODY OF THE TRANSFORMATION -> remember we're in case ad@ApplyDynamic(qual, params) ### */

        /* This creates the tree that does the reflective call (see general comment
         * on the apply-dynamic tree for its format). This tree is simply composed
         * of three successive calls, first to getClass on the callee, then to
         * getMethod on the class, then to invoke on the method.
         * - getMethod needs an array of classes for choosing one amongst many
         *   overloaded versions of the method. This is provided by paramTypeClasses
         *   and must be done on the static type as Scala's dispatching is static on
         *   the parameters.
         * - invoke needs an array of AnyRefs that are the method's arguments. The
         *   erasure phase guarantees that any parameter passed to a dynamic apply
         *   is compatible (through boxing). Boxed ints et al. is what invoke expects
         *   when the applied method expects ints, hence no change needed there.
         * - in the end, the result of invoke must be fixed, again to deal with arrays.
         *   This is provided by fixResult. fixResult will cast the invocation's result
         *   to the method's return type, which is generally ok, except when this type
         *   is a value type (int et al.) in which case it must cast to the boxed version
         *   because invoke only returns object and erasure made sure the result is
         *   expected to be an AnyRef. */
        val t: Tree = {
          val (mparams, resType) = ad.symbol.tpe match {
            case MethodType(mparams, resType) =>
              assert(params.length == mparams.length, ((params, mparams)))
              (mparams, resType)
            case tpe @ OverloadedType(pre, alts) =>
              unit.warning(ad.pos, s"Overloaded type reached the backend! This is a bug in scalac.\n     Symbol: ${ad.symbol}\n  Overloads: $tpe\n  Arguments: " + ad.args.map(_.tpe))
              alts filter (_.paramss.flatten.size == params.length) map (_.tpe) match {
                case mt @ MethodType(mparams, resType) :: Nil =>
                  unit.warning(NoPosition, "Only one overload has the right arity, proceeding with overload " + mt)
                  (mparams, resType)
                case _ =>
                  unit.error(ad.pos, "Cannot resolve overload.")
                  (Nil, NoType)
              }
          }
          typedPos {
            val sym = currentOwner.newValue(mkTerm("qual"), ad.pos) setInfo qual0.tpe
            qual = REF(sym)

            BLOCK(
              ValDef(sym, qual0),
              callAsReflective(mparams map (_.tpe), resType)
            )
          }
        }

        /* For testing purposes, the dynamic application's condition
         * can be printed-out in great detail. Remove? */
        if (settings.debug) {
          def paramsToString(xs: Any*) = xs map (_.toString) mkString ", "
          val mstr = ad.symbol.tpe match {
            case MethodType(mparams, resType) =>
              sm"""|  with
                   |  - declared parameter types: '${paramsToString(mparams)}'
                   |  - passed argument types:    '${paramsToString(params)}'
                   |  - result type:              '${resType.toString}'"""
            case _ => ""
          }
          log(s"""Dynamically application '$qual.${ad.symbol.name}(${paramsToString(params)})' $mstr - resulting code: '$t'""")
        }

        /* We return the dynamic call tree, after making sure no other
         * clean-up transformation are to be applied on it. */
        transform(t)
      /* ### END OF DYNAMIC APPLY TRANSFORM ### */
      }
    }

    override def transform(tree: Tree): Tree = tree match {

      case _: ClassDef
      if (entryPoints != null) &&
         genBCode.isJavaEntryPoint(tree.symbol, currentUnit)
      =>
        // collecting symbols for entry points here (as opposed to GenBCode where they are used)
        // has the advantage of saving an additional pass over all ClassDefs.
        entryPoints ::= tree.symbol
        super.transform(tree)

      /* Transforms dynamic calls (i.e. calls to methods that are undefined
       * in the erased type space) to -- dynamically -- unsafe calls using
       * reflection. This is used for structural sub-typing of refinement
       * types, but may be used for other dynamic calls in the future.
       * For 'a.f(b)' it will generate something like:
       * 'a.getClass().
       * '  getMethod("f", Array(classOf[b.type])).
       * '  invoke(a, Array(b))
       * plus all the necessary casting/boxing/etc. machinery required
       * for type-compatibility (see fixResult).
       *
       * USAGE CONTRACT:
       * There are a number of assumptions made on the way a dynamic apply
       * is used. Assumptions relative to type are handled by the erasure
       * phase.
       * - The applied arguments are compatible with AnyRef, which means
       *   that an argument tree typed as AnyVal has already been extended
       *   with the necessary boxing calls. This implies that passed
       *   arguments might not be strictly compatible with the method's
       *   parameter types (a boxed integer while int is expected).
       * - The expected return type is an AnyRef, even when the method's
       *   return type is an AnyVal. This means that the tree containing the
       *   call has already been extended with the necessary unboxing calls
       *   (or is happy with the boxed type).
       * - The type-checker has prevented dynamic applies on methods which
       *   parameter's erased types are not statically known at the call site.
       *   This is necessary to allow dispatching the call to the correct
       *   method (dispatching on parameters is static in Scala). In practice,
       *   this limitation only arises when the called method is defined as a
       *   refinement, where the refinement defines a parameter based on a
       *   type variable. */

      case tree: ApplyDynamic =>
        transformApplyDynamic(tree)

      /* Some cleanup transformations add members to templates (classes, traits, etc).
       * When inside a template (i.e. the body of one of its members), two maps
       * (newStaticMembers and newStaticInits) are available in the tree transformer. Any mapping from
       * a symbol to a MemberDef (DefDef, ValDef, etc.) that is in newStaticMembers once the
       * transformation of the template is finished will be added as a member to the
       * template. Any mapping from a symbol to a tree that is in newStaticInits, will be added
       * as a statement of the form "symbol = tree" to the beginning of the default
       * constructor. */
      case Template(parents, self, body) =>
        localTyper = typer.atOwner(tree, currentClass)
        transformTemplate(tree)

      case Literal(c) if c.tag == ClazzTag =>
        val tpe = c.typeValue
        typedWithPos(tree.pos) {
          if (isPrimitiveValueClass(tpe.typeSymbol)) {
            if (tpe.typeSymbol == UnitClass)
              REF(BoxedUnit_TYPE)
            else
              Select(REF(boxedModule(tpe.typeSymbol)), nme.TYPE_)
          }

          else tree
        }

     /*
      * This transformation should identify Scala symbol invocations in the tree and replace them
      * with references to a static member. Also, whenever a class has at least a single symbol invocation
      * somewhere in its methods, a new static member should be created and initialized for that symbol.
      * For instance, say we have a Scala class:
      *
      * class Cls {
      *   def someSymbol1 = 'Symbolic1
      *   def someSymbol2 = 'Symbolic2
      *   def sameSymbol1 = 'Symbolic1
      *   val someSymbol3 = 'Symbolic3
      * }
      *
      * After transformation, this class looks like this:
      *
      * class Cls {
      *   private <static> var symbol$1: scala.Symbol
      *   private <static> var symbol$2: scala.Symbol
      *   private <static> var symbol$3: scala.Symbol
      *   private          val someSymbol3: scala.Symbol
      *
      *   private <static> def <clinit> = {
      *     symbol$1 = Symbol.apply("Symbolic1")
      *     symbol$2 = Symbol.apply("Symbolic2")
      *   }
      *
      *   private def <init> = {
      *     someSymbol3 = symbol$3
      *   }
      *
      *   def someSymbol1 = symbol$1
      *   def someSymbol2 = symbol$2
      *   def sameSymbol1 = symbol$1
      *   val someSymbol3 = someSymbol3
      * }
      *
      * The reasoning behind this transformation is the following. Symbols get interned - they are stored
      * in a global map which is protected with a lock. The reason for this is making equality checks
      * quicker. But calling Symbol.apply, although it does return a unique symbol, accesses a locked object,
      * making symbol access slow. To solve this, the unique symbol from the global symbol map in Symbol
      * is accessed only once during class loading, and after that, the unique symbol is in the static
      * member. Hence, it is cheap to both reach the unique symbol and do equality checks on it.
      *
      * And, finally, be advised - Scala's Symbol literal (scala.Symbol) and the Symbol class of the compiler
      * have little in common.
      */
      case Apply(fn, (arg @ Literal(Constant(symname: String))) :: Nil) if fn.symbol == Symbol_apply =>
        def transformApply = {
          // add the symbol name to a map if it's not there already
          val rhs = gen.mkMethodCall(Symbol_apply, arg :: Nil)
          val staticFieldSym = getSymbolStaticField(tree.pos, symname, rhs, tree)
          // create a reference to a static field
          val ntree = typedWithPos(tree.pos)(REF(staticFieldSym))
          super.transform(ntree)
        }
        transformApply

      // Replaces `Array(Predef.wrapArray(ArrayValue(...).$asInstanceOf[...]), <tag>)`
      // with just `ArrayValue(...).$asInstanceOf[...]`
      //
      // See SI-6611; we must *only* do this for literal vararg arrays.
      case Apply(appMeth, List(Apply(wrapRefArrayMeth, List(arg @ StripCast(ArrayValue(_, _)))), _))
      if wrapRefArrayMeth.symbol == currentRun.runDefinitions.Predef_wrapRefArray && appMeth.symbol == ArrayModule_genericApply =>
        super.transform(arg)
      case Apply(appMeth, List(elem0, Apply(wrapArrayMeth, List(rest @ ArrayValue(elemtpt, _)))))
      if wrapArrayMeth.symbol == Predef_wrapArray(elemtpt.tpe) && appMeth.symbol == ArrayModule_apply(elemtpt.tpe) =>
        super.transform(treeCopy.ArrayValue(rest, rest.elemtpt, elem0 :: rest.elems))

      case _ =>
        super.transform(tree)
    }

    /* Returns the symbol and the tree for the symbol field interning a reference to a symbol 'synmname'.
     * If it doesn't exist, i.e. the symbol is encountered the first time,
     * it creates a new static field definition and initialization and returns it.
     */
    private def getSymbolStaticField(pos: Position, symname: String, rhs: Tree, tree: Tree): Symbol = {
      symbolsStoredAsStatic.getOrElseUpdate(symname, {
        val theTyper = typer.atOwner(tree, currentClass)

        // create a symbol for the static field
        val stfieldSym = (
          currentClass.newVariable(mkTerm("symbol$"), pos, PRIVATE | STATIC | SYNTHETIC | FINAL)
            setInfoAndEnter SymbolClass.tpe
        )

        // create field definition and initialization
        val stfieldDef  = theTyper.typedPos(pos)(ValDef(stfieldSym, rhs))
        val stfieldInit = theTyper.typedPos(pos)(REF(stfieldSym) === rhs)

        // add field definition to new defs
        newStaticMembers append stfieldDef
        newStaticInits append stfieldInit

        stfieldSym
      })
    }

  } // CleanUpTransformer

}