Refactored reflection into reflect.api and refl...

Refactored reflection into reflect.api and reflect.internal. Severed the
last remaining dependency on reflect.generic. Review by extempore.

1 files changed, 1302 insertions, 0 deletions

diff --git a/src/compiler/scala/reflect/api/Trees.scala b/src/compiler/scala/reflect/api/Trees.scala
new file mode 100644
index 0000000000..3374b38b51
--- /dev/null
+++ b/src/compiler/scala/reflect/api/Trees.scala
@@ -0,0 +1,1302 @@
+/* NSC -- new Scala compiler
+ * Copyright 2005-2011 LAMP/EPFL
+ * @author  Martin Odersky
+ */
+
+package scala.reflect
+package api
+
+import java.io.{PrintWriter, StringWriter}
+import scala.collection.mutable.ListBuffer
+
+//import scala.tools.nsc.util.{ FreshNameCreator, HashSet, SourceFile }
+
+trait Trees /*extends reflect.generic.Trees*/ { self: Universe =>
+
+  private[scala] var nodeCount = 0
+
+  type Modifiers <: AbsModifiers
+
+  abstract class AbsModifiers {
+    def hasModifier(mod: Modifier.Value): Boolean
+    def allModifiers: Set[Modifier.Value]
+    def privateWithin: Name  // default: EmptyTypeName
+    def annotations: List[Tree] // default: List()
+    def mapAnnotations(f: List[Tree] => List[Tree]): Modifiers
+  }
+
+  def Modifiers(mods: Set[Modifier.Value] = Set(),
+                privateWithin: Name = EmptyTypeName,
+                annotations: List[Tree] = List()): Modifiers
+
+  // ------ tree base classes --------------------------------------------------
+
+  /** The base class for all trees */
+  abstract class Tree extends Product {
+    val id = nodeCount
+    nodeCount += 1
+
+    private[this] var rawpos: Position = NoPosition
+
+    def pos = rawpos
+    def pos_=(pos: Position) = rawpos = pos
+    def setPos(pos: Position): this.type = { rawpos = pos; this }
+
+    private[this] var rawtpe: Type = _
+
+    def tpe = rawtpe
+    def tpe_=(t: Type) = rawtpe = t
+
+    /** Set tpe to give `tp` and return this.
+     */
+    def setType(tp: Type): this.type = { rawtpe = tp; this }
+
+    /** Like `setType`, but if this is a previously empty TypeTree
+     *  that fact is remembered so that resetType will snap back.
+     */
+    def defineType(tp: Type): this.type = setType(tp)
+
+    def symbol: Symbol = null
+    def symbol_=(sym: Symbol) { throw new UnsupportedOperationException("symbol_= inapplicable for " + this) }
+    def setSymbol(sym: Symbol): this.type = { symbol = sym; this }
+
+    def hasSymbol = false
+    def isDef = false
+    def isEmpty = false
+
+    def hasSymbolWhich(f: Symbol => Boolean) = hasSymbol && f(symbol)
+
+    def isTerm: Boolean = this match {
+      case _: TermTree       => true
+      case Bind(name, _)     => name.isTermName
+      case Select(_, name)   => name.isTermName
+      case Ident(name)       => name.isTermName
+      case Annotated(_, arg) => arg.isTerm
+      case _                 => false
+    }
+
+    def isType: Boolean = this match {
+      case _: TypTree        => true
+      case Bind(name, _)     => name.isTypeName
+      case Select(_, name)   => name.isTypeName
+      case Ident(name)       => name.isTypeName
+      case Annotated(_, arg) => arg.isType
+      case _                 => false
+    }
+
+    /** Apply `f` to each subtree */
+    def foreach(f: Tree => Unit) { new ForeachTreeTraverser(f).traverse(this) }
+
+    /** Find all subtrees matching predicate `p` */
+    def filter(f: Tree => Boolean): List[Tree] = {
+      val ft = new FilterTreeTraverser(f)
+      ft.traverse(this)
+      ft.hits.toList
+    }
+
+    /** Returns optionally first tree (in a preorder traversal) which satisfies predicate `p`,
+     *  or None if none exists.
+     */
+    def find(p: Tree => Boolean): Option[Tree] = {
+      val ft = new FindTreeTraverser(p)
+      ft.traverse(this)
+      ft.result
+    }
+
+    /** Is there part of this tree which satisfies predicate `p`? */
+    def exists(p: Tree => Boolean): Boolean = !find(p).isEmpty
+
+    def equalsStructure(that : Tree) = equalsStructure0(that)(_ eq _)
+    def equalsStructure0(that: Tree)(f: (Tree,Tree) => Boolean): Boolean =
+      f(this, that) || ((this.productArity == that.productArity) && {
+        def equals0(this0: Any, that0: Any): Boolean = (this0, that0) match {
+          case (x: Tree, y: Tree)         => f(x, y) || (x equalsStructure0 y)(f)
+          case (xs: List[_], ys: List[_]) => (xs corresponds ys)(equals0)
+          case _                          => this0 == that0
+        }
+        def compareOriginals() = (this, that) match {
+          case (x: TypeTree, y: TypeTree) if x.original != null && y.original != null =>
+            (x.original equalsStructure0 y.original)(f)
+          case _                          =>
+            true
+        }
+
+        (this.productIterator zip that.productIterator forall { case (x, y) => equals0(x, y) }) && compareOriginals()
+      })
+
+    /** The direct child trees of this tree
+     *  EmptyTrees are always omitted. Lists are collapsed.
+     */
+    def children: List[Tree] = {
+      def subtrees(x: Any): List[Tree] = x match {
+        case EmptyTree   => Nil
+        case t: Tree     => List(t)
+        case xs: List[_] => xs flatMap subtrees
+        case _           => Nil
+      }
+      productIterator.toList flatMap subtrees
+    }
+
+    /** Make a copy of this tree, keeping all attributes,
+     *  except that all positions are focused (so nothing
+     *  in this tree will be found when searching by position).
+     */
+    def duplicate: this.type =
+      duplicateTree(this).asInstanceOf[this.type]
+
+    private[scala] def copyAttrs(tree: Tree): this.type = {
+      pos = tree.pos
+      tpe = tree.tpe
+      if (hasSymbol) symbol = tree.symbol
+      this
+    }
+
+    override def toString: String = show(this)
+    override def hashCode(): Int = System.identityHashCode(this)
+    override def equals(that: Any) = this eq that.asInstanceOf[AnyRef]
+  }
+
+  /** Hook to define what toString means on a tree
+   */
+  def show(tree: Tree): String
+
+  trait SymTree extends Tree {
+    override def hasSymbol = true
+    override var symbol: Symbol = NoSymbol
+  }
+
+  trait RefTree extends SymTree {
+    def name: Name
+  }
+
+  abstract class DefTree extends SymTree {
+    def name: Name
+    override def isDef = true
+  }
+
+  trait TermTree extends Tree
+
+  /** A tree for a type.  Note that not all type trees implement
+    * this trait; in particular, Ident's are an exception. */
+  trait TypTree extends Tree
+
+// ----- tree node alternatives --------------------------------------
+
+  /** The empty tree */
+  case object EmptyTree extends TermTree {
+    super.tpe_=(NoType)
+    override def tpe_=(t: Type) =
+      if (t != NoType) throw new UnsupportedOperationException("tpe_=("+t+") inapplicable for <empty>")
+    override def isEmpty = true
+  }
+
+  abstract class MemberDef extends DefTree {
+    def mods: Modifiers
+    def keyword: String = this match {
+      case TypeDef(_, _, _, _)      => "type"
+      case ClassDef(mods, _, _, _)  => if (mods hasModifier Modifier.`trait`) "trait" else "class"
+      case DefDef(_, _, _, _, _, _) => "def"
+      case ModuleDef(_, _, _)       => "object"
+      case PackageDef(_, _)         => "package"
+      case ValDef(mods, _, _, _)    => if (mods hasModifier Modifier.mutable) "var" else "val"
+      case _ => ""
+    }
+    // final def hasFlag(mask: Long): Boolean = mods hasFlag mask
+  }
+
+  /** Package clause
+   */
+  case class PackageDef(pid: RefTree, stats: List[Tree])
+       extends MemberDef {
+    def name = pid.name
+    def mods = Modifiers()
+  }
+
+  abstract class ImplDef extends MemberDef {
+    def impl: Template
+  }
+
+  /** Class definition */
+  case class ClassDef(mods: Modifiers, name: TypeName, tparams: List[TypeDef], impl: Template)
+       extends ImplDef
+
+  /** Singleton object definition
+   */
+  case class ModuleDef(mods: Modifiers, name: TermName, impl: Template)
+       extends ImplDef
+
+  abstract class ValOrDefDef extends MemberDef {
+    def name: TermName
+    def tpt: Tree
+    def rhs: Tree
+  }
+
+  /** Value definition
+   */
+  case class ValDef(mods: Modifiers, name: TermName, tpt: Tree, rhs: Tree) extends ValOrDefDef
+
+  /** Method definition
+   */
+  case class DefDef(mods: Modifiers, name: TermName, tparams: List[TypeDef],
+                    vparamss: List[List[ValDef]], tpt: Tree, rhs: Tree) extends ValOrDefDef
+
+  /** Abstract type, type parameter, or type alias */
+  case class TypeDef(mods: Modifiers, name: TypeName, tparams: List[TypeDef], rhs: Tree)
+       extends MemberDef
+
+  /** <p>
+   *    Labelled expression - the symbols in the array (must be Idents!)
+   *    are those the label takes as argument
+   *  </p>
+   *  <p>
+   *    The symbol that is given to the labeldef should have a MethodType
+   *    (as if it were a nested function)
+   *  </p>
+   *  <p>
+   *    Jumps are apply nodes attributed with label symbol, the arguments
+   *    will get assigned to the idents.
+   *  </p>
+   *  <p>
+   *  Note: on 2005-06-09 Martin, Iuli, Burak agreed to have forward
+   *        jumps within a Block.
+   *  </p>
+   */
+  case class LabelDef(name: TermName, params: List[Ident], rhs: Tree)
+       extends DefTree with TermTree
+
+
+  /** Import selector
+   *
+   * Representation of an imported name its optional rename and their optional positions
+   *
+   * @param name      the imported name
+   * @param namePos   its position or -1 if undefined
+   * @param rename    the name the import is renamed to (== name if no renaming)
+   * @param renamePos the position of the rename or -1 if undefined
+   */
+  case class ImportSelector(name: Name, namePos: Int, rename: Name, renamePos: Int)
+
+  /** Import clause
+   *
+   *  @param expr
+   *  @param selectors
+   */
+  case class Import(expr: Tree, selectors: List[ImportSelector])
+       extends SymTree
+    // The symbol of an Import is an import symbol @see Symbol.newImport
+    // It's used primarily as a marker to check that the import has been typechecked.
+
+  /** Instantiation template of a class or trait
+   *
+   *  @param parents
+   *  @param body
+   */
+  case class Template(parents: List[Tree], self: ValDef, body: List[Tree])
+       extends SymTree {
+    // the symbol of a template is a local dummy. @see Symbol.newLocalDummy
+    // the owner of the local dummy is the enclosing trait or class.
+    // the local dummy is itself the owner of any local blocks
+    // For example:
+    //
+    // class C {
+    //   def foo // owner is C
+    //   {
+    //      def bar  // owner is local dummy
+    //   }
+    // System.err.println("TEMPLATE: " + parents)
+  }
+
+  /** Block of expressions (semicolon separated expressions) */
+  case class Block(stats: List[Tree], expr: Tree)
+       extends TermTree
+
+  /** Case clause in a pattern match, eliminated during explicitouter
+   *  (except for occurrences in switch statements)
+   */
+  case class CaseDef(pat: Tree, guard: Tree, body: Tree)
+       extends Tree
+
+  /** Alternatives of patterns, eliminated by explicitouter, except for
+   *  occurrences in encoded Switch stmt (=remaining Match(CaseDef(...))
+   */
+  case class Alternative(trees: List[Tree])
+       extends TermTree
+
+  /** Repetition of pattern, eliminated by explicitouter */
+  case class Star(elem: Tree)
+       extends TermTree
+
+  /** Bind of a variable to a rhs pattern, eliminated by explicitouter
+   *
+   *  @param name
+   *  @param body
+   */
+  case class Bind(name: Name, body: Tree)
+       extends DefTree
+
+  case class UnApply(fun: Tree, args: List[Tree])
+       extends TermTree
+
+  /** Array of expressions, needs to be translated in backend,
+   */
+  case class ArrayValue(elemtpt: Tree, elems: List[Tree])
+       extends TermTree
+
+  /** Anonymous function, eliminated by analyzer */
+  case class Function(vparams: List[ValDef], body: Tree)
+       extends TermTree with SymTree
+    // The symbol of a Function is a synthetic value of name nme.ANON_FUN_NAME
+    // It is the owner of the function's parameters.
+
+  /** Assignment */
+  case class Assign(lhs: Tree, rhs: Tree)
+       extends TermTree
+
+  /** Conditional expression */
+  case class If(cond: Tree, thenp: Tree, elsep: Tree)
+       extends TermTree
+
+  /** <p>
+   *    Pattern matching expression  (before explicitouter)
+   *    Switch statements            (after explicitouter)
+   *  </p>
+   *  <p>
+   *    After explicitouter, cases will satisfy the following constraints:
+   *  </p>
+   *  <ul>
+   *    <li>all guards are EmptyTree,</li>
+   *    <li>all patterns will be either <code>Literal(Constant(x:Int))</code>
+   *      or <code>Alternative(lit|...|lit)</code></li>
+   *    <li>except for an "otherwise" branch, which has pattern
+   *      <code>Ident(nme.WILDCARD)</code></li>
+   *  </ul>
+   */
+  case class Match(selector: Tree, cases: List[CaseDef])
+       extends TermTree
+
+  /** Return expression */
+  case class Return(expr: Tree)
+       extends TermTree with SymTree
+    // The symbol of a Return node is the enclosing method.
+
+  case class Try(block: Tree, catches: List[CaseDef], finalizer: Tree)
+       extends TermTree
+
+  /** Throw expression */
+  case class Throw(expr: Tree)
+       extends TermTree
+
+  /** Object instantiation
+   *  One should always use factory method below to build a user level new.
+   *
+   *  @param tpt    a class type
+   */
+  case class New(tpt: Tree) extends TermTree
+
+  /** Type annotation, eliminated by explicit outer */
+  case class Typed(expr: Tree, tpt: Tree)
+       extends TermTree
+
+  // Martin to Sean: Should GenericApply/TypeApply/Apply not be SymTree's? After all,
+  // ApplyDynamic is a SymTree.
+  abstract class GenericApply extends TermTree {
+    val fun: Tree
+    val args: List[Tree]
+  }
+
+  /** Type application */
+  case class TypeApply(fun: Tree, args: List[Tree])
+       extends GenericApply {
+    override def symbol: Symbol = fun.symbol
+    override def symbol_=(sym: Symbol) { fun.symbol = sym }
+  }
+
+  /** Value application */
+  case class Apply(fun: Tree, args: List[Tree])
+       extends GenericApply {
+    override def symbol: Symbol = fun.symbol
+    override def symbol_=(sym: Symbol) { fun.symbol = sym }
+  }
+
+  class ApplyToImplicitArgs(fun: Tree, args: List[Tree]) extends Apply(fun, args)
+
+  class ApplyImplicitView(fun: Tree, args: List[Tree]) extends Apply(fun, args)
+
+  /** Dynamic value application.
+   *  In a dynamic application   q.f(as)
+   *   - q is stored in qual
+   *   - as is stored in args
+   *   - f is stored as the node's symbol field.
+   */
+  case class ApplyDynamic(qual: Tree, args: List[Tree])
+       extends TermTree with SymTree
+    // The symbol of an ApplyDynamic is the function symbol of `qual`, or NoSymbol, if there is none.
+
+  /** Super reference, qual = corresponding this reference */
+  case class Super(qual: Tree, mix: TypeName) extends TermTree {
+    // The symbol of a Super is the class _from_ which the super reference is made.
+    // For instance in C.super(...), it would be C.
+    override def symbol: Symbol = qual.symbol
+    override def symbol_=(sym: Symbol) { qual.symbol = sym }
+  }
+
+  /** Self reference */
+  case class This(qual: TypeName)
+        extends TermTree with SymTree
+    // The symbol of a This is the class to which the this refers.
+    // For instance in C.this, it would be C.
+
+  /** Designator <qualifier> . <name> */
+  case class Select(qualifier: Tree, name: Name)
+       extends RefTree
+
+  /** Identifier <name> */
+  case class Ident(name: Name) extends RefTree { }
+
+  class BackQuotedIdent(name: Name) extends Ident(name)
+
+  /** Literal */
+  case class Literal(value: Constant)
+        extends TermTree {
+    assert(value ne null)
+  }
+
+  def Literal(value: Any): Literal =
+    Literal(Constant(value))
+
+  /** A tree that has an annotation attached to it. Only used for annotated types and
+   *  annotation ascriptions, annotations on definitions are stored in the Modifiers.
+   *  Eliminated by typechecker (typedAnnotated), the annotations are then stored in
+   *  an AnnotatedType.
+   */
+  case class Annotated(annot: Tree, arg: Tree) extends Tree
+
+  /** Singleton type, eliminated by RefCheck */
+  case class SingletonTypeTree(ref: Tree)
+        extends TypTree
+
+  /** Type selection <qualifier> # <name>, eliminated by RefCheck */
+  case class SelectFromTypeTree(qualifier: Tree, name: TypeName)
+       extends TypTree with RefTree
+
+  /** Intersection type <parent1> with ... with <parentN> { <decls> }, eliminated by RefCheck */
+  case class CompoundTypeTree(templ: Template)
+       extends TypTree
+
+  /** Applied type <tpt> [ <args> ], eliminated by RefCheck */
+  case class AppliedTypeTree(tpt: Tree, args: List[Tree])
+       extends TypTree {
+    override def symbol: Symbol = tpt.symbol
+    override def symbol_=(sym: Symbol) { tpt.symbol = sym }
+  }
+
+  case class TypeBoundsTree(lo: Tree, hi: Tree)
+       extends TypTree
+
+  case class ExistentialTypeTree(tpt: Tree, whereClauses: List[Tree])
+       extends TypTree
+
+  /** A synthetic tree holding an arbitrary type.  Not to be confused with
+    * with TypTree, the trait for trees that are only used for type trees.
+    * TypeTree's are inserted in several places, but most notably in
+    * `RefCheck`, where the arbitrary type trees are all replaced by
+    * TypeTree's. */
+  case class TypeTree() extends TypTree {
+    private var orig: Tree = null
+    private[scala] var wasEmpty: Boolean = false
+
+    override def symbol = if (tpe == null) null else tpe.typeSymbol
+    override def isEmpty = (tpe eq null) || tpe == NoType
+
+    def original: Tree = orig
+    def setOriginal(tree: Tree): this.type = {
+      def followOriginal(t: Tree): Tree = t match {
+        case tt: TypeTree => followOriginal(tt.original)
+        case t => t
+      }
+
+      orig = followOriginal(tree); setPos(tree.pos);
+      this
+    }
+
+    override def defineType(tp: Type): this.type = {
+      wasEmpty = isEmpty
+      setType(tp)
+    }
+  }
+
+  def TypeTree(tp: Type): TypeTree = TypeTree() setType tp
+
+  // ------ traversers, copiers, and transformers ---------------------------------------------
+
+  val treeCopy = newLazyTreeCopier
+
+  class Traverser {
+    protected var currentOwner: Symbol = definitions.RootClass
+
+    def traverse(tree: Tree): Unit = tree match {
+      case EmptyTree =>
+        ;
+      case PackageDef(pid, stats) =>
+        traverse(pid)
+        atOwner(tree.symbol.moduleClass) {
+          traverseTrees(stats)
+        }
+      case ClassDef(mods, name, tparams, impl) =>
+        atOwner(tree.symbol) {
+          traverseTrees(mods.annotations); traverseTrees(tparams); traverse(impl)
+        }
+      case ModuleDef(mods, name, impl) =>
+        atOwner(tree.symbol.moduleClass) {
+          traverseTrees(mods.annotations); traverse(impl)
+        }
+      case ValDef(mods, name, tpt, rhs) =>
+        atOwner(tree.symbol) {
+          traverseTrees(mods.annotations); traverse(tpt); traverse(rhs)
+        }
+      case DefDef(mods, name, tparams, vparamss, tpt, rhs) =>
+        atOwner(tree.symbol) {
+          traverseTrees(mods.annotations); traverseTrees(tparams); traverseTreess(vparamss); traverse(tpt); traverse(rhs)
+        }
+      case TypeDef(mods, name, tparams, rhs) =>
+        atOwner(tree.symbol) {
+          traverseTrees(mods.annotations); traverseTrees(tparams); traverse(rhs)
+        }
+      case LabelDef(name, params, rhs) =>
+        traverseTrees(params); traverse(rhs)
+      case Import(expr, selectors) =>
+        traverse(expr)
+      case Annotated(annot, arg) =>
+        traverse(annot); traverse(arg)
+      case Template(parents, self, body) =>
+        traverseTrees(parents)
+        if (!self.isEmpty) traverse(self)
+        traverseStats(body, tree.symbol)
+      case Block(stats, expr) =>
+        traverseTrees(stats); traverse(expr)
+      case CaseDef(pat, guard, body) =>
+        traverse(pat); traverse(guard); traverse(body)
+      case Alternative(trees) =>
+        traverseTrees(trees)
+      case Star(elem) =>
+        traverse(elem)
+      case Bind(name, body) =>
+        traverse(body)
+      case UnApply(fun, args) =>
+        traverse(fun); traverseTrees(args)
+      case ArrayValue(elemtpt, trees) =>
+        traverse(elemtpt); traverseTrees(trees)
+      case Function(vparams, body) =>
+        atOwner(tree.symbol) {
+          traverseTrees(vparams); traverse(body)
+        }
+      case Assign(lhs, rhs) =>
+        traverse(lhs); traverse(rhs)
+      case If(cond, thenp, elsep) =>
+        traverse(cond); traverse(thenp); traverse(elsep)
+      case Match(selector, cases) =>
+        traverse(selector); traverseTrees(cases)
+      case Return(expr) =>
+        traverse(expr)
+      case Try(block, catches, finalizer) =>
+        traverse(block); traverseTrees(catches); traverse(finalizer)
+      case Throw(expr) =>
+        traverse(expr)
+      case New(tpt) =>
+        traverse(tpt)
+      case Typed(expr, tpt) =>
+        traverse(expr); traverse(tpt)
+      case TypeApply(fun, args) =>
+        traverse(fun); traverseTrees(args)
+      case Apply(fun, args) =>
+        traverse(fun); traverseTrees(args)
+      case ApplyDynamic(qual, args) =>
+        traverse(qual); traverseTrees(args)
+      case Super(qual, _) =>
+        traverse(qual)
+      case This(_) =>
+        ;
+      case Select(qualifier, selector) =>
+        traverse(qualifier)
+      case Ident(_) =>
+        ;
+      case Literal(_) =>
+        ;
+      case TypeTree() =>
+        ;
+      case SingletonTypeTree(ref) =>
+        traverse(ref)
+      case SelectFromTypeTree(qualifier, selector) =>
+        traverse(qualifier)
+      case CompoundTypeTree(templ) =>
+        traverse(templ)
+      case AppliedTypeTree(tpt, args) =>
+        traverse(tpt); traverseTrees(args)
+      case TypeBoundsTree(lo, hi) =>
+        traverse(lo); traverse(hi)
+      case ExistentialTypeTree(tpt, whereClauses) =>
+        traverse(tpt); traverseTrees(whereClauses)
+      case _ => xtraverse(this, tree)
+    }
+
+    def traverseTrees(trees: List[Tree]) {
+      trees foreach traverse
+    }
+    def traverseTreess(treess: List[List[Tree]]) {
+      treess foreach traverseTrees
+    }
+    def traverseStats(stats: List[Tree], exprOwner: Symbol) {
+      stats foreach (stat =>
+        if (exprOwner != currentOwner) atOwner(exprOwner)(traverse(stat))
+        else traverse(stat)
+      )
+    }
+
+    def atOwner(owner: Symbol)(traverse: => Unit) {
+      val prevOwner = currentOwner
+      currentOwner = owner
+      traverse
+      currentOwner = prevOwner
+    }
+
+    /** Leave apply available in the generic traverser to do something else.
+     */
+    def apply[T <: Tree](tree: T): T = { traverse(tree); tree }
+  }
+
+  protected def xtraverse(traverser: Traverser, tree: Tree): Unit = throw new MatchError(tree)
+
+  // to be implemented in subclasses:
+  type TreeCopier <: TreeCopierOps
+  def newStrictTreeCopier: TreeCopier
+  def newLazyTreeCopier: TreeCopier
+
+  trait TreeCopierOps {
+    def ClassDef(tree: Tree, mods: Modifiers, name: Name, tparams: List[TypeDef], impl: Template): ClassDef
+    def PackageDef(tree: Tree, pid: RefTree, stats: List[Tree]): PackageDef
+    def ModuleDef(tree: Tree, mods: Modifiers, name: Name, impl: Template): ModuleDef
+    def ValDef(tree: Tree, mods: Modifiers, name: Name, tpt: Tree, rhs: Tree): ValDef
+    def DefDef(tree: Tree, mods: Modifiers, name: Name, tparams: List[TypeDef], vparamss: List[List[ValDef]], tpt: Tree, rhs: Tree): DefDef
+    def TypeDef(tree: Tree, mods: Modifiers, name: Name, tparams: List[TypeDef], rhs: Tree): TypeDef
+    def LabelDef(tree: Tree, name: Name, params: List[Ident], rhs: Tree): LabelDef
+    def Import(tree: Tree, expr: Tree, selectors: List[ImportSelector]): Import
+    def Template(tree: Tree, parents: List[Tree], self: ValDef, body: List[Tree]): Template
+    def Block(tree: Tree, stats: List[Tree], expr: Tree): Block
+    def CaseDef(tree: Tree, pat: Tree, guard: Tree, body: Tree): CaseDef
+    def Alternative(tree: Tree, trees: List[Tree]): Alternative
+    def Star(tree: Tree, elem: Tree): Star
+    def Bind(tree: Tree, name: Name, body: Tree): Bind
+    def UnApply(tree: Tree, fun: Tree, args: List[Tree]): UnApply
+    def ArrayValue(tree: Tree, elemtpt: Tree, trees: List[Tree]): ArrayValue
+    def Function(tree: Tree, vparams: List[ValDef], body: Tree): Function
+    def Assign(tree: Tree, lhs: Tree, rhs: Tree): Assign
+    def If(tree: Tree, cond: Tree, thenp: Tree, elsep: Tree): If
+    def Match(tree: Tree, selector: Tree, cases: List[CaseDef]): Match
+    def Return(tree: Tree, expr: Tree): Return
+    def Try(tree: Tree, block: Tree, catches: List[CaseDef], finalizer: Tree): Try
+    def Throw(tree: Tree, expr: Tree): Throw
+    def New(tree: Tree, tpt: Tree): New
+    def Typed(tree: Tree, expr: Tree, tpt: Tree): Typed
+    def TypeApply(tree: Tree, fun: Tree, args: List[Tree]): TypeApply
+    def Apply(tree: Tree, fun: Tree, args: List[Tree]): Apply
+    def ApplyDynamic(tree: Tree, qual: Tree, args: List[Tree]): ApplyDynamic
+    def Super(tree: Tree, qual: Tree, mix: TypeName): Super
+    def This(tree: Tree, qual: Name): This
+    def Select(tree: Tree, qualifier: Tree, selector: Name): Select
+    def Ident(tree: Tree, name: Name): Ident
+    def Literal(tree: Tree, value: Constant): Literal
+    def TypeTree(tree: Tree): TypeTree
+    def Annotated(tree: Tree, annot: Tree, arg: Tree): Annotated
+    def SingletonTypeTree(tree: Tree, ref: Tree): SingletonTypeTree
+    def SelectFromTypeTree(tree: Tree, qualifier: Tree, selector: Name): SelectFromTypeTree
+    def CompoundTypeTree(tree: Tree, templ: Template): CompoundTypeTree
+    def AppliedTypeTree(tree: Tree, tpt: Tree, args: List[Tree]): AppliedTypeTree
+    def TypeBoundsTree(tree: Tree, lo: Tree, hi: Tree): TypeBoundsTree
+    def ExistentialTypeTree(tree: Tree, tpt: Tree, whereClauses: List[Tree]): ExistentialTypeTree
+  }
+
+  class StrictTreeCopier extends TreeCopierOps {
+    def ClassDef(tree: Tree, mods: Modifiers, name: Name, tparams: List[TypeDef], impl: Template) =
+      new ClassDef(mods, name.toTypeName, tparams, impl).copyAttrs(tree)
+    def PackageDef(tree: Tree, pid: RefTree, stats: List[Tree]) =
+      new PackageDef(pid, stats).copyAttrs(tree)
+    def ModuleDef(tree: Tree, mods: Modifiers, name: Name, impl: Template) =
+      new ModuleDef(mods, name, impl).copyAttrs(tree)
+    def ValDef(tree: Tree, mods: Modifiers, name: Name, tpt: Tree, rhs: Tree) =
+      new ValDef(mods, name, tpt, rhs).copyAttrs(tree)
+    def DefDef(tree: Tree, mods: Modifiers, name: Name, tparams: List[TypeDef], vparamss: List[List[ValDef]], tpt: Tree, rhs: Tree) =
+      new DefDef(mods, name, tparams, vparamss, tpt, rhs).copyAttrs(tree)
+    def TypeDef(tree: Tree, mods: Modifiers, name: Name, tparams: List[TypeDef], rhs: Tree) =
+      new TypeDef(mods, name.toTypeName, tparams, rhs).copyAttrs(tree)
+    def LabelDef(tree: Tree, name: Name, params: List[Ident], rhs: Tree) =
+      new LabelDef(name, params, rhs).copyAttrs(tree)
+    def Import(tree: Tree, expr: Tree, selectors: List[ImportSelector]) =
+      new Import(expr, selectors).copyAttrs(tree)
+    def Template(tree: Tree, parents: List[Tree], self: ValDef, body: List[Tree]) =
+      new Template(parents, self, body).copyAttrs(tree)
+    def Block(tree: Tree, stats: List[Tree], expr: Tree) =
+      new Block(stats, expr).copyAttrs(tree)
+    def CaseDef(tree: Tree, pat: Tree, guard: Tree, body: Tree) =
+      new CaseDef(pat, guard, body).copyAttrs(tree)
+    def Alternative(tree: Tree, trees: List[Tree]) =
+      new Alternative(trees).copyAttrs(tree)
+    def Star(tree: Tree, elem: Tree) =
+      new Star(elem).copyAttrs(tree)
+    def Bind(tree: Tree, name: Name, body: Tree) =
+      new Bind(name, body).copyAttrs(tree)
+    def UnApply(tree: Tree, fun: Tree, args: List[Tree]) =
+      new UnApply(fun, args).copyAttrs(tree)
+    def ArrayValue(tree: Tree, elemtpt: Tree, trees: List[Tree]) =
+      new ArrayValue(elemtpt, trees).copyAttrs(tree)
+    def Function(tree: Tree, vparams: List[ValDef], body: Tree) =
+      new Function(vparams, body).copyAttrs(tree)
+    def Assign(tree: Tree, lhs: Tree, rhs: Tree) =
+      new Assign(lhs, rhs).copyAttrs(tree)
+    def If(tree: Tree, cond: Tree, thenp: Tree, elsep: Tree) =
+      new If(cond, thenp, elsep).copyAttrs(tree)
+    def Match(tree: Tree, selector: Tree, cases: List[CaseDef]) =
+      new Match(selector, cases).copyAttrs(tree)
+    def Return(tree: Tree, expr: Tree) =
+      new Return(expr).copyAttrs(tree)
+    def Try(tree: Tree, block: Tree, catches: List[CaseDef], finalizer: Tree) =
+      new Try(block, catches, finalizer).copyAttrs(tree)
+    def Throw(tree: Tree, expr: Tree) =
+      new Throw(expr).copyAttrs(tree)
+    def New(tree: Tree, tpt: Tree) =
+      new New(tpt).copyAttrs(tree)
+    def Typed(tree: Tree, expr: Tree, tpt: Tree) =
+      new Typed(expr, tpt).copyAttrs(tree)
+    def TypeApply(tree: Tree, fun: Tree, args: List[Tree]) =
+      new TypeApply(fun, args).copyAttrs(tree)
+    def Apply(tree: Tree, fun: Tree, args: List[Tree]) =
+      (tree match {
+        case _: ApplyToImplicitArgs => new ApplyToImplicitArgs(fun, args)
+        case _: ApplyImplicitView => new ApplyImplicitView(fun, args)
+        case _ => new Apply(fun, args)
+      }).copyAttrs(tree)
+    def ApplyDynamic(tree: Tree, qual: Tree, args: List[Tree]) =
+      new ApplyDynamic(qual, args).copyAttrs(tree)
+    def Super(tree: Tree, qual: Tree, mix: TypeName) =
+      new Super(qual, mix).copyAttrs(tree)
+    def This(tree: Tree, qual: Name) =
+      new This(qual.toTypeName).copyAttrs(tree)
+    def Select(tree: Tree, qualifier: Tree, selector: Name) =
+      new Select(qualifier, selector).copyAttrs(tree)
+    def Ident(tree: Tree, name: Name) =
+      new Ident(name).copyAttrs(tree)
+    def Literal(tree: Tree, value: Constant) =
+      new Literal(value).copyAttrs(tree)
+    def TypeTree(tree: Tree) =
+      new TypeTree().copyAttrs(tree)
+    def Annotated(tree: Tree, annot: Tree, arg: Tree) =
+      new Annotated(annot, arg).copyAttrs(tree)
+    def SingletonTypeTree(tree: Tree, ref: Tree) =
+      new SingletonTypeTree(ref).copyAttrs(tree)
+    def SelectFromTypeTree(tree: Tree, qualifier: Tree, selector: Name) =
+      new SelectFromTypeTree(qualifier, selector.toTypeName).copyAttrs(tree)
+    def CompoundTypeTree(tree: Tree, templ: Template) =
+      new CompoundTypeTree(templ).copyAttrs(tree)
+    def AppliedTypeTree(tree: Tree, tpt: Tree, args: List[Tree]) =
+      new AppliedTypeTree(tpt, args).copyAttrs(tree)
+    def TypeBoundsTree(tree: Tree, lo: Tree, hi: Tree) =
+      new TypeBoundsTree(lo, hi).copyAttrs(tree)
+    def ExistentialTypeTree(tree: Tree, tpt: Tree, whereClauses: List[Tree]) =
+      new ExistentialTypeTree(tpt, whereClauses).copyAttrs(tree)
+  }
+
+  class LazyTreeCopier extends TreeCopierOps {
+    val treeCopy: TreeCopier = newStrictTreeCopier
+    def ClassDef(tree: Tree, mods: Modifiers, name: Name, tparams: List[TypeDef], impl: Template) = tree match {
+      case t @ ClassDef(mods0, name0, tparams0, impl0)
+      if (mods0 == mods) && (name0 == name) && (tparams0 == tparams) && (impl0 == impl) => t
+      case _ => treeCopy.ClassDef(tree, mods, name, tparams, impl)
+    }
+    def PackageDef(tree: Tree, pid: RefTree, stats: List[Tree]) = tree match {
+      case t @ PackageDef(pid0, stats0)
+      if (pid0 == pid) && (stats0 == stats) => t
+      case _ => treeCopy.PackageDef(tree, pid, stats)
+    }
+    def ModuleDef(tree: Tree, mods: Modifiers, name: Name, impl: Template) = tree match {
+      case t @ ModuleDef(mods0, name0, impl0)
+      if (mods0 == mods) && (name0 == name) && (impl0 == impl) => t
+      case _ => treeCopy.ModuleDef(tree, mods, name, impl)
+    }
+    def ValDef(tree: Tree, mods: Modifiers, name: Name, tpt: Tree, rhs: Tree) = tree match {
+      case t @ ValDef(mods0, name0, tpt0, rhs0)
+      if (mods0 == mods) && (name0 == name) && (tpt0 == tpt) && (rhs0 == rhs) => t
+      case _ => treeCopy.ValDef(tree, mods, name, tpt, rhs)
+    }
+    def DefDef(tree: Tree, mods: Modifiers, name: Name, tparams: List[TypeDef], vparamss: List[List[ValDef]], tpt: Tree, rhs: Tree) = tree match {
+      case t @ DefDef(mods0, name0, tparams0, vparamss0, tpt0, rhs0)
+      if (mods0 == mods) && (name0 == name) && (tparams0 == tparams) &&
+         (vparamss0 == vparamss) && (tpt0 == tpt) && (rhs == rhs0) => t
+      case _ => treeCopy.DefDef(tree, mods, name, tparams, vparamss, tpt, rhs)
+    }
+    def TypeDef(tree: Tree, mods: Modifiers, name: Name, tparams: List[TypeDef], rhs: Tree) = tree match {
+      case t @ TypeDef(mods0, name0, tparams0, rhs0)
+      if (mods0 == mods) && (name0 == name) && (tparams0 == tparams) && (rhs0 == rhs) => t
+      case _ => treeCopy.TypeDef(tree, mods, name, tparams, rhs)
+    }
+    def LabelDef(tree: Tree, name: Name, params: List[Ident], rhs: Tree) = tree match {
+      case t @ LabelDef(name0, params0, rhs0)
+      if (name0 == name) && (params0 == params) && (rhs0 == rhs) => t
+      case _ => treeCopy.LabelDef(tree, name, params, rhs)
+    }
+    def Import(tree: Tree, expr: Tree, selectors: List[ImportSelector]) = tree match {
+      case t @ Import(expr0, selectors0)
+      if (expr0 == expr) && (selectors0 == selectors) => t
+      case _ => treeCopy.Import(tree, expr, selectors)
+    }
+    def Template(tree: Tree, parents: List[Tree], self: ValDef, body: List[Tree]) = tree match {
+      case t @ Template(parents0, self0, body0)
+      if (parents0 == parents) && (self0 == self) && (body0 == body) => t
+      case _ => treeCopy.Template(tree, parents, self, body)
+    }
+    def Block(tree: Tree, stats: List[Tree], expr: Tree) = tree match {
+      case t @ Block(stats0, expr0)
+      if ((stats0 == stats) && (expr0 == expr)) => t
+      case _ => treeCopy.Block(tree, stats, expr)
+    }
+    def CaseDef(tree: Tree, pat: Tree, guard: Tree, body: Tree) = tree match {
+      case t @ CaseDef(pat0, guard0, body0)
+      if (pat0 == pat) && (guard0 == guard) && (body0 == body) => t
+      case _ => treeCopy.CaseDef(tree, pat, guard, body)
+    }
+    def Alternative(tree: Tree, trees: List[Tree]) = tree match {
+      case t @ Alternative(trees0)
+      if trees0 == trees => t
+      case _ => treeCopy.Alternative(tree, trees)
+    }
+    def Star(tree: Tree, elem: Tree) = tree match {
+      case t @ Star(elem0)
+      if elem0 == elem => t
+      case _ => treeCopy.Star(tree, elem)
+    }
+    def Bind(tree: Tree, name: Name, body: Tree) = tree match {
+      case t @ Bind(name0, body0)
+      if (name0 == name) && (body0 == body) => t
+      case _ => treeCopy.Bind(tree, name, body)
+    }
+    def UnApply(tree: Tree, fun: Tree, args: List[Tree]) = tree match {
+      case t @ UnApply(fun0, args0)
+      if (fun0 == fun) && (args0 == args) => t
+      case _ => treeCopy.UnApply(tree, fun, args)
+    }
+    def ArrayValue(tree: Tree, elemtpt: Tree, trees: List[Tree]) = tree match {
+      case t @ ArrayValue(elemtpt0, trees0)
+      if (elemtpt0 == elemtpt) && (trees0 == trees) => t
+      case _ => treeCopy.ArrayValue(tree, elemtpt, trees)
+    }
+    def Function(tree: Tree, vparams: List[ValDef], body: Tree) = tree match {
+      case t @ Function(vparams0, body0)
+      if (vparams0 == vparams) && (body0 == body) => t
+      case _ => treeCopy.Function(tree, vparams, body)
+    }
+    def Assign(tree: Tree, lhs: Tree, rhs: Tree) = tree match {
+      case t @ Assign(lhs0, rhs0)
+      if (lhs0 == lhs) && (rhs0 == rhs) => t
+      case _ => treeCopy.Assign(tree, lhs, rhs)
+    }
+    def If(tree: Tree, cond: Tree, thenp: Tree, elsep: Tree) = tree match {
+      case t @ If(cond0, thenp0, elsep0)
+      if (cond0 == cond) && (thenp0 == thenp) && (elsep0 == elsep) => t
+      case _ => treeCopy.If(tree, cond, thenp, elsep)
+    }
+    def Match(tree: Tree, selector: Tree, cases: List[CaseDef]) =  tree match {
+      case t @ Match(selector0, cases0)
+      if (selector0 == selector) && (cases0 == cases) => t
+      case _ => treeCopy.Match(tree, selector, cases)
+    }
+    def Return(tree: Tree, expr: Tree) = tree match {
+      case t @ Return(expr0)
+      if expr0 == expr => t
+      case _ => treeCopy.Return(tree, expr)
+    }
+    def Try(tree: Tree, block: Tree, catches: List[CaseDef], finalizer: Tree) = tree match {
+      case t @ Try(block0, catches0, finalizer0)
+      if (block0 == block) && (catches0 == catches) && (finalizer0 == finalizer) => t
+      case _ => treeCopy.Try(tree, block, catches, finalizer)
+    }
+    def Throw(tree: Tree, expr: Tree) = tree match {
+      case t @ Throw(expr0)
+      if expr0 == expr => t
+      case _ => treeCopy.Throw(tree, expr)
+    }
+    def New(tree: Tree, tpt: Tree) = tree match {
+      case t @ New(tpt0)
+      if tpt0 == tpt => t
+      case _ => treeCopy.New(tree, tpt)
+    }
+    def Typed(tree: Tree, expr: Tree, tpt: Tree) = tree match {
+      case t @ Typed(expr0, tpt0)
+      if (expr0 == expr) && (tpt0 == tpt) => t
+      case _ => treeCopy.Typed(tree, expr, tpt)
+    }
+    def TypeApply(tree: Tree, fun: Tree, args: List[Tree]) = tree match {
+      case t @ TypeApply(fun0, args0)
+      if (fun0 == fun) && (args0 == args) => t
+      case _ => treeCopy.TypeApply(tree, fun, args)
+    }
+    def Apply(tree: Tree, fun: Tree, args: List[Tree]) = tree match {
+      case t @ Apply(fun0, args0)
+      if (fun0 == fun) && (args0 == args) => t
+      case _ => treeCopy.Apply(tree, fun, args)
+    }
+    def ApplyDynamic(tree: Tree, qual: Tree, args: List[Tree]) = tree match {
+      case t @ ApplyDynamic(qual0, args0)
+      if (qual0 == qual) && (args0 == args) => t
+      case _ => treeCopy.ApplyDynamic(tree, qual, args)
+    }
+    def Super(tree: Tree, qual: Tree, mix: TypeName) = tree match {
+      case t @ Super(qual0, mix0)
+      if (qual0 == qual) && (mix0 == mix) => t
+      case _ => treeCopy.Super(tree, qual, mix)
+    }
+    def This(tree: Tree, qual: Name) = tree match {
+      case t @ This(qual0)
+      if qual0 == qual => t
+      case _ => treeCopy.This(tree, qual)
+    }
+    def Select(tree: Tree, qualifier: Tree, selector: Name) = tree match {
+      case t @ Select(qualifier0, selector0)
+      if (qualifier0 == qualifier) && (selector0 == selector) => t
+      case _ => treeCopy.Select(tree, qualifier, selector)
+    }
+    def Ident(tree: Tree, name: Name) = tree match {
+      case t @ Ident(name0)
+      if name0 == name => t
+      case _ => treeCopy.Ident(tree, name)
+    }
+    def Literal(tree: Tree, value: Constant) = tree match {
+      case t @ Literal(value0)
+      if value0 == value => t
+      case _ => treeCopy.Literal(tree, value)
+    }
+    def TypeTree(tree: Tree) = tree match {
+      case t @ TypeTree() => t
+      case _ => treeCopy.TypeTree(tree)
+    }
+    def Annotated(tree: Tree, annot: Tree, arg: Tree) = tree match {
+      case t @ Annotated(annot0, arg0)
+      if (annot0==annot) => t
+      case _ => treeCopy.Annotated(tree, annot, arg)
+    }
+    def SingletonTypeTree(tree: Tree, ref: Tree) = tree match {
+      case t @ SingletonTypeTree(ref0)
+      if ref0 == ref => t
+      case _ => treeCopy.SingletonTypeTree(tree, ref)
+    }
+    def SelectFromTypeTree(tree: Tree, qualifier: Tree, selector: Name) = tree match {
+      case t @ SelectFromTypeTree(qualifier0, selector0)
+      if (qualifier0 == qualifier) && (selector0 == selector) => t
+      case _ => treeCopy.SelectFromTypeTree(tree, qualifier, selector)
+    }
+    def CompoundTypeTree(tree: Tree, templ: Template) = tree match {
+      case t @ CompoundTypeTree(templ0)
+      if templ0 == templ => t
+      case _ => treeCopy.CompoundTypeTree(tree, templ)
+    }
+    def AppliedTypeTree(tree: Tree, tpt: Tree, args: List[Tree]) = tree match {
+      case t @ AppliedTypeTree(tpt0, args0)
+      if (tpt0 == tpt) && (args0 == args) => t
+      case _ => treeCopy.AppliedTypeTree(tree, tpt, args)
+    }
+    def TypeBoundsTree(tree: Tree, lo: Tree, hi: Tree) = tree match {
+      case t @ TypeBoundsTree(lo0, hi0)
+      if (lo0 == lo) && (hi0 == hi) => t
+      case _ => treeCopy.TypeBoundsTree(tree, lo, hi)
+    }
+    def ExistentialTypeTree(tree: Tree, tpt: Tree, whereClauses: List[Tree]) = tree match {
+      case t @ ExistentialTypeTree(tpt0, whereClauses0)
+      if (tpt0 == tpt) && (whereClauses0 == whereClauses) => t
+      case _ => treeCopy.ExistentialTypeTree(tree, tpt, whereClauses)
+    }
+  }
+
+  abstract class Transformer {
+    val treeCopy: TreeCopier = newLazyTreeCopier
+    protected var currentOwner: Symbol = definitions.RootClass
+    protected def currentMethod = currentOwner.enclMethod
+    protected def currentClass = currentOwner.enclClass
+    protected def currentPackage = currentOwner.toplevelClass.owner
+    def transform(tree: Tree): Tree = tree match {
+      case EmptyTree =>
+        tree
+      case PackageDef(pid, stats) =>
+        treeCopy.PackageDef(
+          tree, transform(pid).asInstanceOf[RefTree],
+          atOwner(tree.symbol.moduleClass) {
+            transformStats(stats, currentOwner)
+          }
+        )
+      case ClassDef(mods, name, tparams, impl) =>
+        atOwner(tree.symbol) {
+          treeCopy.ClassDef(tree, transformModifiers(mods), name,
+                            transformTypeDefs(tparams), transformTemplate(impl))
+        }
+      case ModuleDef(mods, name, impl) =>
+        atOwner(tree.symbol.moduleClass) {
+          treeCopy.ModuleDef(tree, transformModifiers(mods),
+                             name, transformTemplate(impl))
+        }
+      case ValDef(mods, name, tpt, rhs) =>
+        atOwner(tree.symbol) {
+          treeCopy.ValDef(tree, transformModifiers(mods),
+                          name, transform(tpt), transform(rhs))
+        }
+      case DefDef(mods, name, tparams, vparamss, tpt, rhs) =>
+        atOwner(tree.symbol) {
+          treeCopy.DefDef(tree, transformModifiers(mods), name,
+                          transformTypeDefs(tparams), transformValDefss(vparamss),
+                          transform(tpt), transform(rhs))
+        }
+      case TypeDef(mods, name, tparams, rhs) =>
+        atOwner(tree.symbol) {
+          treeCopy.TypeDef(tree, transformModifiers(mods), name,
+                           transformTypeDefs(tparams), transform(rhs))
+        }
+      case LabelDef(name, params, rhs) =>
+        treeCopy.LabelDef(tree, name, transformIdents(params), transform(rhs)) //bq: Martin, once, atOwner(...) works, also change `LamdaLifter.proxy'
+      case Import(expr, selectors) =>
+        treeCopy.Import(tree, transform(expr), selectors)
+      case Template(parents, self, body) =>
+        treeCopy.Template(tree, transformTrees(parents), transformValDef(self), transformStats(body, tree.symbol))
+      case Block(stats, expr) =>
+        treeCopy.Block(tree, transformStats(stats, currentOwner), transform(expr))
+      case CaseDef(pat, guard, body) =>
+        treeCopy.CaseDef(tree, transform(pat), transform(guard), transform(body))
+      case Alternative(trees) =>
+        treeCopy.Alternative(tree, transformTrees(trees))
+      case Star(elem) =>
+        treeCopy.Star(tree, transform(elem))
+      case Bind(name, body) =>
+        treeCopy.Bind(tree, name, transform(body))
+      case UnApply(fun, args) =>
+        treeCopy.UnApply(tree, fun, transformTrees(args)) // bq: see test/.../unapplyContexts2.scala
+      case ArrayValue(elemtpt, trees) =>
+        treeCopy.ArrayValue(tree, transform(elemtpt), transformTrees(trees))
+      case Function(vparams, body) =>
+        atOwner(tree.symbol) {
+          treeCopy.Function(tree, transformValDefs(vparams), transform(body))
+        }
+      case Assign(lhs, rhs) =>
+        treeCopy.Assign(tree, transform(lhs), transform(rhs))
+      case If(cond, thenp, elsep) =>
+        treeCopy.If(tree, transform(cond), transform(thenp), transform(elsep))
+      case Match(selector, cases) =>
+        treeCopy.Match(tree, transform(selector), transformCaseDefs(cases))
+      case Return(expr) =>
+        treeCopy.Return(tree, transform(expr))
+      case Try(block, catches, finalizer) =>
+        treeCopy.Try(tree, transform(block), transformCaseDefs(catches), transform(finalizer))
+      case Throw(expr) =>
+        treeCopy.Throw(tree, transform(expr))
+      case New(tpt) =>
+        treeCopy.New(tree, transform(tpt))
+      case Typed(expr, tpt) =>
+        treeCopy.Typed(tree, transform(expr), transform(tpt))
+      case TypeApply(fun, args) =>
+        treeCopy.TypeApply(tree, transform(fun), transformTrees(args))
+      case Apply(fun, args) =>
+        treeCopy.Apply(tree, transform(fun), transformTrees(args))
+      case ApplyDynamic(qual, args) =>
+        treeCopy.ApplyDynamic(tree, transform(qual), transformTrees(args))
+      case Super(qual, mix) =>
+        treeCopy.Super(tree, transform(qual), mix)
+      case This(qual) =>
+        treeCopy.This(tree, qual)
+      case Select(qualifier, selector) =>
+        treeCopy.Select(tree, transform(qualifier), selector)
+      case Ident(name) =>
+        treeCopy.Ident(tree, name)
+      case Literal(value) =>
+        treeCopy.Literal(tree, value)
+      case TypeTree() =>
+        treeCopy.TypeTree(tree)
+      case Annotated(annot, arg) =>
+        treeCopy.Annotated(tree, transform(annot), transform(arg))
+      case SingletonTypeTree(ref) =>
+        treeCopy.SingletonTypeTree(tree, transform(ref))
+      case SelectFromTypeTree(qualifier, selector) =>
+        treeCopy.SelectFromTypeTree(tree, transform(qualifier), selector)
+      case CompoundTypeTree(templ) =>
+        treeCopy.CompoundTypeTree(tree, transformTemplate(templ))
+      case AppliedTypeTree(tpt, args) =>
+        treeCopy.AppliedTypeTree(tree, transform(tpt), transformTrees(args))
+      case TypeBoundsTree(lo, hi) =>
+        treeCopy.TypeBoundsTree(tree, transform(lo), transform(hi))
+      case ExistentialTypeTree(tpt, whereClauses) =>
+        treeCopy.ExistentialTypeTree(tree, transform(tpt), transformTrees(whereClauses))
+      case _ =>
+        xtransform(this, tree)
+    }
+
+    def transformTrees(trees: List[Tree]): List[Tree] =
+        trees mapConserve (transform(_))
+    def transformTemplate(tree: Template): Template =
+      transform(tree: Tree).asInstanceOf[Template]
+    def transformTypeDefs(trees: List[TypeDef]): List[TypeDef] =
+      trees mapConserve (tree => transform(tree).asInstanceOf[TypeDef])
+    def transformValDef(tree: ValDef): ValDef =
+      if (tree.isEmpty) tree else transform(tree).asInstanceOf[ValDef]
+    def transformValDefs(trees: List[ValDef]): List[ValDef] =
+      trees mapConserve (transformValDef(_))
+    def transformValDefss(treess: List[List[ValDef]]): List[List[ValDef]] =
+      treess mapConserve (transformValDefs(_))
+    def transformCaseDefs(trees: List[CaseDef]): List[CaseDef] =
+      trees mapConserve (tree => transform(tree).asInstanceOf[CaseDef])
+    def transformIdents(trees: List[Ident]): List[Ident] =
+      trees mapConserve (tree => transform(tree).asInstanceOf[Ident])
+    def transformStats(stats: List[Tree], exprOwner: Symbol): List[Tree] =
+      stats mapConserve (stat =>
+        if (exprOwner != currentOwner && stat.isTerm) atOwner(exprOwner)(transform(stat))
+        else transform(stat)) filter (EmptyTree !=)
+    def transformModifiers(mods: Modifiers): Modifiers =
+      mods.mapAnnotations(transformTrees)
+
+    def atOwner[A](owner: Symbol)(trans: => A): A = {
+      val prevOwner = currentOwner
+      currentOwner = owner
+      val result = trans
+      currentOwner = prevOwner
+      result
+    }
+  }
+
+  protected def xtransform(transformer: Transformer, tree: Tree): Tree = throw new MatchError(tree)
+
+  class ForeachTreeTraverser(f: Tree => Unit) extends Traverser {
+    override def traverse(t: Tree) {
+      f(t)
+      super.traverse(t)
+    }
+  }
+
+  class FilterTreeTraverser(p: Tree => Boolean) extends Traverser {
+    val hits = new ListBuffer[Tree]
+    override def traverse(t: Tree) {
+      if (p(t)) hits += t
+      super.traverse(t)
+    }
+  }
+
+  class FindTreeTraverser(p: Tree => Boolean) extends Traverser {
+    var result: Option[Tree] = None
+    override def traverse(t: Tree) {
+      if (result.isEmpty) {
+        if (p(t)) result = Some(t)
+        super.traverse(t)
+      }
+    }
+  }
+
+  protected def duplicateTree(tree: Tree): Tree
+
+/* A standard pattern match
+  case EmptyTree =>
+  case PackageDef(pid, stats) =>
+     // package pid { stats }
+  case ClassDef(mods, name, tparams, impl) =>
+     // mods class name [tparams] impl   where impl = extends parents { defs }
+  case ModuleDef(mods, name, impl) =>                             (eliminated by refcheck)
+     // mods object name impl  where impl = extends parents { defs }
+  case ValDef(mods, name, tpt, rhs) =>
+     // mods val name: tpt = rhs
+     // note missing type information is expressed by tpt = TypeTree()
+  case DefDef(mods, name, tparams, vparamss, tpt, rhs) =>
+     // mods def name[tparams](vparams_1)...(vparams_n): tpt = rhs
+     // note missing type information is expressed by tpt = TypeTree()
+  case TypeDef(mods, name, tparams, rhs) =>                       (eliminated by erasure)
+     // mods type name[tparams] = rhs
+     // mods type name[tparams] >: lo <: hi,  where lo, hi are in a TypeBoundsTree,
+                                              and DEFERRED is set in mods
+  case LabelDef(name, params, rhs) =>
+     // used for tailcalls and like
+     // while/do are desugared to label defs as follows:
+     // while (cond) body ==> LabelDef($L, List(), if (cond) { body; L$() } else ())
+     // do body while (cond) ==> LabelDef($L, List(), body; if (cond) L$() else ())
+  case Import(expr, selectors) =>                                 (eliminated by typecheck)
+     // import expr.{selectors}
+     // Selectors are a list of pairs of names (from, to).
+     // The last (and maybe only name) may be a nme.WILDCARD
+     // for instance
+     //   import qual.{x, y => z, _}  would be represented as
+     //   Import(qual, List(("x", "x"), ("y", "z"), (WILDCARD, null)))
+  case Template(parents, self, body) =>
+     // extends parents { self => body }
+     // if self is missing it is represented as emptyValDef
+  case Block(stats, expr) =>
+     // { stats; expr }
+  case CaseDef(pat, guard, body) =>                               (eliminated by transmatch/explicitouter)
+    // case pat if guard => body
+  case Alternative(trees) =>                                      (eliminated by transmatch/explicitouter)
+    // pat1 | ... | patn
+  case Star(elem) =>                                              (eliminated by transmatch/explicitouter)
+    // pat*
+  case Bind(name, body) =>                                        (eliminated by transmatch/explicitouter)
+    // name @ pat
+  case UnApply(fun: Tree, args)                                   (introduced by typer, eliminated by transmatch/explicitouter)
+    // used for unapply's
+  case ArrayValue(elemtpt, trees) =>                              (introduced by uncurry)
+    // used to pass arguments to vararg arguments
+    // for instance, printf("%s%d", foo, 42) is translated to after uncurry to:
+    // Apply(
+    //   Ident("printf"),
+    //   Literal("%s%d"),
+    //   ArrayValue(<Any>, List(Ident("foo"), Literal(42))))
+  case Function(vparams, body) =>                                 (eliminated by lambdaLift)
+    // vparams => body  where vparams:List[ValDef]
+  case Assign(lhs, rhs) =>
+    // lhs = rhs
+  case If(cond, thenp, elsep) =>
+    // if (cond) thenp else elsep
+  case Match(selector, cases) =>
+    // selector match { cases }
+  case Return(expr) =>
+    // return expr
+  case Try(block, catches, finalizer) =>
+    // try block catch { catches } finally finalizer where catches: List[CaseDef]
+  case Throw(expr) =>
+    // throw expr
+  case New(tpt) =>
+    // new tpt   always in the context: (new tpt).<init>[targs](args)
+  case Typed(expr, tpt) =>                                        (eliminated by erasure)
+    // expr: tpt
+  case TypeApply(fun, args) =>
+    // fun[args]
+  case Apply(fun, args) =>
+    // fun(args)
+    // for instance fun[targs](args)  is expressed as  Apply(TypeApply(fun, targs), args)
+  case ApplyDynamic(qual, args)                                   (introduced by erasure, eliminated by cleanup)
+    // fun(args)
+  case Super(qual, mix) =>
+    // qual.super[mix]     if qual and/or mix is empty, ther are tpnme.EMPTY
+  case This(qual) =>
+    // qual.this
+  case Select(qualifier, selector) =>
+    // qualifier.selector
+  case Ident(name) =>
+    // name
+    // note: type checker converts idents that refer to enclosing fields or methods
+    // to selects; name ==> this.name
+  case Literal(value) =>
+    // value
+  case TypeTree() =>                                              (introduced by refcheck)
+    // a type that's not written out, but given in the tpe attribute
+  case Annotated(annot, arg) =>                                   (eliminated by typer)
+    // arg @annot  for types,  arg: @annot for exprs
+  case SingletonTypeTree(ref) =>                                  (eliminated by uncurry)
+    // ref.type
+  case SelectFromTypeTree(qualifier, selector) =>                 (eliminated by uncurry)
+    // qualifier # selector, a path-dependent type p.T is expressed as p.type # T
+  case CompoundTypeTree(templ: Template) =>                       (eliminated by uncurry)
+    // parent1 with ... with parentN { refinement }
+  case AppliedTypeTree(tpt, args) =>                              (eliminated by uncurry)
+    // tpt[args]
+  case TypeBoundsTree(lo, hi) =>                                  (eliminated by uncurry)
+    // >: lo <: hi
+  case ExistentialTypeTree(tpt, whereClauses) =>                  (eliminated by uncurry)
+    // tpt forSome { whereClauses }
+*/
+}
+