path: root/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala

/* NSC -- new Scala compiler
 * Copyright 2005-2011 LAMP/EPFL
 * @author  Martin Odersky
 */

//todo: allow infix type patterns
//todo verify when stableId's should be just plain qualified type ids

package scala.tools.nsc
package ast.parser

import scala.collection.mutable.{ListBuffer, StringBuilder}
import util.{ SourceFile, OffsetPosition, FreshNameCreator }
import scala.reflect.internal.{ ModifierFlags => Flags }
import Tokens._
import scala.reflect.internal.Chars.{ isScalaLetter }

/** Historical note: JavaParsers started life as a direct copy of Parsers
 *  but at a time when that Parsers had been replaced by a different one.
 *  Later it was dropped and the original Parsers reinstated, leaving us with
 *  massive duplication between Parsers and JavaParsers.
 *
 *  This trait and the similar one for Scanners/JavaScanners represents
 *  the beginnings of a campaign against this latest incursion by Cutty
 *  McPastington and his army of very similar soldiers.
 */
trait ParsersCommon extends ScannersCommon {
  val global : Global
  import global._

  /** This is now an abstract class, only to work around the optimizer:
   *  methods in traits are never inlined.
   */
  abstract class ParserCommon {
    val in: ScannerCommon
    def freshName(prefix: String): Name
    def freshTermName(prefix: String): TermName
    def freshTypeName(prefix: String): TypeName
    def deprecationWarning(off: Int, msg: String): Unit
    def accept(token: Int): Int
  
    /** Methods inParensOrError and similar take a second argument which, should
     *  the next token not be the expected opener (e.g. LPAREN) will be returned
     *  instead of the contents of the groupers.  However in all cases accept(LPAREN)
     *  will be called, so a parse error will still result.  If the grouping is
     *  optional, in.token should be tested before calling these methods.
     */
    @inline final def inParens[T](body: => T): T = {
      accept(LPAREN)
      val ret = body
      accept(RPAREN)
      ret
    }
    @inline final def inParensOrError[T](body: => T, alt: T): T =
      if (in.token == LPAREN) inParens(body)
      else { accept(LPAREN) ; alt }

    @inline final def inParensOrUnit[T](body: => Tree): Tree = inParensOrError(body, Literal(Constant()))
    @inline final def inParensOrNil[T](body: => List[T]): List[T] = inParensOrError(body, Nil)

    @inline final def inBraces[T](body: => T): T = {
      accept(LBRACE)
      val ret = body
      accept(RBRACE)
      ret
    }
    @inline final def inBracesOrError[T](body: => T, alt: T): T =
      if (in.token == LBRACE) inBraces(body)
      else { accept(LBRACE) ; alt }

    @inline final def inBracesOrNil[T](body: => List[T]): List[T] = inBracesOrError(body, Nil)
    @inline final def inBracesOrUnit[T](body: => Tree): Tree = inBracesOrError(body, Literal(Constant()))

    @inline final def inBrackets[T](body: => T): T = {
      accept(LBRACKET)
      val ret = body
      accept(RBRACKET)
      ret
    }

    /** Creates an actual Parens node (only used during parsing.)
     */
    @inline final def makeParens(body: => List[Tree]): Parens =
      Parens(inParens(if (in.token == RPAREN) Nil else body))
  }
}

/** Performs the following context-free rewritings:
 *
 *  <ol>
 *    <li>
 *      Places all pattern variables in Bind nodes. In a pattern, for
 *      identifiers <code>x</code>:<pre>
 *                 x  => x @ _
 *               x:T  => x @ (_ : T)</pre>
 *    </li>
 *    <li>Removes pattern definitions (PatDef's) as follows:
 *      If pattern is a simple (typed) identifier:<pre>
 *        <b>val</b> x = e     ==>  <b>val</b> x = e
 *        <b>val</b> x: T = e  ==>  <b>val</b> x: T = e</pre>
 *
 *      if there are no variables in pattern<pre>
 *        <b>val</b> p = e  ==>  e match (case p => ())</pre>
 *
 *      if there is exactly one variable in pattern<pre>
 *        <b>val</b> x_1 = e <b>match</b> (case p => (x_1))</pre>
 *
 *      if there is more than one variable in pattern<pre>
 *        <b>val</b> p = e  ==>  <b>private synthetic val</b> t$ = e <b>match</b> (case p => (x_1, ..., x_N))
 *                        <b>val</b> x_1 = t$._1
 *                        ...
 *                        <b>val</b> x_N = t$._N</pre>
 *    </li>
 *    <li>
 *       Removes function types as follows:<pre>
 *        (argtpes) => restpe   ==>   scala.Function_n[argtpes, restpe]</pre>
 *    </li>
 *    <li>
 *      Wraps naked case definitions in a match as follows:<pre>
 *        { cases }   ==>   (x => x.match {cases})<span style="font-family:normal;">, except when already argument to match</span></pre>
 *    </li>
 *  </ol>
 */
trait Parsers extends Scanners with MarkupParsers with ParsersCommon {
self =>
  val global: Global
  import global._

  case class OpInfo(operand: Tree, operator: Name, offset: Offset)

  class SourceFileParser(val source: SourceFile) extends Parser {

    /** The parse starting point depends on whether the source file is self-contained:
     *  if not, the AST will be supplemented.
     */
    def parseStartRule =
      if (source.isSelfContained) () => compilationUnit()
      else () => scriptBody()

    def newScanner = new SourceFileScanner(source)

    val in = newScanner
    in.init()

    private val globalFresh = new FreshNameCreator.Default

    def freshName(prefix: String): Name = freshTermName(prefix)
    def freshTermName(prefix: String): TermName = newTermName(globalFresh.newName(prefix))
    def freshTypeName(prefix: String): TypeName = newTypeName(globalFresh.newName(prefix))

    def o2p(offset: Int): Position = new OffsetPosition(source, offset)
    def r2p(start: Int, mid: Int, end: Int): Position = rangePos(source, start, mid, end)

    // suppress warnings; silent abort on errors
    def warning(offset: Int, msg: String) {}
    def deprecationWarning(offset: Int, msg: String) {}

    def syntaxError(offset: Int, msg: String): Unit = throw new MalformedInput(offset, msg)
    def incompleteInputError(msg: String): Unit = throw new MalformedInput(source.content.length - 1, msg)

    /** the markup parser */
    lazy val xmlp = new MarkupParser(this, true)

    object symbXMLBuilder extends SymbolicXMLBuilder(this, true) { // DEBUG choices
      val global: self.global.type = self.global
      def freshName(prefix: String): Name = SourceFileParser.this.freshName(prefix)
    }

    def xmlLiteral : Tree = xmlp.xLiteral
    def xmlLiteralPattern : Tree = xmlp.xLiteralPattern
  }

  class OutlineParser(source: SourceFile) extends SourceFileParser(source) {

    def skipBraces[T](body: T): T = {
      accept(LBRACE)
      var openBraces = 1
      while (in.token != EOF && openBraces > 0) {
        if (in.token == XMLSTART) xmlLiteral()
        else {
          if (in.token == LBRACE) openBraces += 1
          else if (in.token == RBRACE) openBraces -= 1
          in.nextToken()
        }
      }
      body
    }

    override def blockExpr(): Tree = skipBraces(EmptyTree)

    override def templateBody(isPre: Boolean) = skipBraces((emptyValDef, List(EmptyTree)))
  }

  class UnitParser(val unit: global.CompilationUnit, patches: List[BracePatch]) extends SourceFileParser(unit.source) {

    def this(unit: global.CompilationUnit) = this(unit, List())

    override def newScanner = new UnitScanner(unit, patches)

    override def freshTermName(prefix: String): TermName = unit.freshTermName(prefix)
    override def freshTypeName(prefix: String): TypeName = unit.freshTypeName(prefix)

    override def warning(offset: Int, msg: String) {
      unit.warning(o2p(offset), msg)
    }

    override def deprecationWarning(offset: Int, msg: String) {
      unit.deprecationWarning(o2p(offset), msg)
    }

    private var smartParsing = false
    @inline private def withSmartParsing[T](body: => T): T = {
      val saved = smartParsing
      smartParsing = true
      try body
      finally smartParsing = saved
    }

    val syntaxErrors = new ListBuffer[(Int, String)]
    def showSyntaxErrors() =
      for ((offset, msg) <- syntaxErrors)
        unit.error(o2p(offset), msg)

    override def syntaxError(offset: Int, msg: String) {
      if (smartParsing) syntaxErrors += ((offset, msg))
      else unit.error(o2p(offset), msg)
    }

    override def incompleteInputError(msg: String) {
      val offset = source.content.length - 1
      if (smartParsing) syntaxErrors += ((offset, msg))
      else unit.incompleteInputError(o2p(offset), msg)
    }

    /** parse unit. If there are inbalanced braces,
     *  try to correct them and reparse.
     */
    def smartParse(): Tree = withSmartParsing {
      val firstTry = parse()
      if (syntaxErrors.isEmpty) firstTry
      else in.healBraces() match {
        case Nil      => showSyntaxErrors() ; firstTry
        case patches  => new UnitParser(unit, patches).parse()
      }
    }
  }

  final val Local = 0
  final val InBlock = 1
  final val InTemplate = 2

  import nme.raw

  abstract class Parser extends ParserCommon {
    val in: Scanner

    def freshName(prefix: String): Name
    def freshTermName(prefix: String): TermName
    def freshTypeName(prefix: String): TypeName
    def o2p(offset: Int): Position
    def r2p(start: Int, mid: Int, end: Int): Position

    /** whether a non-continuable syntax error has been seen */
    private var lastErrorOffset : Int = -1

    object treeBuilder extends TreeBuilder {
      val global: self.global.type = self.global
      def freshName(prefix: String): Name = freshTermName(prefix)
      def freshTermName(prefix: String): TermName = Parser.this.freshTermName(prefix)
      def freshTypeName(prefix: String): TypeName = Parser.this.freshTypeName(prefix)
      def o2p(offset: Int) = Parser.this.o2p(offset)
      def r2p(start: Int, point: Int, end: Int) = Parser.this.r2p(start, point, end)
    }
    import treeBuilder.{global => _, _}

    /** The types of the context bounds of type parameters of the surrounding class
     */
    private var classContextBounds: List[Tree] = Nil
    @inline private def savingClassContextBounds[T](op: => T): T = {
      val saved = classContextBounds
      try op
      finally classContextBounds = saved
    }

    /** Are we inside the Scala package? Set for files that start with package scala
     */
    private var inScalaPackage = false
    private var currentPackage = ""
    def resetPackage() {
      inScalaPackage = false
      currentPackage = ""
    }
    private lazy val anyValNames: Set[Name] = tpnme.ScalaValueNames.toSet + tpnme.AnyVal

    private def inScalaRootPackage       = inScalaPackage && currentPackage == "scala"
    private def isScalaArray(name: Name) = inScalaRootPackage && name == tpnme.Array
    private def isAnyValType(name: Name) = inScalaRootPackage && anyValNames(name)

    def parseStartRule: () => Tree

    /** This is the general parse entry point.
     */
    def parse(): Tree = {
      val t = parseStartRule()
      accept(EOF)
      t
    }

    /** This is the parse entry point for code which is not self-contained, e.g.
     *  a script which is a series of template statements.  They will be
     *  swaddled in Trees until the AST is equivalent to the one returned
     *  by compilationUnit().
     */
    def scriptBody(): Tree = {
      val stmts = templateStatSeq(false)._2
      accept(EOF)

      def mainModuleName = newTermName(settings.script.value)
      /** If there is only a single object template in the file and it has a
       *  suitable main method, we will use it rather than building another object
       *  around it.  Since objects are loaded lazily the whole script would have
       *  been a no-op, so we're not taking much liberty.
       */
      def searchForMain(): Option[Tree] = {
        /** Have to be fairly liberal about what constitutes a main method since
         *  nothing has been typed yet - for instance we can't assume the parameter
         *  type will look exactly like "Array[String]" as it could have been renamed
         *  via import, etc.
         */
        def isMainMethod(t: Tree) = t match {
          case DefDef(_, nme.main, Nil, List(_), _, _)  => true
          case _                                        => false
        }
        /** For now we require there only be one top level object. */
        var seenModule = false
        val newStmts = stmts collect {
          case t @ Import(_, _) => t
          case md @ ModuleDef(mods, name, template) if !seenModule && (md exists isMainMethod) =>
            seenModule = true
            /** This slightly hacky situation arises because we have no way to communicate
             *  back to the scriptrunner what the name of the program is.  Even if we were
             *  willing to take the sketchy route of settings.script.value = progName, that
             *  does not work when using fsc.  And to find out in advance would impose a
             *  whole additional parse.  So instead, if the actual object's name differs from
             *  what the script is expecting, we transform it to match.
             */
            if (name == mainModuleName) md
            else treeCopy.ModuleDef(md, mods, mainModuleName, template)
          case _ =>
            /** If we see anything but the above, fail. */
            return None
        }
        Some(makePackaging(0, emptyPkg, newStmts))
      }

      if (mainModuleName == newTermName(ScriptRunner.defaultScriptMain))
        searchForMain() foreach { return _ }

      /** Here we are building an AST representing the following source fiction,
       *  where `moduleName` is from -Xscript (defaults to "Main") and <stmts> are
       *  the result of parsing the script file.
       *
       *  {{{
       *  object moduleName {
       *    def main(argv: Array[String]): Unit = {
       *      val args = argv
       *      new AnyRef {
       *        stmts
       *      }
       *    }
       *  }
       *  }}}
       */
      import definitions._

      def emptyPkg    = atPos(0, 0, 0) { Ident(nme.EMPTY_PACKAGE_NAME) }
      def emptyInit   = DefDef(
        NoMods,
        nme.CONSTRUCTOR,
        Nil,
        List(Nil),
        TypeTree(),
        Block(List(Apply(Select(Super(This(tpnme.EMPTY), tpnme.EMPTY), nme.CONSTRUCTOR), Nil)), Literal(Constant(())))
      )

      // def main
      def mainParamType = AppliedTypeTree(Ident(tpnme.Array), List(Ident(tpnme.String)))
      def mainParameter = List(ValDef(Modifiers(Flags.PARAM), nme.argv, mainParamType, EmptyTree))
      def mainSetArgv   = List(ValDef(NoMods, nme.args, TypeTree(), Ident(nme.argv)))
      def mainNew       = makeNew(Nil, emptyValDef, stmts, List(Nil), NoPosition, NoPosition)
      def mainDef       = DefDef(NoMods, nme.main, Nil, List(mainParameter), scalaDot(tpnme.Unit), Block(mainSetArgv, mainNew))

      // object Main
      def moduleName  = newTermName(ScriptRunner scriptMain settings)
      def moduleBody  = Template(List(scalaScalaObjectConstr), emptyValDef, List(emptyInit, mainDef))
      def moduleDef   = ModuleDef(NoMods, moduleName, moduleBody)

      // package <empty> { ... }
      makePackaging(0, emptyPkg, List(moduleDef))
    }

/* --------------- PLACEHOLDERS ------------------------------------------- */

    /** The implicit parameters introduced by `_` in the current expression.
     *  Parameters appear in reverse order.
     */
    var placeholderParams: List[ValDef] = Nil

    /** The placeholderTypes introduced by `_` in the current type.
     *  Parameters appear in reverse order.
     */
    var placeholderTypes: List[TypeDef] = Nil

    def checkNoEscapingPlaceholders[T](op: => T): T = {
      val savedPlaceholderParams = placeholderParams
      val savedPlaceholderTypes = placeholderTypes
      placeholderParams = List()
      placeholderTypes = List()

      val res = op

      placeholderParams match {
        case vd :: _ =>
          syntaxError(vd.pos, "unbound placeholder parameter", false)
          placeholderParams = List()
        case _ =>
      }
      placeholderTypes match {
        case td :: _ =>
          syntaxError(td.pos, "unbound wildcard type", false)
          placeholderTypes = List()
        case _ =>
      }
      placeholderParams = savedPlaceholderParams
      placeholderTypes = savedPlaceholderTypes

      res
    }

    def placeholderTypeBoundary(op: => Tree): Tree = {
      val savedPlaceholderTypes = placeholderTypes
      placeholderTypes = List()
      var t = op
      if (!placeholderTypes.isEmpty && t.isInstanceOf[AppliedTypeTree]) {
        val expos = t.pos
        ensureNonOverlapping(t, placeholderTypes)
        t = atPos(expos) { ExistentialTypeTree(t, placeholderTypes.reverse) }
        placeholderTypes = List()
      }
      placeholderTypes = placeholderTypes ::: savedPlaceholderTypes
      t
    }

    def isWildcard(t: Tree): Boolean = t match {
      case Ident(name1) => !placeholderParams.isEmpty && name1 == placeholderParams.head.name
      case Typed(t1, _) => isWildcard(t1)
      case Annotated(t1, _) => isWildcard(t1)
      case _ => false
    }

/* ------------- ERROR HANDLING ------------------------------------------- */

    var assumedClosingParens = collection.mutable.Map(RPAREN -> 0, RBRACKET -> 0, RBRACE -> 0)

    private var inFunReturnType = false
    @inline private def fromWithinReturnType[T](body: => T): T = {
      val saved = inFunReturnType
      inFunReturnType = true
      try body
      finally inFunReturnType = saved
    }

    protected def skip(targetToken: Int) {
      var nparens = 0
      var nbraces = 0
      while (true) {
        in.token match {
          case EOF =>
            return
          case SEMI =>
            if (nparens == 0 && nbraces == 0) return
          case NEWLINE =>
            if (nparens == 0 && nbraces == 0) return
          case NEWLINES =>
            if (nparens == 0 && nbraces == 0) return
          case RPAREN =>
            nparens -= 1
          case RBRACE =>
            if (nbraces == 0) return
            nbraces -= 1
          case LPAREN =>
            nparens += 1
          case LBRACE =>
            nbraces += 1
          case _ =>
        }
        if (targetToken == in.token && nparens == 0 && nbraces == 0) return
        in.nextToken()
      }
    }
    def warning(offset: Int, msg: String): Unit
    def incompleteInputError(msg: String): Unit
    private def syntaxError(pos: Position, msg: String, skipIt: Boolean) {
      syntaxError(pos pointOrElse in.offset, msg, skipIt)
    }
    def syntaxError(offset: Int, msg: String): Unit
    def syntaxError(msg: String, skipIt: Boolean) {
      syntaxError(in.offset, msg, skipIt)
    }

    def syntaxError(offset: Int, msg: String, skipIt: Boolean) {
      if (offset > lastErrorOffset) {
        syntaxError(offset, msg)
        // no more errors on this token.
        lastErrorOffset = in.offset
      }
      if (skipIt)
        skip(UNDEF)
    }

    def warning(msg: String) { warning(in.offset, msg) }

    def syntaxErrorOrIncomplete(msg: String, skipIt: Boolean) {
      if (in.token == EOF)
        incompleteInputError(msg)
      else
        syntaxError(in.offset, msg, skipIt)
    }

    def expectedMsg(token: Int): String =
      token2string(token) + " expected but " +token2string(in.token) + " found."

    /** Consume one token of the specified type, or signal an error if it is not there. */
    def accept(token: Int): Int = {
      val offset = in.offset
      if (in.token != token) {
        syntaxErrorOrIncomplete(expectedMsg(token), false)
        if ((token == RPAREN || token == RBRACE || token == RBRACKET))
          if (in.parenBalance(token) + assumedClosingParens(token) < 0)
            assumedClosingParens(token) += 1
          else
            skip(token)
        else
          skip(UNDEF)
      }
      if (in.token == token) in.nextToken()
      offset
    }

    /** {{{
     *  semi = nl {nl} | `;`
     *  nl  = `\n' // where allowed
     *  }}}
     */
    def acceptStatSep(): Unit = in.token match {
      case NEWLINE | NEWLINES => in.nextToken()
      case _                  => accept(SEMI)
    }
    def acceptStatSepOpt() =
      if (!isStatSeqEnd)
        acceptStatSep()

    def errorTypeTree    = TypeTree() setType ErrorType setPos o2p(in.offset)
    def errorTermTree    = Literal(Constant(null)) setPos o2p(in.offset)
    def errorPatternTree = Ident(nme.WILDCARD) setPos o2p(in.offset)

    /** Check that type parameter is not by name or repeated. */
    def checkNotByNameOrVarargs(tpt: Tree) = {
      if (treeInfo isByNameParamType tpt)
        syntaxError(tpt.pos, "no by-name parameter type allowed here", false)
      else if (treeInfo isRepeatedParamType tpt)
        syntaxError(tpt.pos, "no * parameter type allowed here", false)
    }

    /** Check that tree is a legal clause of a forSome. */
    def checkLegalExistential(t: Tree) = t match {
      case TypeDef(_, _, _, TypeBoundsTree(_, _)) |
           ValDef(_, _, _, EmptyTree) | EmptyTree =>
             ;
      case _ =>
        syntaxError(t.pos, "not a legal existential clause", false)
    }

/* -------------- TOKEN CLASSES ------------------------------------------- */

    def isModifier: Boolean = in.token match {
      case ABSTRACT | FINAL | SEALED | PRIVATE |
           PROTECTED | OVERRIDE | IMPLICIT | LAZY => true
      case _ => false
    }

    def isLocalModifier: Boolean = in.token match {
      case ABSTRACT | FINAL | SEALED | IMPLICIT | LAZY => true
      case _ => false
    }

    def isTemplateIntro: Boolean = in.token match {
      case OBJECT | CASEOBJECT | CLASS | CASECLASS | TRAIT  => true
      case _                                                => false
    }
    def isDclIntro: Boolean = in.token match {
      case VAL | VAR | DEF | TYPE => true
      case _ => false
    }

    def isDefIntro = isTemplateIntro || isDclIntro

    def isNumericLit: Boolean = in.token match {
      case INTLIT | LONGLIT | FLOATLIT | DOUBLELIT => true
      case _ => false
    }
    def isUnaryOp = isIdent && raw.isUnary(in.name)
    def isRawStar = isIdent && in.name == raw.STAR
    def isRawBar  = isIdent && in.name == raw.BAR

    def isIdent = in.token == IDENTIFIER || in.token == BACKQUOTED_IDENT

    def isLiteralToken(token: Int) = token match {
      case CHARLIT | INTLIT | LONGLIT | FLOATLIT | DOUBLELIT |
           STRINGLIT | INTERPOLATIONID | SYMBOLLIT | TRUE | FALSE | NULL => true
      case _                                                        => false
    }
    def isLiteral = isLiteralToken(in.token)

    def isExprIntroToken(token: Int): Boolean = isLiteralToken(token) || (token match {
      case IDENTIFIER | BACKQUOTED_IDENT |
           THIS | SUPER | IF | FOR | NEW | USCORE | TRY | WHILE |
           DO | RETURN | THROW | LPAREN | LBRACE | XMLSTART => true
      case _ => false
    })

    def isExprIntro: Boolean = isExprIntroToken(in.token)

    def isTypeIntroToken(token: Int): Boolean = token match {
      case IDENTIFIER | BACKQUOTED_IDENT | THIS |
           SUPER | USCORE | LPAREN | AT => true
      case _ => false
    }

    def isTypeIntro: Boolean = isTypeIntroToken(in.token)

    def isStatSeqEnd = in.token == RBRACE || in.token == EOF

    def isStatSep(token: Int): Boolean =
      token == NEWLINE || token == NEWLINES || token == SEMI

    def isStatSep: Boolean = isStatSep(in.token)


/* --------- COMMENT AND ATTRIBUTE COLLECTION ----------------------------- */

    /** Join the comment associated with a definition. */
    def joinComment(trees: => List[Tree]): List[Tree] = {
      val doc = in.flushDoc
      if ((doc ne null) && doc.raw.length > 0) {
        val joined = trees map {
          t =>
            DocDef(doc, t) setPos {
              if (t.pos.isDefined) {
                val pos = doc.pos.withEnd(t.pos.endOrPoint)
                if (t.pos.isOpaqueRange) pos else pos.makeTransparent
              } else {
                t.pos
              }
            }
        }
        joined.find(_.pos.isOpaqueRange) foreach {
          main =>
            val mains = List(main)
            joined foreach { t => if (t ne main) ensureNonOverlapping(t, mains) }
        }
        joined
      }
      else trees
    }

/* ---------- TREE CONSTRUCTION ------------------------------------------- */

    def atPos[T <: Tree](offset: Int)(t: T): T =
      global.atPos(r2p(offset, offset, in.lastOffset max offset))(t)
    def atPos[T <: Tree](start: Int, point: Int)(t: T): T =
      global.atPos(r2p(start, point, in.lastOffset max start))(t)
    def atPos[T <: Tree](start: Int, point: Int, end: Int)(t: T): T =
      global.atPos(r2p(start, point, end))(t)
    def atPos[T <: Tree](pos: Position)(t: T): T =
      global.atPos(pos)(t)

    /** Convert tree to formal parameter list. */
    def convertToParams(tree: Tree): List[ValDef] = tree match {
      case Parens(ts) => ts map convertToParam
      case _          => List(convertToParam(tree))
    }

    /** Convert tree to formal parameter. */
    def convertToParam(tree: Tree): ValDef = atPos(tree.pos) {
      def removeAsPlaceholder(name: Name) {
        placeholderParams = placeholderParams filter (_.name != name)
      }
      tree match {
        case Ident(name) =>
          removeAsPlaceholder(name)
          makeParam(name, TypeTree() setPos o2p(tree.pos.endOrPoint))
        case Typed(Ident(name), tpe) if tpe.isType => // get the ident!
          removeAsPlaceholder(name)
          makeParam(name, tpe)
        case _ =>
          syntaxError(tree.pos, "not a legal formal parameter", false)
          makeParam(nme.ERROR, errorTypeTree setPos o2p(tree.pos.endOrPoint))
      }
    }

    /** Convert (qual)ident to type identifier. */
    def convertToTypeId(tree: Tree): Tree = atPos(tree.pos) {
      convertToTypeName(tree) getOrElse {
        syntaxError(tree.pos, "identifier expected", false)
        errorTypeTree
      }
    }

    /** {{{ part { `sep` part } }}},or if sepFirst is true, {{{ { `sep` part } }}}. */
    final def tokenSeparated[T](separator: Int, sepFirst: Boolean, part: => T): List[T] = {
      val ts = new ListBuffer[T]
      if (!sepFirst)
        ts += part

      while (in.token == separator) {
        in.nextToken()
        ts += part
      }
      ts.toList
    }
    @inline final def commaSeparated[T](part: => T): List[T] = tokenSeparated(COMMA, false, part)
    @inline final def caseSeparated[T](part: => T): List[T] = tokenSeparated(CASE, true, part)
    @inline final def readAnnots[T](part: => T): List[T] = tokenSeparated(AT, true, part)

/* --------- OPERAND/OPERATOR STACK --------------------------------------- */

    /** Modes for infix types. */
    object InfixMode extends Enumeration {
      val FirstOp, LeftOp, RightOp = Value
    }

    var opstack: List[OpInfo] = Nil

    def precedence(operator: Name): Int =
      if (operator eq nme.ERROR) -1
      else {
        val firstCh = operator(0)
        if (isScalaLetter(firstCh)) 1
        else if (nme.isOpAssignmentName(operator)) 0
        else firstCh match {
          case '|'             => 2
          case '^'             => 3
          case '&'             => 4
          case '=' | '!'       => 5
          case '<' | '>'       => 6
          case ':'             => 7
          case '+' | '-'       => 8
          case '*' | '/' | '%' => 9
          case _               => 10
        }
      }

    def checkSize(kind: String, size: Int, max: Int) {
      if (size > max) syntaxError("too many "+kind+", maximum = "+max, false)
    }

    def checkAssoc(offset: Int, op: Name, leftAssoc: Boolean) =
      if (treeInfo.isLeftAssoc(op) != leftAssoc)
        syntaxError(
          offset, "left- and right-associative operators with same precedence may not be mixed", false)

    def reduceStack(isExpr: Boolean, base: List[OpInfo], top0: Tree,
                    prec: Int, leftAssoc: Boolean): Tree = {
      var top = top0
      if (opstack != base && precedence(opstack.head.operator) == prec)
        checkAssoc(opstack.head.offset, opstack.head.operator, leftAssoc)
      while (opstack != base &&
             (prec < precedence(opstack.head.operator) ||
              leftAssoc && prec == precedence(opstack.head.operator))) {
        val opinfo = opstack.head
        opstack = opstack.tail
        val opPos = r2p(opinfo.offset, opinfo.offset, opinfo.offset+opinfo.operator.length)
        val lPos = opinfo.operand.pos
        val start = if (lPos.isDefined) lPos.startOrPoint else  opPos.startOrPoint
        val rPos = top.pos
        val end = if (rPos.isDefined) rPos.endOrPoint else opPos.endOrPoint
        top = atPos(start, opinfo.offset, end) {
          makeBinop(isExpr, opinfo.operand, opinfo.operator, top, opPos)
        }
      }
      top
    }

/* -------- IDENTIFIERS AND LITERALS ------------------------------------------- */

    /** Methods which implicitly propagate the context in which they were
     *  called: either in a pattern context or not.  Formerly, this was
     *  threaded through numerous methods as boolean isPattern.
     */
    trait PatternContextSensitive {
      /** {{{
       *  ArgType       ::=  Type
       *  }}}
       */
      def argType(): Tree
      def functionArgType(): Tree

      private def tupleInfixType(start: Int) = {
        in.nextToken()
        if (in.token == RPAREN) {
          in.nextToken()
          atPos(start, accept(ARROW)) { makeFunctionTypeTree(Nil, typ()) }
        }
        else {
          val ts = functionTypes()
          accept(RPAREN)
          if (in.token == ARROW)
            atPos(start, in.skipToken()) { makeFunctionTypeTree(ts, typ()) }
          else {
            ts foreach checkNotByNameOrVarargs
            val tuple = atPos(start) { makeTupleType(ts, true) }
            infixTypeRest(
              compoundTypeRest(
                annotTypeRest(
                  simpleTypeRest(
                    tuple))),
              InfixMode.FirstOp
            )
          }
        }
      }
      private def makeExistentialTypeTree(t: Tree) = {
        val whereClauses = refinement()
        whereClauses foreach checkLegalExistential
        ExistentialTypeTree(t, whereClauses)
      }

      /** {{{
       *  Type ::= InfixType `=>' Type
       *         | `(' [`=>' Type] `)' `=>' Type
       *         | InfixType [ExistentialClause]
       *  ExistentialClause ::= forSome `{' ExistentialDcl {semi ExistentialDcl}} `}'
       *  ExistentialDcl    ::= type TypeDcl | val ValDcl
       *  }}}
       */
      def typ(): Tree = placeholderTypeBoundary {
        val start = in.offset
        val t =
          if (in.token == LPAREN) tupleInfixType(start)
          else infixType(InfixMode.FirstOp)

        in.token match {
          case ARROW    => atPos(start, in.skipToken()) { makeFunctionTypeTree(List(t), typ()) }
          case FORSOME  => atPos(start, in.skipToken()) { makeExistentialTypeTree(t) }
          case _        => t
        }
      }

      /** {{{
       *  TypeArgs    ::= `[' ArgType {`,' ArgType} `]'
       *  }}}
       */
      def typeArgs(): List[Tree] = inBrackets(types())

      /** {{{
       *  AnnotType        ::=  SimpleType {Annotation}
       *  }}}
       */
      def annotType(): Tree = placeholderTypeBoundary { annotTypeRest(simpleType()) }

      /** {{{
       *  SimpleType       ::=  SimpleType TypeArgs
       *                     |  SimpleType `#' Id
       *                     |  StableId
       *                     |  Path `.' type
       *                     |  `(' Types `)'
       *                     |  WildcardType
       *  }}}
       */
      def simpleType(): Tree = {
        val start = in.offset
        simpleTypeRest(in.token match {
          case LPAREN   => atPos(start)(makeTupleType(inParens(types()), true))
          case USCORE   => wildcardType(in.skipToken())
          case _        =>
            path(false, true) match {
              case r @ SingletonTypeTree(_) => r
              case r => convertToTypeId(r)
            }
        })
      }

      private def typeProjection(t: Tree): Tree = {
        val hashOffset = in.skipToken()
        val nameOffset = in.offset
        val name       = identForType(false)
        val point      = if (name == tpnme.ERROR) hashOffset else nameOffset
        atPos(t.pos.startOrPoint, point)(SelectFromTypeTree(t, name))
      }
      def simpleTypeRest(t: Tree): Tree = in.token match {
        case HASH     => simpleTypeRest(typeProjection(t))
        case LBRACKET => simpleTypeRest(atPos(t.pos.startOrPoint, t.pos.point)(AppliedTypeTree(t, typeArgs())))
        case _        => t
      }

      /** {{{
       *  CompoundType ::= AnnotType {with AnnotType} [Refinement]
       *                |  Refinement
       *  }}}
       */
      def compoundType(): Tree = compoundTypeRest(
        if (in.token == LBRACE) atPos(o2p(in.offset))(scalaAnyRefConstr)
        else annotType()
      )

      def compoundTypeRest(t: Tree): Tree = {
        var ts = new ListBuffer[Tree] += t
        while (in.token == WITH) {
          in.nextToken()
          ts += annotType()
        }
        newLineOptWhenFollowedBy(LBRACE)
        atPos(t.pos.startOrPoint) {
          if (in.token == LBRACE) {
            // Warn if they are attempting to refine Unit; we can't be certain it's
            // scala.Unit they're refining because at this point all we have is an
            // identifier, but at a later stage we lose the ability to tell an empty
            // refinement from no refinement at all.  See bug #284.
            for (Ident(name) <- ts) name.toString match {
              case "Unit" | "scala.Unit"  =>
                warning("Detected apparent refinement of Unit; are you missing an '=' sign?")
              case _ =>
            }
            CompoundTypeTree(Template(ts.toList, emptyValDef, refinement()))
          }
          else
            makeIntersectionTypeTree(ts.toList)
        }
      }

      def infixTypeRest(t: Tree, mode: InfixMode.Value): Tree = {
        if (isIdent && in.name != nme.STAR) {
          val opOffset = in.offset
          val leftAssoc = treeInfo.isLeftAssoc(in.name)
          if (mode != InfixMode.FirstOp) checkAssoc(opOffset, in.name, mode == InfixMode.LeftOp)
          val op = identForType()
          val tycon = atPos(opOffset) { Ident(op) }
          newLineOptWhenFollowing(isTypeIntroToken)
          def mkOp(t1: Tree) = atPos(t.pos.startOrPoint, opOffset) { AppliedTypeTree(tycon, List(t, t1)) }
          if (leftAssoc)
            infixTypeRest(mkOp(compoundType()), InfixMode.LeftOp)
          else
            mkOp(infixType(InfixMode.RightOp))
        } else t
      }

      /** {{{
       *  InfixType ::= CompoundType {id [nl] CompoundType}
       *  }}}
       */
      def infixType(mode: InfixMode.Value): Tree =
        placeholderTypeBoundary { infixTypeRest(compoundType(), mode) }

      /** {{{
       *  Types ::= Type {`,' Type}
       *  }}}
       */
      def types(): List[Tree] = commaSeparated(argType())
      def functionTypes(): List[Tree] = commaSeparated(functionArgType())
    }

    /** Assumed (provisionally) to be TermNames. */
    def ident(skipIt: Boolean): Name =
      if (isIdent) {
        val name = in.name.encode
        in.nextToken()
        name
      } else {
        syntaxErrorOrIncomplete(expectedMsg(IDENTIFIER), skipIt)
        nme.ERROR
      }
    def ident(): Name = ident(true)
    def rawIdent(): Name = try in.name finally in.nextToken()

    /** For when it's known already to be a type name. */
    def identForType(): TypeName = ident().toTypeName
    def identForType(skipIt: Boolean): TypeName = ident(skipIt).toTypeName

    def selector(t: Tree): Tree = {
      val point = in.offset
      //assert(t.pos.isDefined, t)
      if (t != EmptyTree)
        Select(t, ident(false)) setPos r2p(t.pos.startOrPoint, point, in.lastOffset)
      else
        errorTermTree // has already been reported
    }

    /** {{{
     *  Path       ::= StableId
     *              |  [Ident `.'] this
     *  AnnotType ::= Path [`.' type]
     *  }}}
     */
    def path(thisOK: Boolean, typeOK: Boolean): Tree = {
      val start = in.offset
      var t: Tree = null
      if (in.token == THIS) {
        in.nextToken()
        t = atPos(start) { This(tpnme.EMPTY) }
        if (!thisOK || in.token == DOT) {
          t = selectors(t, typeOK, accept(DOT))
        }
      } else if (in.token == SUPER) {
        in.nextToken()
        t = atPos(start) { Super(This(tpnme.EMPTY), mixinQualifierOpt()) }
        accept(DOT)
        t = selector(t)
        if (in.token == DOT) t = selectors(t, typeOK, in.skipToken())
      } else {
        val tok = in.token
        val name = ident()
        t = atPos(start) {
          if (tok == BACKQUOTED_IDENT) new BackQuotedIdent(name)
          else Ident(name)
        }
        if (in.token == DOT) {
          val dotOffset = in.skipToken()
          if (in.token == THIS) {
            in.nextToken()
            t = atPos(start) { This(name.toTypeName) }
            if (!thisOK || in.token == DOT)
              t = selectors(t, typeOK, accept(DOT))
          } else if (in.token == SUPER) {
            in.nextToken()
            t = atPos(start) { Super(This(name.toTypeName), mixinQualifierOpt()) }
            accept(DOT)
            t = selector(t)
            if (in.token == DOT) t = selectors(t, typeOK, in.skipToken())
          } else {
            t = selectors(t, typeOK, dotOffset)
          }
        }
      }
      t
    }

    def selectors(t: Tree, typeOK: Boolean, dotOffset: Int): Tree =
      if (typeOK && in.token == TYPE) {
        in.nextToken()
        atPos(t.pos.startOrPoint, dotOffset) { SingletonTypeTree(t) }
      } else {
        val t1 = selector(t)
        if (in.token == DOT) { selectors(t1, typeOK, in.skipToken()) }
        else t1
      }

    /** {{{
    *   MixinQualifier ::= `[' Id `]'
    *   }}}
    */
    def mixinQualifierOpt(): TypeName =
      if (in.token == LBRACKET) inBrackets(identForType())
      else tpnme.EMPTY

    /** {{{
     *  StableId ::= Id
     *            |  Path `.' Id
     *            |  [id `.'] super [`[' id `]']`.' id
     *  }}}
     */
    def stableId(): Tree =
      path(false, false)

    /** {{{
    *   QualId ::= Id {`.' Id}
    *   }}}
    */
    def qualId(): Tree = {
      val start = in.offset
      val id = atPos(start) { Ident(ident()) }
      if (in.token == DOT) { selectors(id, false, in.skipToken()) }
      else id
    }
    /** Calls `qualId()` and manages some package state. */
    private def pkgQualId() = {
      if (in.token == IDENTIFIER && in.name.encode == nme.scala_)
        inScalaPackage = true

      val pkg = qualId()
      newLineOptWhenFollowedBy(LBRACE)

      if (currentPackage == "") currentPackage = pkg.toString
      else currentPackage = currentPackage + "." + pkg

      pkg
    }

    /** {{{
     *  SimpleExpr    ::= literal
     *                  | symbol
     *                  | null
     *  }}}
     *  @note  The returned tree does not yet have a position
     */
    def literal(isNegated: Boolean = false): Tree = {
      def finish(value: Any): Tree = {
        val t = Literal(Constant(value))
        in.nextToken()
        t
      }
      if (in.token == SYMBOLLIT)
        Apply(scalaDot(nme.Symbol), List(finish(in.strVal)))
      else if (in.token == INTERPOLATIONID)
        interpolatedString()
      else finish(in.token match {
        case CHARLIT   => in.charVal
        case INTLIT    => in.intVal(isNegated).toInt
        case LONGLIT   => in.intVal(isNegated)
        case FLOATLIT  => in.floatVal(isNegated).toFloat
        case DOUBLELIT => in.floatVal(isNegated)
        case STRINGLIT | STRINGPART => in.strVal.intern()
        case TRUE      => true
        case FALSE     => false
        case NULL      => null
        case _         =>
          syntaxErrorOrIncomplete("illegal literal", true)
          null
      })
    }

    private def stringOp(t: Tree, op: TermName) = {
      val str = in.strVal
      in.nextToken()
      if (str.length == 0) t
      else atPos(t.pos.startOrPoint) {
        Apply(Select(t, op), List(Literal(Constant(str))))
      }
    }

    private def interpolatedString(): Tree = atPos(in.offset) {
      val start = in.offset
      val interpolator = in.name
      
      val partsBuf = new ListBuffer[Tree]
      val exprBuf = new ListBuffer[Tree]
      in.nextToken()
      while (in.token == STRINGPART) {
        partsBuf += literal()
        exprBuf += {
          if (in.token == IDENTIFIER) atPos(in.offset)(Ident(ident()))
          else expr()
        }
      }
      if (in.token == STRINGLIT) partsBuf += literal()
      
      val t1 = atPos(o2p(start)) { Ident(nme.StringContext) }
      val t2 = atPos(start) { Apply(t1, partsBuf.toList) }
      t2 setPos t2.pos.makeTransparent
      val t3 = Select(t2, interpolator) setPos t2.pos
      atPos(start) { Apply(t3, exprBuf.toList) }
    }

/* ------------- NEW LINES ------------------------------------------------- */

    def newLineOpt() {
      if (in.token == NEWLINE) in.nextToken()
    }

    def newLinesOpt() {
      if (in.token == NEWLINE || in.token == NEWLINES)
        in.nextToken()
    }

    def newLineOptWhenFollowedBy(token: Int) {
      // note: next is defined here because current == NEWLINE
      if (in.token == NEWLINE && in.next.token == token) newLineOpt()
    }

    def newLineOptWhenFollowing(p: Int => Boolean) {
      // note: next is defined here because current == NEWLINE
      if (in.token == NEWLINE && p(in.next.token)) newLineOpt()
    }

/* ------------- TYPES ---------------------------------------------------- */

    /** {{{
     *  TypedOpt ::= [`:' Type]
     *  }}}
     */
    def typedOpt(): Tree =
      if (in.token == COLON) { in.nextToken(); typ() }
      else TypeTree()

    def typeOrInfixType(location: Int): Tree =
      if (location == Local) typ()
      else startInfixType()

    def annotTypeRest(t: Tree): Tree =
      (t /: annotations(false)) (makeAnnotated)

    /** {{{
     *  WildcardType ::= `_' TypeBounds
     *  }}}
     */
    def wildcardType(start: Int) = {
      val pname = freshTypeName("_$")
      val t = atPos(start)(Ident(pname))
      val bounds = typeBounds()
      val param = atPos(t.pos union bounds.pos) { makeSyntheticTypeParam(pname, bounds) }
      placeholderTypes = param :: placeholderTypes
      t
    }

/* ----------- EXPRESSIONS ------------------------------------------------ */

    /** {{{
     *  EqualsExpr ::= `=' Expr
     *  }}}
     */
    def equalsExpr(): Tree = {
      accept(EQUALS)
      expr()
    }

    def condExpr(): Tree = {
      if (in.token == LPAREN) {
        in.nextToken()
        val r = expr()
        accept(RPAREN)
        r
      } else {
        accept(LPAREN)
        Literal(Constant(true))
      }
    }

    /* hook for IDE, unlike expression can be stubbed
     * don't use for any tree that can be inspected in the parser!
     */
    def statement(location: Int): Tree = expr(location) // !!! still needed?

    /** {{{
     *  Expr       ::= (Bindings | [`implicit'] Id | `_')  `=>' Expr
     *               | Expr1
     *  ResultExpr ::= (Bindings | Id `:' CompoundType) `=>' Block
     *               | Expr1
     *  Expr1      ::= if `(' Expr `)' {nl} Expr [[semi] else Expr]
     *               | try (`{' Block `}' | Expr) [catch `{' CaseClauses `}'] [finally Expr]
     *               | while `(' Expr `)' {nl} Expr
     *               | do Expr [semi] while `(' Expr `)'
     *               | for (`(' Enumerators `)' | `{' Enumerators `}') {nl} [yield] Expr
     *               | throw Expr
     *               | return [Expr]
     *               | [SimpleExpr `.'] Id `=' Expr
     *               | SimpleExpr1 ArgumentExprs `=' Expr
     *               | PostfixExpr Ascription
     *               | PostfixExpr match `{' CaseClauses `}'
     *  Bindings   ::= `(' [Binding {`,' Binding}] `)'
     *  Binding    ::= (Id | `_') [`:' Type]
     *  Ascription ::= `:' CompoundType
     *               | `:' Annotation {Annotation}
     *               | `:' `_' `*'
     *  }}}
     */
    def expr(): Tree = expr(Local)

    def expr(location: Int): Tree = {
      var savedPlaceholderParams = placeholderParams
      placeholderParams = List()
      var res = expr0(location)
      if (!placeholderParams.isEmpty && !isWildcard(res)) {
        res = atPos(res.pos){ Function(placeholderParams.reverse, res) }
        placeholderParams = List()
      }
      placeholderParams = placeholderParams ::: savedPlaceholderParams
      res
    }

    def expr0(location: Int): Tree = in.token match {
      case IF =>
        atPos(in.skipToken()) {
          val cond = condExpr()
          newLinesOpt()
          val thenp = expr()
          val elsep = if (in.token == ELSE) { in.nextToken(); expr() }
                      else Literal(Constant())
          If(cond, thenp, elsep)
        }
      case TRY =>
        atPos(in.skipToken()) {
          val body = in.token match {
            case LBRACE   => inBracesOrUnit(block())
            case LPAREN   => inParensOrUnit(expr())
            case _        => expr()
          }
          def catchFromExpr() = List(makeCatchFromExpr(expr()))
          val catches: List[CaseDef] =
            if (in.token != CATCH) Nil
            else {
              in.nextToken()
              if (in.token != LBRACE) catchFromExpr()
              else inBracesOrNil {
                if (in.token == CASE) caseClauses()
                else catchFromExpr()
              }
            }
          val finalizer = in.token match {
            case FINALLY  => in.nextToken() ; expr()
            case _        => EmptyTree
          }
          Try(body, catches, finalizer)
        }
      case WHILE =>
        val start = in.offset
        atPos(in.skipToken()) {
          val lname: Name = freshTermName(nme.WHILE_PREFIX)
          val cond = condExpr()
          newLinesOpt()
          val body = expr()
          makeWhile(lname, cond, body)
        }
      case DO =>
        val start = in.offset
        atPos(in.skipToken()) {
          val lname: Name = freshTermName(nme.DO_WHILE_PREFIX)
          val body = expr()
          if (isStatSep) in.nextToken()
          accept(WHILE)
          val cond = condExpr()
          makeDoWhile(lname, body, cond)
        }
      case FOR =>
        atPos(in.skipToken()) {
          val enums =
            if (in.token == LBRACE) inBracesOrNil(enumerators())
            else inParensOrNil(enumerators())
          newLinesOpt()
          if (in.token == YIELD) {
            in.nextToken()
            makeForYield(enums, expr())
          } else {
            makeFor(enums, expr())
          }
        }
      case RETURN =>
        atPos(in.skipToken()) {
          Return(if (isExprIntro) expr() else Literal(Constant()))
        }
      case THROW =>
        atPos(in.skipToken()) {
          Throw(expr())
        }
      case IMPLICIT =>
        implicitClosure(in.skipToken(), location)
      case _ =>
        var t = postfixExpr()
        if (in.token == EQUALS) {
          t match {
            case Ident(_) | Select(_, _) | Apply(_, _) =>
              t = atPos(t.pos.startOrPoint, in.skipToken()) { makeAssign(t, expr()) }
            case _ =>
          }
        } else if (in.token == COLON) {
          t = stripParens(t)
          val colonPos = in.skipToken()
          if (in.token == USCORE) {
            //todo: need to handle case where USCORE is a wildcard in a type
            val uscorePos = in.skipToken()
            if (isIdent && in.name == nme.STAR) {
              in.nextToken()
              t = atPos(t.pos.startOrPoint, colonPos) {
                Typed(t, atPos(uscorePos) { Ident(tpnme.WILDCARD_STAR) })
              }
            } else {
              syntaxErrorOrIncomplete("`*' expected", true)
            }
          } else if (in.token == AT) {
            t = (t /: annotations(false)) (makeAnnotated)
          } else {
            t = atPos(t.pos.startOrPoint, colonPos) {
              val tpt = typeOrInfixType(location)
              if (isWildcard(t))
                (placeholderParams: @unchecked) match {
                  case (vd @ ValDef(mods, name, _, _)) :: rest =>
                    placeholderParams = treeCopy.ValDef(vd, mods, name, tpt.duplicate, EmptyTree) :: rest
                }
              // this does not correspond to syntax, but is necessary to
              // accept closures. We might restrict closures to be between {...} only.
              Typed(t, tpt)
            }
          }
        } else if (in.token == MATCH) {
          t = atPos(t.pos.startOrPoint, in.skipToken()) {
            /** For debugging pattern matcher transition issues */
            if (settings.Ypmatnaive.value)
              makeSequencedMatch(stripParens(t), inBracesOrNil(caseClauses()))
            else
              Match(stripParens(t), inBracesOrNil(caseClauses()))
          }
        }
        // in order to allow anonymous functions as statements (as opposed to expressions) inside
        // templates, we have to disambiguate them from self type declarations - bug #1565
        // The case still missed is unparenthesized single argument, like "x: Int => x + 1", which
        // may be impossible to distinguish from a self-type and so remains an error.  (See #1564)
        def lhsIsTypedParamList() = t match {
          case Parens(xs) if xs forall (_.isInstanceOf[Typed]) => true
          case _ => false
        }
        if (in.token == ARROW && (location != InTemplate || lhsIsTypedParamList)) {
          t = atPos(t.pos.startOrPoint, in.skipToken()) {
            Function(convertToParams(t), if (location != InBlock) expr() else block())
          }
        }
        stripParens(t)
    }

    /** {{{
     *  Expr ::= implicit Id => Expr
     *  }}}
     */

    def implicitClosure(start: Int, location: Int): Tree = {
      val param0 = convertToParam {
        atPos(in.offset) {
          var paramexpr: Tree = Ident(ident())
          if (in.token == COLON) {
            in.nextToken()
            paramexpr = Typed(paramexpr, typeOrInfixType(location))
          }
          paramexpr
        }
      }
      val param = treeCopy.ValDef(param0, param0.mods | Flags.IMPLICIT, param0.name, param0.tpt, param0.rhs)
      atPos(start, in.offset) {
        accept(ARROW)
        Function(List(param), if (location != InBlock) expr() else block())
      }
    }

    /** {{{
     *  PostfixExpr   ::= InfixExpr [Id [nl]]
     *  InfixExpr     ::= PrefixExpr
     *                  | InfixExpr Id [nl] InfixExpr
     *  }}}
     */
    def postfixExpr(): Tree = {
      val base = opstack
      var top = prefixExpr()

      while (isIdent) {
        top = reduceStack(true, base, top, precedence(in.name), treeInfo.isLeftAssoc(in.name))
        val op = in.name
        opstack = OpInfo(top, op, in.offset) :: opstack
        ident()
        newLineOptWhenFollowing(isExprIntroToken)
        if (isExprIntro) {
          val next = prefixExpr()
          if (next == EmptyTree)
            return reduceStack(true, base, top, 0, true)
          top = next
        } else {
          val topinfo = opstack.head
          opstack = opstack.tail
          val od = stripParens(reduceStack(true, base, topinfo.operand, 0, true))
          return atPos(od.pos.startOrPoint, topinfo.offset) {
            Select(od, topinfo.operator.encode)
          }
        }
      }
      reduceStack(true, base, top, 0, true)
    }

    /** {{{
     *  PrefixExpr   ::= [`-' | `+' | `~' | `!' | `&'] SimpleExpr
     *  }}}
     */
    def prefixExpr(): Tree = {
      if (isUnaryOp) {
        atPos(in.offset) {
          val name = nme.toUnaryName(rawIdent())
          // val name = nme.toUnaryName(ident())  // val name: Name = "unary_" + ident()
          if (name == nme.UNARY_- && isNumericLit) simpleExprRest(atPos(in.offset)(literal(isNegated = true)), true)
          else Select(stripParens(simpleExpr()), name)
        }
      }
      else simpleExpr()
    }
    def xmlLiteral(): Tree

    /** {{{
     *  SimpleExpr    ::= new (ClassTemplate | TemplateBody)
     *                  |  BlockExpr
     *                  |  SimpleExpr1 [`_']
     *  SimpleExpr1   ::= literal
     *                  |  xLiteral
     *                  |  Path
     *                  |  `(' [Exprs] `)'
     *                  |  SimpleExpr `.' Id
     *                  |  SimpleExpr TypeArgs
     *                  |  SimpleExpr1 ArgumentExprs
     *  }}}
     */
    def simpleExpr(): Tree = {
      var canApply = true
      val t =
        if (isLiteral) atPos(in.offset)(literal())
        else in.token match {
          case XMLSTART =>
            xmlLiteral()
          case IDENTIFIER | BACKQUOTED_IDENT | THIS | SUPER =>
            path(true, false)
          case USCORE =>
            val start = in.offset
            val pname = freshName("x$")
            in.nextToken()
            val id = atPos(start) (Ident(pname))
            val param = atPos(id.pos.focus){ makeSyntheticParam(pname) }
            placeholderParams = param :: placeholderParams
            id
          case LPAREN =>
            atPos(in.offset)(makeParens(commaSeparated(expr)))
          case LBRACE =>
            canApply = false
            blockExpr()
          case NEW =>
            canApply = false
            val nstart = in.skipToken()
            val npos = r2p(nstart, nstart, in.lastOffset)
            val tstart = in.offset
            val (parents, argss, self, stats) = template(false)
            val cpos = r2p(tstart, tstart, in.lastOffset max tstart)
            makeNew(parents, self, stats, argss, npos, cpos)
          case _ =>
            syntaxErrorOrIncomplete("illegal start of simple expression", true)
            errorTermTree
        }
      simpleExprRest(t, canApply)
    }

    def simpleExprRest(t: Tree, canApply: Boolean): Tree = {
      if (canApply) newLineOptWhenFollowedBy(LBRACE)
      in.token match {
        case DOT =>
          in.nextToken()
          simpleExprRest(selector(stripParens(t)), true)
        case LBRACKET =>
          val t1 = stripParens(t)
          t1 match {
            case Ident(_) | Select(_, _) | Apply(_, _) =>
              var app: Tree = t1
              while (in.token == LBRACKET)
                app = atPos(app.pos.startOrPoint, in.offset)(TypeApply(app, exprTypeArgs()))

              simpleExprRest(app, true)
            case _ =>
              t1
          }
        case LPAREN | LBRACE if (canApply) =>
          val app = atPos(t.pos.startOrPoint, in.offset) {
            // look for anonymous function application like (f _)(x) and
            // translate to (f _).apply(x), bug #460
            val sel = t match {
              case Parens(List(Typed(_, _: Function))) =>
                Select(stripParens(t), nme.apply)
              case _ =>
                stripParens(t)
            }
            Apply(sel, argumentExprs())
          }
          simpleExprRest(app, true)
        case USCORE =>
          atPos(t.pos.startOrPoint, in.skipToken()) {
            Typed(stripParens(t), Function(Nil, EmptyTree))
          }
        case _ =>
          t
      }
    }

    /** {{{
     *  ArgumentExprs ::= `(' [Exprs] `)'
     *                  | [nl] BlockExpr
     *  }}}
     */
    def argumentExprs(): List[Tree] = {
      def args(): List[Tree] = commaSeparated {
        val maybeNamed = isIdent
        expr() match {
          case a @ Assign(id, rhs) if maybeNamed =>
            atPos(a.pos) { AssignOrNamedArg(id, rhs) }
          case e => e
        }
      }
      in.token match {
        case LBRACE   => List(blockExpr())
        case LPAREN   => inParens(if (in.token == RPAREN) Nil else args())
        case _        => Nil
      }
    }
    /** A succession of argument lists. */
    def multipleArgumentExprs(): List[List[Tree]] = {
      if (in.token != LPAREN) Nil
      else argumentExprs() :: multipleArgumentExprs()
    }

    /** {{{
     *  BlockExpr ::= `{' (CaseClauses | Block) `}'
     *  }}}
     */
    def blockExpr(): Tree = atPos(in.offset) {
      inBraces {
        if (in.token == CASE) Match(EmptyTree, caseClauses())
        else block()
      }
    }

    /** {{{
     *  Block ::= BlockStatSeq
     *  }}}
     *  @note  Return tree does not carry position.
     */
    def block(): Tree = makeBlock(blockStatSeq())

    /** {{{
     *  CaseClauses ::= CaseClause {CaseClause}
     *  CaseClause  ::= case Pattern [Guard] `=>' Block
     *  }}}
     */
    def caseClauses(): List[CaseDef] = {
      val cases = caseSeparated { atPos(in.offset)(makeCaseDef(pattern(), guard(), caseBlock())) }
      if (cases.isEmpty)  // trigger error if there are no cases
        accept(CASE)

      cases
    }

    // IDE HOOK (so we can memoize case blocks) // needed?
    def caseBlock(): Tree =
      atPos(accept(ARROW))(block())

    /** {{{
     *  Guard ::= if PostfixExpr
     *  }}}
     */
    def guard(): Tree =
      if (in.token == IF) { in.nextToken(); stripParens(postfixExpr()) }
      else EmptyTree

    /** {{{
     *  Enumerators ::= Generator {semi Enumerator}
     *  Enumerator  ::=  Generator
     *                |  Guard
     *                |  val Pattern1 `=' Expr
     *  }}}
     */
    def enumerators(): List[Enumerator] = {
      val enums = new ListBuffer[Enumerator]
      generator(enums, false)
      while (isStatSep) {
        in.nextToken()
        if (in.token == IF) enums += makeFilter(in.offset, guard())
        else generator(enums, true)
      }
      enums.toList
    }

    /** {{{
     *  Generator ::= Pattern1 (`<-' | `=') Expr [Guard]
     *  }}}
     */
    def generator(enums: ListBuffer[Enumerator], eqOK: Boolean) {
      val start  = in.offset
      val hasVal = in.token == VAL
      if (hasVal)
        in.nextToken()

      val pat   = noSeq.pattern1()
      val point = in.offset
      val hasEq = in.token == EQUALS

      if (hasVal) {
        if (hasEq) deprecationWarning(in.offset, "val keyword in for comprehension is deprecated")
        else syntaxError(in.offset, "val in for comprehension must be followed by assignment")
      }

      if (hasEq && eqOK) in.nextToken()
      else accept(LARROW)
      val rhs = expr()
      enums += makeGenerator(r2p(start, point, in.lastOffset max start), pat, hasEq, rhs)
      // why max above? IDE stress tests have shown that lastOffset could be less than start,
      // I guess this happens if instead if a for-expression we sit on a closing paren.
      while (in.token == IF) enums += makeFilter(in.offset, guard())
    }

    def makeFilter(start: Int, tree: Tree) = Filter(r2p(start, tree.pos.point, tree.pos.endOrPoint), tree)

/* -------- PATTERNS ------------------------------------------- */

    /** Methods which implicitly propagate whether the initial call took
     *  place in a context where sequences are allowed.  Formerly, this
     *  was threaded through methods as boolean seqOK.
     */
    trait SeqContextSensitive extends PatternContextSensitive {
      /** Returns Some(tree) if it finds a star and prematurely ends parsing.
       *  This is an artifact of old implementation which has proven difficult
       *  to cleanly extract.
       */
      def interceptStarPattern(top: Tree): Option[Tree]

      def functionArgType(): Tree = argType()
      def argType(): Tree = {
        val start = in.offset
        in.token match {
          case USCORE =>
            in.nextToken()
            if (in.token == SUBTYPE || in.token == SUPERTYPE) wildcardType(start)
            else atPos(start) { Bind(tpnme.WILDCARD, EmptyTree) }
          case IDENTIFIER if treeInfo.isVariableName(in.name) =>
            atPos(start) { Bind(identForType(), EmptyTree) }
          case _ =>
            typ()
        }
      }

      /** {{{
       *  Patterns ::= Pattern { `,' Pattern }
       *  SeqPatterns ::= SeqPattern { `,' SeqPattern }
       *  }}}
       */
      def patterns(): List[Tree] = commaSeparated(pattern())

      /** {{{
       *  Pattern  ::=  Pattern1 { `|' Pattern1 }
       *  SeqPattern ::= SeqPattern1 { `|' SeqPattern1 }
       *  }}}
       */
      def pattern(): Tree = {
        val start = in.offset
        def loop(): List[Tree] = pattern1() :: {
          if (isRawBar) { in.nextToken() ; loop() }
          else Nil
        }
        loop() match {
          case pat :: Nil => pat
          case xs         => atPos(start)(makeAlternative(xs))
        }
      }

      /** {{{
       *  Pattern1    ::= varid `:' TypePat
       *                |  `_' `:' TypePat
       *                |  Pattern2
       *  SeqPattern1 ::= varid `:' TypePat
       *                |  `_' `:' TypePat
       *                |  [SeqPattern2]
       *  }}}
       */
      def pattern1(): Tree = pattern2() match {
        case p @ Ident(name) if in.token == COLON =>
          if (treeInfo.isVarPattern(p))
            atPos(p.pos.startOrPoint, in.skipToken())(Typed(p, compoundType()))
          else {
            syntaxError(in.offset, "Pattern variables must start with a lower-case letter. (SLS 8.1.1.)")
            p
          }
        case p => p
      }

      /** {{{
       *  Pattern2    ::=  varid [ @ Pattern3 ]
       *                |   Pattern3
       *  SeqPattern2 ::=  varid [ @ SeqPattern3 ]
       *                |   SeqPattern3
       *  }}}
       */
      def pattern2(): Tree = {
        val p = pattern3()
        if (in.token != AT) p
        else p match {
          case Ident(nme.WILDCARD) =>
            in.nextToken()
            pattern3()
          case Ident(name) if treeInfo.isVarPattern(p) =>
            in.nextToken()
            atPos(p.pos.startOrPoint) { Bind(name, pattern3()) }
          case _ => p
        }
      }

      /** {{{
       *  Pattern3    ::= SimplePattern
       *                |  SimplePattern {Id [nl] SimplePattern}
       *  SeqPattern3 ::= SeqSimplePattern [ `*' | `?' | `+' ]
       *                |  SeqSimplePattern {Id [nl] SeqSimplePattern}
       *  }}}
       */
      def pattern3(): Tree = {
        val base = opstack
        var top = simplePattern()
        interceptStarPattern(top) foreach { x => return x }

        while (isIdent && in.name != raw.BAR) {
          top = reduceStack(
            false, base, top, precedence(in.name), treeInfo.isLeftAssoc(in.name))
          val op = in.name
          opstack = OpInfo(top, op, in.offset) :: opstack
          ident()
          top = simplePattern()
        }
        stripParens(reduceStack(false, base, top, 0, true))
      }

      /** {{{
       *  SimplePattern    ::= varid
       *                    |  `_'
       *                    |  literal
       *                    |  XmlPattern
       *                    |  StableId  [TypeArgs] [`(' [SeqPatterns] `)']
       *                    |  `(' [Patterns] `)'
       *  SimpleSeqPattern ::= varid
       *                    |  `_'
       *                    |  literal
       *                    |  XmlPattern
       *                    |  `<' xLiteralPattern
       *                    |  StableId [TypeArgs] [`(' [SeqPatterns] `)']
       *                    |  `(' [SeqPatterns] `)'
       *  }}}
       *
       * XXX: Hook for IDE
       */
      def simplePattern(): Tree = {
        val start = in.offset
        in.token match {
          case IDENTIFIER | BACKQUOTED_IDENT | THIS =>
            var t = stableId()
            in.token match {
              case INTLIT | LONGLIT | FLOATLIT | DOUBLELIT =>
                t match {
                  case Ident(nme.MINUS) =>
                    return atPos(start) { literal(isNegated = true) }
                  case _ =>
                }
              case _ =>
            }
            val typeAppliedTree = in.token match {
              case LBRACKET   => atPos(start, in.offset)(TypeApply(convertToTypeId(t), typeArgs()))
              case _          => t
            }
            in.token match {
              case LPAREN   => atPos(start, in.offset)(Apply(typeAppliedTree, argumentPatterns()))
              case _        => typeAppliedTree
            }
          case USCORE =>
            in.nextToken()
            atPos(start, start) { Ident(nme.WILDCARD) }
          case CHARLIT | INTLIT | LONGLIT | FLOATLIT | DOUBLELIT |
               STRINGLIT | INTERPOLATIONID | SYMBOLLIT | TRUE | FALSE | NULL =>
            atPos(start) { literal() }
          case LPAREN =>
            atPos(start)(makeParens(noSeq.patterns()))
          case XMLSTART =>
            xmlLiteralPattern()
          case _ =>
            syntaxErrorOrIncomplete("illegal start of simple pattern", true)
            errorPatternTree
        }
      }
    }
    /** The implementation of the context sensitive methods for parsing outside of patterns. */
    object outPattern extends PatternContextSensitive {
      def argType(): Tree = typ()
      def functionArgType(): Tree = paramType(useStartAsPosition = true)
    }
    /** The implementation for parsing inside of patterns at points where sequences are allowed. */
    object seqOK extends SeqContextSensitive {
      // See ticket #3189 for the motivation for the null check.
      // TODO: dredge out the remnants of regexp patterns.
      // ... and now this is back the way it was because it caused #3480.
      def interceptStarPattern(top: Tree): Option[Tree] =
        if (isRawStar) Some(atPos(top.pos.startOrPoint, in.skipToken())(Star(stripParens(top))))
        else None
    }
    /** The implementation for parsing inside of patterns at points where sequences are disallowed. */
    object noSeq extends SeqContextSensitive {
      def interceptStarPattern(top: Tree) = None
    }
    /** These are default entry points into the pattern context sensitive methods:
     *  they are all initiated from non-pattern context.
     */
    def typ(): Tree      = outPattern.typ()
    def startInfixType() = outPattern.infixType(InfixMode.FirstOp)
    def startAnnotType() = outPattern.annotType()
    def exprTypeArgs()   = outPattern.typeArgs()
    def exprSimpleType() = outPattern.simpleType()

    /** Default entry points into some pattern contexts. */
    def pattern(): Tree = noSeq.pattern()
    def patterns(): List[Tree] = noSeq.patterns()
    def seqPatterns(): List[Tree] = seqOK.patterns() // Also called from xml parser
    def argumentPatterns(): List[Tree] = inParens {
      if (in.token == RPAREN) Nil
      else seqPatterns()
    }
    def xmlLiteralPattern(): Tree

/* -------- MODIFIERS and ANNOTATIONS ------------------------------------------- */

    /** Drop `private` modifier when followed by a qualifier.
     *  Contract `abstract` and `override` to ABSOVERRIDE
     */
    private def normalize(mods: Modifiers): Modifiers =
      if (mods.isPrivate && mods.hasAccessBoundary)
        normalize(mods &~ Flags.PRIVATE)
      else if (mods hasAllFlags (Flags.ABSTRACT | Flags.OVERRIDE))
        normalize(mods &~ (Flags.ABSTRACT | Flags.OVERRIDE) | Flags.ABSOVERRIDE)
      else
        mods

    private def addMod(mods: Modifiers, mod: Long, pos: Position): Modifiers = {
      if (mods hasFlag mod) syntaxError(in.offset, "repeated modifier", false)
      in.nextToken()
      (mods | mod) withPosition (mod, pos)
    }

    private def tokenRange(token: TokenData) =
      r2p(token.offset, token.offset, token.offset + token.name.length - 1)

    /** {{{
     *  AccessQualifier ::= `[' (Id | this) `]'
     *  }}}
     */
    def accessQualifierOpt(mods: Modifiers): Modifiers = {
      var result = mods
      if (in.token == LBRACKET) {
        in.nextToken()
        if (mods.hasAccessBoundary)
          syntaxError("duplicate private/protected qualifier", false)
        result = if (in.token == THIS) { in.nextToken(); mods | Flags.LOCAL }
                 else Modifiers(mods.flags, identForType())
        accept(RBRACKET)
      }
      result
    }

    private val flagTokens: Map[Int, Long] = Map(
      ABSTRACT  -> Flags.ABSTRACT,
      FINAL     -> Flags.FINAL,
      IMPLICIT  -> Flags.IMPLICIT,
      LAZY      -> Flags.LAZY,
      OVERRIDE  -> Flags.OVERRIDE,
      PRIVATE   -> Flags.PRIVATE,
      PROTECTED -> Flags.PROTECTED,
      SEALED    -> Flags.SEALED
    )

    /** {{{
     *  AccessModifier ::= (private | protected) [AccessQualifier]
     *  }}}
     */
    def accessModifierOpt(): Modifiers = normalize {
      in.token match {
        case m @ (PRIVATE | PROTECTED)  => in.nextToken() ; accessQualifierOpt(Modifiers(flagTokens(m)))
        case _                          => NoMods
      }
    }

    /** {{{
     *  Modifiers ::= {Modifier}
     *  Modifier  ::= LocalModifier
     *              |  AccessModifier
     *              |  override
     *  }}}
     */
    def modifiers(): Modifiers = normalize {
      def loop(mods: Modifiers): Modifiers = in.token match {
        case PRIVATE | PROTECTED =>
          loop(accessQualifierOpt(addMod(mods, flagTokens(in.token), tokenRange(in))))
        case ABSTRACT | FINAL | SEALED | OVERRIDE | IMPLICIT | LAZY =>
          loop(addMod(mods, flagTokens(in.token), tokenRange(in)))
        case NEWLINE =>
          in.nextToken()
          loop(mods)
        case _ =>
          mods
      }
      loop(NoMods)
    }

    /** {{{
     *  LocalModifiers ::= {LocalModifier}
     *  LocalModifier  ::= abstract | final | sealed | implicit | lazy
     *  }}}
     */
    def localModifiers(): Modifiers = {
      def loop(mods: Modifiers): Modifiers =
        if (isLocalModifier) loop(addMod(mods, flagTokens(in.token), tokenRange(in)))
        else mods

      loop(NoMods)
    }

    /** {{{
     *  Annotations      ::= {`@' SimpleType {ArgumentExprs}}
     *  ConsrAnnotations ::= {`@' SimpleType ArgumentExprs}
     *  }}}
     */
    def annotations(skipNewLines: Boolean): List[Tree] = readAnnots {
      val t = annotationExpr()
      if (skipNewLines) newLineOpt()
      t
    }
    def constructorAnnotations(): List[Tree] = readAnnots {
      atPos(in.offset)(New(exprSimpleType(), List(argumentExprs())))
    }

    def annotationExpr(): Tree = atPos(in.offset) {
      val t = exprSimpleType()
      if (in.token == LPAREN) New(t, multipleArgumentExprs())
      else New(t, List(Nil))
    }

/* -------- PARAMETERS ------------------------------------------- */

    /** {{{
     *  ParamClauses      ::= {ParamClause} [[nl] `(' implicit Params `)']
     *  ParamClause       ::= [nl] `(' [Params] `)'
     *  Params            ::= Param {`,' Param}
     *  Param             ::= {Annotation} Id [`:' ParamType] [`=' Expr]
     *  ClassParamClauses ::= {ClassParamClause} [[nl] `(' implicit ClassParams `)']
     *  ClassParamClause  ::= [nl] `(' [ClassParams] `)'
     *  ClassParams       ::= ClassParam {`,' ClassParam}
     *  ClassParam        ::= {Annotation}  [{Modifier} (`val' | `var')] Id [`:' ParamType] [`=' Expr]
     *  }}}
     */
    def paramClauses(owner: Name, contextBounds: List[Tree], ofCaseClass: Boolean): List[List[ValDef]] = {
      var implicitmod = 0
      var caseParam = ofCaseClass
      def param(): ValDef = {
        val start = in.offset
        val annots = annotations(false)
        var mods = Modifiers(Flags.PARAM)
        if (owner.isTypeName) {
          mods = modifiers() | Flags.PARAMACCESSOR
          if (mods.isLazy) syntaxError("lazy modifier not allowed here. Use call-by-name parameters instead", false)
          in.token match {
            case v @ (VAL | VAR) =>
              mods = mods withPosition (in.token, tokenRange(in))
              if (v == VAR) mods |= Flags.MUTABLE
              in.nextToken()
            case _ =>
              if (mods.flags != Flags.PARAMACCESSOR) accept(VAL)
              if (!caseParam) mods |= Flags.PrivateLocal
          }
          if (caseParam) mods |= Flags.CASEACCESSOR
        }
        val nameOffset = in.offset
        val name = ident()
        var bynamemod = 0
        val tpt =
          if (settings.YmethodInfer.value && !owner.isTypeName && in.token != COLON) {
            TypeTree()
          } else { // XX-METHOD-INFER
            accept(COLON)
            if (in.token == ARROW) {
              if (owner.isTypeName && !mods.hasLocalFlag)
                syntaxError(
                  in.offset,
                  (if (mods.isMutable) "`var'" else "`val'") +
                  " parameters may not be call-by-name", false)
              else if (implicitmod != 0)
                syntaxError(
                  in.offset,
                  "implicit parameters may not be call-by-name", false)
              else bynamemod = Flags.BYNAMEPARAM
            }
            paramType()
          }
        val default =
          if (in.token == EQUALS) {
            in.nextToken()
            mods |= Flags.DEFAULTPARAM
            expr()
          } else EmptyTree
        atPos(start, if (name == nme.ERROR) start else nameOffset) {
          ValDef((mods | implicitmod | bynamemod) withAnnotations annots, name, tpt, default)
        }
      }
      def paramClause(): List[ValDef] = {
        if (in.token == RPAREN)
          return Nil

        if (in.token == IMPLICIT) {
          in.nextToken()
          implicitmod = Flags.IMPLICIT
        }
        commaSeparated(param())
      }
      val vds = new ListBuffer[List[ValDef]]
      val start = in.offset
      newLineOptWhenFollowedBy(LPAREN)
      if (ofCaseClass && in.token != LPAREN)
        deprecationWarning(in.lastOffset, "case classes without a parameter list have been deprecated;\n"+
                           "use either case objects or case classes with `()' as parameter list.")
      while (implicitmod == 0 && in.token == LPAREN) {
        in.nextToken()
        vds += paramClause()
        accept(RPAREN)
        caseParam = false
        newLineOptWhenFollowedBy(LPAREN)
      }
      val result = vds.toList
      if (owner == nme.CONSTRUCTOR && (result.isEmpty || (result.head take 1 exists (_.mods.isImplicit)))) {
        in.token match {
          case LBRACKET   => syntaxError(in.offset, "no type parameters allowed here", false)
          case EOF        => incompleteInputError("auxiliary constructor needs non-implicit parameter list")
          case _          => syntaxError(start, "auxiliary constructor needs non-implicit parameter list", false)
        }
      }
      addEvidenceParams(owner, result, contextBounds)
    }

    /** {{{
     *  ParamType ::= Type | `=>' Type | Type `*'
     *  }}}
     */
    def paramType(): Tree = paramType(useStartAsPosition = false)
    def paramType(useStartAsPosition: Boolean): Tree = {
      val start = in.offset
      in.token match {
        case ARROW  =>
          in.nextToken()
          atPos(start)(byNameApplication(typ()))
        case _      =>
          val t = typ()
          if (isRawStar) {
            in.nextToken()
            if (useStartAsPosition) atPos(start)(repeatedApplication(t))
            else atPos(t.pos.startOrPoint, t.pos.point)(repeatedApplication(t))
          }
          else t
      }
    }

    /** {{{
     *  TypeParamClauseOpt    ::= [TypeParamClause]
     *  TypeParamClause       ::= `[' VariantTypeParam {`,' VariantTypeParam} `]']
     *  VariantTypeParam      ::= {Annotation} [`+' | `-'] TypeParam
     *  FunTypeParamClauseOpt ::= [FunTypeParamClause]
     *  FunTypeParamClause    ::= `[' TypeParam {`,' TypeParam} `]']
     *  TypeParam             ::= Id TypeParamClauseOpt TypeBounds {<% Type} {":" Type}
     *  }}}
     */
    def typeParamClauseOpt(owner: Name, contextBoundBuf: ListBuffer[Tree]): List[TypeDef] = {
      def typeParam(ms: Modifiers): TypeDef = {
        var mods = ms | Flags.PARAM
        val start = in.offset
        if (owner.isTypeName && isIdent) {
          if (in.name == raw.PLUS) {
            in.nextToken()
            mods |= Flags.COVARIANT
          } else if (in.name == raw.MINUS) {
            in.nextToken()
            mods |= Flags.CONTRAVARIANT
          }
        }
        val nameOffset = in.offset
        // TODO AM: freshName(o2p(in.skipToken()), "_$$"), will need to update test suite
        val pname: TypeName = wildcardOrIdent().toTypeName
        val param = atPos(start, nameOffset) {
          val tparams = typeParamClauseOpt(pname, null) // @M TODO null --> no higher-order context bounds for now
          TypeDef(mods, pname, tparams, typeBounds())
        }
        if (contextBoundBuf ne null) {
          while (in.token == VIEWBOUND) {
            contextBoundBuf += atPos(in.skipToken()) {
              makeFunctionTypeTree(List(Ident(pname)), typ())
            }
          }
          while (in.token == COLON) {
            contextBoundBuf += atPos(in.skipToken()) {
              AppliedTypeTree(typ(), List(Ident(pname)))
            }
          }
        }
        param
      }
      newLineOptWhenFollowedBy(LBRACKET)
      if (in.token == LBRACKET) inBrackets(commaSeparated(typeParam(NoMods withAnnotations annotations(true))))
      else Nil
    }

    /** {{{
     *  TypeBounds ::= [`>:' Type] [`<:' Type]
     *  }}}
     */
    def typeBounds(): TypeBoundsTree = {
      val t = TypeBoundsTree(
        bound(SUPERTYPE, tpnme.Nothing),
        bound(SUBTYPE, tpnme.Any)
      )
      t setPos wrappingPos(List(t.hi, t.lo))
    }

    def bound(tok: Int, default: TypeName): Tree =
      if (in.token == tok) { in.nextToken(); typ() }
      else atPos(o2p(in.lastOffset)) { rootScalaDot(default) }

/* -------- DEFS ------------------------------------------- */


    /** {{{
     *  Import  ::= import ImportExpr {`,' ImportExpr}
     *  }}}
     */
    def importClause(): List[Tree] = {
      val offset = accept(IMPORT)
      commaSeparated(importExpr()) match {
        case Nil => Nil
        case t :: rest =>
          // The first import should start at the position of the keyword.
          t.setPos(t.pos.withStart(offset))
          t :: rest
      }
    }

    /** {{{
     *  ImportExpr ::= StableId `.' (Id | `_' | ImportSelectors)
     *  }}}
     */
    def importExpr(): Tree = {
      val start = in.offset
      def thisDotted(name: TypeName) = {
        in.nextToken()
        val t = atPos(start)(This(name))
        accept(DOT)
        val result = selector(t)
        accept(DOT)
        result
      }
      /** Walks down import `foo.bar.baz.{ ... }` until it ends at a
       *  an underscore, a left brace, or an undotted identifier.
       */
      def loop(expr: Tree): Tree = {
        expr setPos expr.pos.makeTransparent
        val selectors: List[ImportSelector] = in.token match {
          case USCORE   => List(importSelector()) // import foo.bar._;
          case LBRACE   => importSelectors()      // import foo.bar.{ x, y, z }
          case _        =>
            val nameOffset = in.offset
            val name = ident()
            if (in.token == DOT) {
              // import foo.bar.ident.<unknown> and so create a select node and recurse.
              val t = atPos(start, if (name == nme.ERROR) in.offset else nameOffset)(Select(expr, name))
              in.nextToken()
              return loop(t)
            }
            // import foo.bar.Baz;
            else List(makeImportSelector(name, nameOffset))
        }
        // reaching here means we're done walking.
        atPos(start)(Import(expr, selectors))
      }

      loop(in.token match {
        case THIS   => thisDotted(tpnme.EMPTY)
        case _      =>
          val id = atPos(start)(Ident(ident()))
          accept(DOT)
          if (in.token == THIS) thisDotted(id.name.toTypeName)
          else id
      })
    }

    /** {{{
     *  ImportSelectors ::= `{' {ImportSelector `,'} (ImportSelector | `_') `}'
     *  }}}
     */
    def importSelectors(): List[ImportSelector] = {
      val selectors = inBracesOrNil(commaSeparated(importSelector()))
      selectors.init foreach {
        case ImportSelector(nme.WILDCARD, pos, _, _)  => syntaxError(pos, "Wildcard import must be in last position")
        case _                                        => ()
      }
      selectors
    }

    def wildcardOrIdent() = {
      if (in.token == USCORE) { in.nextToken() ; nme.WILDCARD }
      else ident()
    }

    /** {{{
     *  ImportSelector ::= Id [`=>' Id | `=>' `_']
     *  }}}
     */
    def importSelector(): ImportSelector = {
      val start        = in.offset
      val name         = wildcardOrIdent()
      var renameOffset = -1
      val rename       = in.token match {
        case ARROW    =>
          in.nextToken()
          renameOffset = in.offset
          wildcardOrIdent()
        case _ if name == nme.WILDCARD  => null
        case _ =>
          renameOffset = start
          name
      }
      ImportSelector(name, start, rename, renameOffset)
    }

    /** {{{
     *  Def    ::= val PatDef
     *           | var PatDef
     *           | def FunDef
     *           | type [nl] TypeDef
     *           | TmplDef
     *  Dcl    ::= val PatDcl
     *           | var PatDcl
     *           | def FunDcl
     *           | type [nl] TypeDcl
     *  }}}
     */
    def defOrDcl(pos: Int, mods: Modifiers): List[Tree] = {
      if (mods.isLazy && in.token != VAL)
        syntaxError("lazy not allowed here. Only vals can be lazy", false)
      in.token match {
        case VAL =>
          patDefOrDcl(pos, mods withPosition(VAL, tokenRange(in)))
        case VAR =>
          patDefOrDcl(pos, (mods | Flags.MUTABLE) withPosition (VAR, tokenRange(in)))
        case DEF =>
          List(funDefOrDcl(pos, mods withPosition(DEF, tokenRange(in))))
        case TYPE =>
          List(typeDefOrDcl(pos, mods withPosition(TYPE, tokenRange(in))))
        case _ =>
          List(tmplDef(pos, mods))
      }
    }

    private def caseAwareTokenOffset = if (in.token == CASECLASS || in.token == CASEOBJECT) in.prev.offset else in.offset

    def nonLocalDefOrDcl : List[Tree] = {
      val annots = annotations(true)
      defOrDcl(caseAwareTokenOffset, modifiers() withAnnotations annots)
    }

    /** {{{
     *  PatDef ::= Pattern2 {`,' Pattern2} [`:' Type] `=' Expr
     *  ValDcl ::= Id {`,' Id} `:' Type
     *  VarDef ::= PatDef | Id {`,' Id} `:' Type `=' `_'
     *  }}}
     */
    def patDefOrDcl(pos : Int, mods: Modifiers): List[Tree] = {
      var newmods = mods
      in.nextToken()
      val lhs = commaSeparated(stripParens(noSeq.pattern2()))
      val tp = typedOpt()
      val rhs =
        if (tp.isEmpty || in.token == EQUALS) {
          accept(EQUALS)
          if (!tp.isEmpty && newmods.isMutable &&
              (lhs.toList forall (_.isInstanceOf[Ident])) && in.token == USCORE) {
            in.nextToken()
            newmods = newmods | Flags.DEFAULTINIT
            EmptyTree
          } else {
            expr()
          }
        } else {
          newmods = newmods | Flags.DEFERRED
          EmptyTree
        }
      def mkDefs(p: Tree, tp: Tree, rhs: Tree): List[Tree] = {
        //Console.println("DEBUG: p = "+p.toString()); // DEBUG
        val trees =
          makePatDef(newmods,
                     if (tp.isEmpty) p
                     else Typed(p, tp) setPos (p.pos union tp.pos),
                     rhs)
        if (newmods.isDeferred) {
          trees match {
            case List(ValDef(_, _, _, EmptyTree)) =>
              if (mods.isLazy) syntaxError(p.pos, "lazy values may not be abstract", false)
            case _ => syntaxError(p.pos, "pattern definition may not be abstract", false)
          }
        }
        trees
      }
      val trees = (lhs.toList.init flatMap (mkDefs(_, tp.duplicate, rhs.duplicate))) ::: mkDefs(lhs.last, tp, rhs)
      val hd = trees.head
      hd setPos hd.pos.withStart(pos)
      ensureNonOverlapping(hd, trees.tail)
      trees
    }

    /** {{{
     *  VarDef ::= PatDef
     *           | Id {`,' Id} `:' Type `=' `_'
     *  VarDcl ::= Id {`,' Id} `:' Type
     *  }}}
    def varDefOrDcl(mods: Modifiers): List[Tree] = {
      var newmods = mods | Flags.MUTABLE
      val lhs = new ListBuffer[(Int, Name)]
      do {
        in.nextToken()
        lhs += (in.offset, ident())
      } while (in.token == COMMA)
      val tp = typedOpt()
      val rhs = if (tp.isEmpty || in.token == EQUALS) {
        accept(EQUALS)
        if (!tp.isEmpty && in.token == USCORE) {
          in.nextToken()
          EmptyTree
        } else {
          expr()
        }
      } else {
        newmods = newmods | Flags.DEFERRED
        EmptyTree
      }
    }
     */

    /** {{{
     *  FunDef ::= FunSig `:' Type `=' Expr
     *           | FunSig [nl] `{' Block `}'
     *           | this ParamClause ParamClauses (`=' ConstrExpr | [nl] ConstrBlock)
     *           | `macro' FunSig [`:' Type] `=' Expr
     *  FunDcl ::= FunSig [`:' Type]
     *  FunSig ::= id [FunTypeParamClause] ParamClauses
     *  }}}
     */
    def funDefOrDcl(start : Int, mods: Modifiers): Tree = {
      in.nextToken
      if (in.token == THIS) {
        atPos(start, in.skipToken()) {
          val vparamss = paramClauses(nme.CONSTRUCTOR, classContextBounds map (_.duplicate), false)
          newLineOptWhenFollowedBy(LBRACE)
          val rhs = in.token match {
            case LBRACE   => atPos(in.offset) { constrBlock(vparamss) }
            case _        => accept(EQUALS) ; atPos(in.offset) { constrExpr(vparamss) }
          }
          DefDef(mods, nme.CONSTRUCTOR, List(), vparamss, TypeTree(), rhs)
        }
      }
      else {
        val nameOffset = in.offset
        val name = ident()
        if (name == nme.macro_ && isIdent && settings.Xmacros.value)
          funDefRest(start, in.offset, mods | Flags.MACRO, ident())
        else
          funDefRest(start, nameOffset, mods, name)
      }
    }

    def funDefRest(start: Int, nameOffset: Int, mods: Modifiers, name: Name): Tree = {
      val result = atPos(start, if (name.toTermName == nme.ERROR) start else nameOffset) {
        val isMacro = mods hasFlag Flags.MACRO
        val isTypeMacro = isMacro && name.isTypeName
        var newmods = mods
        // contextBoundBuf is for context bounded type parameters of the form
        // [T : B] or [T : => B]; it contains the equivalent implicit parameter type,
        // i.e. (B[T] or T => B)
        val contextBoundBuf = new ListBuffer[Tree]
        val tparams = typeParamClauseOpt(name, contextBoundBuf)
        val vparamss = paramClauses(name, contextBoundBuf.toList, false)
        if (!isMacro) newLineOptWhenFollowedBy(LBRACE)
        var restype = if (isTypeMacro) TypeTree() else fromWithinReturnType(typedOpt())
        val rhs =
          if (isMacro)
            equalsExpr()
          else if (isStatSep || in.token == RBRACE) {
            if (restype.isEmpty) restype = scalaUnitConstr
            newmods |= Flags.DEFERRED
            EmptyTree
          } else if (restype.isEmpty && in.token == LBRACE) {
            restype = scalaUnitConstr
            blockExpr()
          } else {
            if (name == nme.macro_ && isIdent && in.token != EQUALS) {
              warning("this syntactically invalid code resembles a macro definition. have you forgotten to enable -Xmacros?")
            }
            equalsExpr()
          }
        DefDef(newmods, name, tparams, vparamss, restype, rhs)
      }
      signalParseProgress(result.pos)
      result
    }

    /** {{{
     *  ConstrExpr      ::=  SelfInvocation
     *                    |  ConstrBlock
     *  }}}
     */
    def constrExpr(vparamss: List[List[ValDef]]): Tree =
      if (in.token == LBRACE) constrBlock(vparamss)
      else Block(List(selfInvocation(vparamss)), Literal(Constant()))

    /** {{{
     *  SelfInvocation  ::= this ArgumentExprs {ArgumentExprs}
     *  }}}
     */
    def selfInvocation(vparamss: List[List[ValDef]]): Tree =
      atPos(accept(THIS)) {
        newLineOptWhenFollowedBy(LBRACE)
        var t = Apply(Ident(nme.CONSTRUCTOR), argumentExprs())
        newLineOptWhenFollowedBy(LBRACE)
        while (in.token == LPAREN || in.token == LBRACE) {
          t = Apply(t, argumentExprs())
          newLineOptWhenFollowedBy(LBRACE)
        }
        if (classContextBounds.isEmpty) t
        else Apply(t, vparamss.last.map(vp => Ident(vp.name)))
      }

    /** {{{
     *  ConstrBlock    ::=  `{' SelfInvocation {semi BlockStat} `}'
     *  }}}
     */
    def constrBlock(vparamss: List[List[ValDef]]): Tree =
      atPos(in.skipToken()) {
        val stats = selfInvocation(vparamss) :: {
          if (isStatSep) { in.nextToken(); blockStatSeq() }
          else Nil
        }
        accept(RBRACE)
        Block(stats, Literal(Constant()))
      }

    /** {{{
     *  TypeDef ::= type Id [TypeParamClause] `=' Type
     *            | `macro' FunSig `=' Expr
     *  TypeDcl ::= type Id [TypeParamClause] TypeBounds
     *  }}}
     */
    def typeDefOrDcl(start: Int, mods: Modifiers): Tree = {
      in.nextToken()
      newLinesOpt()
      atPos(start, in.offset) {
        val name = identForType()
        if (name == nme.macro_.toTypeName && isIdent && settings.Xmacros.value) {
          funDefRest(start, in.offset, mods | Flags.MACRO, identForType())
        } else {
          // @M! a type alias as well as an abstract type may declare type parameters
          val tparams = typeParamClauseOpt(name, null)
          in.token match {
            case EQUALS =>
              in.nextToken()
              TypeDef(mods, name, tparams, typ())
            case SUPERTYPE | SUBTYPE | SEMI | NEWLINE | NEWLINES | COMMA | RBRACE =>
              TypeDef(mods | Flags.DEFERRED, name, tparams, typeBounds())
            case _ =>
              syntaxErrorOrIncomplete("`=', `>:', or `<:' expected", true)
              EmptyTree
          }
        }
      }
    }

    /** Hook for IDE, for top-level classes/objects. */
    def topLevelTmplDef: Tree = {
      val annots = annotations(true)
      val pos    = caseAwareTokenOffset
      val mods   = modifiers() withAnnotations annots
      tmplDef(pos, mods)
    }

    /** {{{
     *  TmplDef ::= [case] class ClassDef
     *            |  [case] object ObjectDef
     *            |  [override] trait TraitDef
     *  }}}
     */
    def tmplDef(pos: Int, mods: Modifiers): Tree = {
      if (mods.isLazy) syntaxError("classes cannot be lazy", false)
      in.token match {
        case TRAIT =>
          classDef(pos, (mods | Flags.TRAIT | Flags.ABSTRACT) withPosition (Flags.TRAIT, tokenRange(in)))
        case CLASS =>
          classDef(pos, mods)
        case CASECLASS =>
          classDef(pos, (mods | Flags.CASE) withPosition (Flags.CASE, tokenRange(in.prev /*scanner skips on 'case' to 'class', thus take prev*/)))
        case OBJECT =>
          objectDef(pos, mods)
        case CASEOBJECT =>
          objectDef(pos, (mods | Flags.CASE) withPosition (Flags.CASE, tokenRange(in.prev /*scanner skips on 'case' to 'object', thus take prev*/)))
        case _ =>
          syntaxErrorOrIncomplete("expected start of definition", true)
          EmptyTree
      }
    }

    /** {{{
     *  ClassDef ::= Id [TypeParamClause] {Annotation}
     *               [AccessModifier] ClassParamClauses RequiresTypeOpt ClassTemplateOpt
     *  TraitDef ::= Id [TypeParamClause] RequiresTypeOpt TraitTemplateOpt
     *  }}}
     */
    def classDef(start: Int, mods: Modifiers): ClassDef = {
      in.nextToken
      val nameOffset = in.offset
      val name = identForType()
      def isTrait = mods.hasTraitFlag

      atPos(start, if (name == tpnme.ERROR) start else nameOffset) {
        savingClassContextBounds {
          val contextBoundBuf = new ListBuffer[Tree]
          val tparams = typeParamClauseOpt(name, contextBoundBuf)
          classContextBounds = contextBoundBuf.toList
          val tstart = in.offset :: classContextBounds.map(_.pos.startOrPoint) min;
          if (!classContextBounds.isEmpty && isTrait) {
            syntaxError("traits cannot have type parameters with context bounds `: ...' nor view bounds `<% ...'", false)
            classContextBounds = List()
          }
          val constrAnnots = constructorAnnotations()
          val (constrMods, vparamss) =
            if (isTrait) (Modifiers(Flags.TRAIT), List())
            else (accessModifierOpt(), paramClauses(name, classContextBounds, mods.isCase))
          var mods1 = mods
          if (isTrait) {
            if (settings.YvirtClasses && in.token == SUBTYPE) mods1 |= Flags.DEFERRED
          } else if (in.token == SUBTYPE) {
            syntaxError("classes are not allowed to be virtual", false)
          }
          val template = templateOpt(mods1, name, constrMods withAnnotations constrAnnots, vparamss, tstart)
          if (isInterface(mods1, template.body)) mods1 |= Flags.INTERFACE
          val result = ClassDef(mods1, name, tparams, template)
          // Context bounds generate implicit parameters (part of the template) with types
          // from tparams: we need to ensure these don't overlap
          if (!classContextBounds.isEmpty)
            ensureNonOverlapping(template, tparams)
          result
        }
      }
    }

    /** {{{
     *  ObjectDef       ::= Id ClassTemplateOpt
     *  }}}
     */
    def objectDef(start: Int, mods: Modifiers): ModuleDef = {
      in.nextToken
      val nameOffset = in.offset
      val name = ident()
      val tstart = in.offset
      atPos(start, if (name == nme.ERROR) start else nameOffset) {
        val mods1 = if (in.token == SUBTYPE) mods | Flags.DEFERRED else mods
        val template = templateOpt(mods1, name, NoMods, Nil, tstart)
        ModuleDef(mods1, name, template)
      }
    }

    /** {{{
     *  ClassParents       ::= AnnotType {`(' [Exprs] `)'} {with AnnotType}
     *  TraitParents       ::= AnnotType {with AnnotType}
     *  }}}
     */
    def templateParents(isTrait: Boolean): (List[Tree], List[List[Tree]]) = {
      val parents = new ListBuffer[Tree] += startAnnotType()
      val argss = (
        // TODO: the insertion of List(Nil) here is where "new Foo" becomes
        // indistinguishable from "new Foo()".
        if (in.token == LPAREN && !isTrait) multipleArgumentExprs()
        else List(Nil)
      )

      while (in.token == WITH) {
        in.nextToken()
        parents += startAnnotType()
      }
      (parents.toList, argss)
    }

    /** {{{
     *  ClassTemplate ::= [EarlyDefs with] ClassParents [TemplateBody]
     *  TraitTemplate ::= [EarlyDefs with] TraitParents [TemplateBody]
     *  EarlyDefs     ::= `{' [EarlyDef {semi EarlyDef}] `}'
     *  EarlyDef      ::= Annotations Modifiers PatDef
     *  }}}
     */
    def template(isTrait: Boolean): (List[Tree], List[List[Tree]], ValDef, List[Tree]) = {
      newLineOptWhenFollowedBy(LBRACE)
      if (in.token == LBRACE) {
        // @S: pre template body cannot stub like post body can!
        val (self, body) = templateBody(true)
        if (in.token == WITH && self.isEmpty) {
          val earlyDefs: List[Tree] = body flatMap {
            case vdef @ ValDef(mods, name, tpt, rhs) if !mods.isDeferred =>
              List(treeCopy.ValDef(vdef, mods | Flags.PRESUPER, name, tpt, rhs))
            case tdef @ TypeDef(mods, name, tparams, rhs) =>
              List(treeCopy.TypeDef(tdef, mods | Flags.PRESUPER, name, tparams, rhs))
            case stat if !stat.isEmpty =>
              syntaxError(stat.pos, "only type definitions and concrete field definitions allowed in early object initialization section", false)
              List()
            case _ => List()
          }
          in.nextToken()
          val (parents, argss) = templateParents(isTrait)
          val (self1, body1) = templateBodyOpt(isTrait)
          (parents, argss, self1, earlyDefs ::: body1)
        } else {
          (List(), List(List()), self, body)
        }
      } else {
        val (parents, argss) = templateParents(isTrait)
        val (self, body) = templateBodyOpt(isTrait)
        (parents, argss, self, body)
      }
    }

    def isInterface(mods: Modifiers, body: List[Tree]): Boolean =
      mods.hasTraitFlag && (body forall treeInfo.isInterfaceMember)

    /** {{{
     *  ClassTemplateOpt ::= `extends' ClassTemplate | [[`extends'] TemplateBody]
     *  TraitTemplateOpt ::= TraitExtends TraitTemplate | [[`extends'] TemplateBody] | `<:' TemplateBody
     *  TraitExtends     ::= `extends' | `<:'
     *  }}}
     */
    def templateOpt(mods: Modifiers, name: Name, constrMods: Modifiers, vparamss: List[List[ValDef]], tstart: Int): Template = {
      /** Extra parents for case classes. */
      def caseParents() = (
        if (mods.isCase) {
          val arity = if (vparamss.isEmpty || vparamss.head.isEmpty) 0 else vparamss.head.size
          productConstr :: serializableConstr :: {
            Nil
            // if (arity == 0 || settings.YnoProductN.value) Nil
            // else List(
            //   AppliedTypeTree(
            //     productConstrN(arity),
            //     vparamss.head map (vd => vd.tpt.duplicate setPos vd.tpt.pos.focus)
            //   )
            // )
          }
        }
        else Nil
      )
      val (parents0, argss, self, body) = (
        if (in.token == EXTENDS || in.token == SUBTYPE && mods.hasTraitFlag) {
          in.nextToken()
          template(mods.hasTraitFlag)
        }
        else {
          newLineOptWhenFollowedBy(LBRACE)
          val (self, body) = templateBodyOpt(false)
          (List(), List(List()), self, body)
        }
      )

      val tstart0 = if (body.isEmpty && in.lastOffset < tstart) in.lastOffset else tstart
      atPos(tstart0) {
        if (isAnyValType(name)) {
          val parent = if (name == tpnme.AnyVal) tpnme.Any else tpnme.AnyVal
          Template(List(scalaDot(parent)), self, body)
        }
        else {
          val parents = (
            if (!isInterface(mods, body) && !isScalaArray(name)) parents0 :+ scalaScalaObjectConstr
            else if (parents0.isEmpty) List(scalaAnyRefConstr)
            else parents0
          ) ++ caseParents()
          Template(parents, self, constrMods, vparamss, argss, body, o2p(tstart))
        }
      }
    }

/* -------- TEMPLATES ------------------------------------------- */

    /** {{{
     *  TemplateBody ::= [nl] `{' TemplateStatSeq `}'
     *  }}}
     * @param isPre specifies whether in early initializer (true) or not (false)
     */
    def templateBody(isPre: Boolean) = inBraces(templateStatSeq(isPre)) match {
      case (self, Nil)  => (self, List(EmptyTree))
      case result       => result
    }
    def templateBodyOpt(traitParentSeen: Boolean): (ValDef, List[Tree]) = {
      newLineOptWhenFollowedBy(LBRACE)
      if (in.token == LBRACE) {
        templateBody(false)
      } else {
        if (in.token == LPAREN)
          syntaxError((if (traitParentSeen) "parents of traits" else "traits or objects")+
                      " may not have parameters", true)
        (emptyValDef, List())
      }
    }

    /** {{{
     *  Refinement ::= [nl] `{' RefineStat {semi RefineStat} `}'
     *  }}}
     */
    def refinement(): List[Tree] = inBraces(refineStatSeq())

/* -------- STATSEQS ------------------------------------------- */

  /** Create a tree representing a packaging. */
    def makePackaging(start: Int, pkg: Tree, stats: List[Tree]): PackageDef = pkg match {
      case x: RefTree => atPos(start, pkg.pos.point)(PackageDef(x, stats))
    }
/*
        pkg match {
          case id @ Ident(_) =>
            PackageDef(id, stats)
          case Select(qual, name) => // drop this to flatten packages
            makePackaging(start, qual, List(PackageDef(Ident(name), stats)))
        }
      }
*/

    /** Create a tree representing a package object, converting
     *  {{{
     *    package object foo { ... }
     *  }}}
     *  to
     *  {{{
     *    package foo {
     *      object `package` { ... }
     *    }
     *  }}}
     */
    def makePackageObject(start: Int, objDef: ModuleDef): PackageDef = objDef match {
      case ModuleDef(mods, name, impl) =>
        makePackaging(
          start, atPos(o2p(objDef.pos.startOrPoint)){ Ident(name) }, List(ModuleDef(mods, nme.PACKAGEkw, impl)))
    }

    /** {{{
     *  Packaging ::= package QualId [nl] `{' TopStatSeq `}'
     *  }}}
     */
    def packaging(start: Int): Tree = {
      val pkg = pkgQualId()
      val stats = inBracesOrNil(topStatSeq())
      makePackaging(start, pkg, stats)
    }

    /** {{{
     *  TopStatSeq ::= TopStat {semi TopStat}
     *  TopStat ::= Annotations Modifiers TmplDef
     *            | Packaging
     *            | package object objectDef
     *            | Import
     *            |
     *  }}}
     */
    def topStatSeq(): List[Tree] = {
      val stats = new ListBuffer[Tree]
      while (!isStatSeqEnd) {
        stats ++= (in.token match {
          case PACKAGE  =>
            val start = in.skipToken()
            if (in.token == OBJECT)
              joinComment(List(makePackageObject(start, objectDef(in.offset, NoMods))))
            else {
              in.flushDoc
              List(packaging(start))
            }
          case IMPORT =>
            in.flushDoc
            importClause()
          case x if x == AT || isTemplateIntro || isModifier =>
            joinComment(List(topLevelTmplDef))
          case _ =>
            if (!isStatSep)
              syntaxErrorOrIncomplete("expected class or object definition", true)
            Nil
        })
        acceptStatSepOpt()
      }
      stats.toList
    }

    /** {{{
     *  TemplateStatSeq  ::= [id [`:' Type] `=>'] TemplateStat {semi TemplateStat}
     *  TemplateStat     ::= Import
     *                     | Annotations Modifiers Def
     *                     | Annotations Modifiers Dcl
     *                     | Expr1
     *                     | super ArgumentExprs {ArgumentExprs}
     *                     |
     *  }}}
     * @param isPre specifies whether in early initializer (true) or not (false)
     */
    def templateStatSeq(isPre : Boolean): (ValDef, List[Tree]) = checkNoEscapingPlaceholders {
      var self: ValDef = emptyValDef
      val stats = new ListBuffer[Tree]
      if (isExprIntro) {
        in.flushDoc
        val first = expr(InTemplate) // @S: first statement is potentially converted so cannot be stubbed.
        if (in.token == ARROW) {
          first match {
            case Typed(tree @ This(tpnme.EMPTY), tpt) =>
              self = atPos(tree.pos union tpt.pos) { makeSelfDef(nme.WILDCARD, tpt) }
            case _ =>
              convertToParam(first) match {
                case tree @ ValDef(_, name, tpt, EmptyTree) if (name != nme.ERROR) =>
                  self = atPos(tree.pos union tpt.pos) { makeSelfDef(name, tpt) }
                case _ =>
              }
          }
          in.nextToken()
        } else {
          stats += first
          acceptStatSepOpt()
        }
      }
      while (!isStatSeqEnd) {
        if (in.token == IMPORT) {
          in.flushDoc
          stats ++= importClause()
        } else if (isExprIntro) {
          in.flushDoc
          stats += statement(InTemplate)
        } else if (isDefIntro || isModifier || in.token == AT) {
          stats ++= joinComment(nonLocalDefOrDcl)
        } else if (!isStatSep) {
          syntaxErrorOrIncomplete("illegal start of definition", true)
        }
        acceptStatSepOpt()
      }
      (self, stats.toList)
    }

    /** {{{
     *  RefineStatSeq    ::= RefineStat {semi RefineStat}
     *  RefineStat       ::= Dcl
     *                     | type TypeDef
     *                     |
     *  }}}
     */
    def refineStatSeq(): List[Tree] = checkNoEscapingPlaceholders {
      val stats = new ListBuffer[Tree]
      while (!isStatSeqEnd) {
        if (isDclIntro) { // don't IDE hook
          stats ++= joinComment(defOrDcl(in.offset, NoMods))
        } else if (!isStatSep) {
          syntaxErrorOrIncomplete(
            "illegal start of declaration"+
            (if (inFunReturnType) " (possible cause: missing `=' in front of current method body)"
             else ""), true)
        }
        if (in.token != RBRACE) acceptStatSep()
      }
      stats.toList
    }

    /** overridable IDE hook for local definitions of blockStatSeq
     *  Here's an idea how to fill in start and end positions.
    def localDef : List[Tree] = {
      atEndPos {
        atStartPos(in.offset) {
          val annots = annotations(true)
          val mods = localModifiers() withAnnotations annots
          if (!(mods hasFlag ~(Flags.IMPLICIT | Flags.LAZY))) defOrDcl(mods)
          else List(tmplDef(mods))
        }
      } (in.offset)
    }
    */

    def localDef(implicitMod: Int): List[Tree] = {
      val annots = annotations(true)
      val pos = in.offset
      val mods = (localModifiers() | implicitMod) withAnnotations annots
      val defs =
        if (!(mods hasFlag ~(Flags.IMPLICIT | Flags.LAZY))) defOrDcl(pos, mods)
        else List(tmplDef(pos, mods))

      in.token match {
        case RBRACE | CASE  => defs :+ (Literal(Constant()) setPos o2p(in.offset))
        case _              => defs
      }
    }

    /** {{{
     *  BlockStatSeq ::= { BlockStat semi } [ResultExpr]
     *  BlockStat    ::= Import
     *                 | Annotations [implicit] [lazy] Def
     *                 | Annotations LocalModifiers TmplDef
     *                 | Expr1
     *                 |
     *  }}}
     */
    def blockStatSeq(): List[Tree] = checkNoEscapingPlaceholders {
      val stats = new ListBuffer[Tree]
      while (!isStatSeqEnd && in.token != CASE) {
        if (in.token == IMPORT) {
          stats ++= importClause()
          acceptStatSep()
        }
        else if (isExprIntro) {
          stats += statement(InBlock)
          if (in.token != RBRACE && in.token != CASE) acceptStatSep()
        }
        else if (isDefIntro || isLocalModifier || in.token == AT) {
          if (in.token == IMPLICIT) {
            val start = in.skipToken()
            if (isIdent) stats += implicitClosure(start, InBlock)
            else stats ++= localDef(Flags.IMPLICIT)
          } else {
            stats ++= localDef(0)
          }
          acceptStatSepOpt()
        }
        else if (isStatSep) {
          in.nextToken()
        }
        else {
          val addendum = if (isModifier) " (no modifiers allowed here)" else ""
          syntaxErrorOrIncomplete("illegal start of statement" + addendum, true)
        }
      }
      stats.toList
    }

    /** {{{
     *  CompilationUnit ::= {package QualId semi} TopStatSeq
     *  }}}
     */
    def compilationUnit(): Tree = checkNoEscapingPlaceholders {
      def topstats(): List[Tree] = {
        val ts = new ListBuffer[Tree]
        while (in.token == SEMI) in.nextToken()
        val start = in.offset
        if (in.token == PACKAGE) {
          in.nextToken()
          if (in.token == OBJECT) {
            ts ++= joinComment(List(makePackageObject(start, objectDef(in.offset, NoMods))))
            if (in.token != EOF) {
              acceptStatSep()
              ts ++= topStatSeq()
            }
          } else {
            in.flushDoc
            val pkg = pkgQualId()
            if (in.token == EOF) {
              ts += makePackaging(start, pkg, List())
            } else if (isStatSep) {
              in.nextToken()
              ts += makePackaging(start, pkg, topstats())
            } else {
              ts += inBraces(makePackaging(start, pkg, topStatSeq()))
              acceptStatSepOpt()
              ts ++= topStatSeq()
            }
          }
        } else {
          ts ++= topStatSeq()
        }
        ts.toList
      }

      resetPackage()
      topstats() match {
        case List(stat @ PackageDef(_, _)) => stat
        case stats =>
          val start =
            if (stats forall (_ == EmptyTree)) 0
            else {
              val wpos = wrappingPos(stats)
              if (wpos.isDefined) wpos.startOrPoint
              else 0
            }

          makePackaging(start, atPos(start, start, start) { Ident(nme.EMPTY_PACKAGE_NAME) }, stats)
      }
    }
  }
}